GroupDIY

Project Specific Discussions => Microphones => Topic started by: ioaudio on October 12, 2010, 08:01:21 PM

Title: MK47 PCB tube mic kit - build thread
Post by: ioaudio on October 12, 2010, 08:01:21 PM
Availability and pricing see my WM thread : http://www.groupdiy.com/index.php?topic=35667.0

also check chunger's build, super nice & detailed: http://www.groupdiy.com/index.php?topic=47112.0

(http://dl.dropbox.com/u/35386715/MK47%20Kit%20assembled.jpg)

Schematic:

(https://dl.dropboxusercontent.com/u/35386715/MK47%20Schematic.jpg)

PSU Schematic:

(https://dl.dropboxusercontent.com/u/35386715/MK47%20PSU%20schematic.JPG)

Kit:

(https://dl.dropboxusercontent.com/u/35386715/MK47%20Kit.jpg)



break away the rounded pcb part, use file for edges
(https://dl.dropboxusercontent.com/u/35386715/MK47%20assembly/1.jpg)
solder all transformer pins
(https://dl.dropboxusercontent.com/u/35386715/MK47%20assembly/2.jpg)
100K Resistor
(https://dl.dropboxusercontent.com/u/35386715/MK47%20assembly/3.jpg)

(https://dl.dropboxusercontent.com/u/35386715/MK47%20assembly/4.jpg)
30K Resistor
(https://dl.dropboxusercontent.com/u/35386715/MK47%20assembly/5.jpg)

(https://dl.dropboxusercontent.com/u/35386715/MK47%20assembly/6.jpg)

(https://dl.dropboxusercontent.com/u/35386715/MK47%20assembly/7.jpg)
dont forget to trim the ends of the transformer pins
(https://dl.dropboxusercontent.com/u/35386715/MK47%20assembly/8.jpg)
Diode
(https://dl.dropboxusercontent.com/u/35386715/MK47%20assembly/9.jpg)
bend for upright position
(https://dl.dropboxusercontent.com/u/35386715/MK47%20assembly/10.jpg)
check orientation - just like this
(https://dl.dropboxusercontent.com/u/35386715/MK47%20assembly/11.jpg)

(https://dl.dropboxusercontent.com/u/35386715/MK47%20assembly/13.jpg)
1µF 160V
(https://dl.dropboxusercontent.com/u/35386715/MK47%20assembly/14.jpg)
goes to this side
(https://dl.dropboxusercontent.com/u/35386715/MK47%20assembly/15.jpg)

(https://dl.dropboxusercontent.com/u/35386715/MK47%20assembly/16.jpg)

(https://dl.dropboxusercontent.com/u/35386715/MK47%20assembly/17.jpg)

(https://dl.dropboxusercontent.com/u/35386715/MK47%20assembly/18.jpg)
27R Resistor
(https://dl.dropboxusercontent.com/u/35386715/MK47%20assembly/19.jpg)

(https://dl.dropboxusercontent.com/u/35386715/MK47%20assembly/20.jpg)
be careful not tuse too much solder here
(https://dl.dropboxusercontent.com/u/35386715/MK47%20assembly/21.jpg)
3Mohm
(https://dl.dropboxusercontent.com/u/35386715/MK47%20assembly/22.jpg)

(https://dl.dropboxusercontent.com/u/35386715/MK47%20assembly/23.jpg)

(https://dl.dropboxusercontent.com/u/35386715/MK47%20assembly/24.jpg)
2Mohm
(https://dl.dropboxusercontent.com/u/35386715/MK47%20assembly/25.jpg)

(https://dl.dropboxusercontent.com/u/35386715/MK47%20assembly/26.jpg)

(https://dl.dropboxusercontent.com/u/35386715/MK47%20assembly/27.jpg)
trim wires flush to pcb
(https://dl.dropboxusercontent.com/u/35386715/MK47%20assembly/30.jpg)
your cutter will not like this but it works
(https://dl.dropboxusercontent.com/u/35386715/MK47%20assembly/31.jpg)
squeeze gently
(https://dl.dropboxusercontent.com/u/35386715/MK47%20assembly/33.jpg)
like this
(https://dl.dropboxusercontent.com/u/35386715/MK47%20assembly/34.jpg)
bend the contacts down a bit
(https://dl.dropboxusercontent.com/u/35386715/MK47%20assembly/35.jpg)
align with silkscreen
(https://dl.dropboxusercontent.com/u/35386715/MK47%20assembly/36.jpg)

(https://dl.dropboxusercontent.com/u/35386715/MK47%20assembly/37.jpg)

(https://dl.dropboxusercontent.com/u/35386715/MK47%20assembly/38.jpg)

(https://dl.dropboxusercontent.com/u/35386715/MK47%20assembly/40.jpg)
use lots of solder - mhm that smells good
(https://dl.dropboxusercontent.com/u/35386715/MK47%20assembly/41.jpg)

(https://dl.dropboxusercontent.com/u/35386715/MK47%20assembly/42.jpg)

(https://dl.dropboxusercontent.com/u/35386715/MK47%20assembly/43.jpg)

(https://dl.dropboxusercontent.com/u/35386715/MK47%20assembly/44.jpg)
the relais
(https://dl.dropboxusercontent.com/u/35386715/MK47%20assembly/45.jpg)
solder two pins while keeping the relais aligned horizontally
(https://dl.dropboxusercontent.com/u/35386715/MK47%20assembly/46.jpg)
use some glue to secure the relais
(https://dl.dropboxusercontent.com/u/35386715/MK47%20assembly/47.jpg)
trim and file the rounded part
(https://dl.dropboxusercontent.com/u/35386715/MK47%20assembly/48.jpg)
bend the sockt´s pins together, gently - UPDATE: insert the tubes before soldering the sockets, twice in and out to relax the contact strength a bit.
(https://dl.dropboxusercontent.com/u/35386715/MK47%20assembly/49.jpg)

(https://dl.dropboxusercontent.com/u/35386715/MK47%20assembly/50.jpg)

(https://dl.dropboxusercontent.com/u/35386715/MK47%20assembly/51.jpg)
check that the socket sits flush before soldering. solder two opposite pins and check orientation again if needed.
(https://dl.dropboxusercontent.com/u/35386715/MK47%20assembly/52.jpg)

(https://dl.dropboxusercontent.com/u/35386715/MK47%20assembly/53.jpg)
fit the small glass isolators with some super glue
(https://dl.dropboxusercontent.com/u/35386715/MK47%20assembly/54.jpg)

(https://dl.dropboxusercontent.com/u/35386715/MK47%20assembly/55.jpg)
try to not let any glue run into the glass tubes
(https://dl.dropboxusercontent.com/u/35386715/MK47%20assembly/56.jpg)
assemble
(https://dl.dropboxusercontent.com/u/35386715/MK47%20assembly/57.jpg)

(https://dl.dropboxusercontent.com/u/35386715/MK47%20assembly/58.jpg)
solder one of the pads
(https://dl.dropboxusercontent.com/u/35386715/MK47%20assembly/59.jpg)

(https://dl.dropboxusercontent.com/u/35386715/MK47%20assembly/60.jpg)
check for proper orientation and angle before soldering the rest of the pads.
(https://dl.dropboxusercontent.com/u/35386715/MK47%20assembly/61.jpg)

(https://dl.dropboxusercontent.com/u/35386715/MK47%20assembly/62.jpg)
all pads must be soldered
(https://dl.dropboxusercontent.com/u/35386715/MK47%20assembly/63.jpg)
cut-offs from resistors
(https://dl.dropboxusercontent.com/u/35386715/MK47%20assembly/64.jpg)
bridge
(https://dl.dropboxusercontent.com/u/35386715/MK47%20assembly/65.jpg)

(https://dl.dropboxusercontent.com/u/35386715/MK47%20assembly/66.jpg)

(https://dl.dropboxusercontent.com/u/35386715/MK47%20assembly/67.jpg)

(https://dl.dropboxusercontent.com/u/35386715/MK47%20assembly/69.jpg)
100Mohm (yeah thats many ohms)
(https://dl.dropboxusercontent.com/u/35386715/MK47%20assembly/70.jpg)
the high impedance part of the circuit is build floating in the air.
(https://dl.dropboxusercontent.com/u/35386715/MK47%20assembly/71.jpg)
the tube
(https://dl.dropboxusercontent.com/u/35386715/MK47%20assembly/73.jpg)
fit the  tubes now
(https://dl.dropboxusercontent.com/u/35386715/MK47%20assembly/74.jpg)
so the grid pin of the socket is straightened out
(https://dl.dropboxusercontent.com/u/35386715/MK47%20assembly/75.jpg)
the other end of the 100Mohm comes here
(https://dl.dropboxusercontent.com/u/35386715/MK47%20assembly/76.jpg)
check that the pin golden pin is centered and does not touch the pcb
(https://dl.dropboxusercontent.com/u/35386715/MK47%20assembly/77.jpg)
take another piece of wire to build the bridge between the two pins
(https://dl.dropboxusercontent.com/u/35386715/MK47%20assembly/78.jpg)

(https://dl.dropboxusercontent.com/u/35386715/MK47%20assembly/79.jpg)

(https://dl.dropboxusercontent.com/u/35386715/MK47%20assembly/80.jpg)
the second 100Mohm resistor
(https://dl.dropboxusercontent.com/u/35386715/MK47%20assembly/81.jpg)

(https://dl.dropboxusercontent.com/u/35386715/MK47%20assembly/82.jpg)
cut the wire short enough before soldering - should not touch the relais
(https://dl.dropboxusercontent.com/u/35386715/MK47%20assembly/83.jpg)

(https://dl.dropboxusercontent.com/u/35386715/MK47%20assembly/84.jpg)
bend the 10Nf like shown
(https://dl.dropboxusercontent.com/u/35386715/MK47%20assembly/85.jpg)
trim and insert
(https://dl.dropboxusercontent.com/u/35386715/MK47%20assembly/86.jpg)

(https://dl.dropboxusercontent.com/u/35386715/MK47%20assembly/87.jpg)

(https://dl.dropboxusercontent.com/u/35386715/MK47%20assembly/89.jpg)
extend the bridge from the two golden socket pins (grid) to the according relais pin
(https://dl.dropboxusercontent.com/u/35386715/MK47%20assembly/90.jpg)

(https://dl.dropboxusercontent.com/u/35386715/MK47%20assembly/91.jpg)
and extend to "front"
(https://dl.dropboxusercontent.com/u/35386715/MK47%20assembly/92.jpg)

(https://dl.dropboxusercontent.com/u/35386715/MK47%20assembly/93.jpg)
bridge the rear
(https://dl.dropboxusercontent.com/u/35386715/MK47%20assembly/94.jpg)

(https://dl.dropboxusercontent.com/u/35386715/MK47%20assembly/95.jpg)
so that it does not touch the cap
(https://dl.dropboxusercontent.com/u/35386715/MK47%20assembly/96.jpg)

(https://dl.dropboxusercontent.com/u/35386715/MK47%20assembly/97.jpg)

(https://dl.dropboxusercontent.com/u/35386715/MK47%20assembly/98.jpg)

(https://dl.dropboxusercontent.com/u/35386715/MK47%20assembly/99.jpg)
the "heater dropper" - it needs to touch the mic housing for heat transfer like the original U47.
(https://dl.dropboxusercontent.com/u/35386715/MK47%20assembly/100.jpg)
it goes here BUT DO NOT SOLDER IT NOW
(https://dl.dropboxusercontent.com/u/35386715/MK47%20assembly/103.jpg)


An example for mounting the Kit and providing the required heat transfer (t-bone sct700 shown)

(https://dl.dropboxusercontent.com/u/35386715/MK47%20assembly/m1.jpg)

(https://dl.dropboxusercontent.com/u/35386715/MK47%20assembly/m3.jpg)

(https://dl.dropboxusercontent.com/u/35386715/MK47%20assembly/m4.jpg)

(https://dl.dropboxusercontent.com/u/35386715/MK47%20assembly/m5.jpg)

(https://dl.dropboxusercontent.com/u/35386715/MK47%20assembly/m6.jpg)

(https://dl.dropboxusercontent.com/u/35386715/MK47%20assembly/m7.jpg)

(https://dl.dropboxusercontent.com/u/35386715/MK47%20assembly/m8.jpg)

(https://dl.dropboxusercontent.com/u/35386715/MK47%20assembly/m9.jpg)

(https://dl.dropboxusercontent.com/u/35386715/MK47%20assembly/m10.jpg)

(https://dl.dropboxusercontent.com/u/35386715/MK47%20assembly/m11.jpg)

(https://dl.dropboxusercontent.com/u/35386715/MK47%20assembly/m12.jpg)

(https://dl.dropboxusercontent.com/u/35386715/MK47%20assembly/m13.jpg)

(https://dl.dropboxusercontent.com/u/35386715/MK47%20assembly/m14.jpg)

(https://dl.dropboxusercontent.com/u/35386715/MK47%20assembly/m15.jpg)

(https://dl.dropboxusercontent.com/u/35386715/MK47%20assembly/m16.jpg)

(https://dl.dropboxusercontent.com/u/35386715/MK47%20assembly/m17.jpg)

(https://dl.dropboxusercontent.com/u/35386715/MK47%20assembly/m18.jpg)

(https://dl.dropboxusercontent.com/u/35386715/MK47%20assembly/m19.jpg)

(https://dl.dropboxusercontent.com/u/35386715/MK47%20assembly/m20.jpg)

(https://dl.dropboxusercontent.com/u/35386715/MK47%20assembly/m21.jpg)

(https://dl.dropboxusercontent.com/u/35386715/MK47%20assembly/m22.jpg)

(https://dl.dropboxusercontent.com/u/35386715/MK47%20assembly/m23.jpg)




Title: Re: MK47 assembly - lots of pics
Post by: tommypiper on October 12, 2010, 10:16:58 PM
HOly Cow!  Beautiful.  Excellent photo documentaaaation and illusstratttion....  ugh I can hardly type...  What is this?  What are the two tubes?  That's a CCCP relay?  I thought it was a cap!

Excellent! :o

EDIT: I'll answer my own question: http://www.groupdiy.com/index.php?topic=35667.0

Somehow this project flew completely by me -- I didn't know it existed.  I even looked in the White Market and couldn't find it, until I did a search.

And I see now that IS a CCCP cap -- the silver thing is the relay. ;)
Title: Re: MK47 assembly - lots of pics
Post by: gevermil on October 12, 2010, 10:25:58 PM
6028 tube
Eballs seems to have quite a few up for auction .
Anyone want to go in a a case of 100  ;D
Title: Re: MK47 assembly - lots of pics
Post by: Matthew Jacobs on October 13, 2010, 05:35:52 AM
Dude! Awesome!!!!

While we are at it, is it appropriate to talk about capsules in this thread?

I'm thinking Thiersch M7. Is that what you'd recommend max?

How much are they?

JD
Title: Re: MK47 assembly - lots of pics
Post by: baadc0de on October 13, 2010, 05:50:57 AM
Dude! Awesome!!!!

While we are at it, is it appropriate to talk about capsules in this thread?

I'm thinking Thiersch M7. Is that what you'd recommend max?

How much are they?

JD

+1 That's the next thing on my mind in addition to how the hell to make more money to buy all these DIY goodies! And then how to finish the ones I have in the pipeline...
Title: Re: MK47 assembly - lots of pics
Post by: zayance on October 13, 2010, 06:51:28 AM
Dude! Awesome!!!!

While we are at it, is it appropriate to talk about capsules in this thread?

I'm thinking Thiersch M7. Is that what you'd recommend max?

How much are they?

JD

EXPENSIVE, but as usual quality costs, 349.68EUR, including PP fees, Holder and shipping in Europe, and they had a price break of 10% on the Bluline  , 25% on the redline, at that time, IIRC.
Title: Re: MK47 assembly - lots of pics
Post by: Matthew Jacobs on October 13, 2010, 07:46:37 AM
Thanks Zayance

I was expecting the €300-€500 price tag. Nice to have a more accurate price.

If these are the real deal and the best, then I think the price is not to bad...

Skylar's mic body, MK47 kit, PSU and this capsule, puts this mic in the £1000 price range. That's a 1/5 of the current second hand price for a real U47 right? Not to bad......
Title: Re: MK47 assembly - lots of pics
Post by: pH on October 13, 2010, 12:19:55 PM
Has anyone around here tried Beesneez capsules?  I've tried contacting them on the differences between the K47 variations with no response.
Title: Re: MK47 assembly - lots of pics
Post by: TheGuitarist on October 13, 2010, 09:20:59 PM
Ioaudio can you comment on the sonic differences between the mk7 and this 47?


Regarding the beesneez capsules I'm going to be putting the k7 capsule in my pair. Ben will tell you his capsules win hands down against any other capsule. He says the same about the mics.
Title: Re: MK47 assembly - lots of pics
Post by: mata_haze on October 14, 2010, 03:54:39 PM
I WANT ONE!
I WANT ONE!
I WANT ONE!
I WANT ONE!
I WANT ONE!
 ;D ;D ;D ;D ;D
Title: Re: MK47 assembly - lots of pics
Post by: horvitz on October 15, 2010, 08:19:27 AM
Max, great documentation!! I'm really looking forward to this  ;D

Over in the white market thread, we had been discussing the power supply a bit.  It was rightly noted that that wasn't the place for such a discussion.  Perhaps now is the time to pick it up again since we'll be building soon? 

Need to find suitable transformers - there were some good thoughts on perhaps stringing two back-to-back (thanks Kingston).  Also there are the Hammond transformers, although they are expensive, heavy, and would have a (large) wasted secondary - might make more sense for 110V since it seems to be half the price of the 220V version for some reason.  Don't feel so bad about the waste if it's not so expensive.  But of course I'd still like to find something more appropriate.

Axel made a good point about adding a choke like the original PSU.. Is this worth thinking about?

Curious if anyone has given all this any further thought in the last few weeks.

  Brian
Title: Re: MK47 assembly - lots of pics
Post by: Gus on October 15, 2010, 09:05:06 AM
No one asked how the tubes will age?

I would want to know how the tubes age.  I can understand they can be matched at the beginning but how do they track with time?

One thing I would also match is the filaments voltage drop at a set constant currents so both filaments work about the same if they are wired in series.

This all might not matter much and it might be fun to use mismatched tubes but I am suprised no one asked yet.  This was one of the first things I noted when I read about the use of two separate tubes in ||.

 
Title: Re: MK47 assembly - lots of pics
Post by: hop.sing on October 15, 2010, 10:26:26 AM
I don't think it matters much if the tubes are matched or not. They are paralleled and every mismatch will be averaged. It is not pushpull or something. The filaments do not need a perfect match either, they have quite a large operating range. I guess, as long as the tubes are reasonably quite and within their normal operating range, things will be fine, even with aging.
Tobias
Title: Re: MK47 assembly - lots of pics
Post by: mad.ax on October 15, 2010, 11:48:32 AM
In order to know how the tubes will age, I guess our best bet is to build the thing and see by ourselves...
I tend to believe that the benefits from paralleling should overcome the drawbacks from the tubes aging different (if they do...)

Matching filaments sounds sensible, but I bet that those tubes being military grade and from the same batch, one shouldn't find much difference between samples.

Those tubes being dirt cheap (for now :( ), experimenting with voluntary mismatched ones could indeed be a fun, and affordable, game.

A question to Max: I wonder about the 27 ohms resistor whose value is different from the 29 ohms of the original U47 schematic?
Did you choose 27 in order to bias the tubes a little higher than 1.1V? Or is it because carbon comp being prone to drift, you found out that 27 ohms actually measure more in the 29 ballpark?

Axel
Title: Re: MK47 assembly - lots of pics
Post by: pasarski on October 15, 2010, 07:02:21 PM
Unbelievible tutorial! If someone messes this up he must be a wizard of some sort.

What comes to capsules, I'm very happy with my Thiersch red line SWT7. Beezneez capsules are very interesting also. They have been approved by Klaus Heyne himself to be the best K47 copy out there. I think it was the K7 variation he evaluated.
Title: Re: MK47 assembly - lots of pics
Post by: Sredna on October 19, 2010, 09:23:00 AM
no big problems  putting the kit together , but one thing . fitting the tubes into the new sockets after assembling  most of the kit .
an advice from what i experienced which hopefully may help a little .
put the tubes into the sockets before soldering the sockets to the pcb (take care not to break the solder pins , though.),


A very wise tip indeed, it's hard to get the tubes to fit and even harder to get them out.
If you have a 7-pin tube in your junk box, use that instead of risking the 6028s.
Title: Re: MK47 assembly - lots of pics
Post by: ioaudio on October 19, 2010, 09:45:16 AM
thanks, i added the info to the first post.

Psu - i am currently experimenting with choke / no choke.
The original NG psu was made in two versions - with and without the choke.
Triad 553-C-3X should be nice and cheap.

Aging: we are all getting old  ;) i published the tube type so no prob.

27R - the heater string operates at a slightly higher amperage - around 44mA, tube bias around 1,2V
Title: Re: MK47 assembly - lots of pics
Post by: FerrariT on October 19, 2010, 05:22:59 PM
Maybe someone should put together another Thiersch order ???
Title: Re: MK47 assembly - lots of pics
Post by: Matthew Jacobs on October 19, 2010, 06:02:49 PM
Maybe someone should put together another Thiersch order ???

Oh yeah...
Title: Re: MK47 assembly - lots of pics
Post by: fazeka on October 19, 2010, 07:43:08 PM
Maybe someone should put together another Thiersch order ???

Yeah, I was wondering what kind of price break (similar to Ben's) we could get from Thiersch, en masse...  ???
Title: Re: MK47 assembly - lots of pics
Post by: plumsolly on October 20, 2010, 01:40:20 AM
I think a Thiersch group buy was attempted/discussed a couple of years ago and if I recall correctly the price break was not enough to make it worthwhile.

Best, Ben
Title: Re: MK47 assembly - lots of pics
Post by: nashkato on October 20, 2010, 05:43:11 AM
   http://www.tube-town.net/ttstore/product_info.php/info/p2192_Ringkern-Netztrafo-30VA-Preamp.html (http://www.tube-town.net/ttstore/product_info.php/info/p2192_Ringkern-Netztrafo-30VA-Preamp.html)
Title: Re: MK47 assembly - lots of pics
Post by: pasarski on October 20, 2010, 04:28:54 PM


Yeah, I was wondering what kind of price break (similar to Ben's) we could get from Thiersch, en masse...  ???

I didn't find any info on BeezNeez capsules price break. But if there's a appreciable volume discount how about K7 group buy?
Title: Re: MK47 assembly - lots of pics
Post by: Skylar on October 20, 2010, 04:35:39 PM
how about K7 group buy?

http://www.groupdiy.com/index.php?topic=41451.0
Title: Re: MK47 assembly - lots of pics
Post by: pasarski on October 20, 2010, 05:12:36 PM
how about K7 group buy?

http://www.groupdiy.com/index.php?topic=41451.0

Thanks! I've totally missed this.
Title: Re: MK47 assembly - lots of pics
Post by: Sredna on October 22, 2010, 03:11:39 PM
It's working!   ;D


After initial problems with the 1uF MKT capacitor, it sounds quite nice also with a chinese K47 style
capsule.

The MKT had almost a total short, maybe 160V is underrated? Had some peaks of 120V during the finetunig of the PSU.

The PSU is very simple: 160VAC transformer, CRCRCRCRCR C=68uF R=500R 10W

The resistors are getting to hot to touch but not to melt plastic, the mic is warm and cosy...

So now waiting for a Beesneez capsule, Skylars housing, burning in the tubes, testing, testing, testing....

Thanks Max for this project!

Best,

Anders
Title: Re: MK47 assembly - lots of pics
Post by: ioaudio on October 22, 2010, 05:53:04 PM
The MKT had almost a total short, maybe 160V is underrated? Had some peaks of 120V during the finetunig of the PSU.

oh wow - sorry - i can send a replacement, let me know.
160 vdc should be all right (like the original), just bad luck with the cap.

-max
Title: Re: MK47 assembly - lots of pics
Post by: Sredna on October 23, 2010, 09:28:59 AM
Now continuing with burning in of the tubes.

From the beginning they were quiet with occational pops.
Now, after maybe 6 hours, the pops are still there and are
most frequent at startup time.

Max, what are your experiences with these tubes?
Title: Re: MK47 assembly - lots of pics
Post by: ioaudio on October 23, 2010, 09:56:38 AM
let them burn in for at least 24 hours.
how did you solve the heater-droper *s heat flow to the housing?
which housing is in use? can you give some voltage readings?

-max
Title: Re: MK47 assembly - lots of pics
Post by: Sredna on October 24, 2010, 12:59:38 PM
Burnin, burnin...  ;D
Still some snap, crackle and pops but getting better...

Im currently using a SE Electronics Z3300A housing, it's just temporary in the waiting for Skylar's housing.
The heater dropper was soldered with the legs slightly bent as a bow acting as a spring, it's
not that much pressure applied but the housing gets warm and cosy so it works.

Im also thinking about soldering a clip inside the housing tube or maybe install screw connectors on the
PCB and mount the resistor permanent inside the housing.

My readings:

Supply: 105V +/- 0.2V (Variations of +/- 1Volt over several hours, maybe house power variations?)
Heater : 34.8V (Between heater and dropping resistor)
Cathode: 1.3V (Between 27R resistor and pin2/7)
Plate: 43.6V (Obviously too high)
Capsule: 56.3V (At the voltage divider 2M/3M, cant get readings at the backplate)


The plate voltage is about 10V too high, checked the 100k and 30k resistors, they're ok.
Changed to a fresh set of tubes, getting about the same readings but plate voltage is now 50V!

What are your readings Max?

Best,

Anders



Title: Re: MK47 assembly - lots of pics
Post by: ioaudio on October 24, 2010, 01:53:39 PM
your voltages are ok, including the plate.
do not mount the heater dropper on the transformer*s side.
two solutions: either drill&tap the base and mount the resistor or use some heat conductive glue.
-max

Title: Re: MK47 assembly - lots of pics
Post by: Sredna on October 24, 2010, 02:07:15 PM
Ok, thanks! Then I can stop looking for Ra of VF14 ;)

Heater dropper is not on the transformer side. Why? (resistor is wirewound=inductor?)
 
Title: Re: MK47 assembly - lots of pics
Post by: ioaudio on October 24, 2010, 02:11:24 PM
we do not want to grill the transformer  ;)
Title: Re: MK47 assembly - lots of pics
Post by: Jim50hertz on October 26, 2010, 07:11:57 AM
Burnin, burnin...  ;D
Still some snap, crackle and pops but getting better...


Still burnin' and noisy, or better?  :)
Title: Re: MK47 assembly - lots of pics
Post by: Sredna on October 26, 2010, 08:17:52 AM
Its much better but still some occasional pops now and then.

I also changed tubes and the new ones were considerably quieter
from the start and after a shorter burn time almost pop free.

Am now mounting the PSU in a proper enclosure so burn in is on halt but I feel confident
that out of the 6 pairs of tubes I have, Ill find at least one or two working pairs.
Title: Re: MK47 assembly - lots of pics
Post by: Jim50hertz on October 26, 2010, 08:31:54 AM
Good news Anders.  :)

Seems like it's definitely worth having a stock of these around.  Thanks.

Jim
Title: Re: MK47 assembly - lots of pics
Post by: Jim50hertz on October 29, 2010, 04:22:18 AM

Psu - i am currently experimenting with choke / no choke.
The original NG psu was made in two versions - with and without the choke.
Triad 553-C-3X should be nice and cheap.


Hi max, any conclusions r.e. the choke/no choke experiments? 
Title: Re: MK47 assembly - lots of pics
Post by: ioaudio on October 29, 2010, 08:07:29 AM
yes:
1. the choke helps filtering crap from the mains and is a better solution for "poluted" places.
2. unloaded voltage does'nt rise as high as with the resistor-only circuit.

-max

Title: Re: MK47 assembly - lots of pics
Post by: Jim50hertz on October 29, 2010, 09:36:07 AM
Thanks Max, I will go with that then... Do I simply omit the first two 1K resistors and sub the choke in?

Title: Re: MK47 assembly - lots of pics
Post by: nashkato on November 01, 2010, 10:02:32 AM
the triad inductor series offers different types.
max suggested the 10H , 500DCR , 50mA .
there are 7H / 10H , 240 / 270 DCR , 75 /90 mA inductors , too.

any comments on using another one than the 10H/50mA inductor ?






Title: Re: MK47 assembly - lots of pics
Post by: Sredna on November 01, 2010, 11:41:35 AM
The U47N uses 2 X 8Hy.
Title: Re: MK47 assembly - lots of pics
Post by: ioaudio on November 02, 2010, 08:30:14 AM
I've been meaning to update the assembly instructions but could'nt get to it - i hopefully will get some spare time tonight.
Title: Re: MK47 assembly - lots of pics
Post by: tommypiper on November 02, 2010, 12:18:37 PM
yes:
1. the choke helps filtering crap from the mains and is a better solution for "poluted" places.
2. unloaded voltage does'nt rise as high as with the resistor-only circuit.

-max



Is this referring to a PSU schematic or discussion that exists somewhere?  If so, can you point me to it, please?

Are there any PSU schematics or discussions for this project?  What kind of PS and voltage is needed for the relay?  Etc.
Title: Re: MK47 assembly - lots of pics
Post by: zayance on November 02, 2010, 12:21:45 PM
yes:
1. the choke helps filtering crap from the mains and is a better solution for "poluted" places.
2. unloaded voltage does'nt rise as high as with the resistor-only circuit.

-max



Is this referring to a PSU schematic or discussion that exists somewhere?  If so, can you point me to it, please?

Are there any PSU schematics or discussions for this project?  What kind of PS and voltage is needed for the relay?  Etc.

Speaking in base of this one i think:

http://www.groupdiy.com/index.php?topic=35667.220
Title: Re: MK47 assembly - lots of pics
Post by: ioaudio on November 02, 2010, 03:10:24 PM
I just up-ed the PSU schematics to the first post.
Since the triad choke's are very cost-effective you can use two of them in series.
Title: Re: MK47 assembly - lots of pics
Post by: Skylar on November 03, 2010, 01:04:00 PM
Thanks Max. I'm looking forward to getting mine built here pretty soon.
I will share photos when it's done.


This is also a test post, as I'm getting a database error when I try to post in the White Market.
Title: Re: MK47 assembly - lots of pics
Post by: horvitz on November 03, 2010, 02:20:35 PM
Thanks for the updated drawing.  I'm actually working on my PSU layout right now, too.  A question on the 500R/5W trimmer.  Would something like one of those adjustable wirewound chassis mount things work here?  Like this:

http://www.mouser.com/ProductDetail/Ohmite/D25K500E/?qs=sGAEpiMZZMvNd0dY0KymzrlSPm%2fRXd%252bpQI%252bBTbFMc34%3d (http://www.mouser.com/ProductDetail/Ohmite/D25K500E/?qs=sGAEpiMZZMvNd0dY0KymzrlSPm%2fRXd%252bpQI%252bBTbFMc34%3d)

I'd certainly prefer something pcb mountable, but I'm not seeing anything like that in the 5W+ range.

  Brian

Title: Re: MK47 assembly - lots of pics
Post by: Kingston on November 03, 2010, 02:31:44 PM
Thanks for the updated drawing.  I'm actually working on my PSU layout right now, too.  A question on the 500R/5W trimmer.  Would something like one of those adjustable wirewound chassis mount things work here?  Like this:

http://www.mouser.com/ProductDetail/Ohmite/D25K500E/?qs=sGAEpiMZZMvNd0dY0KymzrlSPm%2fRXd%252bpQI%252bBTbFMc34%3d (http://www.mouser.com/ProductDetail/Ohmite/D25K500E/?qs=sGAEpiMZZMvNd0dY0KymzrlSPm%2fRXd%252bpQI%252bBTbFMc34%3d)

I'd certainly prefer something pcb mountable, but I'm not seeing anything like that in the 5W+ range.

  Brian



smaller, cheaper:

http://fi.mouser.com/ProductDetail/Alpha-Taiwan/VW24F-10-195K-B1K/?qs=sGAEpiMZZMtxdMMi52izynF7ZLtMY%252bzpmAcDgBFEwt4%3d

can be easily modified to be PCB mountable. Not 500ohm, but 1K. It's close enough for this task, and accuracy won't suffer. I've used them for this exact task in the past and they work well.
Title: Re: MK47 assembly - lots of pics
Post by: horvitz on November 03, 2010, 02:41:50 PM
Ahh.  Good idea with the pot, Kingston.  Thanks.
Title: Re: MK47 assembly - lots of pics
Post by: Matthew Jacobs on November 04, 2010, 06:59:38 AM
Talking about PSU... I wanna build mine out of wood...

Any things I got to watch out for? Should I line the interior in metal? to protect against hum, fire, health and safety, etc?

JD
Title: Re: MK47 assembly - lots of pics
Post by: Kingston on November 04, 2010, 07:14:38 AM
Should I line the interior in metal?

Yes.

consider wood a decoration only. You still need a fully enclosed metal case inside for electrical safety, and for shielding electromagnetic and especially radio frequency fields.
Title: Re: MK47 assembly - lots of pics
Post by: Matthew Jacobs on November 04, 2010, 07:31:12 AM
Thanks Kingston  :)
Title: Re: MK47 assembly - lots of pics
Post by: horvitz on November 04, 2010, 09:40:28 AM
As much as I don't like their stuff, Hammond has some wood bracketed metal cases now.. At least from the pictures, they don't look too bad.
Title: Re: MK47 assembly - more pics added
Post by: ioaudio on November 04, 2010, 02:49:16 PM
Pictures for the constuction / heat transfer added.
Title: Re: MK47 assembly - more pics added
Post by: baadc0de on November 04, 2010, 04:44:29 PM
FWIW, UPS and FedEx can have nasty "duty handling fee" surcharges into europe, never had these problems with USPS.
Title: Re: MK47 assembly - more pics added
Post by: Denyle Guitars on November 12, 2010, 10:15:11 AM
Anyone know the min diameter for the mic body?
Title: Re: MK47 assembly - more pics added
Post by: tommypiper on November 12, 2010, 12:49:53 PM
Max, thanks for the PSU schematic.  Can you please explain the test switch, and the pattern switch on that schematic?  How will patterns be selected, and which patterns?  What is the test switch?

Also, I don't understand the two parrallel resistors, 680 and 330.

Finally, the 500R pot?  Is that simply to adjust the 105v?

Thanks.
Title: Re: MK47 assembly - more pics added
Post by: grantlack on November 12, 2010, 12:54:21 PM
FWIW, UPS and FedEx can have nasty "duty handling fee" surcharges into europe, never had these problems with USPS.

not to mention that they're outrageously more expensive (2-3x cost) than usps for international.
Title: Re: MK47 assembly - more pics added
Post by: ioaudio on November 12, 2010, 01:26:17 PM
tommy,

the test switch connects a test-load to check the ballbark - voltage before connecting the mic to the psu.
the 680 330 resistor is either / or - to pre-adjust the voltage depending on your mains transformer's output.
500R is for final adjustments.

Patterns are like on a original U47 - omni and cardioid - switched via relais. The actual pattern switch is located in the PSU.

-max
Title: Re: MK47 assembly - more pics added
Post by: nashkato on November 12, 2010, 01:31:37 PM
Quote
   Anyone know the min diameter for the mic body?

im going to go with 50mm diameter , cause thats what i have got anyway.
i put the assembled pcb in to check if it might fit , and yes , though theres not much of a space left.
Title: Re: MK47 assembly - more pics added
Post by: ioaudio on November 12, 2010, 02:12:53 PM
A 50x1mm (inner dia. 48mm) is the absolute minimum.
Title: Re: MK47 assembly - more pics added
Post by: gurkan75 on November 12, 2010, 03:01:07 PM
Just a little thought. The relay looks a lot like the mercury wetted type, which are supposed to be great, but I keep hearing they need to be mounted vertically to work properly? Its probably fine like that, but could this cause problems, if youd for example use the microphone hanging upside down or other positions..?

Never used one before so me I dont know. Or maybe it is a regular relay and I worry too much!
/Johan
Title: Re: MK47 assembly - more pics added
Post by: ioaudio on November 12, 2010, 06:32:49 PM
No problems with the mounting position.
The relais used specifies 70g shock operation environment.
Title: Re: MK47 assembly - more pics added
Post by: horvitz on November 12, 2010, 07:43:17 PM
Max,

Just finalizing my PSU here.. one quick question.  How close is that 2.3K for the test load to the actual draw?  Is it going to be pretty spot on, or just a ballpark?  2.3K/5W resistors are a little hard to find, so I could settle for 2.2K or so, or put a few in series to make exactly 2.3K.  I'm thinking it's not so terribly important to be exactly dead on there.  Thanks.

  Brian
Title: Re: MK47 assembly - more pics added
Post by: TheGuitarist on November 13, 2010, 02:57:51 PM
So still noone knows the sonic differences between the mk7 and the mk47?

Seems myself and another guy who ask get ignored  :-\

Hopefully when more people finish their build we will know.
Title: Re: MK47 assembly - more pics added
Post by: Sredna on November 13, 2010, 08:57:57 PM
The sonic difference is that the MK47 is more creamy with a cherry on the top.  ;)

Why not build and compare yourself, then youll really know.

Besides the different circuit, the housing and capsule play important roles.

Title: Re: MK47 assembly - more pics added
Post by: TheGuitarist on November 14, 2010, 02:21:03 AM
The sonic difference is that the MK47 is more creamy with a cherry on the top.  ;)

Why not build and compare yourself, then youll really know.

Besides the different circuit, the housing and capsule play important roles.



Sure give me 1000 bucks and I'll let you know.
Title: Re: MK47 assembly - more pics added
Post by: Sredna on November 14, 2010, 06:34:06 AM
First you complained about getting ignored, I answered you and now you want 1000 bucks from me!  ;D
If I give you 1000 bucks what then?  ::)

Sorry, dont want to be a smartass but I think its too early to expect a clear answer to
the sonic differences.

Ive built both circuits and tested with the same housing and capsule (sE Electronics Z3300A, Dale M7)
and my impression was that my MK47 has a bit clearer upper end.
But thats just the first impression, no measurements made.
To be able to say some thing usable for others more testing must be done.

Time will tell....

Peace,

Anders
Title: Re: MK47 assembly - more pics added
Post by: Winetree on November 18, 2010, 05:56:50 PM
Got and built my 2 kits yesterday up to the point of mounting the long white unit to the lower body.
I haven't got the body or the diaphram yet. Is that the end of the assembly wiring instructions?
Questions. How do you wire up the plug and the diaphram and do the wires that go to the glass tubes just end there? Is this info posted somewhere?
Title: Re: MK47 assembly - more pics added
Post by: Sredna on November 18, 2010, 06:25:47 PM
Well, I dont know what You mean with "mounting the long white unit to the lower body"  ;)

If you look at the PCB where the glass tubes are mounted there's some text: "rear", "backplate" and "front"

When you'll get your capsule, you'll connect the front, backplane and rear of the capsule to these
points. Witch part that goes where I wouldn't tell!  ;D
Title: Re: MK47 assembly - more pics added
Post by: neodyms on November 22, 2010, 11:43:12 AM
Quote
Does any one finished the PSU and have some photos ?

is it possible to make a special thread for the psu or get the complete part list?

why the 680 and 330 ohms resistance are in parallel in place of a 200 ohms resitance ?
ares they in parallel and Why ?

and a least why a test switch ?

ps: i read the 3 threads about MK47 project but i don't undertand 
this was answered before , don't remember where now.
also this would best be asked in the lab thread.
the 680/330R are either - or . not both in parallel .
the 2K3 (test switch) resistor is to give a ballpark figure of the voltages , before connecting the mic.




so what to do ? plug the 680 or the 330 why this option to have 105 Volts ?

about the 2K3 : sorry but what the goal ? to not distroy the mic ? whynot turn off the PSU before connect the MIC ?
Title: Re: MK47 assembly - more pics added
Post by: Sredna on November 22, 2010, 12:20:48 PM
about the 2K3 : sorry but what the goal ? to not distroy the mic ? whynot turn off the PSU before connect the MIC ?

Yes, and then turn on the PSU and destroy the mic!  ;)

Do this:

* Build the PSU as in the schematic, with both 680 and 330.

* Close the "Test"-switch

* Connect a voltage meter to the out of the PSU

* Do NOT connect the microphone

* Turn the PSU on

* Measure the output voltage, adjust P1 to get 105 Volts

* If the voltage is to high, cut the 330R or 680. If still too high, replace 680 with 1k (or more)

* If too low, bridge the resistors (0 Ohm)

Hope this helps
Title: Re: MK47 assembly - more pics added
Post by: neodyms on November 22, 2010, 01:27:11 PM
ok ! perfect !


2K3 is the microphone's equivalent resistance !
Title: Re: MK47 assembly - more pics added
Post by: neodyms on November 24, 2010, 05:05:36 AM
there was a small mistakeon the PSU schematic
the diode ref is 1N4007
(http://twin-x.com/groupdiy/albums/userpics/MK47_PSU_schematic.JPG)
Title: Re: MK47 assembly - more pics added
Post by: Denyle Guitars on November 24, 2010, 10:59:12 AM
Drink a few martinis (shaken) and you'll never notice the typo.
Title: Re: MK47 assembly - more pics added
Post by: zayance on November 24, 2010, 01:47:39 PM
Drink a few martinis (shaken) and you'll never notice the typo.

Alcool + HT = not a good match  ;D
Title: Re: MK47 assembly - more pics added
Post by: nashkato on November 25, 2010, 06:40:24 AM
6028 tubes
i don't think anybody didn't find those yet , but who knows .
just bought a 10 pieces lot.
that seller offers 100 piece lots  too for 112 euros .
anybody (maybe from the UK ) willing to do some kind of a groupbuy ?
i'd be in for another 30 .
Title: Re: MK47 assembly - more pics added
Post by: Jim50hertz on November 25, 2010, 06:57:52 AM
Hmmm,

I bought a load from a guy here in the UK, I'll contact him and see if he'll be up for selling a load in bulk.

Title: Re: MK47 assembly - more pics added
Post by: moamps on November 26, 2010, 07:22:48 AM
there was a small mistakeon the PSU schematic
the diode ref is 1N4007.....

And the LED1 is reversed.
Title: Re: MK47 assembly - more pics added
Post by: ioaudio on November 26, 2010, 02:03:00 PM
thanks for catching the errors - i corrected the schematics, you might need to re-load the page.

-max
Title: Re: MK47 assembly - more pics added
Post by: nashkato on December 02, 2010, 05:12:53 AM
maybe an obvious question , but it came up when building the PS .

am i right when i say that the mics equivalent DC resistance is actually 2K11 ohm ?
12k then should be the approximate coil resistance of the relais ?
Title: Re: MK47 assembly - more pics added
Post by: bobine on December 04, 2010, 02:59:39 AM
Another PSU question...

The choke is 500 ohms. Should the overall resistance between the first two caps be 500 or 1000 ohms?  It was mentioned at one point that you could use two chokes in series since they were affordable. The alternate resistor shown on the schematic is 1000 ohms.

If using only one choke, should I add a 500 ohm 5w resistor in series? Or does it matter if I can adjust the voltage later in the circuit?

Thanks! 
Title: Re: MK47 assembly - more pics added
Post by: Sredna on December 04, 2010, 06:10:24 AM
If using only one choke, should I add a 500 ohm 5w resistor in series? Or does it matter if I can adjust the voltage later in the circuit?

Depends of what your transformer puts out.

Mine gives a little less than 200 Volts and I had to use 500Ohms all the way.
Title: Re: MK47 assembly - more pics added
Post by: bobine on December 05, 2010, 03:16:34 PM
Success!  Stable.

This is the large Hammond case 513-0900
The Triad VPT230-110 transformer

The test load is a little low, so my test output voltage should run about 108.5 if the mic load is actually 2300.

Thanks to all who've contributed!

Title: Re: MK47 assembly - more pics added
Post by: bobine on December 05, 2010, 11:58:46 PM
Is there an ideal or a standard pinout recommended for 7-pin connectors on this project?  Should there be?

thx


Title: Re: MK47 assembly - more pics added
Post by: Kingston on December 06, 2010, 06:03:27 AM
7 pins? You only need 5... Might be able to even gamble with just 4 if you skip shield wire.
Title: Re: MK47 assembly - more pics added
Post by: bobine on December 06, 2010, 09:58:38 AM
7 pins? You only need 5... Might be able to even gamble with just 4 if you skip shield wire.

True.  But many will be using Skylar's EQU47 body, which is fitted with a 7-pin Binder connector.

This post suggests there are no pinout conventions for tube microphone cables.
http://www.groupdiy.com/index.php?topic=41399.0

Looking at the U47 schematic (6-pin):
1,2  audio
5  105v
3,4,6  0V ground
http://www.gyraf.dk/gy_pd/g7/gic_s.gif

In one of Gyraf's mics (7-pin):
1  0v ground
2  +v
3,4  +/- audio
5 pattern
http://www.gyraf.dk/gy_pd/g7/gic_s.gif

Any interest in having standard pinouts for this mic with 7-pin connectors?

Any advantages to one config over another?  Maybe it would be nice to have a published standard for interchangability or if one of the White Market shops wants to supply a PSU or cable. Maybe it doesn't matter.   

 
Title: Re: MK47 assembly - more pics added
Post by: mad.ax on December 06, 2010, 10:50:16 AM
There so many options and connectors that there cannot be an 'official' standard.

I guess the best bet is to follow the Neumann way... Binder 7-pin are compatible with the old Tuchell connectors used in U67, M249, and the likes...

1-2 audio
3 ground
4 heater
5 B+
6 option (remote control pattern or measuring input)
7 chassis ground

Axel
Title: Re: MK47 assembly - more pics added
Post by: nashkato on December 20, 2010, 07:25:24 AM
 bumping this thread up again
;D finished my mk47 (with a Dale M7 until the beezneez arrive)
no crackling or popping as described before.
pretty straight forward , turned it on and worked.
my 1K / 5 Watt resistors in the PS get rather fast quite hot though ,
i guess i'll change them to 10Watt ?
didn't use a pot in the PS . used a resistor with trial and error to get the 105Volt (at least in the evening , midday when everybody starts cooking , voltage drops to 103 , but that's 2% to 3% )
lost my camera so i'll  post pics when i can lend one.
for the start 2 pics of the bottom with the resistor mounted , and the rails
(http://i190.photobucket.com/albums/z141/nashkato/DSCN0087.jpg)
(http://i190.photobucket.com/albums/z141/nashkato/DSCN0084.jpg)
Title: Re: MK47 assembly - more pics added
Post by: Jim50hertz on December 20, 2010, 08:29:26 AM
bumping this thread up again
;D finished my mk47 (with a Dale M7 until the beezneez arrive)
no crackling or popping as described before.
pretty straight forward , turned it on and worked.
my 1K / 5 Watt resistors in the PS get rather fast quite hot though ,
i guess i'll change them to 10Watt ?
didn't use a pot in the PS . used a resistor with trial and error to get the 105Volt (at least in the evening , midday when everybody starts cooking , voltage drops to 103 , but that's 2% to 3% )
lost my camera so i'll  post pics when i can lend one.
for the start 2 pics of the bottom with the resistor mounted , and the rails
(http://i190.photobucket.com/albums/z141/nashkato/DSCN0087.jpg)
(http://i190.photobucket.com/albums/z141/nashkato/DSCN0084.jpg)

Cool, congrats on the build, sound good?  Need I ask?  ;D
Title: Re: MK47 assembly - more pics added
Post by: JW on January 03, 2011, 03:57:12 PM
So, is there a consensus on where to get the most cost effective capsule mounts these days?
Title: Re: MK47 assembly - more pics added
Post by: Whoops on January 12, 2011, 05:31:28 PM
Can someone please advise me on a Switch to use for the Polar Pattern Selection?

thanks,
best regards
Title: Re: MK47 assembly - more pics added
Post by: Jonkan on January 13, 2011, 07:10:33 PM
Anyone know an european source for the psu choke, or an alternative that might work?

/J
Title: Re: MK47 assembly - more pics added
Post by: nashkato on January 14, 2011, 05:25:16 AM
RS
  http://at.rs-online.com/web/search/searchBrowseAction.html?method=getProduct&R=2508972587 (http://at.rs-online.com/web/search/searchBrowseAction.html?method=getProduct&R=2508972587)
Title: Re: MK47 assembly - more pics added
Post by: Jonkan on January 14, 2011, 05:46:05 AM
Thank you!
Title: Re: MK47 assembly - more pics added
Post by: gary o on January 14, 2011, 07:56:28 AM
PSU related question......This maybe silly question .....Can voltage regulator tubes be used in mic psu ? did I read to add noise ?.....I have some transformers with 250VAC output was thinking of using VR105 regulator

If this is silly idea let me know so I can learn thanks.....
Title: Re: MK47 assembly - more pics added
Post by: ioaudio on January 15, 2011, 02:34:37 AM
many ways to build the PSU - passive with/out choke, aktive with tip pass transistors, tl783 + additional filter, a tube regulated version would be a nice addition :)

BTW, FIY - new batch is ready to ship and a few kits are still available, pls check the white market section.

-max
Title: Re: MK47 assembly - more pics added
Post by: gary o on January 15, 2011, 07:36:44 AM
Thanks Max  take you have got my payment now cheers, looking forward to my kit cant wait....
i'll look into the Tube regulators for PSU....i'll have to go read n learn and ask questions....

Max yr PSU looks great and easy to make its just I have couple larger transformers and chokes & tube regulators laying around here and would like to put them to good use (if workable) and so save a little money for a lovely capsule.

Cheers.
Title: Re: MK47 assembly - more pics added
Post by: JW on January 19, 2011, 11:30:57 AM
For the AC transformer, will the one from Edcor for the MK7 work?

120V 60HZ primary
Dual secondary
160VAC @10MA
12VAC @500MA

Also, are Thiersch and Beezneez the only places to get a capsule mount from?
Title: Re: MK47 assembly - more pics added
Post by: JoeMorris on January 23, 2011, 08:12:27 AM
Received my kit yesterday and built immediately!
Thanks Max, all the parts and board seem of the highest quality - a pleasure to work with and a great design all-round.
Desperately awaiting my Beez-neez order now, guess I can get a PSU together in the meantime...
(apologies for bad cameraphone photo - also dont worry I havent soldered the big resistor)
(http://img.photobucket.com/albums/v312/Touchmaster/mk472.jpg)
Title: Re: MK47 assembly - more pics added
Post by: ioaudio on January 25, 2011, 03:51:57 AM
great - and thanks for the kind words  :)
Title: Re: MK47 assembly - more pics added
Post by: JW on January 25, 2011, 03:18:09 PM
Still trying to figure out if the Edcor transformers for the MK7 will work for Max's MK47 supply.
Is it just a matter of adjusting resistors following the secondary to get the voltage in enough of a ballpark that the pot can adjust to 105V?

This schematic calls for 200V 100mA on the AC secondary, while the Edcor is 160V 10mA. Seems like the biggest issue would potentially be the current rating.
Title: Re: MK47 assembly - more pics added
Post by: luis on January 27, 2011, 08:55:43 AM
I noticed that there is some discussions about the different PSU combinations. Is there any PSU PCB available?

Thanks,
Luis
Title: Re: MK47 assembly - more pics added
Post by: Kingston on January 27, 2011, 09:00:26 AM
This schematic calls for 200V 100mA on the AC secondary, while the Edcor is 160V 10mA. Seems like the biggest issue would potentially be the current rating.

That edcor will burn to ashes if you try to power your MK47 with it.

See ioaudio White Market thread for information on suitable transformers.
Title: Re: MK47 assembly - more pics added
Post by: nashkato on January 27, 2011, 09:46:34 AM
posted this transformer link before in the white market iirc.
http://www.tube-town.net/ttstore/product_info.php/info/p2192_Ringkern-Netztrafo-30VA-Preamp.html
for 230V countries only , though.
reasonable price , works perfectly in my PS .
additionally you may even experiment with tube rectifiers.( like EZ81 ?? )
Title: Re: MK47 assembly - more pics added
Post by: gary o on January 29, 2011, 11:03:53 AM
Made my power supply while waiting for kit used maxes nice schematic used a transformer I had laying around 240VAC output 250Ma bit wasteful really but needs must, I added some resistance to the Max PSU doubles as a studio heater.....I have 104.1 VDC hope 
that is ok?.......
mic is living in temporary accommodation at the moment a chocolate wafer tin & has temporary capsule too a Violet Vin 67 lollipop head (its supposed to sound like a U67 when used with a flat mic amp)?......F**ck this thing has bottom end!! up until now I have agreed with mic gurus here who say mic electronics has less effect on sound than capsule I found this too with my own experiments.......but boy does this circuit have bottom end like none I have DIYed.......

I do have plenty of white noisy mush at the moment......need to look into that maybe something I have done wrong, maybe dirty high impedance section or something.......

just wondering which is best capsule to buy now..........I hear beezneez good but slightly worried about the companies own discription of their own capsules.....they say their k47 is their best capsule yet.......so does that mean their K47C isnt all that ?

Anyway just wanna say thanks to Max for this kit its brilliant....
Title: Re: MK47 assembly - more pics added
Post by: living sounds on January 30, 2011, 06:33:17 PM
Can I use the transformer that came with the T-Bone SCT-700 type mics PSU? There are no ratings on it, it's 5 * 5 * 4 cms in size.
Title: Re: MK47 assembly - more pics added
Post by: Kingston on January 30, 2011, 07:20:09 PM
Can I use the transformer that came with the T-Bone SCT-700 type mics PSU? There are no ratings on it, it's 5 * 5 * 4 cms in size.

No way! It'll burn to ashes. That physical size (usually directly proportional to the power output) is something like 3-10VA, while this project needs something like 30VA to be on the safe side. Again, See ioaudio White Market thread for information on suitable transformers.

People, look at the schematic for once, and not just the static voltage spec of 200VAC needed for B+.

Where does the tube heater get it's current? Where is heater PSU? Then compare to your average G7 based tube mic, or MK7...
Title: Re: MK47 assembly - more pics added
Post by: living sounds on January 30, 2011, 07:45:56 PM

No way! It'll burn to ashes. That physical size (usually directly proportional to the power output) is something like 3-10VA, while this project needs something like 30VA to be on the safe side. Again, See ioaudio White Market thread for information on suitable transformers.

Thanks! I had been wondering about the heater. Still am, actually. Anyway, time to order a transformer...
Title: Re: MK47 assembly - more pics added
Post by: Andy Meyer on February 03, 2011, 02:15:57 AM
I have built the MK47 head amp and now need to mount it into my Tab-Funkenwerk U47 style body.  Has anyone done this?  I am looking for any ideas to do this cleanly.
Title: Re: MK47 assembly - more pics added
Post by: idylldon on February 07, 2011, 06:47:11 PM
So what are the options available for bodies and grilles/head baskets?  Here are the ones I know about:

1.)  The EQU47 group buy, which are VERY well done and affordable, but I missed out on that.  Not sure I want to wait months for the next order.

2.)  Flea products, which are great but pricey.

3.)  Tab/Funkenwerk, which are also nice but pricey.

4.)  BeesNeez, which seem to be a bit less than the above but still quite a bit of $.

5.)  Some of the Chinese mic bodies like the ones in the T-Bone line.

Any others I've missed?  While I would love to have one of the more expensive bodies, I'm not sure it will fit in the budget right now so I was wondering about other alternatives the people have used.

Cheers,
--
Don
Title: Re: MK47 assembly - more pics added
Post by: Jonkan on February 07, 2011, 07:19:45 PM
You could always go hardcore and diy the complete body. Brass or copper pipe+dremel for cutouts+metal mesh for grille +a bit of solder. A bit of creativity+ an endstop which you could either lathe yourself or maybe (as i did) get a friend to help you with. Some sort of internal mounting system and you are good to go. And it will look if not stunning, atleast personal, and if youre carful with details, sound absolutely stunning.

Or....just pay up  ;D

Title: Re: MK47 assembly - more pics added
Post by: JW on February 09, 2011, 04:38:36 PM
Hey guys,
What should the AC fuse be?
Title: Re: MK47 assembly - more pics added
Post by: JW on March 02, 2011, 02:12:19 PM
Okay, I built the power supply up. It's easily adjusted to 105V with the pot, after adding a bit more resistance due to my AC power transformer.

My question is, how much fluctuation is acceptable?

I'm getting a fairly quick fluctuation of about .3VDC.

Title: Re: MK47 assembly - more pics added
Post by: Le Roux on March 04, 2011, 08:43:36 AM
When choosing a transformer, is it wise to get one rated larger than required?

For this project, the schematics call for 200V 100mA for the PSU.
It was recommended in this thread to get a transformer 30VA, "to be on the safe side".

But would 20VA suffice?
Title: Re: MK47 assembly - more pics added
Post by: mrcase on March 08, 2011, 07:45:57 AM
Sourcing parts for my MK47 PSu since I´ve nearly got all my pieces together.
But there are some things I don´t understand or am unsure off...
- unsure how the polar pattern switch works, what are you guys using, normal SPDT?
- I´m thinking of use the mogami 3172 - 6 pol should be enough (since there is no heater) or should I buy a 7pol cable? (I gonna use Skylars body)
- where to connect a jewel light?
- the triad choke substitutes the 1K 5w resistor, no?

I´m sure there´ll be more questions coming up, but thats all for now!

thank you all!
Title: Re: MK47 assembly - more pics added
Post by: mrcase on March 08, 2011, 07:47:10 AM
and here we go ;-)
one more:

is it ok to use wirewound resistors in the psu like the ones from banzai?
http://www.banzaimusic.com/100-Ohm-18k-c-339/
any experience with those?
Title: Re: MK47 assembly - more pics added
Post by: Jim50hertz on March 08, 2011, 08:52:48 AM
Sourcing parts for my MK47 PSu since I´ve nearly got all my pieces together.
But there are some things I don´t understand or am unsure off...
- unsure how the polar pattern switch works, what are you guys using, normal SPDT?
I'm using a Lorlin.

- I´m thinking of use the mogami 3172 - 6 pol should be enough (since there is no heater) or should I buy a 7pol cable? (I gonna use Skylars body)
That'll be fine.  I've seen starquad used without a problem (5 conductor)

- where to connect a jewel light?
If you use the Tube Town trafo there's a 6.3v tap

- the triad choke substitutes the 1K 5w resistor, no?
Yes

one more:

is it ok to use wirewound resistors in the psu like the ones from banzai?
http://www.banzaimusic.com/100-Ohm-18k-c-339/
any experience with those?

I'm using the exact same ones, haven't arrived yet but I don't see a problem, unless they're too large




Title: Re: MK47 assembly - more pics added
Post by: Le Roux on March 08, 2011, 10:21:37 AM
- unsure how the polar pattern switch works, what are you guys using, normal SPDT?
I'm using a Lorlin.

Must you use a switch?
Or can you wire direct?
Title: Re: MK47 assembly - more pics added
Post by: mrcase on March 08, 2011, 11:53:07 AM
Sourcing parts for my MK47 PSu since I´ve nearly got all my pieces together.
But there are some things I don´t understand or am unsure off...
- unsure how the polar pattern switch works, what are you guys using, normal SPDT?
I'm using a Lorlin.

- I´m thinking of use the mogami 3172 - 6 pol should be enough (since there is no heater) or should I buy a 7pol cable? (I gonna use Skylars body)
That'll be fine.  I've seen starquad used without a problem (5 conductor)

- where to connect a jewel light?
If you use the Tube Town trafo there's a 6.3v tap


Thank you!

- the triad choke substitutes the 1K 5w resistor, no?
Yes

one more:

is it ok to use wirewound resistors in the psu like the ones from banzai?
http://www.banzaimusic.com/100-Ohm-18k-c-339/
any experience with those?

I'm using the exact same ones, haven't arrived yet but I don't see a problem, unless they're too large


THANK YOU!! that cleared things up for me!
 


Title: Re: MK47 assembly - more pics added
Post by: Dazazone on March 08, 2011, 05:56:22 PM
Hey max I tried to email u last week about grabbing one of the kits before they all go. Did you get my email ok?  Would love to do this project :D
Title: Re: MK47 assembly - more pics added
Post by: Jim50hertz on March 09, 2011, 05:13:39 AM
- unsure how the polar pattern switch works, what are you guys using, normal SPDT?
I'm using a Lorlin.

Must you use a switch?
Or can you wire direct?

The switch changes the polar pattern from cardioid to omni.  One could hardwire if one wanted only one polar pattern, i.e. cardioid only.

Or am I misunderstanding your question?
Title: Re: MK47 assembly - more pics added
Post by: Le Roux on March 09, 2011, 08:05:28 AM



The switch changes the polar pattern from cardioid to omni.  One could hardwire if one wanted only one polar pattern, i.e. cardioid only.

Or am I misunderstanding your question?

So the switch is merely an on/off for 48V, switching from cardioid to omni?
Sorry, new at mic building...
Title: Re: MK47 assembly - more pics added
Post by: mad.ax on March 09, 2011, 09:46:23 AM
The switch is indeed used to on/off the relay that does the select the pattern.

But that makes me think that we could use the phantom power to remote the pattern change...

Max, what are the coil's characteristics and power consumption of the the HighZ relay?

Even if it cannot be powered directly by phantom power, adding a transistor and a relay instead of a switch inside the PSU could be doable...

Axel
Title: Re: MK47 assembly - more pics added
Post by: Winetree on March 09, 2011, 04:32:03 PM
OK,
Just got my Skylar Mic Bodies and went back to the first page for assembly.
The body is different in the examples. Where are the brackets to mount the P.S.B in the rails?.
Do I still mount the white risistor to the base and extend the wires or let it hang
there's plenty of room.
Title: Re: MK47 assembly - more pics added
Post by: living sounds on March 09, 2011, 04:57:17 PM
OK,
Just got my Skylar Mic Bodies and went back to the first page for assembly.
The body is different in the examples. Where are the brackets to mount the P.S.B in the rails?.
Do I still mount the white risistor to the base and extend the wires or let it hang
there's plenty of room.


The resistor needs to exchange heat with the metal body in order to be cooled down (thermal contact conductance).
Title: Re: MK47 assembly - more pics added
Post by: Winetree on March 10, 2011, 10:37:02 AM
Just put Skylar's mic body in Ben's case. Tight fit.
Had to notch out the dense foam on one end for the mic connector end.
Now I can't close the box. Too much top and bottom foam.
The foam is too dense to compress.
Anybody dealt with this yet?
Title: Re: MK47 assembly - more pics added
Post by: 0dbfs on March 10, 2011, 10:48:14 AM
Max, The white market thread seems to have moved or gone away. Just wanted to post that I received my two kits yesterday. Thanks! Looking forward to it.

On another note from anyone that wants to respond, I was wondering about the tubes. ie; should I plan to buy more and select the best ones? What have y'all experienced with the supplied tubes?

More to follow as the build progresses!

Best,
jonathan
Title: Re: MK47 assembly - more pics added
Post by: bobine on March 10, 2011, 12:21:23 PM
Just put Skylar's mic body in Ben's case. Tight fit.
Had to notch out the dense foam on one end for the mic connector end.
Now I can't close the box. Too much top and bottom foam.
The foam is too dense to compress.
Anybody dealt with this yet?

Same here.  I left the foam in the lid but removed the piece in the bottom (peeled it away from the side pieces). I can put a thin piece of soft foam on the bottom and it fits but doesn't give a lot of protection. Maybe later I'll replace both top and bottom with 1/4" dense foam.
Title: Re: MK47 assembly - more pics added
Post by: bobine on March 11, 2011, 02:26:42 PM
Just finished the mic. First listen:  :) wow, this sounds really nice.

MK47 with Beezneez capsule in EQU47 body.

Huge thanks to all!
Title: Re: MK47 assembly - more pics added
Post by: 0dbfs on March 11, 2011, 02:30:19 PM
Yeah. I missed the boat on that one. Extra lashings with a wet dollar bill are well deserved!

-jb
Title: Re: MK47 assembly - more pics added
Post by: bruno2000 on March 11, 2011, 02:32:38 PM
My kits arrived today, thanks!
Same question as 0dbfs, what about replacement tubes?
Thanks!
Bruno2000
Title: Re: MK47 assembly - more pics added
Post by: crackerzot on March 11, 2011, 08:17:28 PM
Just finished the mic. First listen:  :) wow, this sounds really nice.

MK47 with Beezneez capsule in EQU47 body.

Huge thanks to all!

Sure would love to hear a sample...  I'm getting ready to assemble my kit.  The MK47 and EQ47 arrived on the same day, but I've got to wait 3-4 weeks for my capsule from Thiersch.  Gonna try to get the P/S and cabling sorted while I wait....
Title: Re: MK47 assembly - more pics added
Post by: idylldon on March 12, 2011, 05:18:30 PM
I'm not finding the 14K 1-watt resistors at Mouser.  Are 1-watt really necessary in this position? 

Thanks,
--
Don
Title: Re: MK47 assembly - more pics added
Post by: crackerzot on March 13, 2011, 01:25:46 AM
Assembled my MK47 kit today, but this is the first mic I've ever assembled and could use some advice on where to source some brass angle stock in order to mount the board to Skylar's EQ47 rails.  Also, is there any special advice on how low to mount the board on the side rails?  Just low enough to be able to solder the heater legs to the board while having it make contact with the bottom plate?

Also, if I opt to use heat transferring glue to attach that heat resistor instead of drilling and tapping a hole for a bracket, where do I find such glue?  Sorry for all the noob questions... but I am one.  Cheers.  
Title: Re: MK47 assembly - more pics added
Post by: bobine on March 13, 2011, 01:59:49 AM
I was impatient so I mounted the board with two zip ties. Works great...extra shock protection ;)

I mounted it nearer the top and extended the heater resistor legs with some stiff bus wire so it contacts the bottom of the bell and stays put with spring action. Assembled it warms up nicely, but doesn't feel hot.


btw, I don't have deep experience with a lot of high end microphones, but this is certainly the best mic I have ever used. I used it tonight with a problematic whisky-voiced male singer who usually ends up with an SM7b because LDCs are not flattering.
I'd describe the recording as vivid and engaging; it was interesting to listen to; there was something about the presence of the sound that was fascinating.
There might be a little etching or ringing going on with some notes but overall it is a delight. It's a whole new level for me. I want another.
 
Title: Re: MK47 assembly - more pics added
Post by: crackerzot on March 13, 2011, 03:13:11 AM
Thanks, Bobine, like you, I am in SoCal.  I have extensive experience (decades) behind the microphone (I do voice overs and I'm also a singer) but very little experience INSIDE of them. 

Zip ties.

Now why didn't I think of that?  Ha ha.

I guess I was thinking it was important for the PCB to be grounded to the rails?  Again, my lack of experience with the innards.

That ringing you mention might be microphonics from the tubes?  Very interesting.  I am definitely looking forward to having my mic completed.  Just waiting for the blue line capsule from Thiersch to arrive and I have a friend building the P/S for me so I don't electrocute myself or blow up my new microphone.   My build completion is at least another month out.  I think I'm going to try and put my hands on some 3M heat conductive tape to attach the heater, but your solution sounds better for mic tinkering later on.  If I adhere the heater to the bottom plate, it's going to be more of a PIA when I disassemble the mic.
Title: Re: MK47 assembly - more pics added
Post by: Winetree on March 15, 2011, 11:37:35 PM
OK, got the PSB mounted in skylar's mic body, using nylon ties and the resistor mounted and wired.
How do i wire the 7 pin connecter to the PSB. I see A+ A- B+ B- and pins 1-7?
Same for the capsule wiring. I just want to do it right the first time.
Any help or pictures of finished insides?
Title: Re: MK47 assembly - more pics added
Post by: bobine on March 16, 2011, 12:34:08 AM
I did mine like this, color coded the same at each end. I used Gotham mic cable.

Audio
1 = A- (gray) (connects to pin 3 of XLR at the power supply)
2 = A+ (white) (to pin 2 of XLR at the PS)
Center pin = audio ground (green)  (to pin 1 of XLR)

Power
3 = B- (black [blue in the cable])
4 empty
5 = B+ (red)

Pattern
6 = P (yellow)

Shield to the chassis.

I soldered the wires into the Binder connector, installed the connector in the mic body, mounted the PCB, then attached the wires to the PCB.

I forgot to take pics.  



Title: Re: MK47 assembly - more pics added
Post by: Winetree on March 16, 2011, 01:41:22 AM
Great, Thanks.
Looks like a plan. I'll Use.
What about the capsule?
Title: Re: MK47 assembly - more pics added
Post by: bobine on March 16, 2011, 02:11:03 AM
the capsule.

I left the leads sticking out of the glass tubes about a quarter inch or more. I passed each of the three wires from the capsule through the three holes in the top plate. I decided which side was to be the front and attached that wire to the lead marked "front." Ditto with Rear and the Center plate.  I just placed the wire against the lead and quickly soldered them. I may swap front and back soon to hear the difference. There may be a better or recommended way of doing this... but mine works beautifully. Dead quiet.

Title: Re: MK47 assembly - more pics added
Post by: kante1603 on March 16, 2011, 04:49:47 PM
I'm not finding the 14K 1-watt resistors at Mouser.  Are 1-watt really necessary in this position? 

Thanks,
--
Don

Hi Don,

had the same issue while ordering at Mouser-they have 28k 1 Watt 1% metalfilms so use  two in parallel-I will do so ;)

Best,

Udo.
Title: Re: MK47 assembly - more pics added
Post by: Winetree on March 16, 2011, 08:20:26 PM
Finished my 2, now they are resting in their cases
until I can build the power supplies.
Title: Re: MK47 assembly - more pics added
Post by: idylldon on March 16, 2011, 08:28:41 PM

Hi Don,

had the same issue while ordering at Mouser-they have 28k 1 Watt 1% metalfilms so use  two in parallel-I will do so ;)

Best,

Udo.

Thanks, Udo.  I thought about paralleling a couple of resistors but thought I'd ask to see if I had overlooked something in the Mouser catalog.  I'll go ahead and do as you suggest.

Cheers,
--
Don
Title: Re: MK47 assembly - more pics added
Post by: JamesW on March 21, 2011, 09:12:08 AM
What voltage range can the pattern relay tolerate?

Thanks
Title: Re: MK47 assembly - more pics added
Post by: JW on March 21, 2011, 11:49:36 AM
I'd like to know too.

With the p.s. loaded (with a 2k4 resistor, closest I had) and the pattern switch thrown to break the 12k/14k network, the B+ voltage goes from what was calibrated at 105V (when the switch was throw the other way) up to 111V. Just checking to see if this is normal.
Title: Re: MK47 assembly - more pics added
Post by: Sredna on March 21, 2011, 12:27:09 PM
You simulated the mic with 2,4 kOhm right? Then you also have to simulate the relay, maybe with 12kOhm?  ;)
Title: Re: MK47 assembly - more pics added
Post by: Steph.B on March 21, 2011, 04:58:34 PM
I just received my kit today, thanks Max !

One step closer from the finish line...
Title: Re: MK47 assembly - more pics added
Post by: androidtube on March 21, 2011, 06:52:17 PM
Hello guys, greetings to all from a newbie like me! :)
Someone can tell me if this kit is still available? Thanks.
Title: Re: MK47 assembly - more pics added
Post by: JW on March 23, 2011, 03:34:32 PM
I don't understand what's up with my mic.

I had thought the 2.4K test resistor was an either/or thing to simulate the mic. I had thought it was supposed to be switched out of the circuit when the actual mic was loading the power supply.

However, I'm getting 290 volts or something at the B+ in the mic when the 2.4K resistor is switched out of the power supply circuit. Switch it back in and I get 105V at B+ in the mic.

Second problem is, the 1.5K heater resistor measures fine at 1.5K ohm, but it doesn't drop the voltage at all. I even tested this out of the circuit. I'm guessing I probably have a couple dead tubes now too because they were getting upwards of 290V at the heater. I've yet to see them light up though.

Anybody have an idea what's going on?
Title: Re: MK47 assembly - more pics added
Post by: Sredna on March 23, 2011, 10:05:32 PM
Why do you use such high voltage rated transformer?

What´s the voltage (without mic but with 2.4K resistor) after the rectifier?
Title: Re: MK47 assembly - more pics added
Post by: bobine on March 23, 2011, 10:22:37 PM
Can you take photos of your connections at the mic PCB?

 
Title: Re: MK47 assembly - more pics added
Post by: kante1603 on March 24, 2011, 06:08:38 AM
However, I'm getting 290 volts or something at the B+ in the mic when the 2.4K resistor is switched out of the power supply circuit.

Don´t know what transformer you have used,but in case of having 200 Vs on the secondary it looks a bit like it is the (DC?)-voltage right after the rectifier.200Vac x 1,4= 280 Vdc after the rectifier,meaning "290 Vs or something at the  B+ "...definetely something strange going on.
Maybe you should check your psu first (did you use max´s schemo?).

Best,

Udo.
Title: Re: MK47 assembly - more pics added
Post by: JW on March 24, 2011, 05:56:34 PM
I used the Triad VPT230-110. http://www.mouser.com/ProductDetail/Triad-Magnetics/VPT230-110/?qs=wkKrz7WmEgNNNgyT8w4YqA%3d%3d
I believe the problem is that I hooked up the secondaries in series, rather than parallel. Big dumbSh*t thing to do if that's the issue. I'll have to change the p.s. resistors. Who knows what else.

After the diode rectification (p.s. loaded with 2.4K resistor) I'm getting 327V.

To get the 105V (loaded) (secondaries wired in series) I needed a total of 3.63K ohms resistance, plus the 500R pot to fine tune.

A paralleled secondary on the power transformer is rated to yield 115VAC @ .22A. I'm guessing that would have been the way to go.

What I don't understand is, if I was able to reduce the voltage to 105V with the 2.4K test load (regardless of wiring the secondaries wrong?) , then why don't I get something close to that at the mic, which is supposed to represent a 2.3K load?

Title: Re: MK47 assembly - more pics added
Post by: bobine on March 24, 2011, 06:28:11 PM
I just took my PSU apart to check the voltages.

I have the same Triad transformer. I have the secondary wired in series.

With test load: 103vdc
Without test load: 285vdc

With test load and pattern switch: 108vdv

With mic (no test load): 106vdc  (the 500R pot is not quite enough!)

Pattern switch makes no difference with mic in circuit.

--- where are you measuring voltage with the mic in the circuit?
--- check your cable wiring to see if the B+ is actually getting to the mic PCB
Title: Re: MK47 assembly - more pics added
Post by: JW on March 24, 2011, 07:39:23 PM
Hey Bobine, thanks for checking that.

The B+ voltage is definitely getting to the mic pcb. That was one of the first things I checked. I'm checking at the B+/1.5K resistor tabs in the mic.
Actually (duh), disregard my previous post about being worried about the transformer secondaries. The schematic calls for a 200V secondary, so what I did was correct (series wiring)

But does it make sense that I'm getting 327Vdc exiting the diode bridge?

Title: Re: MK47 assembly - more pics added
Post by: bobine on March 24, 2011, 07:57:27 PM
The PSU doesn't seem to be the problem since you have the right voltages with (105v) and without (290v) the load. The mic isn't acting as a load, apparently, so the problem seems to be there. The 1K5 heater resistor doesn't seem to be in the circuit. Bad solder joint? 
Title: Re: MK47 assembly - more pics added
Post by: kante1603 on March 25, 2011, 01:41:40 AM

But does it make sense that I'm getting 327Vdc exiting the diode bridge?


Yes,absolutely!

Looking at your transformer it is 115V x2(in series)=230V.
230V x 1,4=322 V (after the rectifier).So that´s correct.
Very kind of bobine of comparing his psu to yours!
So the psu seems to be fine.

Checking the solder points arround the 1,5k is a good idea as a next step.

Best,

Udo.
Title: Re: MK47 assembly - more pics added
Post by: JW on March 25, 2011, 03:49:52 PM
Okay, so I've checked and rechecked the 1.5K resistor. I verified that the solder joints are fine by checking downstream on both sides. Continuity is fine, and it's measuring fine at 1.48K ohms.

I also took a couple resistance measurements at other spots. Not sure if these are the right places to be looking yet, but here goes:

1. I'm getting 32K ohms between the 1.5K resistor and where it connects again (after coming out of the tube) at the 27R resistor.
2. I'm getting 11.5K ohms between B+ and ground
3. I'm getting 107K ohms between B+ and where the 1uF output cap connects to the input of the BV8 transformer.
Title: Re: MK47 assembly - more pics added
Post by: bobine on March 25, 2011, 04:24:11 PM
Was the mic disconnected from the PSU for those measurements?

Check to see that the B+ is reaching the heater pins on the tubes.
Check those right angle solder joints and the tube socket joints. 
Title: Re: MK47 assembly - more pics added
Post by: JW on March 25, 2011, 04:50:34 PM
I'm getting 290V at the heater tube pin (after those solder joints) , but no voltage where it exits the tube at the 27R resistor.

Resistances were measured with the mic connected to the supply.
Title: Re: MK47 assembly - more pics added
Post by: bobine on March 25, 2011, 05:01:47 PM
Resistances were measured with the mic connected to the supply.

I asked because if you are measuring resistance through the power supply resistors it doesn't tell you about continuity in the mic circuit.
Title: Re: MK47 assembly - more pics added
Post by: JW on March 25, 2011, 05:38:43 PM
Oops
Okay, without the p.s. connected, I get some pretty high resistance.
Between B+ and ground I get 4.6M ohms
Between the 1.5K resistor and the 27R, I get 5M ohms.

Thanks for helping me with this Bobine. It's probably something obvious.
I've resoldered the tube pins as well as the 90 degree angles.

Is there a suggested value capacitor to take place of the capsule for testing purposes? I'm using an old chinese Nady capsule right now that I haven't verified as working for a long time. But it's what I've been using for initial testing. Not that that is necessarily the issue, but I don't know.

Title: Re: MK47 assembly - more pics added
Post by: bobine on March 25, 2011, 06:18:26 PM
So, looking at the schematic, that tells me that current is not flowing through the heater filaments. I think I'd take out the tubes and test continuity right up to the pins.

Then I'd measure the heater resistance between pins 3 and 4 of the tubes themselves. http://www.westernelectric.com/spec_sheets/408A.pdf

Maybe someone who knows more can help with capsule question.  
Title: Re: MK47 assembly - more pics added
Post by: Skylar on March 25, 2011, 07:47:04 PM
You can measure the capacity of the capsule with an LCR for an exact number.

But 80-100pf is a good place to start.
Title: Re: MK47 assembly - more pics added
Post by: ioaudio on March 25, 2011, 07:47:21 PM
hey JW,

propably forgot the bridge here?

-max
(http://twin-x.com/groupdiy/albums/userpics/423/67.jpg)
Title: Re: MK47 assembly - more pics added
Post by: JW on March 26, 2011, 03:20:35 PM
Hey Max,
Nope. Got the jumper. Thanks everybody. I think I got a bad tube. Resistance between 3 and 4 on one tube is 92 ohms, the other is up around 8M ohms, so I got an order in on one of those 10 pc. lots on ebay. (Resistance measured on the tube pins themselves, out of circuit)
Thanks Bobine!
Title: Re: MK47 assembly - more pics added
Post by: kante1603 on March 26, 2011, 04:50:06 PM
I think I got a bad tube. Resistance between 3 and 4 on one tube is 92 ohms, the other is up around 8M ohms, so I got an order in on one of those 10 pc. lots on ebay. (Resistance measured on the tube pins themselves, out of circuit)
Thanks Bobine!

Glad to hear the issue seems to be solved.
Would you be so kind and tell us when the mic is working and what the problem was?
That would help,including me as i´m about to build one (got one of max´s last kits ;D).

Thank you very much and good luck,

Udo.
Title: Re: MK47 assembly - more pics added
Post by: ioaudio on March 27, 2011, 07:18:43 AM
I think I got a bad tube.
I'd send a free replacement as you wish - on the other hand having a box of tubes for the future is a good plan anyway.



Title: Re: MK47 assembly - more pics added
Post by: horvitz on March 27, 2011, 08:06:15 AM
Well this is interesting timing.  Fired mine up for the first time this morning and checked the voltages to find the exact same symptoms as JW.  Took the tubes out and found one bad.  Fortunately, I was able to take one from my second kit to test and with that the mic fired right up and works. :)

Thanks for your troubleshooting, JW.  Definitely saved me some headache here!  These tubes are fairly inexpensive so I'm going to hit EBay and buy some spares.  It will be good to have them on hand.

  Brian
Title: Re: MK47 assembly - more pics added
Post by: androidtube on March 27, 2011, 08:38:58 AM
Hi Max,

I'm new here, and I now offer my congratulations to the MK 47, very nice.
The kit and 'still available? It is possible to know the price?

Best

Anthony   :)
Title: Re: MK47 assembly - more pics added
Post by: ioaudio on March 27, 2011, 09:33:15 AM
Hi Anthony

sorry the Kits are sold out at the moment.
I will have a new batch but i don't know when i get around it, lots of other things remained undone.
Pls watch the white market for availability.
Title: Re: MK47 assembly - more pics added
Post by: JW on March 27, 2011, 02:18:33 PM
Hey guys,
So, I didn't mention that I had a second kit, and was able to sub in another tube, partly due to embarrassment that I didn't try swapping tubes to begin with. Doh!
Anyhow, the mic is loading the circuit properly now, and the heater is working, and at the correct voltage. Yay.

However, all I'm getting is some really loud hum and microphonic noises. Tried both my original chinese test capsule, and then Dale's M7. Same result. Voltages are good though.

Any ideas?

Max, no need to send another tube. They're not expensive, and I'm gonna get a lot of 10. I'd rather just solicit your help on this thread.
I think it would behoove me to build up my second mic and supply to have something to compare to.
Title: Re: MK47 assembly - more pics added
Post by: drgrateful on March 31, 2011, 12:32:22 PM
Hi, as suggested earlier in this thread, I am going to us this transformer:

http://www.tube-town.net/ttstore/product_info.php/info/p2192_Ringkern-Netztrafo-30VA-Preamp.html

What is an appropriate fuse to use?

Thanks,

Matteo
Title: Re: MK47 assembly - more pics added
Post by: e.oelberg on March 31, 2011, 09:14:49 PM
Hi, as suggested earlier in this thread, I am going to us this transformer:

http://www.tube-town.net/ttstore/product_info.php/info/p2192_Ringkern-Netztrafo-30VA-Preamp.html

What is an appropriate fuse to use?




125mA
Title: Re: MK47 assembly - more pics added
Post by: drgrateful on April 01, 2011, 11:18:24 AM
Hi, as suggested earlier in this thread, I am going to us this transformer:

http://www.tube-town.net/ttstore/product_info.php/info/p2192_Ringkern-Netztrafo-30VA-Preamp.html

What is an appropriate fuse to use?




125mA
Thank you, should it be slow blow?
Title: Re: MK47 assembly - more pics added
Post by: ioaudio on April 01, 2011, 11:28:29 AM
yes, slowblow.
Title: Re: MK47 assembly - more pics added
Post by: Kaspar on April 06, 2011, 12:25:30 PM
OK... got a dumb one (probably audio electronics 101) :-[

I'm using Gotham cable with Skylars EQ47 body. I also followed bobine's suggestion for wiring up the cable.

Audio
1 = A- (gray) (connects to pin 3 of XLR at the power supply)
2 = A+ (white) (to pin 2 of XLR at the PS)
Center pin = audio ground (green)  (to pin 1 of XLR)

Power
3 = B- (black [blue in the cable])
4 empty
5 = B+ (red)

Pattern
6 = P (yellow)

Shield to the chassis.

Did the cable ends first and then went back to wire up the male connector at the body. Everything seemed straightforward until I realized that there is no solder tab for audio ground. What to do with the green (pin 1 of XLR) cable!!!

Do I just leave it? do I tie it to chassis ground?
Title: Re: MK47 assembly - more pics added
Post by: rrowley on April 07, 2011, 08:38:57 AM
Hi All
I have a strange problem with my MK47 build.I've used a BeezNeez capsule from the group buy and Skylars body.
The problem I have is that in cardioid both front and back of the capsule are on,although the back is duller sounding.If I switch to omni the sound becomes quieter and really thin sounding,again both front and back are on.In omni the pattern voltage drops from 48v to 30 volts but if I reverse the the front and back capsule wires I have the same problem but without the voltage drop.The relay checks out fine and all other voltages in the mic are are good.
I'm really hoping I haven't got a bad capsule.What do you guys think?
Many thanks
Rich
Title: Re: MK47 assembly - more pics added
Post by: Denyle Guitars on April 07, 2011, 09:00:06 AM
Is the diode in the correct way?
Title: Re: MK47 assembly - more pics added
Post by: rrowley on April 07, 2011, 09:47:41 AM
Yes,and the relays contacts are open in cardioid and closed in omni
Rich
Title: Re: MK47 assembly - more pics added
Post by: bobine on April 07, 2011, 10:49:56 AM
Hi All
The problem I have is that in cardioid both front and back of the capsule are on,although the back is duller sounding.If I switch to omni the sound becomes quieter and really thin sounding,again both front and back are on.

With mine (same setup), in cardioid, the sound from the front is good (uh, great) and the sound from the back is not good (kind of ugly sounding; certainly duller.) In omni, the overall level is lower and the sound is different, less vivid (partly because it is quieter, partly because there is more room in the sound.) I wouldn't say it is "really thin" but I could understand saying it sounds thinner compared to cardioid.

I can't tell for sure, but it sounds like your mic is behaving like mine is. It sounds so amazing in cardioid that I haven't questioned the rest.
Title: Re: MK47 assembly - more pics added
Post by: Sredna on April 07, 2011, 12:06:08 PM
Sorry for asking such a question, but are you two familiar with how cardioid and omni works?

Just trying to clear out misunderstandings....

Title: Re: MK47 assembly - more pics added
Post by: gemini86 on April 07, 2011, 12:13:48 PM
in cardioid your back diaphragm is disconnected, off. So you're still listening to the front diaphragm, even though you're yelling at the back of it's head.
Title: Re: MK47 assembly - more pics added
Post by: The Frizzle on April 07, 2011, 02:56:16 PM
Do you think it would fit in this case?:
http://www.musik-service.de/mxl-550--551-set-prx395772760de.aspx
Its just 89€ which is like 127$.
But maybe this one is even too cheap and has plastik parts or something?
I like the look tho.


Title: Re: MK47 assembly - more pics added
Post by: pasarski on April 07, 2011, 03:03:02 PM
Hi All
The problem I have is that in cardioid both front and back of the capsule are on,although the back is duller sounding.If I switch to omni the sound becomes quieter and really thin sounding,again both front and back are on.

With mine (same setup), in cardioid, the sound from the front is good (uh, great) and the sound from the back is not good (kind of ugly sounding; certainly duller.) In omni, the overall level is lower and the sound is different, less vivid (partly because it is quieter, partly because there is more room in the sound.) I wouldn't say it is "really thin" but I could understand saying it sounds thinner compared to cardioid.

I can't tell for sure, but it sounds like your mic is behaving like mine is. It sounds so amazing in cardioid that I haven't questioned the rest.

Cardioid pattern is directional. It never sounds good on other side. In omni position there is no proximity effect and the mic will sound relatively thinner compared to cardioid at close distance. Farer away, say one meter or so, there shouldn't be so big difference in frequency response.
Title: Re: MK47 assembly - more pics added
Post by: duy_hoang on April 07, 2011, 03:15:01 PM
Do you think it would fit in this case?:
http://www.musik-service.de/mxl-550--551-set-prx395772760de.aspx
Its just 89€ which is like 127$.
But maybe this one is even too cheap and has plastik parts or something?
I like the look tho.




(I think) this one is better :
http://www.thomann.de/de/thon_flex_cut_universal_mischpult_1.htm
;)
Title: Re: MK47 assembly - more pics added
Post by: The Frizzle on April 07, 2011, 03:41:41 PM
thanks duy_hoang, right your case looks better.
But actually i was thinking of mounting the MK47 inside of the MXL 550 body;)
I'm just not sure if it will fit.
Title: Re: MK47 assembly - more pics added
Post by: rrowley on April 07, 2011, 05:39:09 PM
in cardioid your back diaphragm is disconnected, off. So you're still listening to the front diaphragm, even though you're yelling at the back of it's head.

problem is the back seems to be on in cardioid.Is everyone else seeing a 17v drop when omni is engaged?
Cheers
Rich
Title: Re: MK47 assembly - more pics added
Post by: 0dbfs on April 07, 2011, 07:20:56 PM
thanks duy_hoang, right your case looks better.
But actually i was thinking of mounting the MK47 inside of the MXL 550 body;)
I'm just not sure if it will fit.

MXL 550 Looks to be slightly too narrow at 47mm x 170mm (according to the PDF on their website anyway) but maybe you could file down half a mm around edges of the mk47 PCB? If you pick one up please let us know whether your mk47 PCB's will fit with room for everything. I saw some of the 550/551's advertised for $79/pair. Maybe you could also make a PCB that fits inside this body and still have the SDC for some franken-mic'ing action.

Quote from: The ioaudio
Title: Re: MK47 assembly - more pics added
Post by: ioaudio on November 12, 2010, 02:12:53 pm
A 50x1mm (inner dia. 48mm) is the absolute minimum.

Cheers,
jb
Title: Re: MK47 assembly - more pics added
Post by: Sredna on April 07, 2011, 08:56:27 PM
problem is the back seems to be on in cardioid.
How do you come to this conclution? Did you try to disconnect the diaphragm on the back and compare?

In omni the pattern voltage drops from 48v to 30 volts but if I reverse the the front and back capsule wires I have the same problem but without the voltage drop.The relay checks out fine and all other voltages in the mic are are good.

You mean that the junction between the 14kOhm and 12kOhm resistor in the PSU have 48 Volt?
It should be normal that the voltage drop when you apply a load (relay)...
Not normal is that there's no drop when you rewire your capsule, probably miswiring, check with the step by step instructions.
Title: Re: MK47 assembly - more pics added
Post by: rrowley on April 08, 2011, 12:38:41 PM
problem is the back seems to be on in cardioid.
How do you come to this conclution? Did you try to disconnect the diaphragm on the back and compare?

In omni the pattern voltage drops from 48v to 30 volts but if I reverse the the front and back capsule wires I have the same problem but without the voltage drop.The relay checks out fine and all other voltages in the mic are are good.

You mean that the junction between the 14kOhm and 12kOhm resistor in the PSU have 48 Volt?
It should be normal that the voltage drop when you apply a load (relay)...
Not normal is that there's no drop when you rewire your capsule, probably miswiring, check with the step by step instructions.

Success :) I must have had a bod solder joint as I resoldered some joints and all is now fine
Thanks to all
Rich
Title: Re: MK47 assembly - more pics added
Post by: JW on April 08, 2011, 02:15:55 PM
Hey guys,
Is this sound indicative of bad tubes, or a dirty capsule/high impedance area or something else? http://www.supload.com/listen?s=pSLcIC
Title: Re: MK47 assembly - more pics added
Post by: living sounds on April 08, 2011, 02:52:43 PM
Does anyone else have the problem with the SVT-700 and similar mic bodies that the capsule sits too high, just behind the metal ring surrounding the mic basket? This is already the case with the chinese capsule, and the Beez Neez one will be at the same position. There's no room to lower the base, so the only remedy I see is to saw away the ring...
Title: Re: MK47 assembly - more pics added
Post by: kante1603 on April 08, 2011, 03:45:42 PM
Does anyone else have the problem with the SVT-700 and similar mic bodies that the capsule sits too high, just behind the metal ring surrounding the mic basket? This is already the case with the chinese capsule, and the Beez Neez one will be at the same position. There's no room to lower the base, so the only remedy I see is to saw away the ring...
Hi,
not sure if you meant the SCT-700 (Thomann)?
If so I was able to lower it by using a different holder (used the Thiersch capsule) bringing it about 6mm down.It nearly touched the top of the basket.Not perfect but much better than with the normal holder.Will give it a listen when my psu is done.

Best,

Udo.
Title: Re: MK47 assembly - more pics added
Post by: The Frizzle on April 08, 2011, 04:47:58 PM
Thanks 0dbfs, i won't risk it then, thanks for pointing that out..
I found an inside picture of another mxl mic:
http://recordinghacks.com/images/mic_extras/mxl/MXL2006-circuit.jpg
This is the MXL 2006, which has the minimum 50mm size.
But the PCB holder does not seem to be suitable whith that shape.
So maybe MXL is not the way to go..
Title: Re: MK47 assembly - more pics added
Post by: crackerzot on April 08, 2011, 05:18:35 PM
Would someone be so kind as to help me figure out which pins on the Binder connector for my EQU47 mic shell connect to what on the MK47 board, specifically?

I've got 7 pins on the connector.  Which are unused on the Binder and where do the rest connect on the PCB?  I read an earlier post on the last page, but I'm still a little confused.  Please forgive my ignorance.  This is my first mic build project.

A friend is building the P/S for me according to the schematic on the first post.  I've got my Thiersch capsule.  All that's left for me to do is the connector wiring and install the capsule and the mic will be finished.  Many thanks in advance.

Title: Re: MK47 assembly - more pics added
Post by: living sounds on April 08, 2011, 05:35:30 PM
Hi,
not sure if you meant the SCT-700 (Thomann)?
If so I was able to lower it by using a different holder (used the Thiersch capsule) bringing it about 6mm down.It nearly touched the top of the basket.Not perfect but much better than with the normal holder.Will give it a listen when my psu is done.

Best,

Udo.

Yes, I've got a similar mike (same factory and model, different brand). But then you get it closer to the metal at the bottom, which isn't ideal either....
Title: Re: MK47 assembly - more pics added
Post by: Sredna on April 08, 2011, 06:36:01 PM
Hey guys, Is this sound indicative of bad tubes, or a dirty capsule/high impedance area or something else? http://www.supload.com/listen?s=pSLcIC

Strange sound, doesent sound like the bad tubes I had, maybe a bad connection?
A bad capsule could be noisy or give scratching sounds when breathed on, haven't heard
sound like this from a bad capsule.

Quote
Would someone be so kind as to help me figure out which pins on the Binder connector for my EQU47 mic shell connect to what on the MK47 board, specifically?

It doesent matter as long you keep record of your wiring. Ask your friend how he wired the connector on the PSU and do the soldering accordingly.

Quote
....problem with the SVT-700 and similar mic bodies that the capsule sits too high, just behind the metal ring surrounding the mic basket?

Dont forget that the U47 got the same (or similar) arrangement with the upper part of the capsule behind the ring. Maybe it's part of the sound!  ;)
Title: Re: MK47 assembly - more pics added
Post by: kante1603 on April 08, 2011, 11:00:45 PM
Dont forget that the U47 got the same (or similar) arrangement with the upper part of the capsule behind the ring. Maybe it's part of the sound!  ;)

@living sounds:
Yes-Sredna is right...here a link to pics of the original (scroll down to the 10th pic!):
http://www.jogis-roehrenbude.de/Roehren-Geschichtliches/Neumann-Mikro/U47/U47.htm
Therefore mine must be mounted nearly absolutely right-can´t wait to get this mike up and running!

Cheers,

Udo.
Title: Re: MK47 assembly - more pics added
Post by: JW on April 09, 2011, 01:59:18 PM
Anybody else listen to my sound sample? I've tried two sets of tubes now. Next step is either try another set of tubes or try to clean the capsule (there is a bit of dust on it.) I don't really think it's a bad connection.

On the positive side, despite the cracklies, it sounds amazing. Definitely the best sounding condensor I've ever heard. I'm using Dales M7. In terms of brightness/darkness it's close to my AT4047 (maybe even incrementally darker) but it blows the 4047 away in terms of smoothness/three dimensionality/clarity/creaminess. And the 4047 is not a bad sounding mic.

For folks who aren't finished, you're going to love this mic. Thanks Max! You're a very generous man.

I just have to figure out what's up with the crackly sounds.
Title: Re: MK47 assembly - more pics added
Post by: Sredna on April 09, 2011, 02:15:36 PM
Did you try with another capsule?

Dont try to clean the capsule if there's just some dust on it, you could damage it if you're not very careful.
Just some dust doesn't cause crackles, first when you get a layer with dust and some other things like
tobacco smoke, the contamination starts to leak.

Did you tested breathing at the diaphragm?
Title: Re: MK47 assembly - more pics added
Post by: ioaudio on April 09, 2011, 02:20:48 PM
Be careful Re: cleaning the capsule!
The crackles in your sample sound like a tube during warming up. Leave your mic turned on for 24-48 (or even longer) hours and it should disappear.
thanks for your kind words!
Title: Re: MK47 assembly - more pics added
Post by: kante1603 on April 09, 2011, 02:45:23 PM
Anybody else listen to my sound sample? I've tried two sets of tubes now. Next step is either try another set of tubes or try to clean the capsule (there is a bit of dust on it.) I don't really think it's a bad connection.

I just have to figure out what's up with the crackly sounds.
Hello JW,

I´ve listened to it several times.To me it sounds like a cold solder point or some other bad connection in the audio path (not psu or so).
Can you explain if the crackles occur immediately after turning on the psu or after a while?Maybe it is something about temperature inside the mic when it is warmed up-the pcb will expand (right word?-sorry i´m german...) by some micrometers,it will even bend a bit.If so you might have a hairline-crack somewhere on the pcb.
You can try to use the mic while it is open,listen carefully with headphones and give it some soft(!) kicks or a little pressure to the pcb with something like a match or an other small piece of wooden or of plastic stuff (no conductive material please ;)) and of course you can move all accessible wires.

Move your connection cables too.

Is everything properly grounded?

As said-to me it sounds like "normal" audio crackles and I´m sure you´ll find that out.

Will you please report back when you´re done?

Good luck and best regards from germany,

Udo.
Title: Re: MK47 assembly - more pics added
Post by: JW on April 10, 2011, 03:01:07 PM
Thanks guys.
It's getting better as the tubes age, so I imagine that's the issue. Time will tell.

Max, for verifying voltages, should I be looking for the same voltages in the same spots as on the original U47 schematic?
This is what I'm getting:
1. 105 VDC at B+ (good)
2. 35.7 VDC at the heater (U47 schematic specifies 36V here, so looks good)
3. 1.5 VDC  at the 27R resistor (U47 specifies 1.1V)
4. 5.7 VDC at the capsule backplate (U47 specifies 63V here)
5. 40.7 VDC before output cap (U47 specifies 34V here)

Should the capsule backplate voltage be this low?
Title: Re: MK47 assembly - more pics added
Post by: kante1603 on April 10, 2011, 03:30:39 PM
Thanks guys.
It's getting better as the tubes age, so I imagine that's the issue. Time will tell.

Max, for verifying voltages, should I be looking for the same voltages in the same spot as on the original U47 schematic?

Good to hear!

Udo.
Title: Re: MK47 assembly - more pics added
Post by: Sredna on April 10, 2011, 08:26:44 PM
3. 1.5 VDC  at the 27R resistor (U47 specifies 1.1V)

U47 schematic specifies R3 as 29Ohm

4. 5.7 VDC at the capsule backplate (U47 specifies 63V here)
Should the capsule backplate voltage be this low?

You cant measure voltage with a normal DMM at the capsule, too high impendance.
Measure before R1 (100MOhm)
Title: Re: MK47 assembly - more pics added
Post by: drgrateful on April 11, 2011, 01:08:41 PM
Hello, I'm about to build the PSU. I would like to know:

- What are you guys using for the pattern selection switch?
- What is a suitable led to use for LED1 in the schematics?

Thanks, Matteo

P.S.: for the switch, I was thinking about something nice like the one in the attached picture, but I don't really know where I could find it...

Title: Re: MK47 assembly - more pics added
Post by: ioaudio on April 11, 2011, 02:47:06 PM
JW,

your voltages are OK except:

>> 3. 1.5 VDC  at the 27R resistor (U47 specifies 1.1V) << should be more like 1.2 to 1.3V, probably measurement error?

>> 4. 5.7 VDC at the capsule backplate (U47 specifies 63V here) << as said before, your multimeter is not suited to measure such a high impedance voltage source.

Title: Re: MK47 assembly - more pics added
Post by: JW on April 12, 2011, 01:16:49 PM
Max, you're right. It was actually 1.35V at the 27R resistor.

Also, on the other side of the 100M resistor, the voltage is 55.5 VDC.

So, are these voltages good? The mic sounds great. I'm just wondering how close to the original U47 voltages we should be looking to be.

Now concerning my OTHER MK47, (let's call this one #2) which is only getting noise (both hiss and tube/microphonic/rattling noises):

I'm measuring very similar voltages to MK47 #1, except for right before the output capacitor, which is 48.2VDC (where the original U47 specifies +34VDC, and where MK47#1 measures 40.7V) 

Shouldn't I be hearing the mic working though, if I'm getting voltage right before the output capacitor?
I've re-soldered both the output capacitor pads and all the transformer pads. I even tried bypassing the output cap with another capacitor.
Title: Re: MK47 assembly - more pics added
Post by: Sredna on April 12, 2011, 01:26:49 PM
Check/switch the tubes and check the wiring around the tube sockets.
Seems that the tubes are not drawing any current...
Title: Re: MK47 assembly - more pics added
Post by: living sounds on April 13, 2011, 08:35:13 AM
The mic sounds fantastic! I build mine in an SCT-700 like body with the Beez Neez capsule. Replacing the 10m chinese cable with a short teflon-coated US military copper-silver cable for the audio signal made it sound even better (more high end, clarity). Had some problems with interference but solved that by wrapping lot's of copper wire around the mic side plug. Now the only 'problem' I have is that the mic is sort of noisy, but I guess this is to be expected with a tube mic.

Thanks for a great project! I can't imagine wanting a better sounding mic for vocals and acoustic guitar.
Title: Re: MK47 assembly - more pics added
Post by: madreza on April 14, 2011, 07:47:19 AM
has anybody made a PSU PCB for that mic or not ?
Title: Re: MK47 assembly - more pics added
Post by: Sredna on April 14, 2011, 08:20:42 AM
Not!  ;)
Title: Re: MK47 assembly - more pics added
Post by: kante1603 on April 14, 2011, 08:40:42 AM
has anybody made a PSU PCB for that mic or not ?
Hello madreza,

I don´t think so-do it on veroboard.It´s an easy one-took me 15 minutes ;)
(http://img837.imageshack.us/img837/8264/netzteiloffen.th.jpg)[/URL]


have fun,

Udo.
Title: Re: MK47 assembly - more pics added
Post by: Denyle Guitars on April 14, 2011, 09:43:36 AM
I did mine on turret board and dropped the whole works into an ak47 ammo box. Still looking for a mortar shell for the mic body. ;D
Title: Re: MK47 assembly - more pics added
Post by: drgrateful on April 14, 2011, 01:43:28 PM
I will (partly) answer myself, hoping I won't mislead me  :)

Hello, I'm about to build the PSU. I would like to know:

- What is a suitable led to use for LED1 in the schematics?

Any standard led should work: e.g., you could use this one: http://de.mouser.com/ProductDetail/Everlight/HLMP1700C6A0/?qs=sGAEpiMZZMs4quMj8r4lmqIS%2f%2ftkkeuM0AUUOdksOtY%3d (http://de.mouser.com/ProductDetail/Everlight/HLMP1700C6A0/?qs=sGAEpiMZZMs4quMj8r4lmqIS%2f%2ftkkeuM0AUUOdksOtY%3d)

What are you guys using for the pattern selection switch?
Someone earlier mentioned that a Lorlin switch will do fine. However, a search at Mouser returns 96 matches:
http://it.mouser.com/Lorlin/Electromechanical/Switches/Rotary-Switches/_/N-5g2iZ1z0zlbu/ (http://it.mouser.com/Lorlin/Electromechanical/Switches/Rotary-Switches/_/N-5g2iZ1z0zlbu/)
I am not familiar with these rotary switches, so I could really use some help in the choice... Anyone?

I also found this link good for "inspiration" (even though it refers to the MK7 PSU): http://wiki.nimbleswitch.com/MK7_PSU (http://wiki.nimbleswitch.com/MK7_PSU)
Title: Re: MK47 assembly - more pics added
Post by: Winetree on April 14, 2011, 03:28:39 PM
Wish someone would do a colorbook for the MK47 power supply
it's the only thing that stop me from hearing the built mics. even have the PSU cases.
Thanks for PSU PCB picture. Anything helps.  Looks like I'll venture out
from kitland and  go from scratch. ANY BOM.
Title: Re: MK47 assembly - more pics added
Post by: kante1603 on April 14, 2011, 05:14:22 PM
Wish someone would do a colorbook for the MK47 power supply
it's the only thing that stop me from hearing the built mics. even have the PSU cases.
Thanks for PSU PCB picture. Anything helps.  Looks like I'll venture out
from kitland and  go from scratch. ANY BOM.
BOM?

Look at the first post,there´s a schemo for the psu,all values are written there...just some single parts and a transformer...

The "open" traces simply mean that you have to choose which of the comonents you will use.

So this is what you need for the psu:

1*Mains transformer with a 200VAC secondary,rated at 100mAs
4*Diodes 1N4007,these form the rectifier
3* or 2* resitors,1kohm,5 Watts (if you like to use a choke,here it´s a TRIAD553-C-3x at 10H and 50mAs then you only need 2)
5*capacitors,electrolytic 47uF rated 400V
1* resistor 680 ohms or 300 ohms,5 Watts (you must choose when you´ve measured the output;it´s dependant on the transformer etc.,)
1*resistor 100kohms,1 Watt (pre-resistor for a led if you want one)
1*resistor 2,3kohms,5 Watts (this one is your load when in "test-mode"-it approximately represents the load of the mic while it is not connected as a precaution)
1*resistor 14kohms,1 Watt
1*resistor 12kohms,1 Watt
1*switch,whatever you like and what can handle the voltage (this is for pattern-choice between omni and cardioid)
some normal stuff like a board,some wires,standoffs etc.
1*mains switch,a fuse-holder with fuse (125mAs slowblow recommended)

Udo.
Title: Re: MK47 assembly - more pics added
Post by: Denyle Guitars on April 14, 2011, 05:58:47 PM
I doubt any two psu will look the same. BTW, I used the Triad vtp230-110 mentioned earlier and needed a 1k5 resistor in place of the 680 to get the voltage down. Here's a few shots of mine. It's not pretty but it works.

(http://www.denyleguitars.com/images/mk47psu1.jpg)

(http://www.denyleguitars.com/images/mk47psu2.jpg)

(http://www.denyleguitars.com/images/mk47psu3.jpg)
Title: Re: MK47 assembly - more pics added
Post by: crackerzot on April 18, 2011, 08:55:47 PM
Picked up my P/S today and tried the mic for the first time.  It sounds VERY good.  I've used a lot of high end mics and this is right up there with the best that I've tried.  I went with the Thiersch Blue Line PVC M7 and love the way it sounds.  Lush, warm, and quiet.   Love it.  Thank you Max, for helping me realize a dream I really wasn't sure I could attain.

Title: Re: MK47 assembly - more pics added
Post by: Winetree on April 19, 2011, 01:12:15 AM
Kante1603,
Thanks for the photo of the Perf PSB.
If you could show the bottom of the board, It would help in building one.
Title: Re: MK47 assembly - more pics added
Post by: ioaudio on April 19, 2011, 10:01:49 AM
cool stuff, thanks for your kind words crackerzot!

RE: PSU

Before you plug something to the mains, be sure that it complies to safety.
If you're unsure how to do it, or if it is safe - better get help from someone with experience.
The resistors get HOT - mount them securely, leave some space to the capacitors.
In use, always connect the mic to the psu before power-on.
Title: Re: MK47 assembly - more pics added
Post by: crackerzot on April 19, 2011, 11:32:05 AM
Thanks for the tips, Max.  I'm glad you mentioned the resistors getting HOT, because my friend who built the P/S for me based on your schematic with and noted that they get really hot and wanted me to keep an eye on the P/S to make sure the case wasn't getting too hot to the touch.  The case is warm, certainly, but not too hot to leave my hand on it indefinitely.  I've had the P/S connected to the mic and have had it turned on overnight to let the capacitor and tubes burn-in. 
Title: Re: MK47 assembly - more pics added
Post by: living sounds on April 19, 2011, 12:11:02 PM
In use, always connect the mic to the psu before power-on.


I didn't do that one time, won't happen again, since I got a nice shock from the mic body.
Title: Re: MK47 assembly - more pics added
Post by: crackerzot on April 19, 2011, 01:17:42 PM
Quick question, I'm noticing a very noisy crackling sound while switching the polarity relay.  It's not a huge deal, because when the pattern switches the noise is gone.  It's just during the transition for half a second.  Is this normal operation for the relay? 
Title: Re: MK47 assembly - more pics added
Post by: kante1603 on April 19, 2011, 02:16:10 PM
If you could show the bottom of the board, It would help in building one.

Shure,but as max(ioaudio) said-do not do it on your own when you are not familiar with mains voltages.This is really dangerous and can kill you (no place for joking here!!!).
Here the bottom side,I used nearly all very thick legs of the resistors and massive silver plated wire to form the traces.
With a good amount fo solder it gives an overall stability.

(http://img34.imageshack.us/img34/2441/bottomside.jpg)

Have set it up for testing and left it on for about 2 hours.
As Max said the resistors get hot so take care!Mine are mounted in upright position not only to save space but to give them "air" for a good heat dissipation.This works good when they´re standing free and not touching other parts.Also the pcb will be mounted in a modushop-case which is well ventilated and will have enough space.
Here´s a pic of the working psu-I´m still waiting for my frontpanels but will post when it´s finished.

(http://img808.imageshack.us/img808/1041/psuprototyp.jpg)

Good luck with your build,be carefull and get some help-nothing to feel ashamed here-your health is worth more than anything in the world.....

Best,

Udo.
Title: Re: MK47 assembly - more pics added
Post by: hop.sing on April 19, 2011, 02:48:47 PM
Quick question, I'm noticing a very noisy crackling sound while switching the polarity relay.  It's not a huge deal, because when the pattern switches the noise is gone.  It's just during the transition for half a second.  Is this normal operation for the relay? 
I have no idea of the mk47, but every other mic I own makes a terrible popping noise while switching patterns, so turn down the monitors while doing that, it is perfectly normal.
Title: Re: MK47 assembly - more pics added
Post by: kante1603 on April 19, 2011, 02:55:02 PM
Quick question, I'm noticing a very noisy crackling sound while switching the polarity relay.  It's not a huge deal, because when the pattern switches the noise is gone.  It's just during the transition for half a second.  Is this normal operation for the relay? 
Hello crackerzot,

yes,i think it´s a normal behaviour because all of our condenser mics (e.g.U87s etc.) do so.We are used to turn down the monitor volume first and then switch.

Best,

Udo.
Title: Re: MK47 assembly - more pics added
Post by: JW on April 20, 2011, 02:52:17 PM
Hah! I finally found out what was wrong with my mic. A bad 10nF cap. My fault though. On close inspection I had melted part of it with the iron soldering something else in place. Replaced with a wima and it works. Yay!

Max, do you have any more of those 10nF polystyrenes or could you tell me where to get one of the same brand? I want it to be close to my other MK47 because that one sounds perfect.

Also, this is another question concerning the power supply. Where is the most susceptible part of the power supply to RF interference? I'm getting some of that. Moving the power supply around helps, but I'd like to try and shield the right part if I can. I might have to just go for a total p.s. rebuild after reading a couple of the most recent posts. I have my electrolytics pretty close together. Might want to get them a little more breathing room. By the way, mine is built into a standard military ammo box. Box is closed and I'm still getting unwanted interference. I'm using shielded wire where the audio wires go from the multi conductor cable to the 3 pin XLR connector on their final path to victory.

However, the connections from the p.s. pcb to the pattern switch are not shielded. I imagine this would be the next place to look? For the multi (5) conductor cable, I'm using Canare star quad. It's about 20 ft. long. I don't think this is the issue as that cable has a very nice shielding braid. Part of the reason I chose to use it.

And, 1 more question. . . I'm using a 110V AC neon bulb at the switch rather than the LED in the schematic. This would negate the need for the 100K 1 watt resistor right?
Title: Re: MK47 assembly - more pics added
Post by: hop.sing on April 20, 2011, 03:09:05 PM
I suspect the connection of the cable shielding is the culprit. Do you have it connected to the ground pin and the housing on the mic side and the power supply side?
Just connecting it to one side might not be enough, as I learned the hard way.
Best Tobias
Title: Re: MK47 assembly - more pics added
Post by: crackerzot on April 20, 2011, 03:34:37 PM
Here's a pic of my kit during burn-in yesterday.   :)
Title: Re: MK47 assembly - more pics added
Post by: JW on April 20, 2011, 09:03:27 PM
Hey Tobias,
Yes, the cable shield is connected to ground on both sides. Actually, that's the only way for the mic ground to reach the earth ground because I'm only using 5 conductor cable (including shield). Perhaps I should have a separate ground wire (requiring that I use a different tube mic cable?)
Title: Re: MK47 assembly - more pics added
Post by: Andy Meyer on April 21, 2011, 02:19:04 AM
I am a total newbie and could use some guidance.  I have built my mic and everything is great except that it is noisy.  When in cardioid there is an audible hiss that is constant.  The noise is also there in omni only a lot quieter.  Has anybody experienced this?

In cardioid the backplate seems to be on.  When speaking into the rear of the mic the sound is very bass heavy but just as present as speaking into the front.  The front has clear high end.

I am using the Beez Neez capsule and Tab-Funkenwerk body.  The power supply was designed and built by a good friend of mine.  He designed a regulated supply.  

Even with these issues I can tell that this mic is going to be amazing.

-Andy
Title: Re: MK47 assembly - more pics added
Post by: hop.sing on April 21, 2011, 03:09:26 AM
Hey Tobias,
Yes, the cable shield is connected to ground on both sides. Actually, that's the only way for the mic ground to reach the earth ground because I'm only using 5 conductor cable (including shield). Perhaps I should have a separate ground wire (requiring that I use a different tube mic cable?)
It is uncommon to use the shield as the only ground connection on a microphone, but since you would tie the shield and the ground conductor on both ends of the cable together anyway, I guess it should work, but I maybe wrong, I never tried it.
To test the issue, you could temporarily disconnect the pattern switch conductor and reuse it as a ground connection and see if things change for the better.
It is really important that the connector housings on both sides of the cable are soldered to the shield as well.
Title: Re: MK47 assembly - more pics added
Post by: ioaudio on April 21, 2011, 09:24:44 AM
JW - important - if you ommit the LED connect the 100k resistor from B+ to ground so it works as a "bleeder".
the bleeder drains the capacitors when no load is connected.
I'll send you a replacement 10nF, pls email me a reminder.
Use professional mic cable.

Andy,
how long did you burn in the tubes?
Can you try another capsule?
Title: Re: MK47 assembly - more pics added
Post by: Andy Meyer on April 21, 2011, 12:33:21 PM
Hi Max,

The tubes have burnt in for 50ish hours.  I don't have another capsule that I can try.

Thanks,
Andy
Title: Re: MK47 assembly - more pics added
Post by: crackerzot on April 21, 2011, 02:31:14 PM
I've got a small problem and wonder anyone might have a handle on what the problem is.

When the mic is in omni position, the noise floor is dead quiet.  But when I switch to cardioid pattern, I am hearing a very faint buzz, buried pretty deep in the background, which is why I didn't notice it right away, but it's there.  Any idea what might be causing this?  Again, very quiet in omni, but I hear a low level buzz the second I flip it to cardioid.  I wish it were the other way 'round, because I will be using the mic in cardioid pattern for the most part.

Thanks in advance.

Title: Re: MK47 assembly - more pics added
Post by: Andy Meyer on April 21, 2011, 03:17:39 PM
That is the same problem that I am having. In mine the sound is more of a hiss or wind sound, not a buzz.

Let me know if you figure anything out. I'll do the same.

Andy
Title: Re: MK47 assembly - more pics added
Post by: crackerzot on April 21, 2011, 03:24:52 PM
I've ordered some new tubes to try.  That's where I'm going to start.  I was in error, also.  The noise is still there in omni, but since the level is lowered by going omni, it's just harder to hear.  It's almost inconsequential, this noise, but... not quite...  I've burned in my tubes about 24-26 hours now.  I'm using a Thiersch PVC M7 capsule.  For the most part this thing sounds heavenly...
Title: Re: MK47 assembly - more pics added
Post by: living sounds on April 21, 2011, 03:39:35 PM
Try if you can lower the noise by shielding the plug micside with your hands. I had this problem and solved it with a lot of wire wound around the end of the mic cable.
Title: Re: MK47 assembly - more pics added
Post by: gemini86 on April 21, 2011, 03:58:12 PM
also remember to clean the circuit board of any burnt flux. that can cause hiss as well.
Title: Re: MK47 assembly - more pics added
Post by: madreza on April 21, 2011, 04:15:05 PM
does anybody know how to use a CM-2461NiCo  in MK47 ?

( I just wanna compare ..... )

The problem is that I have 4 wires ..... and the tranny on the MK47 has 8 pins !
Title: Re: MK47 assembly - more pics added
Post by: crackerzot on April 21, 2011, 04:30:27 PM
Try if you can lower the noise by shielding the plug micside with your hands. I had this problem and solved it with a lot of wire wound around the end of the mic cable.

This made no difference.  The noise I'm getting is very, very hard to hear and basically buried in the noise floor, but it's there and I need to address it.  I'm thinking it just might be one of the tubes. 
Title: Re: MK47 assembly - more pics added
Post by: living sounds on April 21, 2011, 04:36:55 PM
Try if you can lower the noise by shielding the plug micside with your hands. I had this problem and solved it with a lot of wire wound around the end of the mic cable.

This made no difference.  The noise I'm getting is very, very hard to hear and basically buried in the noise floor, but it's there and I need to address it.  I'm thinking it just might be one of the tubes. 

Use a spectrum analyzer to determine what you're up against. I had noise in the audio band (fixed as described) and out of the audio band (fixed with a proper PSU enclosure).
Title: Re: MK47 assembly - more pics added
Post by: crackerzot on April 22, 2011, 12:00:36 PM
I've isolated the noise to the P/S.  When I unplug the mic, I can still hear the hum/buzz/whatever at a very low level.  It might be the orientation of the toroidal transformer or it could be something else.  My friend who built it for me is going to troubleshoot and fix it.  Glad it isn't the mic! 
Title: Re: MK47 assembly - more pics added
Post by: kante1603 on April 22, 2011, 02:01:40 PM
I've isolated the noise to the P/S.  When I unplug the mic, I can still hear the hum/buzz/whatever at a very low level.  It might be the orientation of the toroidal transformer or it could be something else.  My friend who built it for me is going to troubleshoot and fix it.  Glad it isn't the mic! 
Hmmm...the pic is very dark,I can´t see much,but all of the ac wires including audio should be twisted and shortened to a propper length.Untwisted ac wires will generate magetic fields which can then be picked up by the audio wires;you feed this into a high gain circuit (your mic pre).You´ll notice this as hum.
Some more things left where we can look at,but only if we can see anything.
Maybe you can take some more with a flashlight from different perspectives?

Best,

Udo.
Title: Re: MK47 assembly - more pics added
Post by: crackerzot on April 22, 2011, 02:06:45 PM
Thanks very much for that info.   ;)
Title: Re: MK47 assembly - more pics added
Post by: kante1603 on April 22, 2011, 02:17:21 PM
Thanks very much for that info.   ;)
You´re welcome.
And another thing-where are you located?Not for finding you :D but is it 50 or 60 Hz-country?
Just asking because if you hear 50(60) Hz the hum comes from before the rectifier,if 100(120)Hz is heard it´s after it then.
Looking at your pic I guess it´s before...mainly thinking of the wires to and from the trafo/power switch.

Best,

Udo.
Title: Re: MK47 assembly - more pics added
Post by: JW on April 22, 2011, 03:07:43 PM
Can someone theorize on why not to use Canare star quad cable? The 4 conductors are 22awg copper. And the shield has a very tight braid. What is the reasoning for needing an extra ground wire?
Title: Re: MK47 assembly - more pics added
Post by: gemini86 on April 22, 2011, 03:32:22 PM
You've run all the current THROUGH the shield, which could be injected into your audio.
Title: Re: MK47 assembly - more pics added
Post by: kante1603 on April 22, 2011, 05:43:26 PM
Can someone theorize on why not to use Canare star quad cable? The 4 conductors are 22awg copper. And the shield has a very tight braid. What is the reasoning for needing an extra ground wire?
I haven´t heard of why not to use starquad-maybe I missed something here,but I´m too lazy to search at the moment.
I have heard somewhere arround here that somebody uses starquad.
Will give it a try on my build as I have a big spool of Gotham Audio Starquad cable.
I don´t see a reason for an extra ground wire as-looking at the schemos and on the pcb-the ground has direct connection to 0v and the microphone-housing via the mounting rails.
Compared this to my original SM69´s psu some minutes ago.The audio grounds,the psu´s 0v and the backplate(where the connectors go)-so the chassis- definetely connect to each other at one screw as to the mic-housing.
Still waiting for my frontpanels so I can´t tell if this works at the moment,but I´m pretty shure it will ;).
Someone here mounted the pcb with cable ties-this can cause problems if no ground-wire runs/connects to the mic body.
You've run all the current THROUGH the shield, which could be injected into your audio.
Yes,but this is dc current-if there´s no ripple then there´s nothing to inject to the audio.
Even if running a seperate wire for grounding:what to do with the cable screen?It must connect somewhere and this will be the chassis ground connected to 0v and so forth....if it doesn´t connect anywhere it is useless.
And something else.In a phantom powered mic the current runs through the shield too!

Best,

Udo.
Title: Re: MK47 assembly - more pics added
Post by: ioaudio on April 23, 2011, 12:49:23 PM
for those interested, new batch is in: http://www.groupdiy.com/index.php?topic=35667.0
Title: Re: MK47 assembly - more pics added
Post by: Andy Meyer on April 23, 2011, 05:24:08 PM
I just replaced the tubes in my mic and I am getting the same "wind" sound that I described in my earlier post.  The "wind" sound is much more noticeable in cardioid.  Does anybody have any ideas?
Title: Re: MK47 assembly - more pics added
Post by: crackerzot on April 23, 2011, 11:51:25 PM
Andy,

Any chance of you posting a sample of your audio?  I'd like to hear what this "wind" noise sounds like.
Title: Re: MK47 assembly - more pics added
Post by: gemini86 on April 24, 2011, 12:45:20 AM
Can someone theorize on why not to use Canare star quad cable? The 4 conductors are 22awg copper. And the shield has a very tight braid. What is the reasoning for needing an extra ground wire?
I haven´t heard of why not to use starquad-maybe I missed something here,but I´m too lazy to search at the moment.
I have heard somewhere arround here that somebody uses starquad.
Will give it a try on my build as I have a big spool of Gotham Audio Starquad cable.
I don´t see a reason for an extra ground wire as-looking at the schemos and on the pcb-the ground has direct connection to 0v and the microphone-housing via the mounting rails.
Compared this to my original SM69´s psu some minutes ago.The audio grounds,the psu´s 0v and the backplate(where the connectors go)-so the chassis- definetely connect to each other at one screw as to the mic-housing.
Still waiting for my frontpanels so I can´t tell if this works at the moment,but I´m pretty shure it will ;).
Someone here mounted the pcb with cable ties-this can cause problems if no ground-wire runs/connects to the mic body.
You've run all the current THROUGH the shield, which could be injected into your audio.
Yes,but this is dc current-if there´s no ripple then there´s nothing to inject to the audio.
Even if running a seperate wire for grounding:what to do with the cable screen?It must connect somewhere and this will be the chassis ground connected to 0v and so forth....if it doesn´t connect anywhere it is useless.
And something else.In a phantom powered mic the current runs through the shield too!

Best,

Udo.

yes, it's DC current, in that it's traveling from A to B, but at varying currents. The current noise is small, but so is the audio signal. I was just explaining the school of thought there, may not necessarily be a problem.
Title: Re: MK47 assembly - more pics added
Post by: Andy Meyer on April 24, 2011, 01:08:58 AM
I'll post a sample as soon as I can.

-Andy
Title: Re: MK47 assembly - more pics added
Post by: Andy Meyer on April 24, 2011, 02:58:42 AM
Here is a link to a sound file of my problem.  The first part is the mic in Cardioid.  The second part is omni.

http://www.ziddu.com/download/14725165/U47NoiseTest.wav.html
Title: Re: MK47 assembly - more pics added
Post by: kante1603 on April 24, 2011, 05:07:53 AM
Here is a link to a sound file of my problem.  The first part is the mic in Cardioid.  The second part is omni.

http://www.ziddu.com/download/14725165/U47NoiseTest.wav.html
Strange-I hear the background noise and what you describe as "windy",don´t know what that is :'(
But the second part has more subsonics-are you shure that this part is the omni?

Udo.
Title: Re: MK47 assembly - more pics added
Post by: Andy Meyer on April 24, 2011, 10:22:22 AM
The second clip is definitely omni. It has a lot less low end when speaking into it.
Title: Re: MK47 assembly - more pics added
Post by: zayance on April 24, 2011, 10:55:12 AM
Quote
are you shure

I use to make the same mistake, fits the discussion tough haha...
Title: Re: MK47 assembly - more pics added
Post by: kante1603 on April 24, 2011, 11:24:11 AM
Quote
are you shure

I use to make the same mistake, fits the discussion tough haha...
Oooooppss....thanx zayance!Too many microphones surrounding me at work :D :D :D
Title: Re: MK47 assembly - more pics added
Post by: Andy Meyer on April 25, 2011, 05:24:02 PM
I am stumped!

I have now tried new tubes, cleaned the flux off of the PCB and re-soldered a few connections without any luck.

I don't want to be stuck with this wind sound.  Any new ideas?

Thanks for the help so far.

Andy
Title: Re: MK47 assembly - more pics added
Post by: 0dbfs on April 25, 2011, 05:28:56 PM
Have you tried replacing the capsule with a capacitor (I don't know, maybe 40pf?) to see if that isolates the source of the sound to capsule or head-amp?

Best,
jb
Title: Re: MK47 assembly - more pics added
Post by: Andy Meyer on April 25, 2011, 08:20:50 PM
I put in a 39pf capacitor in place of the capsule and the noise is there.  It looks like an issue somewhere in the head amplifier.

I am using rubber rings as a spacer between the plexiglass plate and the capsule mount.  Could this be contributing to the problem?

Maybe I got another set of bad tubes?

Thanks,
Andy
Title: Re: MK47 assembly - more pics added
Post by: ioaudio on April 26, 2011, 10:52:58 AM
Andy,

does the noise disappear in the second after you turn of the PSU before the sound fade`s away?
Is your PSU based on a TL783?
Title: Re: MK47 assembly - more pics added
Post by: Andy Meyer on April 26, 2011, 10:46:28 PM
Max,

The wind sound goes out right with the audio.

The PSU is based on a uA723.

Thanks,
Andy
Title: Re: MK47 assembly - more pics added
Post by: crackerzot on April 27, 2011, 06:21:40 PM
Now I've got a problem...    :-\  Last night, I started getting this weird noise it seemed to start out of nowhere.  Don't know if it's the mic, the power supply or the cable.  I opened up the mic and poked around and everything looks good.  It HAD been working great.  So I'm a little puzzled.  I've probably got about 35-40 hours on the tubes now...  Any suggestions on what this might be?

http://www.megaupload.com/?d=F97JZE7F
Title: Re: MK47 assembly - more pics added
Post by: living sounds on April 27, 2011, 07:26:21 PM
Now I've got a problem...    :-\  Last night, I started getting this weird noise it seemed to start out of nowhere.  Don't know if it's the mic, the power supply or the cable.  I opened up the mic and poked around and everything looks good.  It HAD been working great.  So I'm a little puzzled.  I've probably got about 35-40 hours on the tubes now...  Any suggestions on what this might be?

http://www.megaupload.com/?d=F97JZE7F

No idea about that sound, but how do you get so much bass from that mic? Mine sounds great, but even at close proximity its boxy compared to yours. I'm using the Beez Neez capsule.
Title: Re: MK47 assembly - more pics added
Post by: crackerzot on April 27, 2011, 07:33:06 PM
"No idea about the sound", but how do you get so much bass?  Ha ha.  Well.  I'm using a different capsule than you are, for starters.  Thiersch Blue Line M7 (PVC, not mylar).  And you're going to really hate this, but I wasn't even close to the mic.  Well, a foot away, at least.  So, to answer your question, it's the capsule , the basket perhaps, and the magic of my audio chain. 
Title: Re: MK47 assembly - more pics added
Post by: ioaudio on April 27, 2011, 07:42:30 PM
maybe a interconnection, something with the wiring/soldering/isolation of the highZ part.
Sometimes mechanical stuff, the grounding/conductivity between housing parts can bring up all kind of wired sounds.

Title: Re: MK47 assembly - more pics added
Post by: living sounds on April 27, 2011, 07:45:42 PM
"No idea about the sound", but how do you get so much bass?  Ha ha.  Well.  I'm using a different capsule than you are, for starters.  Thiersch Blue Line M7 (PVC, not mylar).  And you're going to really hate this, but I wasn't even close to the mic.  Well, a foot away, at least.  So, to answer your question, it's the capsule , the basket perhaps, and the magic of my audio chain.  

I don`t think it's the M7, I've got mics with M7's in them that don't sound like that either. I've also got a reskinned M7 on its way to me that I might try in the mic, but highly doubtfull about the impact on the bass. So what was in that chain? :-)
Title: Re: MK47 assembly - more pics added
Post by: crackerzot on April 27, 2011, 07:47:18 PM
maybe a interconnection, something with the wiring/soldering/isolation of the highZ part.
Sometimes mechanical stuff, the grounding/conductivity between housing parts can bring up all kind of wired sounds.



Thanks, Max.  Are you talking about the mic or in the P/S?  The real strange thing is that it just started out of nowhere and is intermittent, so it's hard to trace.  Could it be a tube?  I bought some spares.  I suppose I could swap them in and at least eliminate that possibility...  It's the same kind of noise I get when switching the pattern.  ???
Title: Re: MK47 assembly - more pics added
Post by: 0dbfs on April 27, 2011, 07:51:55 PM
... and the magic of my audio chain. 
Man ! Gotta love that fairy dust :)

You should hear what he sounds like standing next to you.

Cheers,
Jb
Title: Re: MK47 assembly - more pics added
Post by: crackerzot on April 27, 2011, 08:00:28 PM
PM sent about the chain.  But I left out one major element in the listing.  My voice.  Sorry.  Heh.
Title: Re: MK47 assembly - more pics added
Post by: Andy Meyer on April 27, 2011, 08:05:01 PM
Could part of my "wind" issue be in the grounding?  If I take off the headbasket and body tube I am left with nothing but buzz.  Is that how it's supposed to be?  Like I said the wind sound is only in cardioid.

Just throwing out questions as I am completely stumped on this.  I am learning a lot though!

-Andy
Title: Re: MK47 assembly - more pics added
Post by: living sounds on April 27, 2011, 08:09:57 PM
Thanks! So you actually EQed some low end in? But, yes, your voice is really low, too. :-)
Title: Re: MK47 assembly - more pics added
Post by: crackerzot on April 28, 2011, 12:31:58 AM
No EQ.  Some compression, though.  Andy, I recently had my basket and tube off my mic when I was troubleshooting a loose connection with the gent who built my power supply, and as I recall, we did NOT get ground hum when the mic was in that state.  I don't know how you mounted the PCB to your mic frame, but make sure nothing is touching any component on your PCB except on the ground planes on the sides.
Title: Re: MK47 assembly - more pics added
Post by: ioaudio on April 28, 2011, 02:05:17 AM
If I take off the headbasket and body tube I am left with nothing but buzz.  Is that how it's supposed to be?

yes that's normal and the bothersome part when troubleshooting a mic - you have to assemble it after each change - or put it in a magnetic shilding box (cheap trick: cash box)
Title: Re: MK47 assembly - more pics added
Post by: crackerzot on April 28, 2011, 04:22:10 PM
Just wanted to let you guys know that I solved my noise problem referenced above and it had nothing to do with the Mk47 kit.  That noise was isolated to an old toggle that was used on the P/S to switch the pattern.  Further up in the thread, I asked if it was common to hear a lot of scratchy pop sounds when switching pattern and was told "yes".  Well, that wasn't quite right.  After hitting the switch with contact cleaner and working it back and forth a few dozen times, all I hear now is one 'audio' "click" when switching the pattern and the random noise spikes are now gone.  Hip hip hooray.  ;D
Title: Re: MK47 assembly - more pics added
Post by: kante1603 on April 29, 2011, 03:16:20 AM
Just wanted to let you guys know that I solved my noise problem referenced above and it had nothing to do with the Mk47 kit.  That noise was isolated to an old toggle that was used on the P/S to switch the pattern.
Hello crackerzot,
congrats for solving the issue finally ;)-this thread is going to be a very good trouble-shooter for everybody here.

Quote
Further up in the thread, I asked if it was common to hear a lot of scratchy pop sounds when switching pattern and was told "yes".  Well, that wasn't quite right.  After hitting the switch with contact cleaner and working it back and forth a few dozen times, all I hear now is one 'audio' "click" when switching the pattern and the random noise spikes are now gone.  Hip hip hooray.  ;D

Maybe my english is still too bad,but as said normally switching patterns do cause some kind of noise like a pop or a click-very short of course and not "scratchy".So some of my mics do more,some less-but they do!But not so loud that the monitors will explode! ;D
Anyway,we´re used to turn the volume down first,then switch.

Have a lot of fun with your new microphone,

best regards,

Udo.
Title: Re: MK47 assembly - more pics added
Post by: ytsestef on April 29, 2011, 07:35:42 PM
Congratulations ioaudio, seems like a very sweet project! I have two questions:
1) Can I make a matched pair? Do I have to match the tubes or what?
2) Can the PSU handle two mics?

Thanks!
Title: Re: MK47 assembly - more pics added
Post by: mrcase on April 30, 2011, 06:48:55 AM
OK. stupid questions maybe but I have to ask! I have sucessfully built my psu  ;D but I am not sure about grounding...
Do you connect the 0v in the PSU to chassis ground or not?
Do you do some kind of stargrounding (like connecting the ground from the power plug, 0v and xlr pin1 together) or is it not necessary?
what happens with the xlr1 ground since there is no pad for audio ground on the mk47 pcb? Just let it float?

thank you all!
can`t wait to hear the mic!

cheers
martin

Title: Re: MK47 assembly - more pics added
Post by: Sredna on April 30, 2011, 09:34:54 AM
So, finally got my MK47 with Beezneez Capsule and Skylar body finished with a mock up PSU.

Sounds pretty good and after +48 Hrs. burn in time there is no pop or crackling noise anymore.

The tubes though, are quite microphonic (sic!) I have tested about 8 different Philips JAN 6028 tubes
without big difference. Some rubber foam around the tubes help some but still got some ringing
and rattling when knocking against the mic body. Suspending the whole PCB is the next step.

Any tips, thoughts?

Thanks Max for a really nice sounding project!
Title: Re: MK47 assembly - more pics added
Post by: madreza on May 01, 2011, 04:52:25 AM
Hi guys,

where did you get your 7 core cables for the microphone ?
and what connector did you use on the PSU side ?
( God Neutriks 7pin are expensive !!!! )
Title: Re: MK47 assembly - more pics added
Post by: Sredna on May 01, 2011, 05:20:42 AM
Sommer cable
http://www.sommercable.com/2__produkte/2__030_meterware/2__200_0186.html

or

http://www.thomann.de/gb/the_tbone_xlr_ersatzkabel.htm


You can use a 5-pin connector, no need for 7 in this case...
Title: Re: MK47 assembly - more pics added
Post by: ioaudio on May 01, 2011, 10:19:25 AM
1) Can I make a matched pair? Do I have to match the tubes or what?
2) Can the PSU handle two mics?

1: Most important
a. capsule matching
b. tubes matching
The Kit an it's parts (esp. transformer and coupling cap) are close enough

2: the passive version cannot be used for two mics.
I recommend using one PSU / mic


RE: microphonics:
If you have a bigger U47 type housing it should be possible to float the whole PCB with rubber mounts inside the rails.
However using a proper shock mount for the mic should solve this problem.
Title: Re: MK47 assembly - more pics added
Post by: ytsestef on May 01, 2011, 09:29:57 PM
Thanks for the answers, ioaudio!!

1) Capsule matching goes without saying, I was worrying about the circuit (transformers etc), glad to know I only have to match the tubes (there is an option to buy a matched pair of RK-47s, has anyone tried this?).

2) I could build 2 PSU's in one box to cut down costs, although I think this would inherit more impracticality than benefits. I guess I'll stick to two PSUs, at least then I could take one on the road :)

Thanks again!

EDIT: One more question, could I use a bridge rectifier instead of 4x 1n4007 for the PSU? If yes, 1.5A / 400V should be ok?
Title: Re: MK47 assembly - more pics added
Post by: babyhead on May 01, 2011, 09:44:17 PM
ioaudio-

I have an extra body from an old run of your mic bodies, the one with the Z grill. Not using an inside caliper, I measure 47.5mm. Earlier you said 48mm was the absolute. Is there .25mm I can sand away or otherwise make magically disappear?

Thanks.
Title: Re: MK47 assembly - more pics added
Post by: ioaudio on May 02, 2011, 08:40:13 AM
could I use a bridge rectifier instead of 4x 1n4007 for the PSU?

sure!

babyhead, the kit fits the tube as is (should actually read 48mm inner diameter)
Title: Re: MK47 assembly - more pics added
Post by: babyhead on May 02, 2011, 04:01:35 PM
Ahh... Magic! Cheap Chinese ruler.
Title: Re: MK47 assembly - more pics added
Post by: mrcase on May 03, 2011, 11:03:01 AM
I did mine like this, color coded the same at each end. I used Gotham mic cable.

Audio
1 = A- (gray) (connects to pin 3 of XLR at the power supply)
2 = A+ (white) (to pin 2 of XLR at the PS)
Center pin = audio ground (green)  (to pin 1 of XLR)

Power
3 = B- (black [blue in the cable])
4 empty
5 = B+ (red)
Pattern
6 = P (yellow)

Shield to the chassis.

Can somebody please explain  me how the shield is connected to the psu chassis? is it also connected to the micbody?
and shouldn´t the shield be connected to xlr1 like with any other "normal" mic cable? and where does the audio ground go to on the mic side????
al lot of questions - i know ;-)

THANK YOU ALL

cheers!
Title: Re: MK47 assembly - more pics added
Post by: mata_haze on May 03, 2011, 01:03:50 PM
Hello everybody,
I am starting this project tomorrow morning.
I have bought a PSU, capsule and body from Beesneez.
the PSU B+ is built around a Tip41 transistor and it uses a couple of zener to set the output voltage.
nominal voltage without anything connected it's 118 VDC.
is it too much ? shall I replace one of the zeners to achieve 105?

Best,
Mattia.
Title: Re: MK47 assembly - more pics added
Post by: madreza on May 05, 2011, 05:56:07 AM
I have a newbie question :

what the choke is for ?
( as I'm waiting for all the last parts to finish my Mic ........ )
Title: Re: MK47 assembly - more pics added
Post by: Sredna on May 05, 2011, 07:21:39 AM
To smooth the ripple.

In some U47N schematics there is a 2 x 8Hy (double) choke, in some there´s just caps and resistors.
Title: Re: MK47 assembly - more pics added
Post by: mrclunk on May 05, 2011, 07:46:16 AM
Speaking of chokes is the value very important?
I've a couple of big ones in some old test gear, i know they'll be able to handle the current but they could be 30H+
bigger is better?

I think i may have to change the resistor values a little for the correct voltages.
Title: Re: MK47 assembly - more pics added
Post by: ioaudio on May 05, 2011, 12:42:45 PM

the PSU B+ is built around a Tip41 transistor and it uses a couple of zener to set the output voltage.
nominal voltage without anything connected it's 118 VDC.
is it too much ? shall I replace one of the zeners to achieve 105?
Maybe the voltage comes down a bit when loaded - you can quickly hook up a 2,2k 5w resistor and check.

The original choke is 2 x 8H wound on the same core - which adds up to 32H in total, but with the capacitor hanging on the center tap it's a bit more complex to simulate what's really going on.
One can use 2 chokes with 16H to come closer to the original.
Title: Re: MK47 assembly - more pics added
Post by: kante1603 on May 05, 2011, 04:30:31 PM
So finally i´m done and my frontpanels for the psu arrived 2 days ago.
Have done a quick check and everything works;it seemed to be a bit noisy but I´ve only had my mBox (1st generation) with a lousy mic pre and a sh***y phoneamp and no reference.Apart from that I´ve got no hum or anything else.There was a small RF-noise when the b+ and b- weren´t fixed to their final positions;they were hanging quite close to the audio lines crossing them.Listening to it while moving them solved this completely!

Burn-In-Time now....

People:Do your wirings carefully as this part is very sensitive;that means shorten them to proper length and where needed twist them.
For those who asked what to do with the pin1 on XLR output:I did mine after AES48 meaning I connected it directly to the chassis right on it´s D-Series connector´s mounting screw using tooth lock washers and eyelet-works perfect.
And for those who don´t believe cabling can be done with starquad:It works!I have done a 10 meters(!) cable with no noticable issues.
I will do some more with sommer cable (sc-octave tube) not because of audio issues but the cable I used is Gotham-Starquad (the thin one)-this is good seeing it electronically but not mechanically.It gets easily twisted and isn´t nice for laying it propperly on the floor.

Here are some pics:
(http://img5.imageshack.us/img5/5365/transformerseite.th.jpg) (http://img5.imageshack.us/i/transformerseite.jpg/)
(http://img571.imageshack.us/img571/1123/rhrenseite.th.jpg) (http://img571.imageshack.us/i/rhrenseite.jpg/)
(http://img810.imageshack.us/img810/7634/psuimtestoffen.th.jpg) (http://img810.imageshack.us/i/psuimtestoffen.jpg/)
(http://img101.imageshack.us/img101/3013/plugo.th.jpg) (http://img101.imageshack.us/i/plugo.jpg/)
(http://img585.imageshack.us/img585/5980/front2fd.th.jpg) (http://img585.imageshack.us/i/front2fd.jpg/)
(http://img694.imageshack.us/img694/4784/einzelteile.th.jpg) (http://img694.imageshack.us/i/einzelteile.jpg/)
(http://img813.imageshack.us/img813/9224/baby1z.th.jpg) (http://img813.imageshack.us/i/baby1z.jpg/)

I used thomann the t.bone sct700 for mic body (is only 149 Euros and comes with case,shockmount,cables etc) and thiersch capsule.
The bodytube has very deep and ugly engravings-filled them with 2k glue and sanded it;after that put on "Hammerite" blue laquer.Done.
PCB fits very well,take care when choosing thiersch:Order the short (52mm) mounts for a good position.

Will post some more pics of the psu if wanted,must take them over the weekend then.

What else can I say than THANK YOU MAX for a great project and THANKS TO ALL OF YOU here in the forum!!!
It was a great experience for me since this is my first DIYed microphone.

Deeply impressed,

yours,

Udo.

P.S.:Oh,did I mention that a second kit arrived two days ago? ;D
 
Title: Re: MK47 assembly - more pics added
Post by: 0dbfs on May 05, 2011, 05:14:59 PM
Awww 680 grams. She's very cute.

And how have you named her?

Cheers,
jb
Title: Re: MK47 assembly - more pics added
Post by: madreza on May 05, 2011, 05:20:25 PM
thanks Sredna for the info ! so it's better to use it !?
Title: Re: MK47 assembly - more pics added
Post by: kante1603 on May 06, 2011, 02:02:26 AM
Awww 680 grams. She's very cute.

And how have you named her?


Hi,
not decided yet because I don´t know if it is male or female maybe "BLU47"? :D :D :D

Udo.
Title: Re: MK47 assembly - more pics added
Post by: Winetree on May 09, 2011, 07:58:14 PM
Looking for a 7-pin chassis mount connector for Grand Master PSU box. Needs to fit the XLR
pre-drilled hole. Any part numbers?
Title: Re: MK47 assembly - more pics added
Post by: Songguy on May 09, 2011, 10:17:46 PM
Hi all,
If someone could put together a psu kit would be happy purchase one. I'm not fully confident building from schematics alone. If someone wants to stuff a psu board I may be interested in purchasing that as well.

Cheers,
Chris
Title: Re: MK47 assembly - more pics added
Post by: Denyle Guitars on May 10, 2011, 08:28:01 AM
Has anyone experimented with different sized mesh? Do you have a favorite or can someone take measurements? I don't have a mic here to measure. I'm putting together a raw materials order for a mic body and the range of wire size/holes per inch is making my head spin. I know the head basket design is a whole different science, I'm just looking for a good starting point. It'll be approx 77mm outside diameter, if that matters.
Title: Re: MK47 assembly - more pics added
Post by: idylldon on May 13, 2011, 12:18:14 PM
I just finished my power supply and it was right at 105 when I fired it up.  There wasn't enough adjustment on the pot (I used a 1K), so I had to use a 1K 5W resistor in place of the 330/670.  That put the adjustment area almost in the center of the pot's travel.  I used the Triad toroid and the choke, and I measure about 3mV of ripple at the output, which seems pretty good.  Since I'm using a found case for the power supply, I now have to disassemble it and give it a nice paint job.  Once that's done and I get my cable and connectors, I'll hook up the mic and give 'er a go.

So far, so good.

BTW, the mesh is discussed in great length in the thread where Skylar is working out the details for his mic body. 

Here are the measurements:

The screening is as follows (from brabb):

Quote
front layer, 0.25cm square
finer middle layer, 0.05cm
inside layer 0.2cm

There might be more discussion about this further along in the thread.

http://www.groupdiy.com/index.php?topic=30742.0

Cheers,
--
Don
Title: Re: MK47 assembly - more pics added
Post by: Winetree on May 13, 2011, 12:55:20 PM
Thanks to Bobine and all his help.
Got my power supply Almost finished. Fired it up and getting 106vdc with pot all the way.
Will replace a 1K with a 1.5K to try and center pot. Just need the 7 pin connectors and some cable.
Wanna hear the mic BAD.

Title: Re: MK47 assembly - more pics added
Post by: Winetree on May 13, 2011, 01:00:38 PM
PSU BOARD
Title: Re: MK47 assembly - more pics added
Post by: crackerzot on May 13, 2011, 01:54:21 PM
So is the 15-20 second warm-up time before audio that I'm getting about what's expected with this mic and P/S combo?
Title: Re: MK47 assembly - more pics added
Post by: idylldon on May 14, 2011, 10:25:00 PM
So is the 15-20 second warm-up time before audio that I'm getting about what's expected with this mic and P/S combo?

Yes.  It takes a bit for the heaters to get the cathodes up to temperature.

Well, I finished my power supply and all the voltages are fine but the fuse blows after about an hour.  It seems thermal related and it happens even when I leave the case open for extra cooling.  Has anyone else experienced this? 

Cheers,
--
Don


Title: Re: MK47 assembly - more pics added
Post by: ioaudio on May 15, 2011, 03:13:14 PM
which fuse do you use? is the transformer getting hot?
Title: Re: MK47 assembly - more pics added
Post by: idylldon on May 15, 2011, 03:21:55 PM
which fuse do you use? is the transformer getting hot?

.125 amp slow blow and the transformer is running pretty cool.  The 5-watt resistors are getting way too hot, though, so I think they're up against their design limit using this transformer and the voltage it's putting out.  I'm going to test the tubes to make sure there isn't a problem there since it seems folks have had some issues with them.  I'll most likely have to get some higher-wattage resistors to cure the problem for good.  

Cheers,
--
Don
Title: Re: MK47 assembly - more pics added
Post by: ioaudio on May 15, 2011, 03:25:36 PM
as per request: feeler for the Mk47 PSU http://www.groupdiy.com/index.php?topic=44296.0
Title: Re: MK47 assembly - more pics added
Post by: ioaudio on May 15, 2011, 03:28:26 PM
which fuse do you use? is the transformer getting hot?

.125 amp slow blow

..which is appropriate for 230 VAC countries - you need to double this value for the US.
Title: Re: MK47 assembly - more pics added
Post by: idylldon on May 15, 2011, 03:50:29 PM
which fuse do you use? is the transformer getting hot?

.125 amp slow blow

..which is appropriate for 230 VAC countries - you need to double this value for the US.

Aha!  I just saw someone posted that value and I wasn't paying attention to the 120/230 voltage difference.  I'll try a 1/4-amp slow blow.  Thanks for the clarification.

Cheers,
--
Don
Title: Re: MK47 assembly - more pics added
Post by: JW on May 15, 2011, 07:02:30 PM
Despite what Udo said, I think the RF issue I'm having is related to the Canare Star Quad cable I'm using, unless I'm grounding things wrong? Can somebody comment on my grounding scheme?

I have the mic's ground (B-, which is also connected to the mic housing) connected to the Star Quad shield, which connects to pin 3 of my 5 pin XLR on the power supply side.

Pin 1 of the output XLR is also connected to this spot. Connected there as well, of course, is the ground from the power supply pcb. The p.s. pcb ground is connected from the spot that Max's schematic says to the chassis.  This spot on the chassis is where the earth ground is connected as well.

Does this make sense?

I think the issue is the star quad because when I move the cable around and listen, the strength of the RF frequencies changes. (I'm moving the cable without moving the power supply or the mic.)

Also, a totally unrelated question: does anybody have a part number or link to some appropriately sized perf board from Mouser?
Title: Re: MK47 assembly - more pics added
Post by: idylldon on May 15, 2011, 08:56:02 PM
Got it all dialed in now.  I decided to put some heat sinks on the resistors and move them off the board so they get as much cooling as possible.  I also put some venting in the case I'm using to house the PS to ensure a bit of airflow.

The mic sounds incredible, very balanced throughout the frequency range and there are no sibilance issues at all.  I think this will become my go-to vocal mic and I can't wait to put it through its paces on some sessions I have booked this week.

Thanks to everyone involved in this project!  You guys are freakin' amazing and I appreciate your efforts immensely.

Cheers,
--
Don
Title: Re: MK47 assembly - more pics added
Post by: drgrateful on May 16, 2011, 03:39:26 AM
Also, a totally unrelated question: does anybody have a part number or link to some appropriately sized perf board from Mouser?

I am using this one: http://www2.mouser.com/ProductDetail/BusBoard-Prototype-Systems/PR2H3U/?qs=VEfmQw3KOavWaKpcqBqhXQ%3d%3d (http://www2.mouser.com/ProductDetail/BusBoard-Prototype-Systems/PR2H3U/?qs=VEfmQw3KOavWaKpcqBqhXQ%3d%3d)

It is larger than needed for this project, but fits perfectly in the Grand Master Audio PSU box. You may want to cut the perf board, depending on how you intend to put the PSU/Choke in the box.

I also have a question: for P1 (the 500R, 5W, pot in the schematics) I would like to use something like

http://www2.mouser.com/ProductDetail/CTS/026TB32R501B1A1/?qs=GxOUx7aO6ny%2fLYTjImZnNQ%3d%3d (http://www2.mouser.com/ProductDetail/CTS/026TB32R501B1A1/?qs=GxOUx7aO6ny%2fLYTjImZnNQ%3d%3d)

or (this is 1K, but should do anyway):

http://www2.mouser.com/ProductDetail/Alpha-Taiwan/VW24F-10-195K-B1K/?qs=sGAEpiMZZMtxdMMi52izynF7ZLtMY%252bzpmAcDgBFEwt4%3d (http://www2.mouser.com/ProductDetail/Alpha-Taiwan/VW24F-10-195K-B1K/?qs=sGAEpiMZZMtxdMMi52izynF7ZLtMY%252bzpmAcDgBFEwt4%3d)

However, this is the only part I am missing and I would prefer not to have to pay 20 euro of shipping fees (this is the Mouser shipping fee to Europe) just for this. Is anybody aware of a source for this part in Europe?
Title: Re: MK47 assembly - more pics added
Post by: Jim50hertz on May 16, 2011, 07:41:34 AM
This one maybe?

http://www.tube-town.net/ttstore/product_info.php/info/p4385_Rheostat-Alpha-1-kOhm---5-Watt.html (http://www.tube-town.net/ttstore/product_info.php/info/p4385_Rheostat-Alpha-1-kOhm---5-Watt.html)
Title: Re: MK47 assembly - more pics added
Post by: drgrateful on May 16, 2011, 11:34:51 AM
This one maybe?

http://www.tube-town.net/ttstore/product_info.php/info/p4385_Rheostat-Alpha-1-kOhm---5-Watt.html (http://www.tube-town.net/ttstore/product_info.php/info/p4385_Rheostat-Alpha-1-kOhm---5-Watt.html)
Thanks, that's just what I needed!
Title: Re: MK47 assembly - more pics added
Post by: JW on May 16, 2011, 07:29:05 PM
Can someone theorize on why not to use Canare star quad cable? The 4 conductors are 22awg copper. And the shield has a very tight braid. What is the reasoning for needing an extra ground wire?
I haven´t heard of why not to use starquad-maybe I missed something here,but I´m too lazy to search at the moment.
I have heard somewhere arround here that somebody uses starquad.
Will give it a try on my build as I have a big spool of Gotham Audio Starquad cable.
I don´t see a reason for an extra ground wire as-looking at the schemos and on the pcb-the ground has direct connection to 0v and the microphone-housing via the mounting rails.
Compared this to my original SM69´s psu some minutes ago.The audio grounds,the psu´s 0v and the backplate(where the connectors go)-so the chassis- definetely connect to each other at one screw as to the mic-housing.
Still waiting for my frontpanels so I can´t tell if this works at the moment,but I´m pretty shure it will ;).
Someone here mounted the pcb with cable ties-this can cause problems if no ground-wire runs/connects to the mic body.
You've run all the current THROUGH the shield, which could be injected into your audio.
Yes,but this is dc current-if there´s no ripple then there´s nothing to inject to the audio.
Even if running a seperate wire for grounding:what to do with the cable screen?It must connect somewhere and this will be the chassis ground connected to 0v and so forth....if it doesn´t connect anywhere it is useless.
And something else.In a phantom powered mic the current runs through the shield too!

Best,

Udo.

yes, it's DC current, in that it's traveling from A to B, but at varying currents. The current noise is small, but so is the audio signal. I was just explaining the school of thought there, may not necessarily be a problem.

Still not sure if Star Quad is my problem. If it didn't cost like $75 to order new cables and connectors, I would just do it, but if I get 7 conductor cable and find out the star quad isn't the problem, that would be a bummer. Would running all the current through my cable's shield inject RF frequencies into the audio?

Does my grounding scheme (a couple posts back) seem okay? Did I explain it well enough?

Thanks for all the help everybody
Title: Re: MK47 assembly - more pics added
Post by: Winetree on May 17, 2011, 03:00:33 PM
Got the 7 pin connectors for mic and PSU.
Can I use Mogami W3172 tube mic cable with 6 wires and shield?
Title: Re: MK47 assembly - more pics added
Post by: idylldon on May 17, 2011, 05:16:03 PM
As per bobine's post,

Quote
Audio
1 = A- (gray) (connects to pin 3 of XLR at the power supply)
2 = A+ (white) (to pin 2 of XLR at the PS)
Center pin = audio ground (green)  (to pin 1 of XLR)

Power
3 = B- (black [blue in the cable])
4 empty
5 = B+ (red)

Pattern
6 = P (yellow)

Shield to the chassis.

Your six wires and shield should be fine.

Cheers,
--
Don
Title: Re: MK47 assembly - more pics added
Post by: JW on May 18, 2011, 01:46:42 PM
Don,
What is the difference between B- and "audio ground?"
Title: Re: MK47 assembly - more pics added
Post by: idylldon on May 18, 2011, 02:00:08 PM
Don,
What is the difference between B- and "audio ground?"

Nothing really.  They both ultimately get connected to the same place; that is, ground.  I attached the audio ground to the B- pad/ground plane in the mic and then ran it to pin 1 in the XLR connector back at the power supply.  My mic has ZERO hum and works flawlessly.

Cheers,
--
Don
Title: Re: MK47 assembly - more pics added
Post by: kante1603 on May 18, 2011, 02:10:39 PM
I attached the audio ground to the B- pad/ground plane in the mic and then ran it to pin 3 in the XLR connector back at the power supply.
You mean pin 1,no?
Best,
Udo.
Title: Re: MK47 assembly - more pics added
Post by: idylldon on May 18, 2011, 02:16:13 PM
You mean pin 1,no?
Best,
Udo.

Yep.  Thanks for the catch.  I corrected my post.

Cheers,
--
Don

Title: Re: MK47 assembly - more pics added
Post by: JW on May 20, 2011, 05:26:50 PM
Okay, just wanted to let you guys know. Try not to use Canare Star Quad cable for this application. I was using a 6 meter cable (20ft.)
and was getting horrible RF interference. I even jerry-rigged a separate ground wire to see if the problem was related to running the current through the shield as speculated earlier.

I finally found in my cable box a 10 ft. strand of Gotham GAC-7 (lucky! I forgot I had it) Problem solved. Albeit, it could be the cable length itself, but a 20ft. tube mic cable shouldn't be a problem, and with star quad it was.

Should've listened to you a long time ago Max!
Title: Re: MK47 assembly - more pics added
Post by: ioaudio on May 21, 2011, 10:59:41 AM
glad that it works  :)
Title: Re: MK47 assembly - more pics added
Post by: Winetree on May 21, 2011, 06:16:02 PM
Just about done with the PSU. Used 3-1k1 10 watt power resistors.
 It puts the adj pot in the center and they run cooler than the 5 watt.
 Looking at the schematic how is the pattern switch wired?
Title: Re: MK47 assembly - more pics added
Post by: bobine on May 24, 2011, 12:00:23 AM
Used 3-1k1 10 watt power resistors.

That's a good idea. I'm about to start my second PS, so I'll try that.

the pattern switch is an SPDT that either puts the relay in the circuit or connects the 12K dummy load.
Title: Re: MK47 assembly - more pics added
Post by: mrcase on May 24, 2011, 06:49:17 AM
Hey all!

I finished my MK47!   Sounds incredible! Really, really good. I´m very happy and satisfied! Thank you Max, Skylar, Grandmaster and everybody!!!!!!
the only thing not working yet is the pattern switch, gotta check that out....

here´s a pic of my finished set:
(https://lh5.googleusercontent.com/-uEo_pE31ma8/TduGJCK5luI/AAAAAAAAACM/g5cHw4p32a0/s912/C360_2011-05-24%2B12-15-46.jpg)
Title: Re: MK47 assembly - more pics added
Post by: crackerzot on May 24, 2011, 03:30:25 PM
Looks great!  Love the box, where did you get it or did you build it yourself?
Title: Re: MK47 assembly - more pics added
Post by: mrcase on May 24, 2011, 04:34:12 PM
thanks! the box is from the beesneez group buy. I don´t know if he sells them seperately...
Title: Re: MK47 assembly - more pics added
Post by: Winetree on May 25, 2011, 03:00:56 PM
Hooked up the mics to the power supply. No load, no glow, no go.
Read the earlier posts. Looks like I'll be lookin for tubes.
Title: Re: MK47 assembly - more pics added
Post by: idylldon on May 25, 2011, 06:11:25 PM
Hooked up the mics to the power supply. No load, no glow, no go.
Read the earlier posts. Looks like I'll be lookin for tubes.

Do you have the correct voltages from the power supply when the mic isn't connected?  It's hard to believe that both tubes have inoperative heaters. 

Cheers,
--
Don
Title: Re: MK47 assembly - more pics added
Post by: Winetree on May 25, 2011, 06:26:10 PM
Yes, many times. 105vdc loaded, 292 vdc unloaded.
First mic loads and adjusts to 105vdc. Pluged in it just hums, no audio.
Second doesn't even load power supply. 292vdc at PSB.
Pulled tubes can only check pin resistance. Ordered 10 NOS tubes.
Title: Re: MK47 assembly - more pics added
Post by: gemini86 on May 26, 2011, 12:47:01 PM
Wow... if I bought tubes every time something didn't work the first power-up, I'd be swimming in them by now. :)
Title: Re: MK47 assembly - more pics added
Post by: bobine on May 26, 2011, 01:36:18 PM
Is the power getting to the mic on the correct wires?  Do you have power at the heater pins?  Someone had a similar problem a few pages back and tracked it down.
Title: Re: MK47 assembly - more pics added
Post by: JW on May 27, 2011, 02:21:28 PM
Yes,
Concerning your problem with the high voltage, (292V) I was getting around that voltage and it turned out it was a bad tube, not loading the circuit.

Funny, I actually had the same problem as with your other mic as well. Adjustable to 105V but no sound other than hum/hiss. This problem turned out to be a bad cap (10nF cap.) I had partially melted it with my soldering iron without noticing, though I imagine your problem in this regard could be one of a number of things. Try resoldering the 90 degree tabs. And look real close at the high impedance area.
Title: Re: MK47 assembly - more pics added
Post by: JoeMorris on May 28, 2011, 05:16:33 AM
Awww 680 grams. She's very cute.

And how have you named her?


Hi,
not decided yet because I don´t know if it is male or female maybe "BLU47"? :D :D :D

Udo.

looks very good mate (although photos are now down!)
i have also bought a t bone 700 for this purpose. do you have any hints/particular issues i should look out for? Did you use the psu case that comes with the t bone?
Title: Re: MK47 assembly - more pics added
Post by: kante1603 on May 28, 2011, 06:19:37 AM


looks very good mate (although photos are now down!)
i have also bought a t bone 700 for this purpose. do you have any hints/particular issues i should look out for? Did you use the psu case that comes with the t bone?

Hello Joe,
thanks for the compliment.I´m really sorry that the photos are gone,I´ll try to upluad them as soon as possible (having an issue at imageshack at the moment-I´ve lost all(!!!) of my photographs there and I don´t know why.But they are all here on my drives so I can bring them back again,piece by piece which will be a lot of work and waiting :'(

O.K.,about the t-bone:There´s less space inside than for example in skylars mic body but it works pretty well.Max´s guide for assembly is very good and I did it the same way.
You will have to be carefull with the small screws-these are weak,so use a very good fitting screwdriver and take some patience.
The big cap I had was fitted with holders having mounting holes at its sides-it is easy to remove them and just file them.
Also I had to slightly widen up the mounting holes on the pcb (with a small drill)-easy job.
I especially like the tube because it is made of steel and easy to sand and laquer.It´s a good conductor from bottom to top and shielding is super-fine.
Don´t know what capsule you will use,I have a Thiersch.I had to use the smallest holder I was able to get;after that the position was nearly exactly as in the original-cool!
About the psu:I used a modushop case;the model is called "Galaxy  Maggiorato",the type I used is "GX-187".Here some links:
http://www.modu.it/frontale_nero.jpg
http://www.modushop.biz/ecommerce/cat037_l2.php?n=1#3
the t-bone housing is much too small thinking about putting in a pcb,a potentiometer,a choke (i used the Triad) and a torroid and taking care of good ventilation (parts on the pcb get pretty hot!).
Apart from all of that I needed a certain amount of super-glue to fix the "flightcase" aluminium-profiles;now it´s fine.
The included shockmount is pretty good,but the cable is bull***t;mine was soldered very bad and had partly missing isolation/shrink tubes.
So I built new ones because the connectors where very cheap ones too.Now I have neutriks.

Conclusio:The t-bone set contains a lot of usefull things and is absolutely worth the money (it´s 149,-Euros here including shipping),getting a case plus shockmount is fantastic...therefore i started to build a second of those babies-putting in a "real" microphone is a lot of fun;the result is an awesome sounding mic.

Well,i think that was all for the moment,hope to have helped,

best regards from germany,

Udo.

P.S.:Here some pics again:

(http://img806.imageshack.us/img806/4784/einzelteile.th.jpg) (http://img806.imageshack.us/i/einzelteile.jpg/)
(http://img825.imageshack.us/img825/9191/frontplattenbestckt2.th.jpg) (http://img825.imageshack.us/i/frontplattenbestckt2.jpg/)
(http://img837.imageshack.us/img837/8264/netzteiloffen.th.jpg) (http://img837.imageshack.us/i/netzteiloffen.jpg/)
(http://img43.imageshack.us/img43/2372/netzteilseitlich.th.jpg) (http://img43.imageshack.us/i/netzteilseitlich.jpg/)
(http://img541.imageshack.us/img541/5216/front2a.th.jpg) (http://img541.imageshack.us/i/front2a.jpg/)




Edit:Case-type corrected to "GX-187".Pics added.
Title: Re: MK47 assembly - more pics added
Post by: JoeMorris on May 30, 2011, 05:12:58 AM
Thanks for your info Udo,
Should be most useful for my own build, which I hope is as successful as yours! I havent built the psu innards yet but imagined theyd probably be too big for that little psu case, would have been handy though! I am due to have the Beez-neez capsule from the groupbuy (if it ever arrives!) so am a little concerned about the capsule mount I'll get with it now, as I doubt it will be a small one...
Title: Re: MK47 assembly - more pics added
Post by: idylldon on May 31, 2011, 07:18:35 PM
I thought I'd share some pics of my finished build.  Needless to say, I'm ecstatic about how this mic sounds and looks.  I'm debating about building another one because this one sounds so great.

(http://www1.mediafire.com/imgbnc.php/2830b0066c5c94b36d866c3b76d89211d0c734388edb061156c6af5c9d0cc42a5g.jpg) (http://www.mediafire.com/imageview.php?quickkey=f7sgrgr7gbvh5rv&thumb=4)

(http://www2.mediafire.com/imgbnc.php/858f5fc068b2bfebab5e12a69a1f0ba64a414f500611a325448fd851712749045g.jpg) (http://www.mediafire.com/imageview.php?quickkey=rgb5c3x3b3fhfd5&thumb=4)

(http://www4.mediafire.com/imgbnc.php/d41c64715a00655ed199761662636878e6610761072ee9e625412b26388b6acb5g.jpg) (http://www.mediafire.com/imageview.php?quickkey=va7e1nm379hndao&thumb=4)

The PS case has a nice lid that covers the switches, test points, and voltage adjust knob.  When on, the PS is damn near bulletproof.  I love finding these old cases and putting them back in to use.

BTW, my mic has the Bees Neez group-buy capsule and it was well worth the wait.

Cheers,
--
Don
Title: Re: MK47 assembly - more pics added
Post by: mrcase on May 31, 2011, 07:35:56 PM
Uhhh. Nice build. Love it. great idea putting the test points for the voltage on the panel. what kind of connectors are those?

cheers
martin
Title: Re: MK47 assembly - more pics added
Post by: idylldon on May 31, 2011, 07:41:50 PM
Uhhh. Nice build. Love it. great idea putting the test points for the voltage on the panel. what kind of connectors are those?

cheers
martin

Thanks!  They're actually test jacks that I got from my father-in-law when he was cleaning out his garage.  He was a physicist at Hughes and had collected a lot of electronic stuff over the years.  When he moved, I inherited all of it.  These hold the regular diameter probe tips tightly and have a bit of a retro look to them because . . . well . . . they are old.  I used some on my PM670 build as well to make those voltage adjustments easier.

Cheers,
--
Don
Title: Re: MK47 assembly - more pics added
Post by: kante1603 on June 01, 2011, 01:14:00 PM
Hi Don,

congrats to your build-very well done,I love this very robust style.
Good idea putting testing pot and measuring points to the outside with the ability to cover it.

Thumbs,

Udo. ;)
Title: Re: MK47 assembly - more pics added
Post by: Winetree on June 06, 2011, 07:37:03 PM
Got some new tubes. Finally got a pair to work and have  both mics working. Sound Great.
Still having problems with the patterns. Have wired the switch  2 ways and still no true omni.
Only switches front sides of capsule. Omni should turn on both sides. I know I've asked this question 2 times before but what is the correct way to wire up the Pattern switch.
A diagram using the schematic would be best.
Also,  I notice a little difference in gain and sound. Because I don't have a tube tester, I picked any 2-6028's tubes for the two mics.  Would it make a difference to purchase 4 matched tubes for the 2 mics to sound the same.
Title: Re: MK47 assembly - more pics added
Post by: idylldon on June 06, 2011, 09:15:17 PM


A diagram using the schematic would be best.

(http://www1.mediafire.com/imgbnc.php/10bf847a0c588f5a6f8b439f61febfefc1f92163ff5ae1332ced2db3fbc02d0e5g.jpg) (http://www.mediafire.com/imageview.php?quickkey=t49c4ij71y4n4zd&thumb=4)

Basically, you just want to be able to switch from the end of the 14K resistor to either the 12K resistor or the pattern terminal.

Cheers,
--
Don
Title: Re: MK47 assembly - more pics added
Post by: Winetree on June 06, 2011, 10:02:22 PM
Thanks, I'm sure the diagram will help many. That's the way I have it hooked up.
When I flip the switch, I just changes the dominate side to the back side.
Shouldn't both sides be almost equal in volume when in omni?

Title: Re: MK47 assembly - more pics added
Post by: crackerzot on June 16, 2011, 03:38:24 AM
Shouldn't both sides be almost equal in volume when in omni?
No, later U47's addressed this issue, but the earlier U47's  had a discernible drop in overall level when splitting to both sides of the diaphragm.   A level drop is normal operation with these kits when in omni mode.
Title: Re: MK47 assembly - more pics added
Post by: Sredna on June 16, 2011, 06:07:14 AM
What´s the difference in circuit between early and late U47´s?

Title: Re: MK47 assembly - more pics added
Post by: etiefenthaler on June 19, 2011, 12:17:42 PM
Hi,
could you recommend a spdt switch for pattern control and test switch?

thanks a lot
Erich
Title: Re: MK47 assembly - more pics added
Post by: crackerzot on June 24, 2011, 08:33:11 PM
What´s the difference in circuit between early and late U47´s?

Sorry for the tardy reply...  I can't recall with specificity what Neumann did, but something was added to the circuit so that the gain would be brought back to the same level in omni as it was in cardio.  I remember reading about this in a fairly in depth article about U47's not too long ago.

As a small aside, and a shameless plug, I thought some might be interested to know that the M47 kit is being used in a worldwide theatrical promotion campaign right now for the new Disney film "Winnie The Pooh", on commercials now airing worldwide.  I voiced all the commercials that are being aired on radio and TV with my new mic. 
Title: Re: MK47 assembly - more pics added
Post by: androidtube on June 29, 2011, 02:28:17 PM
Sorry guys, is surely already been said, the transformer may be good that you can see the link for the PSU power? Thanks  :)

http://www.tube-town.net/ttstore/product_info.php/info/p2192_Ringkern-Netztrafo-30VA-Preamp.html

Best

Anthony
Title: Re: MK47 assembly - more pics added
Post by: kante1603 on June 30, 2011, 03:51:55 AM
Sorry guys, is surely already been said, the transformer may be good that you can see the link for the PSU power? Thanks  :)

http://www.tube-town.net/ttstore/product_info.php/info/p2192_Ringkern-Netztrafo-30VA-Preamp.html

Best

Anthony
Hello Anthony,

yes-it´s a perfect match.I used them on my builds taking the 230v primary (we´re in germany) and the 200v secondary so you can build it right after max´s schematics.Also there´s an 6.3v secondary;I took it to drive a very nice Fender jewellamp for "power on".

Hope to have helped,

have fun,

Udo ;)
Title: Re: MK47 assembly - more pics added
Post by: androidtube on June 30, 2011, 04:05:19 PM
Hi Udo, thanks for your answer, I is been very helpful.  :)
Title: Re: MK47 assembly - more pics added
Post by: EEMO1 on July 05, 2011, 06:48:23 AM

 how do I find out which alternative choke to triad would be usable?

 i've been looking at this Hammond 157J choke (10H, 65mA, 205ohm, Max oper. voltage 400V).

 the resistance is different to the triad and so I need to calculate a series resistor to match the resistance of the choke-resistor in parallel on the scematic?

 right?
Title: Re: MK47 assembly - more pics added
Post by: Kingston on July 05, 2011, 07:10:06 AM
that choke will work fine. all you need to do is add the difference of resistance to the next 1k resistor. triad is 500 ohm, hammond is 200. That makes the next resistor in line 1k3. or thereabouts.
Title: Re: MK47 assembly - more pics added
Post by: rascalseven on July 05, 2011, 09:45:35 PM
Any USA sources for a 200vac 100mA power transformer for this psu?

I'm talking with Edcor about a simple, open frame psu transformer with these specs, and they can do, but I'm not gonna hassle with them if there is something off-the-shelf somewhere else (unless it's prohibitively expensive).

If there isn't something immediately available, then how about a group buy?  If interested in organizing a group buy please email me at r7fm (at) tx (dot) rr (dot) com, and let me know.  If there's interest, I may move forward.

Peace,

JC
Title: Re: MK47 assembly - more pics added
Post by: rascalseven on July 05, 2011, 09:50:54 PM
Just answered my own question  :P

http://www.antekinc.com/details.php?p=603

Has 6.3v taps, but they can just be ignored.  The current rating and price are quite good.

JC
Title: Re: MK47 assembly - more pics added
Post by: EEMO1 on July 07, 2011, 10:19:08 AM
that choke will work fine. all you need to do is add the difference of resistance to the next 1k resistor. triad is 500 ohm, hammond is 200. That makes the next resistor in line 1k3. or thereabouts.

 thanks kingston,

 about what I also thought... now I know.
Title: Re: MK47 assembly - more pics added
Post by: zayance on July 10, 2011, 05:39:33 AM
Hi Guys, one of you HT specialist could take a look at the PSU layouts i made for this project?
Maybe i've made some rookie mistakes.....
First i wanted to do myself one for radial Caps and using 70um copper PCB board,
and i tought it might help others to have some home etching files,
I know ioaudio proposed his service for pcb layout and or veroboard instruction etc..
So i'm not trying to steal his work here, it's just that i wanted to finish this project soon, and tought of helping out...

It's the copy past of ioaudio's schematic.




(http://img849.imageshack.us/img849/7617/mk47psu.png)

EDITED: Going only with Radial only, as Axial seems really hard to find these days, did a search and not much results.....

Fits Caps of 10/7.5 and 5.08mm Pitch, Max Diameter of 22mm and Resistors of 25mm to 35mm long 10mm Diam or more,


(http://img20.imageshack.us/img20/6620/redrawnradial1075508mmd.jpg)

A PCB version with the help and comments of Kingston and Mr Clunk, thanks to them.
I'll make a final adjustment, and If this works nicely, then i can post the files for people, if ioaudio is ok with that, but use at your own risks!


Files for etching:

http://www.sendspace.com/file/1245x3
Title: Re: MK47 assembly - more pics added
Post by: zayance on July 11, 2011, 09:57:02 AM
Anyone?
I guess it's ok as is, i mean i'm using Eagle so...
But i wanted to have a secong tought.
Anyway i'll be doing one Radial for myself i'll report back...
Title: Re: MK47 assembly - more pics added
Post by: Kingston on July 11, 2011, 10:00:40 AM
looks good to me, both of them. although I don't quite see the point for the separate test terminal, since you achieve the same just by inserting the test load in main B+ out. There's also no point in that separate axial version. It just takes more space and the caps are not easily available, at least in as high quality as radial. The era of axial caps is about over.

[edit]

looking at the radial version in more detail, there might be an issue with the ground path. This kind of autorouted faked "ground plane", might not be optimal. You will not know for sure until you test, but the path of those electrolytic ground points should be in series to the star ground. Now the path is somewhat undefined, and you might get better results with a series ground bus, instead of this autorouter semi ground plane. With this in mind, the axial version looks perfect actually.
Title: Re: MK47 assembly - more pics added
Post by: mrclunk on July 11, 2011, 10:15:37 AM
I'd add that perhaps those radial caps are a touch close to the 5w resistors which will get fairly hot. Maybe give'em a more little air!
edit:
hold on have you changed the radial version? I'm sure those resistors were between the caps before... maybe i'm losing it.
Title: Re: MK47 assembly - more pics added
Post by: zayance on July 11, 2011, 10:24:08 AM
Quote
I don't quite see the point for the separate test terminal, since you achieve the same just by inserting the test load in main B+ out.

Yes true, I'll change to a 3 screw terminal for Pot and Test Load, seems more convenient to have it on screw terminal...

Quote
looking at the radial version in more detail, there might be an issue with the ground path. This kind of autorouted faked "ground plane", might not be optimal. You will not know for sure until you test, but the path of those electrolytic ground points should be in series to the star ground. Now the path is somewhat undefined, and you might get better results with a series ground bus, instead of this autorouter semi ground plane. With this in mind, the axial version looks perfect actually.

Yes i see what you mean, hmmm i'll try to redo one radial with a series ground bus.

Quote
I'd add that perhaps those radial caps are a touch close to the 5w resistors which will get fairly hot. Maybe give'em a more little air!
edit:
hold on have you changed the radial version? I'm sure those resistors were between the caps before... maybe i'm losing it.

Yes Edited the pic, and you're right a little air would be better sure...
Resistor sizes are 21*10 (22.5mm pitch)

Thanks for the feedback guys. I'll repost a "better grounded" Radial for you guys to have a look


Title: Re: MK47 assembly - more pics added
Post by: zayance on July 11, 2011, 11:28:52 AM
Allright redrawn a Radial, i had time so i did it right away.

Stayed on the GND Plane, because beside the fact that it's easier for a Rookie like me, even if this one is pretty straight forward, it's that it saves the etching bath to have less copper to take away, so my preference as a home etcher goes to Gnd Plane, but i made it like the Axial, and Resistor have a lot more space.



EDIT: PCB on top
Title: Re: MK47 assembly - more pics added
Post by: Kingston on July 11, 2011, 01:47:58 PM
Hi, that ground path looks better. I still don't quite see the point for that separate "test" terminal slot. I mean, it's the exact same thing as putting a resistor between ground and 105V output so why not just use that for testing as well. Also, it seems that the autorouter has left some very thin traces of unnecessary ground "planes" between some traces and in some corners. It would be a safer and more error proof PCB if you cleaned those up. Actually, looking at it more, it seems that the autorouter has even failed in several places. R7 in that bigger caps version has a dangerously thin ground path. Similarly the led in the smaller caps version is hanging by a thread.
Title: Re: MK47 assembly - more pics added
Post by: zayance on July 11, 2011, 02:40:14 PM
Edited and redrawned/cleaned the bigger Caps version.
I'll do the same for the other one if this version looks better.
For the Test Terminal, of course doing as you said is possible, i just tought makin it external and imbedded would make it easier for the less experimented ones?
Anyway i took it out here, saves space....
Title: Re: MK47 assembly - more pics added
Post by: Kingston on July 11, 2011, 02:50:57 PM
Looks good now. Instead of having a separate small caps version, maybe you could just accommodate different size electrolytics on this one PCB? The difference in size is small enough that you might as well always etch the bigger one.
Title: Re: MK47 assembly - more pics added
Post by: zayance on July 11, 2011, 02:57:18 PM
Looks good now. Instead of having a separate small caps version, maybe you could just accommodate different size electrolytics on this one PCB? The difference in size is small enough that you might as well always etch the bigger one.

Yes of course i can add on top a different pitch version as well, i did that on first drawing of the axial one, but that was too much space for nothing.
Adding on top makes the pads hard to know where to drill, going from 10mm to 7.5mm, the holes are blended, but maybe i could make a Cap that will have better view of the different hole places, i'll try that, doable i think.

I've actually did just on slight mod on this one, i changed the Two Pattern resistor terminals to be more "clear" to the outside connection, 14k beeing in the middle of the switch....

Thanks for the Help Kingston.
Title: Re: MK47 assembly - more pics added
Post by: mrclunk on July 13, 2011, 06:36:41 AM
PSU PCB looks nice Z.

I'm almost finished building my mic but have a question about capsule mounting.
I'm using Skylar's body with the Beez Neez capsule + holder.

Skylar's body comes with a clear chunk of plastic attached where the capsule mounts.
Do i need to screw the capsule mount on top of this or can i just mount the capsule straight onto the metal top plate?

Will the rubber shock mount of the capsule holder isolate the capsule from the body enough?
I remember reading in an other thread a while ago that the material used to isolate the capsule is important.
thanks

EDIT: Ha, If i'd just read Skylar's manual for his body...
The clear plastic part is just for use with the Thierch capsule holder, so the capsule is at the same height as a real U47.
http://equinoxsystems.net/support/manuals/
Title: Re: MK47 assembly - more pics added
Post by: Jim50hertz on July 14, 2011, 04:00:14 AM
The height of the K7 capsule mount was calculated for using the clear plastic mount.  Designed to be optimum in Skylar's mic body.
Title: Re: MK47 assembly - more pics added
Post by: mrclunk on July 14, 2011, 05:33:12 AM
oh really, ok thanks. I'm going to mount it and turn her on tonight.  :)
I've a cheap capsule out of an SE2000 mic to test it with first.
Its a single sided capsule but that won't matter for testing purposes right? Just keep it in cardiod?
Or is a 47pf cap in the right ball park for testing?
Title: Re: MK47 assembly - more pics added
Post by: ioaudio on July 15, 2011, 03:07:20 PM
unfortunately all the pics are down at the moment - i'm just back from vacation and will look into that asap.
Title: Re: MK47 assembly - more pics added
Post by: kante1603 on July 15, 2011, 03:11:35 PM
unfortunately all the pics are down at the moment - i'm just back from vacation and will look into that asap.
Welcome back Max ;D
Udo.
Title: my mk47
Post by: etiefenthaler on July 15, 2011, 03:33:23 PM
Hi


Finished my mk 47 today.

Components:
capsule: ck 12 delrin (leftover from akg 414 upgrade)
ioaudio kit - thanks a lot max :)
thomann sct 700 micbody
gotham cable 10m
mouse+ tubetown parts for powersupply
binder connector.

Powersupply: (took me a day)

(http://www.flutemusic.ch/pic%207.JPG)

modified sct 700 micbody. Soldered the bottom and the tube and gave a hammerite finish. For mounting the binder connector I had to use my lathe.

(http://www.flutemusic.ch/pic%206.JPG)

parallel 2m ohm resistor for 80v
(http://www.flutemusic.ch/pic%205.JPG)

(http://www.flutemusic.ch/pic%204.JPG)

(http://www.flutemusic.ch/pic%203.JPG)

first testrun  :( horrible sound and 80 % hum 
#1 Due to my hameritefinish the tube had no contact to mesh - part
#2 the binderconnector touched the brass block

after 2 hours of "dremeling" all was fine :)
(http://www.flutemusic.ch/pic%202.JPG)

First testrun at my Studio. My first impression:
the sound is bright but not harsch.  The different impedances of my isa 828  affect this mik much more than my other mics. (schoeps, akg414)
Building the microphone took me two days.
(http://www.flutemusic.ch/pic%201.JPG)


Again, thanks a lot max and group diy.

Looking foreward using this mic at my studio.  ;D

Erich T.
Title: Re: MK47 assembly - more pics added
Post by: ioaudio on July 15, 2011, 05:00:32 PM
great work udo - did you use the linear CK12 or the treble-hyped version?
pls check heat in your PSU after running for a couple of hours.

pics are back up again - let me know if something is missing.
Title: Re: MK47 assembly - more pics added
Post by: kante1603 on July 15, 2011, 05:10:04 PM
great work udo
Max,I think you swapped our names:This is Erich´s work,not mine!

BTW:Congrats Erich!

Udo ;)
Title: Re: MK47 assembly - more pics added
Post by: etiefenthaler on July 15, 2011, 07:20:52 PM
@max
it is the linear of my 80's 414buls tl.

had the psu and mic running until now (4 hours) heat is no issue :)  used 10 W resistors ..

again thanks a lot. building was a pleasure.

Erich
Title: Re: MK47 assembly - more pics added
Post by: living sounds on July 19, 2011, 11:09:11 AM
Anyone else build the mic with the Beez Neez capsule? I like the sound of my mic a lot, but it really doesn't produce a lot of bass. Is this how it's supposed to sound? I shot it out against a Gefell M71, and the latter has a little more low mids and less high end (and doesn't sound quite as smooth and silky and tube-y), but otherwise is pretty similar in frequency response. This is using the mic in cardioid mode, of course.
Title: Re: MK47 assembly - more pics added
Post by: ioaudio on July 19, 2011, 11:37:36 AM
sorry for the mix-up udo/erich!

living, do you use a capsule from the group-buy?  Maybe try connecting the Gefell capsule with the MK47 amplifier for a direct comparison?
Title: Re: MK47 assembly - more pics added
Post by: ioaudio on July 19, 2011, 11:59:48 AM
btw, i have a summer special sale on the mk47 kits - pls check the white market.
Title: Re: MK47 assembly - more pics added
Post by: living sounds on July 19, 2011, 12:22:21 PM
sorry for the mix-up udo/erich!

living, do you use a capsule from the group-buy?  Maybe try connecting the Gefell capsule with the MK47 amplifier for a direct comparison?

I won't risk that, but if someone I send a capsule two years ago for reskinning finally returns it to me I will check it with that capsule. :-)

But there should be other people who build it with the Beez Neez capsule, how much bass do you get out of the mic?
Title: Re: MK47 assembly - more pics added
Post by: zayance on July 19, 2011, 01:34:01 PM
Sory to hijack  :-[

redrawn the board to fit bigger resistors as well (on p.19), better to have some Choices on the resistors side also, so will fit most 5W to 7W resistors, as well as some of the 10W, depends on their pitch of course, but it's always good to have those resistors a little over the PCB, so possible to bend the legs anyway....
Waiting for the power transformer and will test drive, but i"m sure it will work as suppose to anyway....


Title: Re: MK47 assembly - more pics added
Post by: mrclunk on July 21, 2011, 12:02:08 PM
Anyone else using the Tube Town transformer having an issue with in-rush current?
I keep blowing T125mA fuses... If i stick a 250mA fuse in its fine.

Pretty sure its not my wiring, every thing seems fine.
I'm using a much bigger choke than necessary  could that cause the psu to draw more current?

What are the little gadgets that you can add before a transformer to suppress in-rush currents?

edit: The quiescent current while on measures 60mA so it must just be in-rush, my DMM doesn't catch the current peak. (or the fuses i bought are faulty?)
Title: Re: MK47 assembly - more pics added
Post by: idylldon on July 21, 2011, 12:28:45 PM
Anyone else using the Tube Town transformer having an issue with in-rush current?
I keep blowing T125mA fuses... If i stick a 250mA fuse in its fine.

Are you using slow-blow fuses?  That's what I used in mine to accommodate the inrush current.

Cheers,
--
Don
Title: Re: MK47 assembly - more pics added
Post by: mrclunk on July 21, 2011, 01:05:03 PM
Yeah, i used slow blows, think the fuses must be marked wrong seeing as that's the point of slow blows...
I noticed a current spike of 160mA a minute ago when i turned on btw.
Title: Re: MK47 assembly - more pics added
Post by: gary o on July 21, 2011, 03:40:35 PM
I cannot get rid of popping a cracking sounds on this mic.....Ive re built it re wired it  tried all sorts but I cant find the problem......only thing I can think of is a or both tubes.......anyone have problems with the  tubes ?....

Thanks
Title: Re: MK47 assembly - more pics added
Post by: mrclunk on July 22, 2011, 07:35:31 AM
Success! :)

Turned on this morning and it didn't go bang. Sounds nice, certainly full bodied.

Omni's not 100%, sounds like the back is slightly louder than the front, but need to test further.

Lots of very intermittent pops but i'm hoping this is just the tubes burning in. Apart from that, very quiet.
Like others have said its pretty microphonic but maybe with a decent shock mount this will be ok.
Anyone noticed how the elastic strings in new shock mounts are always way too tight to absorb much. Give me a perished oldie anyday.
I'll get some some pics up soon.
thanks
paul
Title: Re: MK47 assembly - more pics added
Post by: idylldon on July 22, 2011, 11:54:18 AM
Like others have said its pretty microphonic but maybe with a decent shock mount this will be ok.

This is caused by the tubes.  These tubes are dead cheap so stock up on some and change them out until you find a nice quiet pair.  My mic is dead quiet and isn't microphonic at all.  Remember, all the major mic mfgs. back in the day (Neumann, etc.) screened the tubes for microphone usage and only the best/quietest ended up in their mics.  My guess is they rejected a lot even then.   There's no reason to have a microphonic problem in a mic of this caliber.

Cheers,
--
Don
Title: Re: MK47 assembly - more pics added
Post by: gary o on July 27, 2011, 06:33:13 PM
This thing is driving me insane it wont stop popping cracking farting......trying allsorts to find the cause ....A weired thing happend, I sprayed some switch cleaner on the around the board & tubes sockets & now there is purple liquid coming from a tube socket....its like ink,  the switch cleaner is clear.......

My 1uf capacitor that goes to the O/P tran is getting quite warm......I have 45 volts on the tube side of it......is that ok ?
Title: Re: MK47 assembly - more pics added
Post by: gary o on July 28, 2011, 07:28:23 AM
Think Im having some bad luck.......reading back on other DIYers problems I seem to have them all.....the pops & cracks wont go away.....the only thing I can think is its the tubes, il have to try n get some others to try.....I lost full response turned out to be my 10 nf capacitor went dead I replaced it with same value got full sound back.....the large 1 uf cap was getting quite warm I have 45V on the plates , I read back in this thread that should be ok......mine gets warm tho .....does anyone else notice this ? on inspection the terminals are dis colouring, i think its been leaking.....it also stinks a nasty smell.....I thought this must be the cause of the pops n crackles.......NOOooo sadly but have stuck a 1uf 250V poly there which stays cool....inbetween all this the mic sounds good..........
Title: Re: MK47 assembly - more pics added
Post by: bruno2000 on August 02, 2011, 01:24:43 PM
Just finished building up one of these, but the output level seems really low.  Any ideas?  What mic should I compare it to as far as output level?
Thanks in advance!
Best,
Bruno2000
Title: Re: MK47 assembly - more pics added
Post by: Jim50hertz on August 02, 2011, 04:38:10 PM
Finished building mine today.  Sounds incredible! Thanks Max for providing such an accessible route to DIY mic heaven. :)
Title: Re: MK47 assembly - more pics added
Post by: JoeMorris on August 12, 2011, 08:24:24 AM
Finished mine, all works - except pattern switch which I haven't wired up yet due to lack of a 14k resistor - and sounds very nice (LOADS of bass, this thing is big all the way down in a way I've not experienced with my cheap mics). 

For the moment, while I try to source a 5W trimmer for the PSU, I just tried to get as close as I could with fixed resistors that i had, it is currently running at around 102V with the mic plugged in but it seems to work fine, I can only presume of course that 105V is where you will be getting optimum performance, but I have nothing to compare the sound with.

What effects should running it at 3%-ish below specced voltage have? Will it affect the sound much? I plan to finish the psu to spec when i can, but it would be good to know.
Title: Re: MK47 assembly - more pics added
Post by: ioaudio on August 12, 2011, 01:04:24 PM
...but the output level seems really low. 

reading what you posted on the capsule thread i think your problem is solved now?

>>Finished building mine today.  Sounds incredible! Thanks Max for providing such an accessible route to DIY mic heaven.

great, congrats and thanks for the nice words!

>>What effects should running it at 3%-ish below specced voltage have?
thants no problem at all.

-max
Title: Re: MK47 assembly - more pics added
Post by: Andy Meyer on August 15, 2011, 02:22:33 PM
I have now been using my mic pretty extensively over the past couple of weeks and an issue has come up. 

I am getting loud steady pops in the audio path.  The sound resembled when I first was burning in the tubes.  The problem seems to happen at random times.  I have used the mic for hours flawlessly and then all of a sudden the popping starts.  Sometimes it starts popping within 10 minutes of being turned on.

I have tried swapping the tubes out without success.  All of the tubes have been sufficiently burned in.

Things I have tried:

-Steady PSU Voltage at 105.1v
-Visually inspected all solder joints and components for cracks.
-Swapped tubes

I have the feeling that the popping has to do with the mic warming up.  The only thing is that after the popping starts it usually goes away after a while.  Could this be an issue with the capsule?

Thanks,
Andy
Title: Re: MK47 assembly - more pics added
Post by: 0dbfs on August 15, 2011, 02:31:48 PM
Sounds like tube issues.

You can however replace the capsule with a capacitor and test to confirm (I think maybe 40-60pF?) that it's not the capsule. I have also heard of people overheating the tube for a short period of time to refresh and tube. I guess this probably "cleans" the cathode or something. I don't know too much about that procedure but some searches might lend some more detailed info.

Hope that helps!

Cheers,
Jonathan

Title: Re: MK47 assembly - more pics added
Post by: gary o on August 15, 2011, 07:14:28 PM
Andy I have same problems a few posts back on this page .....I havent solved it still....I have just about given up.....had one bad capacitor & I think my oil capacitor is leaking oil  buts its not the cause of my noises.....only thing I can think is a tube or both are bad..... I havent got others to try sadly harder to get in UK.......good luck with yours Andy let us know if you find the cause...
Title: Re: MK47 assembly - more pics added
Post by: nashkato on August 15, 2011, 07:35:03 PM
Quote
   I havent got others to try sadly harder to get in UK
you have seen those ?
  http://cgi.ebay.at/ws/eBayISAPI.dll?ViewItem&item=190401256090&ssPageName=STRK:MEWAX:IT (http://cgi.ebay.at/ws/eBayISAPI.dll?ViewItem&item=190401256090&ssPageName=STRK:MEWAX:IT)
Title: Re: MK47 assembly - more pics added
Post by: Andy Meyer on August 16, 2011, 07:55:50 PM
I tried swapping the capsule out with a capacitor and the popping continues.  At least I know it's not the capsule.

Any other ideas?

-Andy
Title: Re: MK47 assembly - more pics added
Post by: bruno2000 on August 17, 2011, 07:53:21 AM
Just finished building up one of these, but the output level seems really low.  Any ideas?  What mic should I compare it to as far as output level?
Thanks in advance!
Best,
Bruno2000

Problem was with transformer connections.  Both work great now.
Just FYI, the output seems to be a few dB hotter than a U87, but more natural sounding.
Best,
Bruno2000
Title: Re: MK47 assembly - more pics added
Post by: gary o on August 17, 2011, 02:53:02 PM
Thanks Nashkato I may end up trying some....
Glad your sorted bruno2000

Andy here what I tried....sadly didnt work for me but maybe for you.....hope so

I burnt tubes in for 3 days , I thought i had solved it but no the pops came back...
My oil capacitor was getting warm & smells foul , I think it is leaking so I changed it for a modern cap
At one point sound went very thin turned out the small capacitor died , so i replaced that..
tried different capsules...
re soldered all joints...
cleaned tube pins & sockets
swapped tubes round
swapped last remaining capacitor as someone else had a problem with theirs

I need to get power supply checked a friend will help me....
After that il have to buy some tubes to try...

Good luck with yours, be interesting to hear how you get on.....

Title: Re: MK47 assembly - more pics added
Post by: Andy Meyer on August 17, 2011, 03:36:38 PM
I am going to try replacing the 10nF cap.  When I tap on it I can get it to recreate the popping sound that I hear.  It's worth a shot at this point.

I can't imagine how frustrated you must be with all that you have tried.  I am hoping to get mine healthy soon.

-Andy
Title: Re: MK47 assembly - more pics added
Post by: gary o on August 17, 2011, 04:31:12 PM
Thats sounds promising Andy as I said my 10nf totally died , think those caps are nos its also why I suspected my other caps....I kinda given up on the mic for now but I hope you can fix yours.
Title: Re: MK47 assembly - more pics added
Post by: mata_haze on August 21, 2011, 02:12:43 PM
Hello Everybody,
I have built two of these amazing mics and they sound awesome...really incredible.
I have used Ioaudio psu (no regulators just the 5W pot) , beesneez capsule (awaiting substitution of one of the two due to diaphram being glued ...).
They worked at the first shot, the only problem is that when I switch for OMNI I get a loud crackle at the output (on both) and I have no idea what it could be due to.
yes its a crackle (like tube going). I am currently burning them in, they have been on for about 24h now but the noise is still there. they are absolutely fine in CARDIOID.

any ideas?

Mattia.
Title: Re: MK47 assembly - more pics added
Post by: gary o on August 21, 2011, 03:00:04 PM
Switch .....could try removing it & hard wire omni.....
Title: Re: MK47 assembly - more pics added
Post by: mata_haze on August 27, 2011, 07:39:02 AM
Gone,
I left the two microphones on for 48h and now they are as quite as a mouse...
nice!

thank you for the suggestion Gary o.

Best,
Mattia.
Title: Re: MK47 assembly - more pics added
Post by: AW_music on September 01, 2011, 09:13:14 AM
This is our version of the PSU for this incredible MIC !!

(http://img535.imageshack.us/img535/8826/20110824aa.jpg) (http://imageshack.us/photo/my-images/535/20110824aa.jpg/)

(http://img220.imageshack.us/img220/4708/20110825aa.jpg) (http://imageshack.us/photo/my-images/220/20110825aa.jpg/)

Thanks to Mata _ HAze
Title: Re: MK47 assembly - more pics added
Post by: mata_haze on September 04, 2011, 10:44:26 AM
this was a goooood project the mic sounds really really good!
thank you ioaudio for the kit, grand master for the case!
thank you aw_music for the FANTASTIC implementation !

YEAH!

Best,
Mattia.
Title: Re: MK47 assembly - more pics added
Post by: Denyle Guitars on September 07, 2011, 09:15:05 AM
^Totally agree, this was a fun project. I'm still putting on the finishing touches but it passed the burn in and initial audio tests with flying colors.

psu
(http://www.denyleguitars.com/diy/images/mk47psu_1.jpg)

and mic
(http://www.denyleguitars.com/diy/images/mk47_1.jpg)
Title: Re: MK47 assembly - more pics added
Post by: kante1603 on September 07, 2011, 09:41:24 AM
Very well done!!

May I ask what type of resistors (the golden ones) you used?
I also like the idea of building the guiderails of hex metal-standoffs-cool!

Congrats,

Udo.
Title: Re: MK47 assembly - more pics added
Post by: Denyle Guitars on September 07, 2011, 09:55:01 AM
Vishay resistors: http://www.mouser.com/catalog/specsheets/rhnh.pdf (http://www.mouser.com/catalog/specsheets/rhnh.pdf)

Another shot of the mic, to be dubbed the "Stealth Pipe."
(http://www.denyleguitars.com/diy/images/mk47_2.jpg)
Title: Re: MK47 assembly - more pics added
Post by: ioaudio on September 07, 2011, 11:03:37 AM
looks top!
Title: Re: MK47 assembly - more pics added
Post by: etiefenthaler on September 11, 2011, 08:17:55 AM
Hi Denyle Guitars


Nice build !

I am interested in the carbon tube.
Did you make the carbon tube by yourself or where have you bought it?

Erich
Title: Re: MK47 assembly - more pics added
Post by: Denyle Guitars on September 12, 2011, 08:25:22 AM
I found a 2 ft tube on ebay for $10. I was thinking how cool it would be to have a non resonant mic body, then I remembered freshman physics.  :)
Title: Re: MK47 assembly - more pics added
Post by: bobine on September 20, 2011, 01:52:37 AM
My mic has recently begun crackling and popping while warming up and I remembered others here have had that happen. I'd been planning to open it up and remount the PCB so I finally got around to it tonight (I had hung the PCB from the rails with zip ties and wanted to try a more solid arrangement with angle brackets).

When I reassembled everything, the crackling was much, much worse.  I took the mic apart again and hung it up -- sans body -- and explored where it was most sensitive to interference...wow, even a wooden stick around the capsule wires will cause noise...

I noticed that the capsule wires would pass near the body tube when it was assembled so I rearranged them so they'd be well away from any surface. When I put the mic back together again, the crackling stopped a few seconds after it powered up and remained stable.

So I'm wondering if moving the capsules wires would help others with crackling problems. Tomorrow I'll try to deliberately induce crackling to see if the position of the capsule wires really is a factor.
 
Title: Re: MK47 assembly - more pics added
Post by: bobine on September 20, 2011, 02:04:43 AM
I just noticed something strange: My MK47 with Beezneez K7 has an extremely narrow spike at 8165hz (and another at 16330hz). The 8K spike creates a lot of sibilance, though it's not hard to notch out. I noticed it on the Ozone 4 spectrum.

What could be causing this?  It also happens in omni mode. It's definitely the mic and nothing else in the chain. I looked at recordings from six months ago and it is there, too.
Title: Re: MK47 assembly - more pics added
Post by: gary o on September 20, 2011, 05:34:20 AM
Bobine.... hi I have loads popping and cracking ,,,Im not gonna say mine has stopped BUT for now its has gone away after I sprayed switch cleaner over components & scrubbed with cotton bud......dont know if that cured it or if it disturbed something but for now at least its silent.....

I still cant record anything as next door decided to get a F**kin cockerel & it wont shut up .....Im off to buy a gun!

best of luck
Title: Re: MK47 assembly - more pics added
Post by: madreza on September 23, 2011, 01:57:49 PM
Hi Guys

Finished mine, First test , Just a big Hum :)
once fixed the ground problem,
sounds awesome .... ( almost :) )
I have a problem :
the output level is quite low !!!
I have to push the gain really up to get something ( but it sounds good ! )

my PSU voltage is fine
what else can I Check ?

another question :
is there a side on the beez neez capsule ? ( I mean it only depends on how it is wired and any side can be the front or what ??? )


Thanks
Title: Re: MK47 assembly - more pics added
Post by: bpucekov on September 23, 2011, 02:50:37 PM
yes any side can be front
Title: Re: MK47 assembly - more pics added
Post by: madreza on September 24, 2011, 06:14:42 AM
Thanks :)
and what about the low Output level ? anybody has an idea ?
Title: Re: MK47 assembly - more pics added
Post by: zayance on September 25, 2011, 12:30:06 PM
Thanks :)
and what about the low Output level ? anybody has an idea ?

in the thread:

Quote
Just finished building up one of these, but the output level seems really low.  Any ideas?  What mic should I compare it to as far as output level?
Thanks in advance!
Best,
Bruno2000

Quote
Problem was with transformer connections.  Both work great now.
Just FYI, the output seems to be a few dB hotter than a U87, but more natural sounding.
Best,
Bruno2000


Maybe same problem?
Title: Re: MK47 assembly - more pics added
Post by: bobine on September 26, 2011, 01:24:50 PM
Hi Max...  I was wondering if it would be possible to add a "rumble filter" to this circuit. I looked at the U67 and U87 schematics but don't quite understand how to do it.  What are the implications using a HP filter before the amp? It seems quite delicate up there...

b
Title: Re: MK47 assembly - more pics added
Post by: gary o on September 28, 2011, 07:46:36 AM
I think I just about throw the towel in .....I simply cannot stop this mic from cracking & popping ....I bought 10  nos tubes but still pops with those I replaced all the caps, powers supply is silent with other mics....I thought I solved it after cleaning the board & components one more time the noises stopped for a good while, last night I sat working for hours on the PC listening to the mic for noises silence was golden, yet today I record 1 verse of a song & its starts & doesnt stop! I give up....

Question is the transformer ratio the same as a real BV8 & was that 12:1 ? Im thinking of using this tranformer for another mic C12 style or Royer I wonder if would work....

Thanks
Title: Re: MK47 assembly - more pics added
Post by: bobine on September 28, 2011, 10:33:25 AM
Hi gary o... maybe if you posted photos someone would see something... the capsule, the top bits, the replaced caps. Which capsule and body are you using?

You said the crackling started when you began to use it. Is the crackling triggered by sound?

Also, how were you able to test the power supply with other mics?

I get a brief bit of crackling as it warms up but then it becomes stable. I have a second MK47 ready to swap in when I find the time. I absolutely love this mic. It seems a shame to give up on it. 
Title: Re: MK47 assembly - more pics added
Post by: gary o on September 29, 2011, 06:44:33 AM
Thanks bobine ...The cracks are not triggered by sound..... they seem totally random, they can start at any time I have had hours of silence, hours of silence with one or two cracks, Ive hours of cracking & nothing else....

The noises can be fairly quiet but more so really violent & often in sustained attacks as if dragging the HT lead all over the circuit sounds terrible.

I had a tech friend check over the mic & solder joints & also the power supply he found nothing wrong I suggested it could be a capacitor......I have already replaced the 3 capacitors, the small first died....the paper oils smell strange & seems to ooze a little oil I guess... also was getting warm.....I thought this was my problem but no....I replaced the other 1 uf anyway

The power supply I made I can produce 120V via switch I use it to power AKG C28A & a SP TB1(C12 ish) I made from scratch.....

The MK47 is in a large metal can for now not a real mic casing I have a violet vin 67 lollypop fitted I have also tried a lomo lollypop a Oktava MK101 head, ADK Vienna head & a RK47 capsule with solid tube grill......I have other expimental mics made this way SP Tb1, Ela M250, sony C37A, G7 havent had a single crackle from any of them.....

Sadly its gettiing messy where i have swapped components so many times now ......my best spell of silence came after spraying switch cleaner over board & components & cleaning with cotton bud......but this even could be coincedence ....the pops came back I clean again & so on....

I had to leave the thing alone for now as I will break it the next time it cracks.. Iv took the lolly off it and disconnected it from the PSU as it was hard wired.....If i get inspiration and patience I might have another go.......I might just take it completly apart and re assemble point to point like my other mics....next time I order from farnell I will order knew resistors......

last night I made a very quick royer circuit point to point worked first go no pops & crackles



Title: Re: MK47 assembly - more pics added
Post by: nashkato on September 29, 2011, 07:23:01 AM
when building my first G7 i had the same problem .
(i build it on pertinax perfboard though )
the crackling just wouldn´t stop.and was about to throw the f****ing thing into the trash.
i got a can of this and use it since then with best results.
  http://at.rs-online.com/web/p/reinigungsfluessigkeiten/4586980/ (http://at.rs-online.com/web/p/reinigungsfluessigkeiten/4586980/)
(sorry don´t have an english link here , this is actually a destinated pcb cleaner.)
(the G7 never worked on pertinax though )
maybe your cleaner leaves residue on the pcb ?
you made sure to clean the brown pieces of flux , they don´t come off with cleaner and cotton buds ?
(i dont´use Q-tips , they tear up , i use old toothbrushes)

since then all my G7´s and the Mk47 worked from the start without any popping or crackling.







Title: Re: MK47 assembly - more pics added
Post by: bobine on September 29, 2011, 02:52:32 PM
Any ideas on the source of this sharp spike at 8165hz? There is a larger spike an octave above (and perhaps the hint of one around 4khz). Could these be lower harmonics of much a higher frequency oscillation?
This is the MK47 (BN capsule) by itself in a closed room. You can also see why I'm interested in a rumble filter. :-\   


EDIT:  I just did some more tests and ruled out the microphone! Looking at the power supply, now.
Title: Re: MK47 assembly - more pics added
Post by: Andy Meyer on September 29, 2011, 10:32:28 PM
Hey Gary O,

I had an issue that sounds just like the issue that you are having. In mine I swapped out the 1k5 5 watt resistor. The one that shipped with the kit was bad. I have not had a single pop since!  It took me forever to figure this out but it works now.

This mic is so so great. Don't give up on it.

Andy
Title: Re: MK47 assembly - more pics added
Post by: gary o on September 30, 2011, 09:19:04 AM
Well thanks guys for all your kind advice you did inspire me......Nashkato I did throw mine in the trash silly & costly i know but felt good for about 5 seconds.......after trying the transformer in a quick royer mic I made in protest to the cracking, I scooped up the pieces.......The 10nf cap was broke it was the second one I replaced that....I resoldered a few joints agian & cleaned as I went....Andy the 1K5 had come off so I left it off I connected 2 x 680 R & a 150R high wattage resistors together to make well 1510R it was what was laying around.....put it all back in the case connected lollypop head....

and.......No pops crackles.......but Im not gonna hold my breath.....thanks for the help.....

bobine what powers supply do you use.....

Thanks once again...
Title: Re: MK47 assembly - more pics added
Post by: etiefenthaler on October 01, 2011, 07:46:36 AM
Hi,

speech sample male voice.

for reference schoeps mk4 cardioid

http://flutemusic.ch/schoepsmk4sprache.wav (http://flutemusic.ch/schoepsmk4sprache.wav)

Max mk47 with AKG ck12 delrin capsule

http://flutemusic.ch/U47testsprache.wav (http://flutemusic.ch/U47testsprache.wav)

Recording chain: dav preamp - mytek 8x192 converter - reaper


sorry- my doughter was practicing the cello downstairs.


Erich T.
Title: Re: MK47 assembly - more pics added
Post by: monkey on October 01, 2011, 06:34:05 PM
I've been thinking that a U48 configuration (w/ Fig 8 instead of omni) might be more useful to me than a U47. The only real difference between the circuits is that the 48 has a 1nf cap between the switch and back diaphragm, a couple 150M resisters (with a 10nf cap to ground in between) feeding back to the 1k5 (1k7 on a real 47/48) heater dropper resistor.

This seems like it would be a straightforward mod. Is there something I'm not considering? The only part that seems like it could be problematic is that it would mean running a wire around the top pcb down to the heater resistor. Would that introduce interference or something?

Assuming it's doable at all, it would also be nice to be able to switch between omni and fig 8, which would probably have to be an internal switch, but would be less of a hassle if you decided you really needed the other pattern than just not having it.

Thoughts?
Title: Re: MK47 assembly - more pics added
Post by: nashkato on October 02, 2011, 07:39:20 PM
some voice recordings made with MK47 with Dale M7.
soundcloud (http://soundcloud.com/mylionsoul)
Title: Re: MK47 assembly - more pics added
Post by: baadc0de on October 03, 2011, 10:26:43 AM
I'm sourcing a potentiometer for the power supply. Are these specs OK?

Max. operating voltage: 120V
Breakdown voltage: 200V

Thanks in advance,
baadc0de.
Title: Re: MK47 assembly - more pics added
Post by: zayance on October 03, 2011, 10:44:14 AM
I'm sourcing a potentiometer for the power supply. Are these specs OK?

Max. operating voltage: 120V
Breakdown voltage: 200V

Thanks in advance,
baadc0de.

http://www.tube-town.net/ttstore/product_info.php/info/p4385_Rheostat-Alpha-1-kOhm---5-Watt.html
Title: Re: MK47 assembly - more pics added
Post by: bobine on October 03, 2011, 10:45:03 AM
I'm sourcing a potentiometer for the power supply. Are these specs OK?

Max. operating voltage: 120V
Breakdown voltage: 200V

Thanks in advance,
baadc0de.

The one I used was 5 watts 500 volts.  From Mouser, CTS part #:  026TB32R501B1A1

Title: Re: MK47 assembly - more pics added
Post by: monkey on October 03, 2011, 03:10:34 PM
Sold out.
Title: Re: MK47 assembly - more pics added
Post by: idylldon on October 03, 2011, 05:30:04 PM
Hi everyone! Although I have been soaking up the wealth of information here for months, this is my first post. I am very interested in buying an Mk47 kit. Does anyone know if they are currently in stock for purchase? I tried emailing Max from io audio, but he did not reply and I don't want to bother him if they are sold out. If that is the case, I definitely want to get in line!

There's a thread in the White Market where you should post your interest.  At this time, he's sold out but trying to get an idea of interest before moving ahead with the next production run.

Cheers,
--
Don
Title: Re: MK47 assembly - more pics added
Post by: lonepariah on October 03, 2011, 05:42:04 PM
Thanks for the advice Don, I will check there. I really hope there is enough interest.

Chris
Title: Re: MK47 assembly - more pics added
Post by: soundcollage on October 05, 2011, 03:57:14 AM
What is the importance of the extra leads going to the glass tubes? Why not mount the front directly to the grid socket pin and the rear directly to the relay pin? The only thing I can think of is to prevent possible proximity problems if the flexible wires move close to another component during assembly, and if that's the case would it not be better to put the glass insulators in the top mounting plate and run stiff bus wire from the grid pin and relay up through them and solder the (shortened if necessary) capsule leads to them there?
Title: Re: MK47 assembly - more pics added
Post by: Jonkan on October 05, 2011, 10:17:19 AM
Ok quick question. Im testing my Psu and with no mic connected, test switch on (2k3 load), im getting either 105v or 0v on the pattern selector. This isnt correct right? Why is there no voltage drop over the 14k resistor?

Or should i connect the mic and test this again?

/J
Title: Re: MK47 assembly - more pics added
Post by: bobine on October 05, 2011, 10:27:46 AM
Ok quick question. Im testing my Psu and with no mic connected, test switch on (2k3 load), im getting either 105v or 0v on the pattern selector. This isnt correct right?

Or should i connect the mic and test this again?

/J

According to the schematic, you should have 48v or 0v at the pattern selector. So don't attach the mic until you fix it!
Do you have the 14K resistor before the pattern switch?  Check the schematic: In the off position, you will have 14K plus 12K resistance to simulate the relay load.
Title: Re: MK47 assembly - more pics added
Post by: Jonkan on October 05, 2011, 10:36:44 AM
Ah, stupid me. I measured in the incorrect place! I measured at the pattern supply, but theres no relay load there when mic isnt connected. When i measure after the 14k resistor, i get 48v!

That seems much better!

/J
Title: Re: MK47 assembly - more pics added
Post by: toffifee on October 05, 2011, 05:25:01 PM
What is the importance of the extra leads going to the glass tubes? Why not mount the front directly to the grid socket pin and the rear directly to the relay pin?

Exactly what I thought and then did - works!
Title: Re: MK47 assembly - more pics added
Post by: Peps on October 10, 2011, 09:41:34 PM
Hi Max (and everybody else),

I have assembled a MK47 (with a Sigfried Thiersch PVC capsule) and it sounds fine and behaves exemplary. But I can't help worrying about the PSU. The HT keeps wandering slowly between 104.5 V and 105.5 V in an approximately one minute cycle. I use two chokes in series (see attached picture) - could that be the cause of this phenomena? Would it be better to have the second filter capacitor connected between the chokes ( more in line with the original U47 PSU, I think)?
Could the physical aligment of the chokes have an influence (magnetic coupling)? I have them lined up one after the other with about two centimeters in between. Whaddayathink?
I would appreciate any ideas!

Thanks
Peps
Title: Re: MK47 assembly - more pics added
Post by: mad.ax on October 11, 2011, 05:04:51 AM
First thing to check would be your AC wall voltage. Does it keeps wandering slowly between 229 and 231V by chance?

Axel
Title: Re: MK47 assembly - more pics added
Post by: Denyle Guitars on October 11, 2011, 08:51:50 AM
Mine drifts by more than 1 volt, so you're doing pretty well to keep it b/t 104.5 and 105.5. What I did was set my DMM range to 750v so I don't see it drift.  ;D
Title: Re: MK47 assembly - more pics added
Post by: soundcollage on October 12, 2011, 08:59:07 PM
Would it not be more effective with a cap to ground between the chokes? Though, I doubt that has anything to do with the drift.
Title: Re: MK47 assembly - more pics added
Post by: Peps on October 14, 2011, 09:59:36 PM
First thing to check would be your AC wall voltage. Does it keeps wandering slowly between 229 and 231V by chance?

Axel

Axel, you were absolutely right! I feel a bit stupid - it is a unregulated supply after all ... 8)

Would it not be more effective with a cap to ground between the chokes? Though, I doubt that has anything to do with the drift.

That's what I meant when I said "capacitor between the chokes". I guess I should try that.

Thanks for the support!
Peps
Title: Re: MK47 assembly - more pics added
Post by: gec on October 15, 2011, 04:07:09 AM
I'm to order a Thiersch Blue capsule for my microphone, I'm using a T-Bone Sct700 body.
Is the STW 7 (blue line) capsule with the "STS 7 c (52mm)" holder the right combination for the body?
Thanks...
Title: Re: MK47 assembly - more pics added
Post by: kante1603 on October 15, 2011, 06:26:59 AM
I'm to order a Thiersch Blue capsule for my microphone, I'm using a T-Bone Sct700 body.
Is the STW 7 (blue line) capsule with the "STS 7 c (52mm)" holder the right combination for the body?
Thanks...
Hi,

I did the same except of the capsule (red line),but it´s identical in mechanics.Most important thing is to take the "C"-Type of the STS7.The others will bring the capsule too close to the top.Looking through the basket against some light shows that the position is nearly exactly the same as it was in the original!

So-YES!-perfect choice!

Have fun with this awesome microphone,

Udo ;)
Title: Re: MK47 assembly - more pics added
Post by: bobine on October 15, 2011, 11:46:20 AM
I'm curious to try a Thiersch capsule for my second MK47.  Has anyone compared one to the Beezneez K7 from the group buy?  Compared red line to blue line?

On the other hand, the Beezneez capsule sounds so incredibly good, I would't want to be disappointed! Mainly I'm curious to learn how these things sound.

btw...I fired up the 2nd MK47 last night and it sounds and behaves exactly like the first one. Success!
Title: Re: MK47 assembly - more pics added
Post by: soundcollage on October 16, 2011, 06:52:06 AM
I figured that's what you meant Peps, I was just hoping someone else would weigh in on the subject as I'm about to start construction on my power supply.
Title: Re: MK47 assembly - more pics added
Post by: monkey on October 20, 2011, 12:16:01 PM
Got my MK47 up and working, with a Thiersch red line capsule and Equinox body. I've burned in the tubes and it is mostly quiet and basically sounds okay.

I notice that it's a little pointy sounding in the high mids and there's some slight distortion, which is mostly noticeable on sustained notes. The brightness almost sounds like it could be harmonics generated by the distortion vs a shaped response, and there's plenty of lows. Since this is generally considered a darker circuit, and is known for smooth mids, I'm assuming this isn't quite right? (It's been a few years since I've used a real U47, but I remember it being anything but peaky sounding.) I know the Thiersch blue line is supposed to have smoother highs, but the red should still be on the smooth side compared to most mics.

Here are my readings:

Supply: 105V
Heater : 38.1V (Between heater and dropping resistor)
Cathode: 1.22V (Between 27R resistor and pin 2/7)
Plate(?): 43.5V (at the jumper)
Capsule: 56.6V (At the voltage divider)
Output cap: 43.3V

These seem in the ballpark. Thoughts?

@Bobine... did you ever track down the source of your mysterious 4/8k spike? I wonder if this something similar.
Title: Re: MK47 assembly - more pics added
Post by: bobine on October 20, 2011, 01:18:06 PM
@Bobine... did you ever track down the source of your mysterious 4/8k spike? I wonder if this something similar.

I think my spikes are coming from my AC supply or distribution or the PS. I get them even with the mic disconnected from the cable (but only if the cable is attached to the PS). Happens with both power supplies.
Title: Re: MK47 assembly - more pics added
Post by: monkey on October 26, 2011, 05:43:50 PM
If you keep dividing 8165(hz) by 2, you eventually get to 63.7. Harmonics of AC unfiltered source noise? (I know nothing about these things).
Title: Re: MK47 assembly - more pics added
Post by: Le Roux on October 26, 2011, 08:57:54 PM
Finished mine with a Blue line Thiersch capsule.
Burned in tubes for 24 hrs until no pops

Had lots of room noise, maybe a slight hum and lacking low end.
(I tried the capacitor instead of capsule and ruled out power supply)

Changed up for a Dale M7, which sounded thin, and far away. Cracked and popped alot.

Went back to the Thiersch, and it lost all jam. I mean, I have to turn my pre-amp up almost all the way just to hear it.

Recordings are horrible, very thin, however there is no room noise of hum.

Tried resoldering capsule wires with no luck

When I first tried the mic, it sounded good, and its just been getting worse.

Any idea's?
Thanks

Also, should I be able to measure 60V across front capsule to rear? Or front to backplate?
I am only able to measure around 7V
Title: Re: MK47 assembly - more pics added
Post by: monkey on October 26, 2011, 10:11:03 PM
Check your voltages. Search the thread for where to measure and what they should be.

How have wired your ground? With missing low end, I'd also look at the transformer connections.

Good luck!
Title: Re: MK47 assembly - more pics added
Post by: gary o on November 02, 2011, 04:28:02 PM
Quick question my power supply voltage seems to have crept up to 109 VDC only 4 volts but is this 4 volts too much what effect will this have......shorter tube life .....change to sound.....both ....

Thanks ....by the way touch wood no popping still ......
Title: Re: MK47 assembly - more pics added
Post by: zayance on November 02, 2011, 04:43:09 PM
Quick question my power supply voltage seems to have crept up to 109 VDC only 4 volts but is this 4 volts too much what effect will this have......shorter tube life .....change to sound.....both ....

Thanks ....by the way touch wood no popping still ......

Don't you have a HT pot for tweaking?
Title: Re: MK47 assembly - more pics added
Post by: nashkato on November 02, 2011, 05:33:45 PM
Quote
  Also, should I be able to measure 60V across front capsule to rear? Or front to backplate?
I am only able to measure around 7V
a usual Multimeter (10MΩ) won´t be able to measure accurately in the HiZ area.


Title: Re: MK47 assembly - more pics added
Post by: gary o on November 02, 2011, 10:20:12 PM
Zayance.....I have no trimmer pot....it will mean changing fixed resitor values in my case....id like to learn what would higher or even lower voltage would do in this mic circuit , wondering if critical to the U47 ish sound

thanks
Title: Re: MK47 assembly - more pics added
Post by: jordan s on November 08, 2011, 05:41:46 AM
i finished my PSU tonight. All seems well. I'm able to easily get 105V, however, when I have the test switch on, the 2.3K resistor gets awfully hot. I can feel the heat and smell it and after being on for a few minutes, it starts to smoke a little. I'm using this part from mouser:
http://www.mouser.com/ProductDetail/Vishay/AC05000002401JAC00/?qs=R4%2fAj8xQbdXdY28FMFLRcw%3d%3d

It's actually 2.4k because I couldn't find a 2.3k but it's rated at 5W and the stats say that it has a operating voltage up to 275C which is pretty hot. you guys think that maybe because this is only in circuit for a short time while I check the voltage, it shouldn't be a problem?

Also, I wanted to make sure I wired the power transformer correctly. I'm using the triad VPT230-110. On the primaries, I have blue and violet tied to neutral and brown and grey on hot. The secondaries are in series with red and orange tied together and capped off, yellow and black individually are going to the opposite ends of the rectifier diodes. On one end I measure 147V and the other is 133V while the transformer is in the circuit. Seems odd to me, is this correct?
Title: Re: MK47 assembly - more pics added
Post by: nashkato on November 08, 2011, 06:16:17 AM
well , as far as i can see from the datasheet of the triad PT , the wiring seems to be ok  living in a 115V country .
Title: Re: MK47 assembly - more pics added
Post by: madreza on November 08, 2011, 12:59:06 PM
Hi Guys,

I have 105V for the pattern !!! it's weird !
I Also get the same voltage for the light !

when Mic isn't plugged I have more than 300V everywhere !
what should I do ?
Title: Re: MK47 assembly - more pics added
Post by: zayance on November 08, 2011, 02:15:51 PM
Hi Guys,

I have 105V for the pattern !!! it's weird !
I Also get the same voltage for the light !

when Mic isn't plugged I have more than 300V everywhere !
what should I do ?

Haven't built mine yet, but 300V without the Mic plugged it's tottaly normal,
even if 300V is maybe a little High, but you could have a high Mains voltage so...
on Ioaudio's schematic, the Test circuit, has a 2.4K test load, wich is the Mic's
Equivalent resistance, and that's when you have 105V, when the PSU is loaded
with the Mic, not without.......

105V at the pattern, well i had same doubt when doing the PSU,
but don't forget that the relay inside the Mic has a resistance too,
and so it must be connected also.

105 at the light? LED you mean?? Normal to have 105V going there....
If it's jewel light, aren't you using a 6.3VAC line for it?
Title: Re: MK47 assembly - more pics added
Post by: madreza on November 08, 2011, 02:20:53 PM
Thanks Zayance :)
even with the mic connected, I have 105 V on the pattern. A managed to have 53V trying different resistor combination . is that too high or is that ok ?
Title: Re: MK47 assembly - more pics added
Post by: zayance on November 08, 2011, 02:26:18 PM
Thanks Zayance :)
even with the mic connected, I have 105 V on the pattern. A managed to have 53V trying different resistor combination . is that too high or is that ok ?

hmmm, well like said haven't build mine yet, but for checking pattern voltage,
shouldn't you be checking on the Relay?
Title: Re: MK47 assembly - more pics added
Post by: bobine on November 08, 2011, 02:28:11 PM
Look at the schematic again.  You should have a 14K resistor in the circuit when the relay is switched on. You should have a 12K resistor as a dummy load when the relay is switched off.  You want 48v at the relay.

Maybe a photo?


(Also note the 100K resistor in the LED circuit)
Title: Re: MK47 assembly - more pics added
Post by: madreza on November 08, 2011, 02:45:03 PM
So, there's no risk to switch on the relay ? even if I have 105V inside the PSU ?
Title: Re: MK47 assembly - more pics added
Post by: zayance on November 08, 2011, 02:59:46 PM
Well the idea behind it if i get it correctly is that when pattern is on one of the position,
you should not have 105V on Pattern OUT (normal), and on the other, you feed 105 volts
across a 14K and the Relay, wich has also a resistance that should be
about 12K i believe, and so having about 48V at it.
So for knowing that you should switch the pattern that sends the 105V to the relay,
or just check the relay you'll get the point, if you check the Voltage across the 12K resistor when in off position,
then you have about half voltage ;), get it?

But if you made some tweaks as you said before than this would be off i guess.

Title: Re: MK47 assembly - more pics added
Post by: bobine on November 08, 2011, 03:16:57 PM
At the wires that leave the power supply going to the relay, you should have 48v.   

I certainly would NOT want to send 105v to the relay.

Title: Re: MK47 assembly - more pics added
Post by: madreza on November 08, 2011, 04:35:05 PM
That's what I thought :)
Thanks Zayance for your mail ;)
I gotta find the right combination ! thanks Bobine for your help
Title: Re: MK47 assembly - more pics added
Post by: jordan s on November 08, 2011, 05:31:27 PM
I think I'm experiencing the same thing. I followed the polarity switch wiring diagram that was supplied earlier in this thread. When the switch is in one position, the relay is getting the 105V going through the 14K resistor, which doesn't really drop it much, in my case, it's still about 105V. With the switch in the other position, the relay is sitting between the 14k resistor connected to 105V and the 12k resistor at 0V which rounds out to about 48V.

It makes sense to me that wired in that way, the relay would see 105V but it makes me wonder if that diagram is correct. What I'm thinking is maybe in one switch position it should sit between the 14k and 12k resistors to get 48v and in the other position, it should only see the 12k resistor to ground. Does this sound right?

Also, I'm completely unable to get my voltage at 105V now when last night it was no problem? It's at 111V with the pot turned all the way. Maybe the voltage in my building is different? Perhaps I need to up the value of the resistor feeding the pot. It's 1.5k right now (due to using the triad choke.)
Title: Re: MK47 assembly - more pics added
Post by: bobine on November 08, 2011, 05:49:32 PM
I think I'm experiencing the same thing. I followed the polarity switch wiring diagram that was supplied earlier in this thread.

In the ON position, the relay is in the circuit with current flowing from 105V, through the 14K resistor, through the relay, then to ground.

In the OFF position, the relay is out of the circuit.  Current will flow through the 14K resistor, through the 12K resistor, then to ground.

Quote
Also, I'm completely unable to get my voltage at 105V now when last night it was no problem? It's at 111V with the pot turned all the way. Maybe the voltage in my building is different? Perhaps I need to up the value of the resistor feeding the pot. It's 1.5k right now (due to using the triad choke.)

I had that problem, too. I had to increase the value of one of the resistors before the pot so I could get 105V somewhere in the middle of its range.   My voltage drifts around by a few volts over time, but not by that much.  It does depend on what's coming in from the street.
Title: Re: MK47 assembly - more pics added
Post by: jordan s on November 08, 2011, 06:29:46 PM
Ok, thanks. That's how I currently have it configured. It just so happens that 105V going through the 14k resistor is still about 105V. When the switch is off, the relay terminal is essentially floating, but there is 48V between the 14k and 12k resistors.
Title: Re: MK47 assembly - more pics added
Post by: bobine on November 08, 2011, 06:33:44 PM
Okay... i just opened mine up to measure the voltages :P

Measured at the center pole of the pattern switch (between center pole and ground).
no mic attached:
   mic dummy load switched in, pattern relay switch off:  49V
   mic dummy load switched in, pattern relay switch on (omni): 113V
   mic dummy load switched out, pattern relay switch off: 138V
   mic dummy load switched out, pattern relay switch on: 330V

with MK47 mic attached:
   dummy load switched out, pattern relay switch off: 53V
   dummy load switched out, pattern relay switch on (omni): 51V

AND, with the mic attached, I measured the B+ as 111V with the pot at maximum R.   I got 105V with the dummy load.  I have two power supplies, so I need to modify this one, too.  This is a new MK47, so good thing I checked!
   
Title: Re: MK47 assembly - more pics added
Post by: jordan s on November 08, 2011, 06:55:06 PM
Thanks for the info. Looks like I have things set up properly, I just don't have the mic to check with yet but I'm getting pretty much the same readings as you with the dummy switch. I still can't figure out why my 2.3k dummy resistor is burning up but since I only need it for a moment while adjusting voltage, I'm not going to worry about it too much. Can't wait to get that MK47 kit in the mail.
Title: Re: MK47 assembly - more pics added
Post by: zayance on November 08, 2011, 06:59:26 PM
Quote
I still can't figure out why my 2.3k dummy resistor is burning up but since I only need it for a moment while adjusting voltage

While testing, i had a 25W, and it was getting very hot too after some time,
this is only for checking purpose, so as long as all the rest is ok, i guess all is good then....

Better have higher wattage Dummy loads for whatever i think...
Title: Re: MK47 assembly - more pics added
Post by: bobine on November 08, 2011, 07:32:52 PM
some more voltage tests:

Mic/PS #1: 
B+ with mic attached:  105V
B+ with dummy load:   102V

Mic/PS #2:
B+ with mic attached: 111V
B+ with dummy load:  106V
So, I need to modify PS#2 to bring the pot within range.

Difference between the two mics on the same PS:  3V

I have no obvious heating problem with the dummy resistor.

Title: Re: MK47 assembly - more pics added
Post by: nashkato on November 08, 2011, 07:38:43 PM
Quote
Well the idea behind it if i get it correctly is that when pattern is on one of the position,
you should not have 105V on Pattern OUT (normal), and on the other, you feed 105 volts
across a 14K and the Relay, wich has also a resistance that should be
about 12K i believe, and so having about 48V at it.
So for knowing that you should switch the pattern that sends the 105V to the relay,
or just check the relay you'll get the point, if you check the Voltage across the 12K resistor when in off position,
then you have about half voltage , get it?

But if you made some tweaks as you said before than this would be off i guess.

EDIT: Seems I got it wrong   

EDIT EDIT: not that much actually...

just my 2 cents ...
in fact it´s a simple voltage divider .
kirchhoff says : U = Ur1 + Ur2   (105V = U(above 14k ) + U(above 12k)) equals : 26k = 105V ; 12k = ? =>
(12*105)/26 = 48,46V

total load would be 26k paralled 2k3  =  2k11 thats what gives you the 105V .
Title: Re: MK47 assembly - more pics added
Post by: madreza on November 08, 2011, 08:54:57 PM
hmmm ok !
Actualy I had a connection problem so now, I get 48V at the center pattern switch pin
Can someone explain me why when I switch the pattern On I get 110V at the same center pin ???
I think that is not correct

I think I'll leave it all for tomorrow ....

Thanks Zayance for your messages by the way :D
If I got it right You were wrong when you said you were right to say that you were wrong ! ( or something like that :D )

Good night all !
Title: Re: MK47 assembly - more pics added
Post by: zayance on November 09, 2011, 04:50:06 AM
Quote
If I got it right You were wrong when you said you were right to say that you were wrong ! ( or something like that  )

yep  :)


Quote
Can someone explain me why when I switch the pattern On I get 110V at the same center pin
I think that is not correct

Mic attached? As reference to ground? means Pin 2 and pin3 of Output Voltage terminal?
Or when yu check HT when Switching Pattern ON Pin 1 and 3? If that then it's correct also, you get a
slightly higher HT when Relay gets in the circuit if i get it correctly....


@nashkato: yes, that's what i meant, with relay, it's a simple voltage divider.
well that's what i understood about it...
Title: Re: MK47 assembly - more pics added
Post by: madreza on November 09, 2011, 06:06:23 AM
in fact that's Mic attached
Pin 2 and 3 of power terminal
and Pin 1 and 3 the voltage raises too ! ( and it shouldn't ) to 110V
I mean if there is a 12K load in the circuit ( the relay ) it should keep almost the same voltage than when the dummy 12K is in the circuit
So the HT voltage should not raise !
something seems to be wrong !
Title: Re: MK47 assembly - more pics added
Post by: jordan s on November 09, 2011, 06:53:40 PM
Well, I added a 300 ohm resistor in series with the 1.5k feeding the pot and now I'm able to get 105V no problem. I did find that the voltage in my apartment jumps around from 118V to 121V and this causes my power supply to jump around too. Anyway, I'm calling this done until I get my MK47 built and test it for good. I built it out of a heavy duty steel Hammond case and painted it with hammertone spray paint. The size is really a bit much for what's needed and it was a pain to drill through but not bad. I got the "leather" strap from ebay/china for like $7 or something.
(http://farm7.static.flickr.com/6118/6330501526_e53807d4f4_z.jpg)
(http://farm7.static.flickr.com/6111/6329752643_da6ef5b565.jpg)(http://farm7.static.flickr.com/6046/6330509420_e1568bff90.jpg)
Title: Re: MK47 assembly - more pics added
Post by: bobine on November 09, 2011, 08:20:51 PM
Yeah, but it looks badass.   I think I used the next size smaller Hammond case.

Nice.
Title: Re: MK47 assembly - more pics added
Post by: madreza on November 11, 2011, 07:13:09 AM
Ok ! My fault !
I had a bad wire contact

but still can't make the 6.3V light work !
tried to plug a LED and it worked
how can I make that work ?
Title: Re: MK47 assembly - more pics added
Post by: zayance on November 11, 2011, 07:33:24 AM
Quote
but still can't make the 6.3V light work !
tried to plug a LED and it worked
how can I make that work ?

If you're talking about the PCB connection?
It's made for a LED not for a Light Bulb. (as on ioaudio's schematic)
Light bulb needs a 6.3VAC (if your light bulb needs that)
So if you got yourself the Power transformer from Tube Town,
then you're good to go.

If you tried the light bulb on the PCB connection, then it must be fried.....
Title: Re: MK47 assembly - more pics added
Post by: grantlack on November 11, 2011, 11:43:32 AM
success!!!  both psu's are passing 105V and both mics are passing audio.  the mics are dead quiet, but have a bit of an 'am radio' quality to them.  likely culprits are a) lack of burn-in, b) hi-z sections need attention, c) i'm unaccustomed to the 'u47 sound,' or d) crappy test headphones.  we'll see how they behave after 24 hours of power.  here's a shot of my supply boards, decided to throw together a layout for mental stimulation and ease of racking.  i'll be building more tube mics in the near future, so i figured i'd do a big ol' psu box to keep me warm in the iowa winter!  if anybody's interested in the layout/bom for etching, i could easily get that sorted out.

only thing i might change in the future would be to move the rectification off-board and closer to the toroid, it's fine now but i could see ac hash getting into my audio as i add more supplies to the case.
Title: Re: MK47 assembly - more pics added
Post by: bobine on November 11, 2011, 12:07:14 PM
Congrats.  What capsules are you using?
Title: Re: MK47 assembly - more pics added
Post by: grantlack on November 11, 2011, 12:31:50 PM
Thanks! It would still be a pile of parts without a couple of your posts, that triad toroid does nicely with 1K's throughout. I opted for the BeezNeez K7's in Skylar's bodies, though I'd like to try some of Dale's design down the road.
Title: Re: MK47 assembly - more pics added
Post by: bobine on November 11, 2011, 12:49:34 PM
I LOVE the BeezNeez.  They definitely should not sound like AM radio. 

I like my Chuck D M7, too. It's a little less vivid, but has a nice quality to it. It glows rather than sparkles.


Here are a set of sweeps comparing the capsules. Same mic electronics, PS, and body in the same set up.  Line voltage changes and warm up times might affect overall levels a little bit.
->This doesn't represent the true frequency responses, only the relative responses of the capsules to each other. 
Title: Re: MK47 assembly - more pics added
Post by: jordan s on November 11, 2011, 01:07:36 PM
So I'm finishing my MK47 now but I have to ask, what exactly is the purpose of having capsule connections run through the glass tubes? Am I supposed to solder the capsule leads on the bottom part? Would there be anything wrong with soldering the capsule leads directly to the relay pins?
Title: Re: MK47 assembly - more pics added
Post by: glimmertwins on November 11, 2011, 02:14:57 PM
Yeah, but it looks badass.   I think I used the next size smaller Hammond case.

Nice.

Just curious - would that be the 1453B - the 6x6x9.5 or the 1453C 7x7x11?
Title: Re: MK47 assembly - more pics added
Post by: monkey on November 11, 2011, 02:36:25 PM
@grantlack, can you expand on what you mean by "am radio" sound?

Title: Re: MK47 assembly - more pics added
Post by: grantlack on November 11, 2011, 03:34:03 PM
@grantlack, can you expand on what you mean by "am radio" sound?

It's midrangey, not quite nasal in quality but bothersome in the same way. Seems like the LF is rolled off as well. The tonal quality is consistent across both microphones, so it may be something induced in the supply rather than the microphones themselves. Inductor proximity?
Title: Re: MK47 assembly - more pics added
Post by: monkey on November 11, 2011, 03:44:46 PM
Interesting. I have something going on in the mids as well, which I think of as sounding "pointy" which seems like maybe distortion at certain frequencies. I notice it mostly on vocals, and then more on certain syllables (and not sibilant ones, per se).

My supply is sort of improvised, so that seems like a more likely culprit than say the capsule or amp. What would inductor proximity  do?
Title: Re: MK47 assembly - more pics added
Post by: jordan s on November 11, 2011, 03:51:30 PM
Yeah, but it looks badass.   I think I used the next size smaller Hammond case.

Nice.

Just curious - would that be the 1453B - the 6x6x9.5 or the 1453C 7x7x11?
It's the 6x6x9.5. Be warned that the thick steel can be a bit difficult, but it's do-able.
Title: Re: MK47 assembly - more pics added
Post by: grantlack on November 11, 2011, 04:09:32 PM
Haha well I just had an epiphany and found my gremlin, I had improv'ed a crimp/insulation displacement/solderless XLR onto the signal leads since I don't have any female DB25's at my disposal. Used the same one for both tests. The insulation on the - lead was left intact. DUH. Sounding like a dream now!
Title: Re: MK47 assembly - more pics added
Post by: bobine on November 11, 2011, 05:04:47 PM
I used the Hammond 513-0900

Length     8.63 in   
Width:   4.75 in   
Height:   3.5 in


the steel is no fun
Title: Re: MK47 assembly - more pics added
Post by: BladeSG on November 12, 2011, 03:01:43 AM
Does anyone know if the generic Beezneez PSU will work with this MK47?
Title: Re: MK47 assembly - more pics added
Post by: jordan s on November 13, 2011, 03:12:12 PM
She's finished! No pops, clicks or hums. So far from testing this out at home, all is well and it sounds great. Just burning it in for a few days now. I can't wait to get this in the studio. I used the aforementioned $50 spider shock mount from ebay but it needed some modifications. I removed the thick foam and put in some thinner felt but the mic still wouldn't fit so I removed the original screws, sawed off the the thumbscrew part from the threading and JB Welded them on to longer hex screws. So far it's holding up well.
(https://fbcdn-sphotos-a.akamaihd.net/hphotos-ak-ash4/386760_698792527321_31000366_34119663_1514212962_n.jpg)(https://fbcdn-sphotos-a.akamaihd.net/hphotos-ak-ash4/375441_698792776821_31000366_34119665_1171479631_n.jpg)
(https://fbcdn-sphotos-a.akamaihd.net/hphotos-ak-ash4/312163_698808769771_31000366_34119753_528037831_n.jpg)(https://fbcdn-sphotos-a.akamaihd.net/hphotos-ak-ash4/318418_698808724861_31000366_34119750_1872273404_n.jpg)
Title: Re: MK47 assembly - more pics added
Post by: grantlack on November 13, 2011, 06:58:52 PM
as i look at the u48 schematic, it appears that the fig8 pattern was accomplished by simply switching a 1nF cap into the signal path between the membranes.  any reason the same approach couldn't be taken in the mk47?  the execution would be simple enough, it's just a matter of whether it would behave the same.  i tend to find omni to be less useful in my day-to-day work.
Title: Re: MK47 assembly - more pics added
Post by: Marc Duchesne on November 13, 2011, 07:20:47 PM
Finished my MK47 in an Equinox body and capsule. Good combination...
Guys, this mic sounds just hands down gorgeous...

I pumped it into a seventh circle N72 pre (neve design) direct to the converters, I am just stumped with the 3D sound of my vocal, which is not the greatest by the way... Wow. I am very impressed.

The construction went straight forward, no glitches, just silent at 50% level on the mic pre.

You will be impressed with it. I will try to upload some sound samples of a good singer to let you evaluate.

Now, I am waiting for my LA2A case...

Regards,
-marc
Title: Re: MK47 assembly - more pics added
Post by: Marc Duchesne on November 13, 2011, 07:21:39 PM
Few notes:
- The B- and the XLR pin 1 (XLR ground) will both go to same ground.

- When you are testing the 48VDC patern voltage, flip the switch to omni side (so the 14K and 12 resistors have continuity between them) and measure the 48VDC voltage across the 12Kohms resistor and ground (the 12K resistor really represent the mic patern relay coil impedance load simulation) it took me a while to figure this one out. So, don't go measure this one on the patern output lead going to the mic, you will get 105 VDC (unloaded) or 0VDC switched out, which is normal.

-Make sure you replace your multimeter battery... (Stupid me)...

Regards !
-marc
Title: Re: MK47 assembly - more pics added
Post by: Marc Duchesne on November 13, 2011, 07:28:52 PM
Jordan, I did purchase a Pelluso shockmount that I have not received yet (the mount seems the same as yours). Wondering if I will have to modify it. I have the same capsule / body as you.
Title: Re: MK47 assembly - more pics added
Post by: jordan s on November 14, 2011, 12:42:41 PM
One more question before I close this up for good. My led is pretty dim. After the 100k resistor it's only getting 1.6V. Would it adversely affect anything to put a different resistor here to get a brighter led?
Title: Re: MK47 assembly - more pics added
Post by: lonepariah on November 14, 2011, 02:20:53 PM
Does anyone know if the AMI U47 PSU (or any other U47 PSU) will work with the MK47?
Title: Re: MK47 assembly - more pics added
Post by: mad.ax on November 15, 2011, 03:51:49 AM
as i look at the u48 schematic, it appears that the fig8 pattern was accomplished by simply switching a 1nF cap into the signal path between the membranes.  any reason the same approach couldn't be taken in the mk47?  the execution would be simple enough, it's just a matter of whether it would behave the same.  i tend to find omni to be less useful in my day-to-day work.

If your plan is to make a MK48 (sacrifice the omni patern to favor a figure 8 ) it's doable.
Pay attention to the U48 schematic. It's not just a matter of adding a cap and a resistor, you also need to modify the voltage divider.
In the U47 the 2M/3M extract 60V from the 105V PSU in order to polarize the front of the capsule. If you'd polarize the back with 105V, you wouldn't get a real figure 8 pattern (cause you'd need 120V). So for the U48 they changed the voltage divider  to 3M/3M. That gives 52.5V to the front, and then 105V at the back is right.
You can do the same with the MK47. Just keep in mind that, just like with a real U48, you'll loose a bit of sensitivity because of the lower polarization voltage.

Axel
Title: Re: MK47 assembly - more pics added
Post by: Marc Duchesne on November 15, 2011, 09:52:15 AM
Jordan S:
One more question before I close this up for good. My led is pretty dim. After the 100k resistor it's only getting 1.6V. Would it adversely affect anything to put a different resistor here to get a brighter led?


I have a red LED that I extended beside the poser switch at front. Mine is bright enough.  I have 680 ohms and 100K  resistor into the circuit. May be use a different LED although a led is pretty straight forward... Your resistor is same as mine wright...

-marc
Title: Re: MK47 assembly - more pics added
Post by: zayance on November 15, 2011, 11:25:42 AM
Jordan S:
One more question before I close this up for good. My led is pretty dim. After the 100k resistor it's only getting 1.6V. Would it adversely affect anything to put a different resistor here to get a brighter led?


I have a red LED that I extended beside the poser switch at front. Mine is bright enough.  I have 680 ohms and 100K  resistor into the circuit. May be use a different LED although a led is pretty straight forward... Your resistor is same as mine wright...

-marc

It's a little normal to be dimmed, U=RI tells us you get only about 1.5mA to the LED at 105V (3mA at 300V) not much (Actually corrected my stupid calculation mistake on one of my reply to Madreza's post, a moment of "woops"), but it lights, most used Light Bulb, more authentic...
But of course you can tweak the LED resistor of 100K here, it's DIY, just use U=RI and P=UI for both loaded and unloaded HT for safety....
Title: Re: MK47 assembly - more pics added
Post by: Marc Duchesne on November 15, 2011, 03:33:57 PM
I just ordered one of these. Though they were nice for a pop filter...

The one I ordered is front aluminium and black at the back.

http://www.thehookstudios.com/filters.html

Will let you know how they work out...

Marc
Title: Re: MK47 assembly - more pics added
Post by: jrasia on November 16, 2011, 12:47:54 PM
Need opinions of mounting the 1k5 resistor 'heater' from MK47 kit.
Looks like Max is using a slight different resistor than the one pictured in the build.
Is it wise to mount this resistor to the side rail, or is it advised to mount is only to the end cap of the mic body(equ47)?  The side rail would prevent me from having to extented the leads, but I wonder if it would cause interference or other issues leaking into the the PCB. Also, could I 'fasten' the resistor using an epoxy instead of using a brass plate to keep it down?  Just how hot does this thing get?

Lastly, can someone PLEASE provide the proper pinout for the 7 pin connector to the MK47?   Can't seem to find on here.  The build is going nicely I just need these last issues clarified.

Thanks

Jason

Title: Re: MK47 assembly - more pics added
Post by: zayance on November 16, 2011, 01:04:11 PM
Quote
Is it wise to mount this resistor to the side rail, or is it advised to mount is only to the end cap of the mic body(equ47)?

I'd say up to you, and testing it,  Aluminium may be better at dissipating tough....

Quote
could I 'fasten' the resistor using an epoxy instead of using a brass plate to keep it down?  Just how hot does this thing get?

Not a good idea in my opinion, when you say Epoxy, you mean gluing it?
First Epoxy won't have a good mechanical attachement in case of whatever,
And will crackle or come apart with time, it's a mic, lots of things will happen
to it in studio......
I think this one heats up a little, so even that won't make the epoxy last forever,
even if it can take up some heat on paper...
And the epoxy Chemical may damage the resistor in time? Just a tought here....

I'd go for brass or aluminium plate, and a screw with a secured washer....
Leads isolated of course....

But i'm not an expert...
Title: Re: MK47 assembly - more pics added
Post by: jordan s on November 16, 2011, 02:02:33 PM
I epoxied a small aluminum tab on to the side of the end cap to hold the resistor in place. If the worst thing that happens is the tab coming off, the resistor is pretty much held into place by tension from the leads anyway so I'm not too worried about it.
Title: Re: MK47 assembly - more pics added
Post by: zayance on November 16, 2011, 04:42:44 PM
Quote
Need opinions of mounting the 1k5 resistor 'heater' from MK47 kit.

Quote
I epoxied a small aluminum tab on to the side of the end cap to hold the resistor in place. If the worst thing that happens is the tab coming off, the resistor is pretty much held into place by tension from the leads anyway so I'm not too worried about it.

Not much left for opinions :), cool that it works for you, it's DIY whatever fits best your needs, tools, preferences etc.....As long as it works and does what it's suppose to do....1....2....1....2....check....ssssss....p..p...p...p...p
Title: Re: MK47 assembly - more pics added
Post by: Marc Duchesne on November 16, 2011, 10:51:36 PM
Need opinions of mounting the 1k5 resistor 'heater' from MK47 kit.
Looks like Max is using a slight different resistor than the one pictured in the build.
Is it wise to mount this resistor to the side rail, or is it advised to mount is only to the end cap of the mic body(equ47)?  The side rail would prevent me from having to extented the leads, but I wonder if it would cause interference or other issues leaking into the the PCB. Also, could I 'fasten' the resistor using an epoxy instead of using a brass plate to keep it down?  Just how hot does this thing get?

---Dont use epoxy, make yourself a nice little U shaped bracket and install it on the side rail to hold the resistor. You can also use some silicone to hold the U bracket on the body side rail. Could also put some thermal grease underneat the resistor. 

Lastly, can someone PLEASE provide the proper pinout for the 7 pin connector to the MK47?   Can't seem to find on here.  The build is going nicely I just need these last issues clarified.

Audio
1 = A- (gray) (connects to pin 3 of XLR at the power supply)
2 = A+ (white) (to pin 2 of XLR at the PS)
Center pin = audio ground (green)  (to pin 1 of XLR)

Power
3 = B- (black [blue in the cable])
4 empty
5 = B+ (red)

Pattern
6 = P (yellow)

Shield to the chassis.
Title: Re: MK47 assembly - more pics added
Post by: JamesW on November 16, 2011, 10:58:49 PM
I bolted an wirewound chassis mount resistors  Mouser#71-RH0051K500FC02 to the end cap worked great
Title: Re: MK47 assembly - more pics added
Post by: Skylar on November 17, 2011, 12:17:04 AM
Thermally conductive adhesive/epoxy should work fine. There are special adhesives made for this sort of thing. Google it.

Regarding pinouts:
If you're building both the mic and power supply it doesn't matter! It's up to you to decide whatever pinout you want! If you want the B+ voltage to be pin 4, then it's pin 4. Just make sure you stick to the same pinout for the mic and power supply.
Title: Re: MK47 assembly - more pics added
Post by: jrasia on November 17, 2011, 06:32:35 PM
Thanks for all the responses fellas!  Greatly appreciated.

In regards to the pinout....I know I could technically wire it any way I want....but is there a standard?
I mean, what if I wanted to use an original u47 PSU or an aftermarket PSU for that matter? 
I know the PSU should deliver 105 VDC @ approx 55mA and thats about it.

I don't think I'll be building my own PSU as I don't have a means of etching my own PCB boards.

Can someone recommend an off the shelf PSU that has switchable patterns?  Beezneez, or Peluso?
Title: Re: MK47 assembly - more pics added
Post by: lonepariah on November 17, 2011, 09:37:42 PM

Can someone recommend an off that shelf PSU that has switchable patterns?  Beezneez, or Peluso?

I am also interested in this. Any recommendations?
Title: Re: MK47 assembly - more pics added
Post by: imo on November 18, 2011, 02:33:40 AM
the power supply is very easily built point to point(or with tag boards) you can get these at any place that sells amp building parts. I think it is helpful to build power supplies; a linear and easy way to understand circuit flow. Plus, if you need to change resistors you aren't burning traces in the process.
I think the U47 pinout is:
1- Signal-
2 signal +
3 ground
5 B+
6 pattern

Hope this helps
Ian
Title: Re: MK47 assembly - more pics added
Post by: david-p on November 18, 2011, 11:54:03 AM
Whatever the pins used by the original U47, if you are using a vacuum tube amplifier I advise not following the same convention.  It appears to be a little-known fact that you could get an exciting electric shock if you plugged the Neumann U-47 mike into a cable that was already connected to a switched-on power supply.  This was because the HT pin mated before the ground pin. 

For instance, if you are using the Equinox body and the excellent 7-pin Binder connector, you will notice that pin 7 (the centre one) mates first.  To avoid the effect described above, this should be the ground connection.  Since the voltages you choose for your power supply are likely to be different from those used by Neumann, the choice of function for the rest of the pins is up to you.

David
Title: Re: MK47 assembly - more pics added
Post by: electrisizer on November 18, 2011, 12:55:36 PM
hi need to replace one tube...

do you have a good source for germany?

do the tubes have to be a matched pair?
Title: Re: MK47 assembly - more pics added
Post by: monkey on November 18, 2011, 01:51:36 PM
Whatever the pins used by the original U47, if you are using a vacuum tube amplifier I advise not following the same convention.  It appears to be a little-known fact that you could get an exciting electric shock if you plugged the Neumann U-47 mike into a cable that was already connected to a switched-on power supply.  This was because the HT pin mated before the ground pin. 

This isn't true: Neumann made pin 5 of the Tuchel connectors for U47/48, etc (carrying B+) is shorter than the rest for this very reason.
Title: Re: MK47 assembly - more pics added
Post by: david-p on November 18, 2011, 02:40:34 PM
Whatever the pins used by the original U47, if you are using a vacuum tube amplifier I advise not following the same convention.  It appears to be a little-known fact that you could get an exciting electric shock if you plugged the Neumann U-47 mike into a cable that was already connected to a switched-on power supply.  This was because the HT pin mated before the ground pin. 

This isn't true: Neumann made pin 5 of the Tuchel connectors for U47/48, etc (carrying B+) is shorter than the rest for this very reason.

You make think that it is not true; but I write as one who has experienced the effect live -- with a microphone that may well have been manufactured earlier than the one you refer to...

David
Title: Re: MK47 assembly - more pics added
Post by: mad.ax on November 19, 2011, 04:23:01 AM
Regarding the 'standard' pinout for the Binder connector, I suggest using the pinout of the Neumann mics using that same connector. KM253 & M250.
Just forget about pin4 (since you don't need heater voltage) and use pin 3 for switching the relay.
Axel
Title: Re: MK47 assembly - more pics added
Post by: mad.ax on November 19, 2011, 04:27:23 AM

Can someone recommend an off that shelf PSU that has switchable patterns?  Beezneez, or Peluso?

I am also interested in this. Any recommendations?

If you mean switchable patterns as in omni/cardio selcted by a relay as in the MK47, there isn't any to my knowledge. DIY!
If you mean switchable patterns as the usual 9 positions switch or potentiometer, that won't work with the MK47.

Axel
Title: Re: MK47 assembly - more pics added
Post by: Benny on November 19, 2011, 11:35:44 AM
Just finished my MK47 with Skylar body and Q47 capsule. It works perfectly from first powerup. No noise, hum, pops or whatever. It just sounds great. I'll let the tubes burn in now and start further testing tomorrow. Thanks to Max and Skylar for a great project.
Title: Re: MK47 assembly - more pics added
Post by: lonepariah on November 19, 2011, 06:55:16 PM

Can someone recommend an off that shelf PSU that has switchable patterns?  Beezneez, or Peluso?

I am also interested in this. Any recommendations?

If you mean switchable patterns as in omni/cardio selcted by a relay as in the MK47, there isn't any to my knowledge. DIY!
If you mean switchable patterns as the usual 9 positions switch or potentiometer, that won't work with the MK47.

Axel

Thanks Max. Yes, I was referring to omni/cardioid.

Looks like I'm going to have to do some studying before I start my build...

Best,

Chris
Title: Re: MK47 assembly - more pics added
Post by: baadc0de on December 01, 2011, 06:00:09 AM
I've done my first of two (finally got the cable sorted out) but nothing much happens on power noise.. I just get loads of hum and funny noises that differ if someone steps up to the mic or not, so I guess the outside world is influencing it a bit.

From what I read it could be a number of things.. from the 10nF styro to the big cap.. I'll measure some things up.. my B+ is at correct voltage, heaters power up..
Title: Re: MK47 assembly - more pics added
Post by: grantlack on December 01, 2011, 07:25:23 AM
If your plan is to make a MK48 (sacrifice the omni patern to favor a figure 8 ) it's doable.
In the U47 the 2M/3M extract 60V from the 105V PSU in order to polarize the front of the capsule. If you'd polarize the back with 105V, you wouldn't get a real figure 8 pattern (cause you'd need 120V). So for the U48 they changed the voltage divider  to 3M/3M. That gives 52.5V to the front, and then 105V at the back is right.
Glad I asked, I was working from a non-original (and incorrect) document. Still should be a pretty simple adjustment, I'll give it a whirl once I get more familiar with the mics.

I've done my first of two (finally got the cable sorted out) but nothing much happens on power noise.. I just get loads of hum and funny noises that differ if someone steps up to the mic or not, so I guess the outside world is influencing it a bit.

From what I read it could be a number of things.. from the 10nF styro to the big cap.. I'll measure some things up.. my B+ is at correct voltage, heaters power up..
Have you fired up the psu without the mic and listened to audio output? Sounds like it's in the mic, but might as well rule out other things where you can.
Title: Re: MK47 assembly - more pics added
Post by: baadc0de on December 01, 2011, 12:08:24 PM
Hey..

no, without the power supply the mic is ofcourse dead silent. The B+ comes to the mic at a healthy 100-105V.

This is what it sounds like, 21dB gain (result of normalization) in the DAW and my TC electronics preamp set at half gain, without the pad.
http://dl.dropbox.com/u/12679166/xx.mp3

I'm including this sample because it may help someone later or someone might remember something.. it's a power on cycle, so it starts silent and then ramps up.
Title: Re: MK47 assembly - more pics added
Post by: grantlack on December 01, 2011, 12:31:55 PM
no, without the power supply the mic is ofcourse dead silent. The B+ comes to the mic at a healthy 100-105V.
seems silly on its face, yes, but if you were picking up hum in your audio signal from the power supply/cable it would likely still be audible even without the microphone attached.

the crackle sounds like my tubes did in my first mic before a good two days of burn-in, though mine was much more intermittent.  if you've already done a burn-in, have you double-checked your cable shield/chassis grounding?  i had an mkl-2500 with poor grounding, and the handling noise was similar to this.
Title: Re: MK47 assembly - more pics added
Post by: baadc0de on December 01, 2011, 12:51:40 PM
I've actually missed a link from tube grid to front capsule.. I can hear myself now faintly within all the noise (which is still much louder than the signal) but at least something is happening. Gotcha on the cable thing, just never happened to me before. Also, no burn in performed here yet.. but I'm confused about the really low signal from the mic, I thoughtI should resolve that first before I have the guts to leave the mic on for more than a few minutes..
Title: Re: MK47 assembly - more pics added
Post by: baadc0de on December 01, 2011, 12:58:19 PM
Also, I measured DC between the front and backplate or the back and backplate and it was like 4.7Volts both cases... isn't that very very low? Or is this measured differently?
Title: Re: MK47 assembly - more pics added
Post by: grantlack on December 01, 2011, 01:05:17 PM
could it be that one leg of your audio is disconnected or shorted to ground?  my output was crazy low when i made that goof, and it was more like a noise to signal ratio than the right way around.

not entirely sure on the capsule voltage, hi-z does funny things to multimeters.
Title: Re: MK47 assembly - more pics added
Post by: baadc0de on December 01, 2011, 01:58:39 PM
well, touche..

the A+ and A- leads were reversed.. I somehow assumed that the righ hand one was A+ but it is actually A-.. though that didn't fix much. The level is still very very low and I seem to have a grounding issue. The buzz/hum is mostly 60hz harmonics and a lot of them go away if I touch the binder connector and the pattern switch.

Is the power supply (I used zayance's PCB version) supposed to connect to ground at the 0V output? I have it setup that way, so pin1 from 3-pin XLR, pin1 from 7-pin XLR and the 0V from power supply are all going to ground and at the other end of the cable, that's going to the B- connection. The PCB inside the mic isn't connected to the body with anything metal.. is that a problem?
Title: Re: MK47 assembly - more pics added
Post by: zayance on December 01, 2011, 02:26:39 PM
well, touche..

the A+ and A- leads were reversed.. I somehow assumed that the righ hand one was A+ but it is actually A-.. though that didn't fix much. The level is still very very low and I seem to have a grounding issue. The buzz/hum is mostly 60hz harmonics and a lot of them go away if I touch the binder connector and the pattern switch.

Is the power supply (I used zayance's PCB version) supposed to connect to ground at the 0V output? I have it setup that way, so pin1 from 3-pin XLR, pin1 from 7-pin XLR and the 0V from power supply are all going to ground and at the other end of the cable, that's going to the B- connection. The PCB inside the mic isn't connected to the body with anything metal.. is that a problem?

Common practice, if i'm correct, is to connect the Mic body to your GND also, and Star Ground in the PSU, like the G7.
BUT iirc, ioaudios PCB has one side as GND (B-), so depends on how you attached it (plastic zip or metal) then the connection should do if metal of course....
Title: Re: MK47 assembly - more pics added
Post by: grantlack on December 01, 2011, 02:42:15 PM
like tony said, definitely make sure your mic body is well-grounded.  if you didn't connect the grounding tab of the binder connector to the shield, that might be sufficient.  if not, make sure whatever pin you used for ground in the cable is solidly grounded inside the chassis.  easiest with all that unsolderable aluminum is to just attach a decent gauge wire to the cup of your ground pin and slip the stripped end between two of the rail mounting screws.  tighten the hell out of it and voila.
Title: Re: MK47 assembly - more pics added
Post by: baadc0de on December 04, 2011, 05:48:32 AM
Well, the signal is getting up after a few hours of burning in, so I guess the mic is working better and better..

that said, it's still very very noisy..

I have zero ohms between the body and the mains ground, also between any panel mounted switch and ground, between either the 3-pin XLR pin1 and ground or the 7-pin XLR pin1 and ground. XLR shield tabs are connected to grounds.

EDIT: what's really funny is that if I take a separate wire and connect it to a PSU panel on/off switch, the other side goes to the binder connector shield - nothing happens, or maybe the noise goes up a few dB.. however, if I touch both of these with my fingers (!) the noise starts to subside after about half a second and goes down in level quite a bit.. help?? This is waay beyond my grasp / understanding.
Title: Re: MK47 assembly - more pics added
Post by: baadc0de on December 05, 2011, 02:14:06 AM
There had to be an explicit wire going from the body (the support profile) to the B- spot. Then the mic is quiet (not really really quiet, but quiet enough). Huzzah.
Title: Re: MK47 assembly - more pics added
Post by: baadc0de on December 05, 2011, 02:20:01 PM
I knew it was too good to be true. While the ground noise went away, the popping, swooshing and whatever else this mic is capable of is back in spades. It goes up and down in intensity, volume, at random. I recorded such great takes with it in the morning and now in the evening it's playing up with me. I'm so so mad because it works so great when it does work!
Title: Re: MK47 assembly - more pics added
Post by: zayance on December 05, 2011, 02:24:13 PM
I knew it was too good to be true. While the ground noise went away, the popping, swooshing and whatever else this mic is capable of is back in spades. It goes up and down in intensity, volume, at random. I recorded such great takes with it in the morning and now in the evening it's playing up with me. I'm so so mad because it works so great when it does work!

Flux cleaned the board? Any spare tubes?
Title: Re: MK47 assembly - more pics added
Post by: 0dbfs on December 05, 2011, 03:32:03 PM
I just finished two of these, and two mk7's over the weekend (all these mic-parts had been sitting around for a while so I turned up the DIY-DIAL to 11 and knocked them out)...

There was GND noise which went away when I lifted the cable shield on the mic end and connected shield to chassis on the PSU end. I have the B- / GND connections from the PCB's wired to pin7 & 6 on the binder... No special connection from the EQU47 body to PCB (just the rails touching the GND area on the PCB because of how I mounted it)...

Out of four mic's I have only one wich had pops/swooshing (two mic's using the supplied 6028's, and the two mk7's using pf86's).... It didn't go away on it's own and followed the tubes when swapped.

I tried additional troubleshooting to rule out other issues. Reheated all Hi-Z nodes, cleaned, cleaned, cleaned, swapped the 10nf (backplate to gnd) styro, rejuvinated the tube pins with a small hobby file, overheated & underheated the tubes for hours and even days on end in some cases... I did all of those troubleshooting items after discovering the noises and while waiting for additional 6028's to arrive (100x @ $89.- so they should last a while). 6028's arrived Saturday. I swapped the first two in from the carton and they are great now as of late last night!

Just brought the mic's into the studio today to start using them on sessions in earnest. Have sessions booked all week starting tomorrow so we'll see how the mic's hold up. I'm sure they'll be fine but have not yet connected them up in the live room. I am expecting that it will take a little while to really get to know these new friends well. I am looking forward to it very much.

A/B'd against an MXL 2001 at home in the shop ($20 doner-mic for another project) with my voice and there was absolutely no comparison. The 2001 was a cheap ebay purchase so no telling what it's condition really is but I didn't have any other mic at home to compare so....

Sounded so good I literally fell to my knees and wept tears of joy. Very real tears. This was before any A/B test with the mxl.

I am planning to take the final PSU readings (in their semi-permanent installed locations) and adjust accordingly since they are unregulated. I have found that all four mic's are a bit low on the B+ and heater voltages when supplied with 120V (almost exact) from the wall so may need to adjust some PSU resistors.

Actually, I ended up initially installing the 680 Ohm resistor in the Mk47 PSU and swapping it out with the 330 to get into the 105V range... 680 ohms value there was going to max 101V maybe. With the 330 installed I get between about 101V and 112V when I have 120 on the PSU primary.

My cable shield ended up being connected at one end to get rid of "gnd-loop" noise. New tubes fixed the popping/swooshing. I also did some other fixes for the pops/swooshes but they didn't actually go away until I swapped the tubes.

Cheers,
jonathan
Title: Re: MK47 assembly - more pics added
Post by: 0dbfs on December 21, 2011, 04:09:57 PM
Wow. Every almost artist I put one of these up for immediately wants to buy one.
You know the story:
We talk about sourcing the parts literally from around the globe... The fact that certain parts are pretty "custom" or at a minimum special-order and in many cases are literally handcrafted. Waiting and delivery periods and/or delays...

Anticipation builds....

And we are not disappointed. No we are not disappointed. Quite the opposite.

I generally work with fairly high profile talent. A good combination of musical and spoken vocal talent as well as significant instrumental talent.

When they "do their thing" and put the headphones on it's all over. Work day is over. We're immediately in the zone. It's just smiles for miles.

Thanks Max! These are awesome and that's an understatement.

Merry xmas and happy holidays!

Best,
jonathan
Title: Re: MK47 assembly - more pics added
Post by: JamesW on December 26, 2011, 11:15:41 PM
Need opinions of mounting the 1k5 resistor 'heater' from MK47 kit.
 

Thanks

Jason
Here is a pic of my mounting I've used it twice now worked great
Title: Re: MK47 assembly - more pics added
Post by: Marc Duchesne on December 29, 2011, 12:44:40 PM
Hi everyone, in reference to popping noise that would not disappear after a couple days, I experienced the same problem and it went away when I replaced the 1.5Kohms filament resistor to a 10W with heat sink mounted in the botom part as JamesW did above , thanks for the photo. I searched for this one quite a lot and got the tip from a post I read in the forum can't remember where, anyways, thank's to this person. An unstable filament current that was... So first thing let the tube settle for a couple days, than replace the resistor if symptoms persist.  Hope this helps anyone...
Title: Re: MK47 assembly - more pics added
Post by: etiefenthaler on December 30, 2011, 06:26:02 AM
Hi

want to show some pictures. I built two mk47 this year. I love them.

Max - thanks a lot.

Erich
Title: Re: MK47 assembly - more pics added
Post by: etiefenthaler on December 30, 2011, 06:27:46 AM
and another picture
Title: Re: MK47 assembly - more pics added
Post by: kante1603 on December 30, 2011, 06:43:26 AM
Wunderschön Erich-echt jetzt!

Udo ;)
Title: Re: MK47 assembly - more pics added
Post by: lonepariah on January 03, 2012, 02:54:52 PM
Hi, I am transformer shopping for my MK47 PSU. I am located in the US, so it needs to be 115v. I am looking for suggestions, what are you guys using?

Will something like the link below work, or is there a better/cheaper alternative? Thanks.

http://www.alliedelec.com/search/productdetail.aspx?SKU=70218047

Also, what is being used for patten selection switch?
Title: Re: MK47 assembly - more pics added
Post by: 0dbfs on January 03, 2012, 05:01:49 PM
Antek AN-05T200 50VA Toroidal worked nicely here.

Cheers,
Jonathan
Title: Re: MK47 assembly - more pics added
Post by: 0dbfs on January 05, 2012, 12:18:42 PM
I've got one mk47 installed in a broadcast studio as an announcer mic. This mic sounds very nice and performed exceptionally in other environments. This environment must have a high RF level for whatever reason.

In any case, the mic is picking up a radio station pretty far down in the noise floor. Audible if you listen closely but dwarfed by any source audio. I intend to try some different grounding schemes but this is what I have implemented at the moment:

- MK47-PCB-GND connection is connected to a conductor on the cable (happens to be the larger heater return conductor on the 7 conductor gotham cable). This is connected in the PSU.
- Mic body (EQU47) is grounded via the support rails touching/mounted to the MK47 PCB.
- Tube-mic-cable shield is connected on the mic end and disconnected on the PSU end (there was hum with it connected on the PSU end).

I'll try some different things to fix this and report back any findings but am interested in anyone else's experiences with picking up RF and solutions that worked.

Cheers,
jb


EDIT:
This reference has some good info on RFI issues:
http://audiosystemsgroup.com/RFI-Ham.pdf
Still need to test and confirm the exact source of the issue in this case as well as the solution.
Title: Re: MK47 assembly - more pics added
Post by: hop.sing on January 10, 2012, 03:43:53 AM
Quote
- Tube-mic-cable shield is connected on the mic end and disconnected on the PSU end (there was hum with it connected on the PSU end).
That is probably the reason for picking up RF. In my experience you have to connect both ends of the shield to eliminate rf issues with a microphone.
And if you connect ground and shield on both (mic end and psu end) connectors, there should be no reason for hum, since there is no ground loop. But you still have to watch the Power supply, I always had good luck with my star ground at the mic cable connector in the PSU, so housing, cable shield and main ground meet there. It has been the quietest solution for me.
Good luck, I hope it helps, those things can be really troublesome.
Title: Re: MK47 assembly - more pics added
Post by: david-p on January 10, 2012, 03:58:59 PM
I think you have a grounding problem.  Reconnect the screen at the PS end of the cable and seek a different solution to the hum.  I have put a longer screw at the bottom of one of the struts of my EQU47 body, with a nut and solder tag, to which my circuit, and the ground from the power supply are referenced.

David
Title: Re: MK47 assembly - more pics added
Post by: wave on January 10, 2012, 07:09:32 PM
Antek AN-05T200 50VA Toroidal worked nicely here.

Cheers,
Jonathan

Jonathan,

How did you wire up this transformer? Did you make your own PCB for the PSU?
Title: Re: MK47 assembly - more pics added
Post by: 0dbfs on January 10, 2012, 09:23:11 PM
Here is a picture of the PSU before I wired it up. I just made the perfboard look like the schematic. With this Antek transformer I initially wired with the 680 ohm resistor and the voltage was too low so I just paralleled the 330 ohm over that one and it was fine.

I wired the primaries in parallel for 115V with the line-voltage switched through the power switch then tied back and capped the unused secondary taps. I just used the tap for 200V to feed in to 0V and 200V on the bridge rectifier.

I'll try to get some better photo's next time I open them up.

Cheers,
jonathan
Title: Re: MK47 assembly - more pics added
Post by: poctop on January 11, 2012, 04:23:02 PM
In the case this might be of interest to anyone,  i am starting this project and would like to share this cart ,  i decided to upsclale the power supply to 10 watts and use a 50 Va for 10 dollarsextra there are some neutrik connector  in there too just check the quantity to make sure because i always grab some extra when i order at mouser.
there is also a power entry module with fuse and emi filter inside that might help here.

http://www.mouser.com:80/ProjectManager/ProjectDetail.aspx?AccessID=7078b436c0

Cheers,
Dany,
 :D ;)

Title: Re: MK47 assembly - more pics added
Post by: wave on January 11, 2012, 05:05:04 PM
In the case this might be of interest to anyone,  i am starting this project and would like to share this cart ,  i decided to upsclale the power supply to 10 watts and use a 50 Va for 10 dollarsextra there are some neutrik connector  in there too just check the quantity to make sure because i always grab some extra when i order at mouser.
there is also a power entry module with fuse and emi filter inside that might help here.

http://www.mouser.com:80/ProjectManager/ProjectDetail.aspx?AccessID=7078b436c0

Cheers,
Dany,
 :D ;)

Thanks for sharing!
With this power transformer what resistor values need to be swapped to get the same 105v as on the original schematic?
Title: Re: MK47 assembly - more pics added
Post by: poctop on January 11, 2012, 05:58:36 PM
I think it is the 330-680  swapped for a single 1.5 K as per kingston , 
Cheers ,
Dan,
Title: Re: MK47 assembly - more pics added
Post by: JamesW on January 16, 2012, 10:37:29 PM
Here is #2 works great
Title: Re: MK47 assembly - more pics added
Post by: JamesW on January 16, 2012, 10:39:36 PM
PSU gut shot
Title: Re: MK47 assembly - more pics added
Post by: wave on January 16, 2012, 11:20:46 PM
PSU gut shot

Looks great! Congrats!

I have a couple questions:
How did you create your psu board?
What kind of transformer is in there?
How did you get your logo on the psu panel?

Cheers!
Wave
Title: Re: MK47 assembly - more pics added
Post by: JamesW on January 16, 2012, 11:37:41 PM
the board is done P-T-P with eyelets just like fender amps

the transformer is Antek AN-05t200

the logo is water slip decal done with inkjet

Title: Re: MK47 assembly - more pics added
Post by: david-p on January 17, 2012, 10:50:20 AM
James (W):

Where did you get the box for the power supply?

I am intrigued by the two vacuum tubes... Do you dispense with an output transformer?  Is the circuit posted anywhere?

If these details are given in the preceding 28 pages and I have missed them, please let me know; otherwise, answers would be appreciated.

Many thanks,

David


Title: Re: MK47 assembly - more pics added
Post by: SKJGProject on January 17, 2012, 11:32:10 AM
eeeeehhhhm, did you check the very first post???? ioaudios mk47 pcb is the thing in the pic and what people were talking about the whole 28 pages  :o
Title: Re: MK47 assembly - more pics added
Post by: david-p on January 17, 2012, 12:13:47 PM
eeeeehhhhm, did you check the very first post???? ioaudios mk47 pcb is the thing in the pic and what people were talking about the whole 28 pages  :o

Thanks for pointing this out: I hadnt realized that there are two 29-page threads on the same subject, and that this one is different from the other -- which I had read completely!

However, while there are two valves on the pcb, there is only one in the circuit diagram on the first page.

Also, I cant find any details for the PSU box.

David
Title: Re: MK47 assembly - more pics added
Post by: JamesW on January 17, 2012, 01:38:28 PM

[/quote]



Also, I cant find any details for the PSU box.

David

[/quote]

This PSU box is a copy of the first box I purchased from Grand Master Audio. The main part Hammond #cwsc424nk and cwcp4. This is not a quick and easy solution but it does look like the original.
Title: Re: MK47 assembly - more pics added
Post by: Skylar on January 17, 2012, 02:59:33 PM
eeeeehhhhm, did you check the very first post???? ioaudios mk47 pcb is the thing in the pic and what people were talking about the whole 28 pages  :o

Thanks for pointing this out: I hadnt realized that there are two 29-page threads on the same subject, and that this one is different from the other -- which I had read completely!

However, while there are two valves on the pcb, there is only one in the circuit diagram on the first page.


The two threads are two entirely different mics, both by ioaudio.

This thread covers the MK47, whereas the other thread (http://www.groupdiy.com/index.php?topic=30124.0) covers the MK7.

The schematic on the front page of this thread shows a "tube" that ioaudio calls the "VF14r." There is no such tube—it's simply a moniker for two 6028 tubes in parallel, which approximates the operating conditions of the orginal U47 tube, the ridiculously rare and expensive VF14M. Using this arrangement allows you to keep the rest of the parts identical to the U47's circuit in the hope of replicating said mic's sound.
 
Title: Re: MK47 assembly - more pics added
Post by: david-p on January 17, 2012, 06:12:39 PM
The plot thickens.  The thread Skylar refers to is actually a new one to me.

I was referring to http://www.groupdiy.com/index.php?topic=35667.0 (http://www.groupdiy.com/index.php?topic=35667.0)

 :)

David
Title: Re: MK47 assembly - more pics added
Post by: Skylar on January 17, 2012, 06:58:14 PM
The plot thickens.  The thread Skylar refers to is actually a new one to me.

I was referring to http://www.groupdiy.com/index.php?topic=35667.0 (http://www.groupdiy.com/index.php?topic=35667.0)

 :)

David

ahhhh, I think that was just the feeler/announcement thread. That might have been made before the White Market existed.
Title: Re: MK47 assembly - more pics added
Post by: wave on January 18, 2012, 02:34:28 AM
James,
I forgot to ask what capsule you went with? Also, what did you source for a body?
Title: Re: MK47 assembly - more pics added
Post by: JamesW on January 18, 2012, 10:08:47 AM
James,
I forgot to ask what capsule you went with? Also, what did you source for a body?

Look at the post above yours that handsome Dude will sell you both. I purchased both my BeesNeez capsules on the blackmarket.
Title: Re: MK47 assembly - more pics added
Post by: wave on January 18, 2012, 01:57:43 PM
James,
I forgot to ask what capsule you went with? Also, what did you source for a body?

Look at the post above yours that handsome Dude will sell you both. I purchased both my BeesNeez capsules on the blackmarket.

Oh Ive been on the Equinox website quite a few times! I was just wondering what you used  ;)

Thanks
Title: Re: MK47 assembly - more pics added
Post by: mrcase on January 19, 2012, 07:55:42 PM
hey!

unfortunately my mic stopped working :-( was working great for a few months then suddendly I got a higher noise level then checked the wiring and it stopped working completely.  :'(
It was always sensitive if I moved mic cable, producing crackles and stuff.
One thing I was wondering.
Where do you connect the screen of the tubemic cable to? do you connect it to XLR1 and to the mic case?
where did you put it in the miccase? (before I didnt connect it to the mic case, but now I think I should?)

here is how I did my mic cable:

1 A+
2 A-
3 B-
4 -
C Screen ??
5 B+
6 Pattern


thanks for your help!
martin
Title: Re: MK47 assembly - more pics added
Post by: mrcase on January 20, 2012, 08:02:38 AM
ok. one strange thing. I got continuity between A+ and A- on the pcb? thats not normal is it?
Please help!!!!!!!
Title: Re: MK47 assembly - more pics added
Post by: Majestic12 on January 20, 2012, 08:23:49 AM
A+ and A- are the transformers secondary side it's a normal thing to have low resistance here....
Title: Re: MK47 assembly - more pics added
Post by: mrcase on January 20, 2012, 09:16:26 AM
thanks. sorted it out.
somehow the cable soldered to A+ lost contact. I resoldered it and all is fine now!
phew!

cheers
martin
Title: Re: MK47 assembly - more pics added
Post by: evanmurphy on January 20, 2012, 07:42:49 PM
JamesW,
Your PSU looks killer! Any chance you could snap a photo of your point to point work from above when you have some time? I'm about to do mine on turret board the same way, but I'm still a bit of a newbie. I think I've got it all figured out based on the schem but it'd be nice to have something to compare it to when I'm done.

Deeply appreciate it if you do get around to it!

-E
Title: Re: MK47 assembly - more pics added
Post by: drgrateful on January 21, 2012, 03:34:51 AM
The solution proposed by JamesW a few posts above for the 1k5 resistor seems very clean and I would like to follow it. The resistor is Mouser#71-RH0051K500FC02

However, ordering just that from Mouser would be expensive in terms of shipping fee (I am in Italy). Could anybody suggest where I could source that resistor in Europe?

Matteo
Title: Re: MK47 assembly - more pics added
Post by: JamesW on January 21, 2012, 12:01:33 PM
JamesW,
Your PSU looks killer! Any chance you could snap a photo of your point to point work from above when you have some time? I'm about to do mine on turret board the same way, but I'm still a bit of a newbie. I think I've got it all figured out based on the schem but it'd be nice to have something to compare it to when I'm done.

Deeply appreciate it if you do get around to it!

-E
This is the best view I have as the mic is in service.

The solution proposed by JamesW a few posts above for the 1k5 resistor seems very clean and I would like to follow it. The resistor is Mouser#71-RH0051K500FC02

However, ordering just that from Mouser would be expensive in terms of shipping fee (I am in Italy). Could anybody suggest where I could source that resistor in Europe?

Matteo
Please be advised that these small package resister needs to be bolted down to help dissipate the heat. This worked well on the Equinox mic base and I also used thermal paste.
Title: Re: MK47 assembly - more pics added
Post by: drgrateful on January 21, 2012, 12:14:20 PM
]Please be advised that these small package resister needs to be bolted down to help dissipate the heat. This worked well on the Equinox mic base and I also used thermal paste.

Thanks JamesW, I also have an EQU47 mic body . For bolting down the resistor, did you use self-threading screws or had to first drill holes and then use a tap?

Also, could anybody please look at the following voltages? In the PSU, I am measuring the following voltages, between center pole of the pattern switch (i.e. the end of the 14k resistor) and ground, with no mic attached:

- mic dummy load switched in, pattern relay switch off:  46V
- mic dummy load switched in, pattern relay switch on (omni): 105V
- mic dummy load switched out, pattern relay switch off: 118V
- mic dummy load switched out, pattern relay switch on (omni): 296V

By pattern relay switch off I mean: continuity between the 14k and 12k resistors, so that, if I understand correctly, the mic is *not* in omni.

Am I in the ballpark?
Title: Re: MK47 assembly - more pics added
Post by: evanmurphy on January 21, 2012, 06:52:37 PM
JamesW,
Your PSU looks killer! Any chance you could snap a photo of your point to point work from above when you have some time? I'm about to do mine on turret board the same way, but I'm still a bit of a newbie. I think I've got it all figured out based on the schem but it'd be nice to have something to compare it to when I'm done.

Deeply appreciate it if you do get around to it!

-E

This is the best view I have as the mic is in service.

This is more than helpful, thank you kindly!
Title: Re: MK47 assembly - more pics added
Post by: drgrateful on January 22, 2012, 10:42:57 AM
I think I need some help in wiring the PSU. Hoping this will also be helpful to others, I drew the image attached, starting from an image posted earlier. I am going to use a 7 pin connector and GAC-7 cable. Is this wiring correct? My main doubt concerns the best way for the shield, B- and the audio ground to reach 0V...

Thanks, Matteo
Title: Re: MK47 assembly - more pics added
Post by: poctop on January 22, 2012, 01:21:06 PM
Hi There would someone know if the Original U47 tube had a impedance out switch 50-200,
what would be the config off Max traffo off the board 50-200,
any comments,
thanks Dan,
Title: Re: MK47 assembly - more pics added
Post by: poctop on January 22, 2012, 01:36:30 PM
Got it Sorry can't read anymore  :-\
D
Title: Re: MK47 assembly - more pics added
Post by: poctop on January 23, 2012, 01:17:26 PM
Hi to All, ,  just some experimentation with my finish build i dont know if it works now PSU warming up,
i have installed all 10W and my 1K runs at 85deg C and my final dropping wich is 1.5K runs at 115 degC  the %W pot runs at about 60degC
i also used a 10W heater dropper and my casing is arround 40degC , this is after running for about 1H,
Cheers, 

Title: Re: MK47 assembly - more pics added
Post by: poctop on January 23, 2012, 03:48:09 PM
Hi there ,  i fired the thing up and yes marvelous potential but there is a small issue i cannot explain ,  the output is great but i have do have some humming only in the cardiod pattern but no hum in the omni pattern has someone had issue similar to this one the mic pcb attach point is grounded to the mic body and then runs trough the cable shield to the 0V of the PSU ,  would my problem would be the fact that i am running trough the shield or something stupid i am missing if that would be the case then i would expect both pattern to hum the same ?

Any Help ? or suggestions,
Thanks
Dany,
Title: Re: MK47 assembly - more pics added
Post by: poctop on January 23, 2012, 06:03:49 PM
Well it seems my back diaprhagme  is not working either in omni , hope it is related, :(
Title: Re: MK47 assembly - more pics added
Post by: drgrateful on January 25, 2012, 04:24:42 AM
I made some more research about how to wire the GAC-7 cable. I came across this interesting discussion on GAC-3 cables, that also applies to GAC-7:

http://www.gearslutz.com/board/geekslutz-forum/474307-what-i-hope-exhaustive-thread-soldering-gotham-gac-3-a.html (http://www.gearslutz.com/board/geekslutz-forum/474307-what-i-hope-exhaustive-thread-soldering-gotham-gac-3-a.html)

In summary, the suggestion (even if not completely unanimous) is (the sentence refers to three pin XLRs):

"Cable shield and cable ground (where provided, as in GAC 3) must be connected to pin 1 on both connectors AND to the sleeves (metal housings) of BOTH connectors" (Klaus Heyne)

So, translating to the GAC-7 and the seven pin connector where, according to the suggestions above, audio ground is connected to the center pin, we should connect the audio ground (green) to the center pin and the shield to the connector shell, and then jumper to the center pin. This should be done at both ends.

Since, even in the discussion above, there seem to be some caveats for this configuration, I would like to know what others are doing here. Also:

- For connecting A+ and A-, in the PSU,  between the seven pin female connector and the three pin female XLR, are you using twisted wires, or shielded wires, as in the picture I posted above?
- For RF interference, do you find clamp on ferrite chokes useful in our case?

I think discussing these details might save some headaches. They are far from obvious (at least for me) and they seem to be important.
Title: Re: (BUILD) MK47 tube mic kit assembly - new batch in
Post by: poctop on January 25, 2012, 08:37:38 PM
So finally found the problem :  wich is bad power supply case design with hole at not the right logical spot hence the Omni Cardiod switch shall not be on the same side as the power and test Switch,    So AC power was too near of the Car-omni switch making it humm in the audio when switch off,  So the story is put you pattern switch on the output-input side, the mike is working perfectly in cardiod, with no buzz Nor hum,   

the onlything that i find is that the omni pattern sound a bit weak from the back,  i checked the 48 and the relay operation and it is all fine,  i will try another capsule to find out more,

Cheers,
Dan ,
Title: Re: (BUILD) MK47 tube mic kit assembly - new batch in
Post by: 0dbfs on January 25, 2012, 09:33:01 PM
You can do another capsule to test or you can also reverse the leads to see if the issue follows front/back.
Another capsule may have the "same problem" too.

Cheers,
jb
Title: Re: (BUILD) MK47 tube mic kit assembly - new batch in
Post by: poctop on January 25, 2012, 10:16:10 PM
Thanks,  0dbfs,

I am starting to think this is all my head now,  i tried reversing the lead but i am not sure the problems follow ,  time to take a rest  :P
that pattern switch-ac-humm-too-near-when-off thing just sucked my brain :o,  i have Max transfo for now i will try a CM2461NiCo somtime soon,

Cheers,
D
Title: Re: MK47 assembly - more pics added
Post by: Denyle Guitars on January 26, 2012, 05:16:40 PM
I think I need some help in wiring the PSU. Hoping this will also be helpful to others, I drew the image attached, starting from an image posted earlier. I am going to use a 7 pin connector and GAC-7 cable. Is this wiring correct? My main doubt concerns the best way for the shield, B- and the audio ground to reach 0V...

Thanks, Matteo

That's more or less how I did mine, although there's some redundancy in your drawing. Assuming the pattern switch is near the XLR connectors, just take the wires from the switch to 7p connector.  Since your using GAC-7, you can also ground pin 4, same as pin 3, for the same reason. Not sure how much noise reduction it'll net. I used Mogami cable that was previously made up for another mic, so I wired mine accordingly.

Here's another shot of mine.
(http://www.denyleguitars.com/diy/images/mk47_3.jpg)
Title: Re: (BUILD) MK47 tube mic kit assembly
Post by: poctop on January 26, 2012, 10:33:08 PM
Hi All, i tried CM2461NiCo and i like Max trafo still it sounds more neumann to me ,  and also anyone know about that bypass russian cap
is this one on the original used ? worthed to try an orange drop there ,  ?

D

Title: Re: (BUILD) MK47 tube mic kit assembly
Post by: drgrateful on January 27, 2012, 05:32:28 AM
Assuming the pattern switch is near the XLR connectors, just take the wires from the switch to 7p connector.
Yes, I thought it would have been more clear the way I drew it, but you are probably right: I updated the wiring diagram.

Since your using GAC-7, you can also ground pin 4, same as pin 3, for the same reason.
I hadn't thought of that. Thanks for the suggestion.
Title: Re: (BUILD) MK47 tube mic kit assembly
Post by: drgrateful on January 28, 2012, 10:26:25 AM
I have to correct my post above with voltage readings. I had set the PSU pot so that the B+ voltage was 105v, but without having continuity between the 12k and 14k resistors (the pattern switch confused me). So, don't make my same mistake: the PSU pot has to be set while having continuity between the 14k and 12k resistors. Now, these are my readings (between the center pole of the pattern switch, i.e. the end of the 14k resistor, and ground, with no mic attached):

- mic dummy load switched in, pattern relay switch off:  48V
- mic dummy load switched in, pattern relay switch on (omni): 110V
- mic dummy load switched out, pattern relay switch off: 120V
- mic dummy load switched out, pattern relay switch on (omni): 299V
Title: Re: (BUILD) MK47 tube mic kit assembly
Post by: poctop on February 02, 2012, 03:46:19 PM
No ones has any information on this CCCP bypass cap,  was this cap in the original circuit or just the one that fitted there the most ?
any substition experiment out there ?
DAn,
Title: Re: (BUILD) MK47 tube mic kit assembly
Post by: SKJGProject on February 03, 2012, 10:37:36 PM
anybody knows a source for the little bastards in germany??? i can't find them and don't want to spend 20€ shipping just for 2 20cent pieces...

These little guys are your friends:
     (http://i73.photobucket.com/albums/i222/skylargray/47/th_EQU47-mount_04.jpg) (http://s73.photobucket.com/albums/i222/skylargray/47/EQU47-mount_04.jpg)
Mouser PN: 534-621

I used 2 of them on one of my MK7s along with short 4-40 flat undercut brass screws.
     (http://i73.photobucket.com/albums/i222/skylargray/47/th_EQU47-mount_03.jpg) (http://s73.photobucket.com/albums/i222/skylargray/47/EQU47-mount_03.jpg)     (http://i73.photobucket.com/albums/i222/skylargray/47/th_EQU47-mount_02.jpg) (http://s73.photobucket.com/albums/i222/skylargray/47/EQU47-mount_02.jpg)
On this build, all the wiring is solid-core silver teflon, and it's STIFF, which really helps keep the board in place. In fact, I can remove the brackets, and the PCB is still held in place solidly under the support of only the wiring.


Now, mounting the G7 takes a little more imagineering.
Using parts that I had lying around...
     (http://i73.photobucket.com/albums/i222/skylargray/47/th_EQU47-mount_01.jpg) (http://s73.photobucket.com/albums/i222/skylargray/47/EQU47-mount_01.jpg)
This one is fun. Looks a little steam-punk, but we like that kind of thing around here, right?
There are plenty of ways this could be done better, but this improvised approach works in a pinch and provides some adjust-ability.
[You will notice that the side rails are all bent outta shape. That's the result of my testing procedures...of course, they still work fine. A trip to the vise will straighten them back up again.]   
Title: Re: (BUILD) MK47 tube mic kit assembly
Post by: grantlack on February 04, 2012, 12:15:18 AM
anybody knows a source for the little bastards in germany??? i can't find them and don't want to spend 20€ shipping just for 2 20cent pieces...

i'm placing a mouser order soon, i can send some your way if you want to drop me a line by pm.
Title: Re: (BUILD) MK47 tube mic kit assembly
Post by: kante1603 on February 04, 2012, 01:48:18 AM
anybody knows a source for the little bastards in germany??? i can't find them and don't want to spend 20€ shipping just for 2 20cent pieces...

Hi,

in germany this could work,mounting stuff for D-Subs like this:

http://www.reichelt.de/Befestigungssaetze/SV-WMG/index.html?;ACTION=3;LA=444;GROUP=C125;GROUPID=3212;ARTICLE=19873;START=0;SORT=artnr;OFFSET=500;SID=11Ts03q38AAAIAAD4EOiM488d01c62fad0a865a65237798186f50

or at Bürklin (if you have an account),they have nearly all sizes as well as massive small cubes ("Gewindewürfel"):

https://www.buerklin.com/default.asp?event=ShowPHNode(SE,vt,6007)&l=d&jump=PHNode_SE_vt_6007&ajaxLoadPHNodeTagId=PHNode_SE_vt_6007&ajaxLoad=true

If you want real diy then go to "OBI" and get yourself an L-bracket (aluminium) in 1 or 2m pieces and cut/drill them to the size you need (available starting from 10mm sides) ;).

Best regards from germany,

Udo.
Title: Re: (BUILD) MK47 tube mic kit assembly
Post by: bezen4uk on February 04, 2012, 02:16:53 AM
No ones has any information on this CCCP bypass cap,  was this cap in the original circuit or just the one that fitted there the most ?
any substition experiment out there ?
DAn,
Hi Dan,
These are russian "MBGO" paper-in-oil capacitors. Not original, just same type.  I'd use modern Wima FKP4 or MKP4 or vintage Siemens PIO caps.
Title: Re: (BUILD) MK47 tube mic kit assembly
Post by: poctop on February 04, 2012, 11:45:28 AM
No ones has any information on this CCCP bypass cap,  was this cap in the original circuit or just the one that fitted there the most ?
any substition experiment out there ?
DAn,
Hi Dan,
These are russian "MBGO" paper-in-oil capacitors. Not original, just same type.  I'd use modern Wima FKP4 or MKP4 or vintage Siemens PIO caps.


Thanks bezen4uk this is exactely the information i needed ,
Super,  will probably try a orange drop sometime in there , just to see,
Title: Transformer of PSU
Post by: Ishi on February 05, 2012, 09:20:14 AM
Please give me advice about the PSU transformer of MK47.

The wall socket of my country is 100v. Can I just get the transformer which can convert 100v into 200v? The following transformer seems to increase 115v to 230v. Although it seems that this transformer increases 100v to 200v, isn't there any mistake in my thought? Can this transformer work MK47 in the country of 100v?

http://us.mouser.com/Search/ProductDetail.aspx?R=VPT230-220virtualkey55310000virtualkey553-VPT230-220
Title: Re: (BUILD) MK47 tube mic kit assembly
Post by: poctop on February 05, 2012, 10:12:26 AM
This is the transformer i used so it is ok wire it in parralle for 120V contry and replace the 680 330 pair with a 1.5 K with the 1K pot 5 W and youl be fine ,

Dany,
Title: Re: (BUILD) MK47 tube mic kit assembly
Post by: dandeurloo on February 06, 2012, 10:41:44 PM
I built my kit up during my daughter nap today!  Nice kit.  I can't wait to figure out what capsule I'm gonna try and get the PSU going.

Thanks Ioaudio.  Good work.
Title: Re: (BUILD) MK47 tube mic kit assembly
Post by: electrisizer on February 08, 2012, 05:03:09 PM
hi,

my build is complete (first batch + beezneez capsule + t.bone housing), but mik dosent work the right way...


i have lot of "windy" noise and the output is very very low... on the other hand the mik is very sensitive in case of touching or moving. perhaps a grounding problem?

the cable is the original t.bone and seems not to be in best condition, but  measuring doesnt advertise any problem.

does anyone have an idea?
Title: Re: (BUILD) MK47 tube mic kit assembly
Post by: drgrateful on February 09, 2012, 09:57:09 AM
For those who might be interested, 1K5 10W aluminium housed, chassis-mount resistors similar to that used by JamesW can be found in Europe from RS-Online. The RS Stock No. is 252-2530 or 720-4827. Tolerance is 5%, but it should suffice.
Title: Re: (BUILD) MK47 tube mic kit assembly
Post by: nashkato on February 09, 2012, 04:49:16 PM
 :)
Quote
  Tolerance is 1%, but it should suffice.
;)

 :o did you use precision components inside your mic ??
Title: Re: (BUILD) MK47 tube mic kit assembly
Post by: drgrateful on February 10, 2012, 08:06:52 AM
:o did you use precision components inside your mic ??

No, sorry, I meant 5% tolerance. I corrected my post.  ;)

Matteo
Title: Re: [BUILD] MK47 tube mic kit - new batch @ white market
Post by: Volume11 on February 13, 2012, 06:54:00 PM
Hey guys, I am working on building the power supply and I am having trouble locating some of the parts on mousers site. Can someone please tell me what fuse type and value would be most appropriate. A mouser part number would really help me out :). This is for a US model.  Also, what lamp have people used and liked so far? I have noticed a lot of Fender amp style lamps being used, which I think looks really cool.
Thanks
Title: Re: [BUILD] MK47 tube mic kit - new batch @ white market
Post by: wave on February 14, 2012, 02:42:51 AM
Hey guys, I am working on building the power supply and I am having trouble locating some of the parts on mousers site. Can someone please tell me what fuse type and value would be most appropriate. A mouser part number would really help me out :). This is for a US model.  Also, what lamp have people used and liked so far? I have noticed a lot of Fender amp style lamps being used, which I think looks really cool.
Thanks

I think these will work

http://www.mouser.com/Search/ProductDetail.aspx?R=20105000021virtualkey57610000virtualkey576-20105000021

If you use a power transformer with a 6.3 VAC tap you can use this

http://tubedepot.com/lamps.html

-Dave
Title: Re: [BUILD] MK47 tube mic kit - new batch @ white market
Post by: madreza on February 14, 2012, 07:15:40 AM
Hi Guys
I have strange noises coming out of the mics from time to time ( it can work for hours and suddenly noise ! )
http://dl.free.fr/dIzDp5o9a
a sample in the link

in 1 of my mics, I think i have a transformer problem. how can I test that ?

Cheers
Title: Re: [BUILD] MK47 tube mic kit - new batch @ white market
Post by: Volume11 on February 14, 2012, 04:28:28 PM
Hey guys, I am working on building the power supply and I am having trouble locating some of the parts on mousers site. Can someone please tell me what fuse type and value would be most appropriate. A mouser part number would really help me out :). This is for a US model.  Also, what lamp have people used and liked so far? I have noticed a lot of Fender amp style lamps being used, which I think looks really cool.
Thanks

I think these will work

http://www.mouser.com/Search/ProductDetail.aspx?R=20105000021virtualkey57610000virtualkey576-20105000021

If you use a power transformer with a 6.3 VAC tap you can use this

http://tubedepot.com/lamps.html

-Dave

Thanks!
Title: Re: [BUILD] MK47 tube mic kit - new batch @ white market
Post by: poctop on February 17, 2012, 05:50:39 PM
Hope it can help for givig an idea where the capsule should end,
Cheers,
Dany
Title: Re: (BUILD) MK47 tube mic kit assembly
Post by: wave on February 17, 2012, 07:52:47 PM
This is the transformer i used so it is ok wire it in parralle for 120V contry and replace the 680 330 pair with a 1.5 K with the 1K pot 5 W and youl be fine ,

Dany,
Dany
Are you saying that if the VPT230-110 is used the 680/330 resistor pair is switched for a 1.5K and the 500 ohm 5W pot is switched for a 1K 5W pot?

Dave
Title: Re: (BUILD) MK47 tube mic kit assembly
Post by: grantlack on February 17, 2012, 08:49:49 PM
Are you saying that if the VPT230-110 is used the 680/330 resistor pair is switched for a 1.5K and the 500 ohm 5W pot is switched for a 1K 5W pot?

Dave

yep, i mentioned this previously but should have been more clear.  i used a 1k pot and 1k resistor this way with no problems dialing in either psu.
Title: Re: [BUILD] MK47 tube mic kit - new batch @ white market
Post by: david-p on February 17, 2012, 09:44:30 PM
Hey guys, I am working on building the power supply and I am having trouble locating some of the parts on mousers site. Can someone please tell me what fuse type and value would be most appropriate. A mouser part number would really help me out :). This is for a US model.  Also, what lamp have people used and liked so far? I have noticed a lot of Fender amp style lamps being used, which I think looks really cool.
Thanks

I find it easier to get simple things like these at Radio Shack.

David
Title: Re: [BUILD] MK47 tube mic kit - new batch @ white market
Post by: grantlack on February 17, 2012, 10:07:13 PM
david- what's yours fused at?  the inrush current blows a .125A fast-acting every time here, and i haven't been able to find slo-blo's even close at a brick and mortar store.  the mouser price for a typical glass fuse is a bit high.
Title: Re: [BUILD] MK47 tube mic kit - new batch @ white market
Post by: david-p on February 18, 2012, 08:33:36 AM
If you are using a toroidal transformer, which I am not, you need a slow blow fuse.  I dont usually bother with fuses that small.  0.5 Amp is the smallest I use, even 1 Amp, on the basis that if something is going to go wrong it will blow a fuse that size easily!

David
Title: Re: [BUILD] MK47 tube mic kit - new batch @ white market
Post by: electrisizer on February 19, 2012, 06:47:07 AM
Hello again
Ive still no glue for my problems with that built.

Lot of windy noise very low output...
When the capsule is unsoldered the mik is quiet. All voltages are good.

Could a faulty capsule cause such strange mik behavior?
I would be glad to get some help :)
Title: Re: [BUILD] MK47 tube mic kit - new batch @ white market
Post by: kante1603 on February 19, 2012, 07:41:11 AM
Hello again
Ive still no glue for my problems with that built.

Lot of windy noise very low output...
When the capsule is unsoldered the mik is quiet. All voltages are good.

Could a faulty capsule cause such strange mik behavior?
I would be glad to get some help :)
Hi,

you wrote about using the t-bone housing in your previous post.
If you´re unsure about your capsule simply put in the original one and see what happens (check in cardioid mode-as far as I remember it is a single sided capsule).
Always assembling the complete housing for testing is a must-otherwise you´ll pick up tons of noise (or do max´s trick putting it in metall coin box ("Münztresor"/"Geldkassette")).
This piece must have a well done shielding,so exept for the housing the wiring between psu and mic must be done pretty well too.
Please don´t use the cable that was delivered with the microphone:I opened mine and noticed super-bad solder joints and unisolated part carrying the B+ nearly touching the xlr housing-HORROR!
Use a good cable and follow the instructions in this thread as there is a lot of information about this issue.
BTW:Have you burnt in the tubes for 48-72 hours?-Could solve some problems concerning noise...
About lowish level on output:Don´t know what you mean or what gain you must have to get a good signal.On the other hand it is well known that the level falls back about some dB when the mic is in omni mode-exactly like it was in the original u47.You can find infos on that on the Neumann homepage looking for "Historische Mikrofone".

Hope to have helped and good luck,

Udo.

Edit:Forgot to mention that you should check the mic housing for good continuity too.When assembled measure the resistance from headbasket to the housings bottom;from there to the psu ground.Shoud end up very close to 0 ohms.


Title: Re: [BUILD] MK47 tube mic kit - new batch @ white market
Post by: electrisizer on February 20, 2012, 12:59:40 PM
thanks kante!!!

today ive tried the original t.bone capsule - no change.

ive ordered an high end micro cable right now... i measured a 0.2 ohm resistance between capsule housing and mic bottom and 19 ohm!!! to the PSU ground. i think thats the faulty dog  :)

the low output means that my G9 preamp is cranked up nearly all the way to get an useable level. other miks need (maximal) a 45 o clock setting. but perhaps a new cable does the job...
Title: Re: [BUILD] MK47 tube mic kit - new batch @ white market
Post by: kante1603 on February 20, 2012, 02:00:34 PM
thanks kante!!!

today ive tried the original t.bone capsule - no change.

ive ordered an high end micro cable right now... i measured a 0.2 ohm resistance between capsule housing and mic bottom and 19 ohm!!! to the PSU ground. i think thats the faulty dog  :)

the low output means that my G9 preamp is cranked up nearly all the way to get an useable level. other miks need (maximal) a 45 o clock setting. but perhaps a new cable does the job...
Good to hear it is not the capsule!
So you should get your build cleared up first(talking about grounding of course).
19 ohms is waaaayyyyyyyyyyyy toooooooo much,hahaha.......
A good cable should do it,correctly hooked up!
About low level again:what other microphones did you compare it to-condenser or dynamic types?
Anyway,get propper grounding first,then you can talk or write about the "real" signal much better since the noise level you have at the moment can be pretty high!

Cheers,

Udo.
Title: Re: MK47 assembly - more pics added
Post by: Volume11 on February 22, 2012, 03:19:58 PM
PSU gut shot
Hi James,
 Is your transformer wired for 115v? I bought the same one and was about to wire it up using a single red and single black lead for 115v, until I noticed yours. Do I need both red and both black to achieve 115v. I'm not sure what your standard is in Canada. (noobie here)

Thanks
Title: Re: MK47 assembly - more pics added
Post by: wave on February 22, 2012, 04:44:09 PM
PSU gut shot
Hi James,
 Is your transformer wired for 115v? I bought the same one and was about to wire it up using a single red and single black lead for 115v, until I noticed yours. Do I need both red and both black to achieve 115v. I'm not sure what your standard is in Canada. (noobie here)

Thanks

If you are using the Antek transformer you wire both red wires together and both black wires together then wire the reds to the switch and the blacks to the -V in from the power inllet for 115V operation.
Wire one red to one black then wire the other red to the switch and the other black to the -V in from the power inlet for 230V operation.
In both cases you use another wire from the +V in from the power inlet to the other pole of the SPST switch
So looking at James's pic he is wired for 115V operation (through a fuse)
Make sense?

Dave
Title: Re: MK47 assembly - more pics added
Post by: Volume11 on February 22, 2012, 08:59:01 PM
PSU gut shot
Hi James,
 Is your transformer wired for 115v? I bought the same one and was about to wire it up using a single red and single black lead for 115v, until I noticed yours. Do I need both red and both black to achieve 115v. I'm not sure what your standard is in Canada. (noobie here)

Thanks

If you are using the Antek transformer you wire both red wires together and both black wires together then wire the reds to the switch and the blacks to the -V in from the power inllet for 115V operation.
Wire one red to one black then wire the other red to the switch and the other black to the -V in from the power inlet for 230V operation.
In both cases you use another wire from the +V in from the power inlet to the other pole of the SPST switch
So looking at James's pic he is wired for 115V operation (through a fuse)
Make sense?

Dave

That all makes perfect sense! Thanks again for the help, I really appreciate it.

Chad
Title: Re: [BUILD] MK47 tube mic kit - new batch @ white market
Post by: LHS on February 23, 2012, 03:49:52 PM
I spoke to the folks at Tab-Funkenwerk recently about buying the Thiersch blue line capsule as well as having them make my power supply and got this response:

"When using a relay for switching, the relay will kick back voltage in the circuit anywhere from 5-7 times the amount that is needed to switch it in the first place.  So a 48V relay can kick back over 300V if not properly shunted within the circuit.  In this layout most of that kick back will hit the capsule and some may go all the way back to the tube.  A spike in voltage of this size can damage both the capsule and the tube over time"

Is this a real danger in this mic circuit? Has anyone experience damage to the capsule/tube thus far?
Title: Re: [BUILD] MK47 tube mic kit - new batch @ white market
Post by: kante1603 on February 23, 2012, 04:44:10 PM
I spoke to the folks at Tab-Funkenwerk recently about buying the Thiersch blue line capsule as well as having them make my power supply and got this response:

"When using a relay for switching, the relay will kick back voltage in the circuit anywhere from 5-7 times the amount that is needed to switch it in the first place.  So a 48V relay can kick back over 300V if not properly shunted within the circuit.  In this layout most of that kick back will hit the capsule and some may go all the way back to the tube.  A spike in voltage of this size can damage both the capsule and the tube over time"

Is this a real danger in this mic circuit? Has anyone experience damage to the capsule/tube thus far?
Hi,

looking at the schemo there is a diode strapped over relais coil,so all good.

Cheers,

Udo.
Title: Re: [BUILD] MK47 tube mic kit - new batch @ white market
Post by: mrvision on February 24, 2012, 04:10:05 PM
My finished unit... I took my time to carefully build the project and it worked without mayor problems at first. The only problem I had was the noisy tubes, but I had some tested spare tubes that I got from a trusted source just in case I had the same problem that a lot of people were having with the tubes included with the kit. I replaced them with tested ones and the problem was gone. My next build I will probably experiment a mod to use 6AK5 tubes (same electrical properties/different heater). There are more options and brands to try than the 6028.

I will post some pictures to share some ideas, thank you to the others that have already contributed with some good DIY ideas about this project.

The capsule is the Beezneez from the group buy, very happy with it.

Thanks to ioaudio (mk-47 circuit) and skylar (Mic body) for making this happen.
Title: Re: [BUILD] MK47 tube mic kit - new batch @ white market
Post by: mrvision on February 24, 2012, 04:12:31 PM
more pictures...
Title: Re: [BUILD] MK47 tube mic kit - new batch @ white market
Post by: mrvision on February 24, 2012, 04:14:04 PM
Mic:
Title: Re: [BUILD] MK47 tube mic kit - new batch @ white market
Post by: mrvision on February 24, 2012, 04:15:12 PM
PSU:
Title: Re: [BUILD] MK47 tube mic kit - new batch @ white market
Post by: david-p on February 24, 2012, 04:15:45 PM
My finished unit... I took my time to carefully build the project and it worked without mayor problems at first. The only problem I had was the noisy tubes, but I had some tested spare tubes that I got from a trusted source just in case I had the same problem that a lot of people were having with the tubes included with the kit. I replaced them with tested ones and the problem was gone. My next build I will probably experiment a mod to use 6AK5 tubes (same electrical properties/different heater). There are more options and brands to try than the 6028.
It looks magnificent!

Where did you get the shock mount and PSU box with the handle?

David
Title: Re: [BUILD] MK47 tube mic kit - new batch @ white market
Post by: mrvision on February 24, 2012, 08:58:04 PM


Thank you David, The Box is a Recycled SONY CMA Camera PSU, I Paid about $35 shipped on ebay, removed the guts (it has a nice 50V transformer btw) I just did some holes with my bench drill and repainted it with hammered finish spray paint. The handle is a 4-3/8 In. Senna Leather with Satin Nickel and the Shockmount is a Beezneez from the group buy.

Marv
Title: Re: MK47 assembly - more pics added
Post by: Volume11 on February 25, 2012, 07:22:27 AM
Need opinions of mounting the 1k5 resistor 'heater' from MK47 kit.
 

Thanks

Jason
Here is a pic of my mounting I've used it twice now worked great

Anyone have a part number for this resistor?

Thanks
Title: Re: MK47 assembly - more pics added
Post by: zayance on February 25, 2012, 08:22:22 AM
Need opinions of mounting the 1k5 resistor 'heater' from MK47 kit.
 

Thanks

Jason
Here is a pic of my mounting I've used it twice now worked great



Anyone have a part number for this resistor?

Thanks

I think it would be this one.

http://fr.mouser.com/ProductDetail/Arcol/HS10-1K5-1/?qs=sGAEpiMZZMtlubZbdhIBIKR5oQtBrv7qwqZcsowM%252bXM%3d

Or RS 252-2530

Be sure to fit the treated bolt that locks the Male binder in place before poiting where to drill holes for it. Never know.
Title: Re: [BUILD] MK47 tube mic kit - new batch @ white market
Post by: gurkan75 on February 25, 2012, 05:25:16 PM
Hi, I have got a question: what is the correct way to determine capsule polarization voltage? Seems to me that measuring before the 100M resistor gives me about 5V less than what theoretically should be at the voltage divider..

It was mentioned earlier that the Beezneez capsule likes to see 60V, trying to make sure that is what I am supplying.

Title: Re: MK47 assembly - more pics added
Post by: Volume11 on February 25, 2012, 08:53:36 PM
Need opinions of mounting the 1k5 resistor 'heater' from MK47 kit.
 

Thanks

Jason
Here is a pic of my mounting I've used it twice now worked great



Anyone have a part number for this resistor?

Thanks

I think it would be this one.

http://fr.mouser.com/ProductDetail/Arcol/HS10-1K5-1/?qs=sGAEpiMZZMtlubZbdhIBIKR5oQtBrv7qwqZcsowM%252bXM%3d

Or RS 252-2530

Be sure to fit the treated bolt that locks the Male binder in place before poiting where to drill holes for it. Never know.

Thanks for the heads up. I just went to check the q47 page with Skylers bodies and capsules. I remember the link for the correct 7 pin binder connector is in there. For some reason I can't get into the thread. It says that it no longer exists or I don't have permission. Anyone have the part number for this piece? Sorry for all of the ridiculous questions, I'm just having a hard time finding it online.

Thanks

Chad
Title: Re: [BUILD] MK47 tube mic kit - new batch @ white market
Post by: LHS on February 25, 2012, 10:09:11 PM
The binder part # is 09 0042 00 07 (just ordered mine yesterday). It's sold at binder-usa.com or binder-connector.de if you're in Europe.
Title: Re: [BUILD] MK47 tube mic kit - new batch @ white market
Post by: david-p on February 25, 2012, 10:20:03 PM
Hi, I have got a question: what is the correct way to determine capsule polarization voltage? Seems to me that measuring before the 100M resistor gives me about 5V less than what theoretically should be at the voltage divider..

It was mentioned earlier that the Beezneez capsule likes to see 60V, trying to make sure that is what I am supplying.

60v is the usual polarizing voltage for nearly all mike capsules.

David
Title: Re: [BUILD] MK47 tube mic kit - new batch @ white market
Post by: Volume11 on February 26, 2012, 07:31:56 PM
The binder part # is 09 0042 00 07 (just ordered mine yesterday). It's sold at binder-usa.com or binder-connector.de if you're in Europe.

Thanks, but that looks like a female connector. Is that correct ( if it really matters), or is this one more ideal.. http://www.binder-usa.com/psearch_detail.php?pid=5203
Title: Re: [BUILD] MK47 tube mic kit - new batch @ white market
Post by: LHS on February 26, 2012, 08:11:39 PM
Not sure which part of the cable you were asking about. The part number I mentioned attaches to the mic. The part you listed attaches to the power supply. And then there's the panel mount on the PSU.

Binder series 691

Female cable-mount (available in my webstore) : 09 0042 00 07 (http://www.binder-usa.com/psearch_detail.php?pid=5204)

Male cable-mount : 09 0041 00 07 (http://www.binder-usa.com/psearch_detail.php?pid=5203)

Female panel-mount : 09 0044 00 07 (http://www.binder-usa.com/psearch_detail.php?pid=5206)

Also:


You can use Binder connectors on the PSU end. The ones I am using are the 691-Series 7-pin.
What I would actually recommend is to use Amphenol-Tuchel connectors on the PSU end.
Why? Because they're less expensive & more readily available.

So you could build a cable that has:
Binder 7-pin Female cable-mount connector on one side (this connects to the mic),
Amphenol T 3475 002 or T 3475 001 Male cable-mount on the other end.
Then at the PSU use an Amphenol Female panel-mount T 3478 000.

Now the $25,000 question...why not just use Amphenol all around in the first place?
a) because I wouldn't have been able to integrate it into the end-cap as well the Binder
b) the binder is larger in size which looks better and is slightly easier to solder/assemble.
Title: Re: [BUILD] MK47 tube mic kit - new batch @ white market
Post by: drgrateful on February 27, 2012, 07:39:01 AM
Hi, I was about to solder the capsule termination wires when I noticed that they are a bit too short to be soldered after the glass tubes (I am using a Thiersch blue line capsule). I don't know if this has been asked before, but is it ok to solder the wires before the glass tubes (i.e. on the side with written "front", "rear" and "back-plate")? If yes, is there any particular spot where it is preferable to solder the termination wires (e.g. closer to the glass tubes or closer to the grid and relay pins)? Or maybe any point connected to the appropriate lead will be fine? Thanks, Matteo
Title: Re: [BUILD] MK47 tube mic kit - new batch @ white market
Post by: micaddict on February 27, 2012, 01:31:14 PM
mrvision wrote:

Quote
My next build I will probably experiment a mod to use 6AK5 tubes (same electrical properties/different heater). There are more options and brands to try than the 6028.

Anyone else like to comment on this?
Title: Re: [BUILD] MK47 tube mic kit - new batch @ white market
Post by: david-p on February 27, 2012, 08:16:27 PM
Hi, I was about to solder the capsule termination wires when I noticed that they are a bit too short to be soldered after the glass tubes (I am using a Thiersch blue line capsule). I don't know if this has been asked before, but is it ok to solder the wires before the glass tubes (i.e. on the side with written "front", "rear" and "back-plate")? If yes, is there any particular spot where it is preferable to solder the termination wires (e.g. closer to the glass tubes or closer to the grid and relay pins)? Or maybe any point connected to the appropriate lead will be fine? Thanks, Matteo

No problem in soldering extra wire to the capsule leads, but try to leave the original leads as long as possible, and make sure the joint cant short on anything.  Also, and this is VERY important, cover the capsule with cardboard or something to prevent any solder or hot flux from getting on the diaphragm.

David
Title: Re: [BUILD] MK47 tube mic kit - new batch @ white market
Post by: zayance on February 28, 2012, 04:10:17 AM
Hi, I was about to solder the capsule termination wires when I noticed that they are a bit too short to be soldered after the glass tubes (I am using a Thiersch blue line capsule). I don't know if this has been asked before, but is it ok to solder the wires before the glass tubes (i.e. on the side with written "front", "rear" and "back-plate")? If yes, is there any particular spot where it is preferable to solder the termination wires (e.g. closer to the glass tubes or closer to the grid and relay pins)? Or maybe any point connected to the appropriate lead will be fine? Thanks, Matteo

No problem in soldering extra wire to the capsule leads, but try to leave the original leads as long as possible, and make sure the joint cant short on anything.  Also, and this is VERY important, cover the capsule with cardboard or something to prevent any solder or hot flux from getting on the diaphragm.

David

Use Thiersch Plastic cover, perfect for that....
Title: Re: [BUILD] MK47 tube mic kit - new batch @ white market
Post by: drgrateful on February 28, 2012, 08:41:21 AM
No problem in soldering extra wire to the capsule leads, but try to leave the original leads as long as possible, and make sure the joint cant short on anything.  Also, and this is VERY important, cover the capsule with cardboard or something to prevent any solder or hot flux from getting on the diaphragm.

David

OK, thanks. Then I will go to plan B and use some wire stripped from the pair inside a mic cable and solder it to the capsule leads, then isolating it with some heat-shrink tubing.

Use Thiersch Plastic cover, perfect for that....

Yes, but I have already attached the capsule to the support... I think I will go with something like this:

(http://img.photobucket.com/albums/v283/jazz347/47-inspired%20mic%20build/DSC01051.jpg)
Title: Re: [BUILD] MK47 tube mic kit - new batch @ white market
Post by: zayance on February 28, 2012, 08:46:20 AM
hmmm, well maybe, but it could also be risky like this also? i said the plastic given with Thiersh because it's a thick one,
and won't melt of flux spread on it, well not as fast as your plastic.... And it's for the same reason people said cardboard or so...
Anyway do as you like... I would take out the capsule, protect with Thiersch box and do the cable jobby....
A couple of minutes to take it out and do it carefully is better than sending it back for reskining imho, well that's in the worst case scenario...
Anyway be carefull.
Title: Re: [BUILD] MK47 tube mic kit - new batch @ white market
Post by: drgrateful on March 01, 2012, 08:23:46 AM
OK, I soldered some extra wire taken from a Gotham GAC-3 cable. Everything seems to have gone fine (at least as far as I can see now).
Title: Re: [BUILD] MK47 tube mic kit - new batch @ white market
Post by: micaddict on March 01, 2012, 01:51:25 PM
Quote
Quote from: grantlack on November 13, 2011, 06:58:52 pm
as i look at the u48 schematic, it appears that the fig8 pattern was accomplished by simply switching a 1nF cap into the signal path between the membranes.  any reason the same approach couldn't be taken in the mk47?  the execution would be simple enough, it's just a matter of whether it would behave the same.  i tend to find omni to be less useful in my day-to-day work.

If your plan is to make a MK48 (sacrifice the omni patern to favor a figure 8 ) it's doable.
Pay attention to the U48 schematic. It's not just a matter of adding a cap and a resistor, you also need to modify the voltage divider.
In the U47 the 2M/3M extract 60V from the 105V PSU in order to polarize the front of the capsule. If you'd polarize the back with 105V, you wouldn't get a real figure 8 pattern (cause you'd need 120V). So for the U48 they changed the voltage divider  to 3M/3M. That gives 52.5V to the front, and then 105V at the back is right.
You can do the same with the MK47. Just keep in mind that, just like with a real U48, you'll loose a bit of sensitivity because of the lower polarization voltage.

Axel

"If you'd polarize the back with 105V, you wouldn't get a real figure 8 pattern (cause you'd need 120V)."

Does this mean that without the voltage divider modification you'd get either cardioid or hypercardioid?
Title: Re: [BUILD] MK47 tube mic kit - new batch @ white market
Post by: Monoklang on March 02, 2012, 07:13:50 AM
Hi, I'm gathering all parts needed for the MK47 PSU, I've read this thread 3 times but still have a newbie question left:

I want 3 toggle switches (card-omni, power on/off and the test switch)

What kind of switches do I need. There are like a 2000 to choose from and I just want to be sure that choose the right ones. I'm at mouser.

Contact form SPDT or DPDT?
Should it be "on-off" or "on-on", I mean should all three switches be 2 positions switches?
And what voltage should they be able to handle? (230V in my country) does that even matter?

That's it. Thank you all for all information!
Title: Re: [BUILD] MK47 tube mic kit - new batch @ white market
Post by: wave on March 02, 2012, 11:08:43 AM
Hi, I'm gathering all parts needed for the MK47 PSU, I've read this thread 3 times but still have a newbie question left:

I want 3 toggle switches (card-omni, power on/off and the test switch)

What kind of switches do I need. There are like a 2000 to choose from and I just want to be sure that choose the right ones. I'm at mouser.

Contact form SPDT or DPDT?
Should it be "on-off" or "on-on", I mean should all three switches be 2 positions switches?
And what voltage should they be able to handle? (230V in my country) does that even matter?

That's it. Thank you all for all information!

Power and test can be SPST. Pattern switch is SPDT

Dave
Title: Re: [BUILD] MK47 tube mic kit - new batch @ white market
Post by: david-p on March 02, 2012, 03:51:24 PM
And what voltage should they be able to handle? (230V in my country) does that even matter?

It doesn't matter.

David
Title: Re: [BUILD] MK47 tube mic kit - new batch @ white market
Post by: Monoklang on March 02, 2012, 03:55:52 PM
Thanks!

And what about the On-off-on, on-none-off and on-none-on ... thing?

There's a lot of options, and I have never bought those before.

Regards
John
Title: Re: [BUILD] MK47 tube mic kit - new batch @ white market
Post by: wave on March 03, 2012, 04:29:21 AM
Thanks!

And what about the On-off-on, on-none-off and on-none-on ... thing?

There's a lot of options, and I have never bought those before.

Regards
John

For the SPDT I get on-none-on

Dave
Title: Re: [BUILD] MK47 tube mic kit - new batch @ white market
Post by: drgrateful on March 03, 2012, 07:11:52 AM
Here are some pictures for my build:

http://s1071.photobucket.com/albums/u507/drgrateful/U47%20clone/ (http://s1071.photobucket.com/albums/u507/drgrateful/U47%20clone/)

It's been working wonderfully since when I first connected it four hours ago.  :) :) :)
Title: Re: [BUILD] MK47 tube mic kit - new batch @ white market
Post by: micaddict on March 03, 2012, 10:34:57 AM
Looking good!

Is that a Skylar headbasket?
Title: Re: [BUILD] MK47 tube mic kit - new batch @ white market
Post by: drgrateful on March 03, 2012, 12:00:00 PM
Is that a Skylar headbasket?
Yep, it's an EQU47 body by Skylar (Equinox Systems).
Title: Re: [BUILD] MK47 tube mic kit - new batch @ white market
Post by: micaddict on March 03, 2012, 12:24:19 PM
It looks smoother/rounder than any other Equinox I've seen (including the improved ones on the site).
Too round ain't good, either (early Fleas are plain ugly IMO), but some of the EQ47 almost look trapezium-like. (Perhaps more so in the first batch.)
 __
/  \

Yours looks just right to my eyes. 

If Skylar has one left like that, I'm bait.

Skylar, you there?
Title: Re: [BUILD] MK47 tube mic kit - new batch @ white market
Post by: daddymac on March 04, 2012, 06:55:36 AM
Hey drgrateful,

Nice work!

How does it sound with the Thiersch capsule?
Do you made a comparaison with another mics? Brand/Model? 

I'm on my MK47 too but it not finished yet.
I sent you a PM and asked about the PSU case that is in your pictures.

It's exactly the style of PSU case that I'm looking for.

I have spent a lot of time searching on the web but I have found it.

Can you tell where you buyed it? Please.

Thanks in advance for sharing infos , links & opinions

Jam
Title: Re: [BUILD] MK47 tube mic kit - new batch @ white market
Post by: mad.ax on March 04, 2012, 09:19:16 AM
Use Thiersch Plastic cover, perfect for that....

Yes, but I have already attached the capsule to the support...

The Thiersch plastic cover trick works with the capsule attached to its holder ;)
Axel

(http://twin-x.com/groupdiy/albums/userpics/thumb_Protection_capsule.JPG) (http://twin-x.com/groupdiy/albums/userpics/Protection_capsule.JPG)
Title: Re: [BUILD] MK47 tube mic kit - new batch @ white market
Post by: drgrateful on March 04, 2012, 01:10:52 PM
How does it sound with the Thiersch capsule?
Do you made a comparaison with another mics? Brand/Model? 
Well, I am using it thorugh a Seventh Circle Audio N72 pre and, to me, it sounds wonderful. To be honest, I am not the most qualified person to make comparisons with other high end mics: for example, I never heard an original U47. There are people in this group much, much, more qualified to give you an answer. I can only say that it promises to give extremely good results in my home studio. Anyway, in the end, I have learned that questions like yours can hardly get definitive answers.

It's exactly the style of PSU case that I'm looking for.
I have spent a lot of time searching on the web but I have found it.
Can you tell where you buyed it? Please.
You can find it here:
http://www.groupdiy.com/index.php?topic=47865.0 (http://www.groupdiy.com/index.php?topic=47865.0)

The Thiersch plastic cover trick works with the capsule attached to its holder ;)
Thanks, I'm sure your suggestion will be very useful!
Title: Re: [BUILD] MK47 tube mic kit - new batch @ white market
Post by: Skylar on March 04, 2012, 01:20:32 PM
It looks smoother/rounder than any other Equinox I've seen (including the improved ones on the site).
Too round ain't good, either (early Fleas are plain ugly IMO), but some of the EQ47 almost look trapezium-like. (Perhaps more so in the first batch.)
 __
/  \

Yours looks just right to my eyes. 

If Skylar has one left like that, I'm bait.

Skylar, you there?

I would be willing to bet that his headbasket isn't as rounded as it appears in the photos.

I wonder if drgrateful has a picture of this headbasket from a high vantage point above the unit looking down from 12+ inches away? Sometimes when you photograph headbaskets (wow, I've done my fair share of that!), they look more curved than they should depending on camera/lens/vantage point/closeness to subject...you start getting a fisheye effect the closer you are to the subject with some cameras.

Anyway, I bet the headbasket wouldn't look so rounded from further away looking down slightly...like this:

(http://equinoxsystems.net/wp-content/uploads/2011/09/EQU47-2-HB01.jpg)

In any case, if you want to add more rounding to the top mesh, you can shape it by hand or make a wooden punch to help you shape it (personally, I wouldn't do this, but it can be done).


 
Title: Re: [BUILD] MK47 tube mic kit - new batch @ white market
Post by: drgrateful on March 05, 2012, 06:54:11 AM
Hi Skylar,

here are a couple more pictures, taken from about 30-40cm away (and zooming in):

(http://i1071.photobucket.com/albums/u507/drgrateful/U47%20clone/P1050657JPG_small.jpg)

(http://i1071.photobucket.com/albums/u507/drgrateful/U47%20clone/P1050655JPG_small.jpg)
Title: Re: [BUILD] MK47 tube mic kit - new batch @ white market
Post by: Skylar on March 05, 2012, 10:50:32 AM
Thanks. That's what I expected it to look like. Looks like all our other headbaskets.
I knew there was no way a rounded top could have passed through QA (5 individuals, including myself, inspect every unit).
Title: Re: [BUILD] MK47 tube mic kit - new batch @ white market
Post by: micaddict on March 06, 2012, 09:07:16 AM
Skylar and drgrateful, thanks for elaborating.
The camera lens explanation seems plausible.

OK, before people get the wrong impression here, I hate the round look of the older "bowler hat" Fleas (new Fleas look fine though) and I like the Equinox, especially the improved versions.
And by "trapezium" I mean not only flat on top but also at the angled bit, if that makes sense, with a relatively sudden kink. But if at all (I didn't see them in the flesh) those were likely from the first batch.
It's just that the one in drgrateful's earlier picture looked extra nice and smooth, for some reason. That's all.

Also, I personally thanked Skylar for the great work and for starting all this.

Oh, and the kits were sold out anyway.

BTW here's a pic of ten originals and yes, they did vary:

(http://www.southerntracks.com/time_machine/NEUMANN%20U47.JPG)

Title: Re: [BUILD] MK47 tube mic kit - new batch @ white market
Post by: micaddict on March 06, 2012, 12:38:28 PM
Now let's get back to the electronics kit, please.  :)
Title: Re: [BUILD] MK47 tube mic kit - new batch @ white market
Post by: David R. on March 06, 2012, 03:05:47 PM
Hi all.  Please forgive me if this is a stupid question, just thought it was better to ask than not.  I was in on the TNC group buy a while ago and bought one the tube mics, the ACM1200, a C12 "style" mic with one 12AX tube in it..  It came with a power supply.  Can I use this power supply to power the MK47? 

Thanks.
Title: Re: [BUILD] MK47 tube mic kit - new batch @ white market
Post by: 0dbfs on March 06, 2012, 03:21:44 PM
Hi all.  Please forgive me if this is a stupid question, just thought it was better to ask than not.  I was in on the TNC group buy a while ago and bought one the tube mics, the ACM1200, a C12 "style" mic with one 12AX tube in it..  It came with a power supply.  Can I use this power supply to power the MK47? 

Thanks.

No you can't use that PSU without mods...

I also have those mic's and have started an m49 conversion here:
http://www.groupdiy.com/index.php?topic=44667.0

I traced the PCB and came up with this schematic of the acm1200 psu:
http://www.groupdiy.com/index.php?action=dlattach;topic=44667.0;attach=12049;image

Interestingly, it does have a 200V PT and very similar layout to the MK47 PSU... As a matter of fact if you compare the two schematics you could quite easily mod the acm1200 PSU by changing some resistors, adding a pot, etc...

I don't think max's transformer/PCB/tubes will fit into one of these apex460 style bodies.

Best Luck!
-jb
Title: Re: [BUILD] MK47 tube mic kit - new batch @ white market
Post by: Monoklang on March 08, 2012, 01:39:30 PM
I haven't start building this PSU yet. I have ordered all parts and now I just want to make sure I am on the right track.

Is this right? I have never drawn this types of things before, so excuse me if it's smeared and maybe hard to see every part. I've read this thread like 10 times, to figure out every detail. But my PSU skills are limited...

The part I'm most lost in is the wiring between Mains - on/off switch - fuse - torodial

If someone have a couple of minutes, I would really appreciate some help.

Best regards
John
Title: Re: [BUILD] MK47 tube mic kit - new batch @ white market
Post by: david-p on March 08, 2012, 01:56:35 PM
Is this right? I have never drawn this types of things before, so excuse me if it's smeared and maybe hard to see every part. I've read this thread like 10 times, to figure out every detail. But my PSU skills are limited...

The part I'm most lost in is the wiring between Mains - on/off switch - fuse - torodial

In what way are you lost, please, John?  I dont see a problem with the switch/fuse/transformer connections.  As I recall it, the 1k resistor is an alternative to the choke. Is the lamp grounded by its body to chassis? It will need a return

Also, assuming you are using the same Binder connector that I am (Skylar body), I advise you to connect pin 7 to your B- pin 3 (at both ends).  This gives a lower resistance for the ground connection and, just as importantly, pin 7 connects first and it is good that this be the ground.

David
Title: Re: [BUILD] MK47 tube mic kit - new batch @ white market
Post by: Sredna on March 08, 2012, 02:15:55 PM
Yes, it´s either the choke or the 1k resistor, not both in parallell.

The 680R/330R (200R+130R) combo is for adjustment to 105V (together with the pot), just add or take them out until the voltage is correct.
Title: Re: [BUILD] MK47 tube mic kit - new batch @ white market
Post by: Monoklang on March 08, 2012, 02:31:54 PM
So I have done a lot right :)

Ok, so I:
- remove the first 1k 5W. So it's just the choke.
- Connect pin 3 & 7 in all Binder connectors (PSU, cable connectors and mic)

About the lamp, I'm not sure how to connect it. I've ordered a  Fender Jewel light, a 6,3V bulb and a fender lamp holder from Tube-Town:
http://www.tube-town.net/ttstore/product_info.php/info/p465_Fender-Lamp-Holder.html

And I know the the Torodials sec is 6,3V

But about that return, do I take the 0V from the torodial (as in link it from the IEC's neutral?)

I'm really happy that I pulled this off by reading that PSU scheme and by looking at this threads pictures.

..or well I haven't built the thing yet...

Thank you all
Title: Re: [BUILD] MK47 tube mic kit - new batch @ white market
Post by: david-p on March 08, 2012, 05:48:47 PM
So I have done a lot right :)
YES
Quote
Ok, so I:

- remove the first 1k 5W. So it's just the choke.  YES!

- Connect pin 3 & 7 in all Binder connectors (PSU, cable connectors and mic)

Thinking about it, it is not clear how many separate wires you have in your cable.  I was assuming that you have 7, but if you only have 6 core cable, I advise using pin 7 instead of pin 3 for the reason I stated.
 
Quote
About the lamp, I'm not sure how to connect it. I've ordered a  Fender Jewel light, a 6,3V bulb and a fender lamp holder from Tube-Town:
http://www.tube-town.net/ttstore/product_info.php/info/p465_Fender-Lamp-Holder.html
OK.  I can see two terminals on this.
 
Quote

But about that return, do I take the 0V from the torodial (as in link it from the IEC's neutral?)
To advise on where the return goes I would need to know the model of transformer you are using.
 
Quote
And I know the the Torodials sec is 6,3V
The light you have chosen is likely to be much brighter than you want.  I would have advised an LED with a resistor in series to reduce the brightness: 390 ohms would be a good start with a red LED. This can be increased in value to lessen the brightness.

David
Title: Re: [BUILD] MK47 tube mic kit - new batch @ white market
Post by: Volume11 on March 08, 2012, 08:03:38 PM
Hi guys, I just finished my mk47 build with skylers u47 style body and q47 capsule. Lucky for me it fired up on the first try and it sounds unbelievable to my ears. This is by far the best quality mic I own so far. My only concerns are my voltage readings. I just want to double check with you guys to see if everything seems to be standard.

Test switch in omni I get 112vdc at b+ and 112vdc at the pattern point
Test switch in cardioid I get 105vdc at b+ and 48.5vdc after the 14k resistor

Mic connected in omni I get 98.6vdc at b+ and  45.3vdc at the pattern point
Mic connected in cardioid I get 98.5vdc at b+ and 45vdc after the 14k resistor

45.3vdc at the pattern point seems low to me, but my knowledge can't tell me for sure. Should it match the b+ voltage?

Big thanks to Max, Skyler, and everyone contributing on this forum.
Title: Re: [BUILD] MK47 tube mic kit - new batch @ white market
Post by: Volume11 on March 08, 2012, 09:09:49 PM
(http://img855.imageshack.us/img855/1209/imag0213hm.th.jpg) (http://imageshack.us/photo/my-images/855/imag0213hm.jpg/)
(http://img826.imageshack.us/img826/5069/imag0289ye.th.jpg) (http://imageshack.us/photo/my-images/826/imag0289ye.jpg/)
(http://img840.imageshack.us/img840/3624/imag0287fr.th.jpg) (http://imageshack.us/photo/my-images/840/imag0287fr.jpg/)
(http://img688.imageshack.us/img688/5791/imag0288a.th.jpg) (http://imageshack.us/photo/my-images/688/imag0288a.jpg/)
Title: Re: [BUILD] MK47 tube mic kit - new batch @ white market
Post by: Monoklang on March 09, 2012, 03:22:51 AM
Thinking about it, it is not clear how many separate wires you have in your cable.  I was assuming that you have 7, but if you only have 6 core cable, I advise using pin 7 instead of pin 3 for the reason I stated.

The cable I will use is this one:
http://www.thomann.de/se/sommer_cable_sc_octave_tube.htm

So there is 7 wires but 2 of them is thicker (twisted in picture). Good for ground?

To advise on where the return goes I would need to know the model of transformer you are using.

This is the torodial I will be using:
http://www.tube-town.net/ttstore/product_info.php/info/p2192_Torodial-30VA.html

The light you have chosen is likely to be much brighter than you want.  I would have advised an LED with a resistor in series to reduce the brightness: 390 ohms would be a good start with a red LED. This can be increased in value to lessen the brightness.

David

This doesn't look to be too bright I think, but I guess I will find out and can switch to LED if that's the case.
http://angela.com/fenderredpilotlightjewelforguitaramps.aspx

Thank You!
/ John
Title: Re: [BUILD] MK47 tube mic kit - new batch @ white market
Post by: david-p on March 09, 2012, 11:17:08 AM
The cable I will use is this one:
http://www.thomann.de/se/sommer_cable_sc_octave_tube.htm

So there is 7 wires but 2 of them is thicker (twisted in picture). Good for ground?
As I understand it, like the U47, you have only one supply for this design, and both the HT and the valve heater are powered off it.  Use the two fat wires for B+ and ground (pin 7!).

Quote
This is the torodial I will be using:
http://www.tube-town.net/ttstore/product_info.php/info/p2192_Torodial-30VA.html
OK: use the two green wires for the light.  Twist them together, but dont ground either of them.

David
Title: Re: [BUILD] MK47 tube mic kit - new batch @ white market
Post by: Songguy on March 11, 2012, 12:11:36 PM
Quick PSU question..

If I opt to use the 6.3v tap on my trafo do I need to install the 100k 1w resistor?
Title: Re: [BUILD] MK47 tube mic kit - new batch @ white market
Post by: wave on March 11, 2012, 12:21:14 PM
Quick PSU question..

If I opt to use the 6.3v tap on my trafo do I need to install the 100k 1w resistor?

If you are using the 6.3 VAC tap for a jewel light and not using a LED then you still need the 100K resistor as a bleeder for the cap. You will have to jumper where the LED is

Dave
Title: Re: [BUILD] MK47 tube mic kit - new batch @ white market
Post by: 0dbfs on March 11, 2012, 12:37:03 PM
Quick PSU question..

If I opt to use the 6.3v tap on my trafo do I need to install the 100k 1w resistor?

If you are using the 6.3 VAC tap for a jewel light and not using a LED then you still need the 100K resistor as a bleeder for the cap. You will have to jumper where the LED is

Dave

Even so, having the led installed is a nice visual to confirm the caps are drained before proceeding with work. The jewel lamp will extinguish when ac mains are off. Led would stay lit for a couple minutes.

This is what I have experienced.

Cheers,
Jb
Title: Re: [BUILD] MK47 tube mic kit - new batch @ white market
Post by: wave on March 11, 2012, 12:39:34 PM
Quick PSU question..

If I opt to use the 6.3v tap on my trafo do I need to install the 100k 1w resistor?

If you are using the 6.3 VAC tap for a jewel light and not using a LED then you still need the 100K resistor as a bleeder for the cap. You will have to jumper where the LED is

Dave

Even so, having the led installed is a nice visual to confirm the caps are drained before proceeding with work. The jewel lamp will extinguish when ac mains are off. Led would stay lit for a couple minutes.

This is what I have experienced.

Cheers,
Jb

Very true. I was kinda assuming he wasn't even sourcing the LED.

Dave
Title: Re: [BUILD] MK47 tube mic kit - new batch @ white market
Post by: Songguy on March 11, 2012, 05:08:02 PM
Thanks for the clarification folks.

Btw I couldn't find a 2.3k 5w res. I did find a 2.25k and a 2.4k 5w. Would either of these be an acceptable replacement?
Title: Re: [BUILD] MK47 tube mic kit - new batch @ white market
Post by: mrvision on March 11, 2012, 05:48:42 PM
For the 2.3k test load resistor here in America I used a 1.1k and a 1.2k in series

Mouser:

594-AC05W1K100J
594-AC05W1K200J

Btw the 2.3k resistor is for testing and initial setup only, you have to readjust voltages once you have the microphone connected to the psu. In my case I first adjusted the voltage to 105V with the 2.3k dummy load, then with the real load (mic) the voltage was 109V, then readjusted the voltage again to 105V and closed the psu box.
Title: Re: [BUILD] MK47 tube mic kit - new batch @ white market
Post by: Songguy on March 12, 2012, 12:25:35 PM
So with the mic hooked up you had to swap that 2.3k with a resistor that would give you 106v?

Also I'm having a real hard time finding a 14k 1w res. does this need to be a metal film res. or is there another more available type I could use.
Thanks for your help with this.
Chris
Title: Re: [BUILD] MK47 tube mic kit - new batch @ white market
Post by: david-p on March 12, 2012, 12:53:12 PM
I'm having a real hard time finding a 14k 1w res. does this need to be a metal film res. or is there another more available type I could use.
Chris,

27k in parallel with 30k, 1/2 watt each, or 4x56k 1/4 in parallel.  I find it a useful trick to share the wattage in this way.

David
Title: Re: [BUILD] MK47 tube mic kit - new batch @ white market
Post by: kante1603 on March 12, 2012, 01:26:38 PM
So with the mic hooked up you had to swap that 2.3k with a resistor that would give you 106v?
Hi Chris,

no-look at the schemo:The "test"-switch is for giving the psu a load similar to the connected mic by switching in this 2,3k/5w resistor
before!!! you connect the mic.This is to proof your psu is working before killing your beloved microphone.
If everything is measuring fine with the switched-in resistor power down your psu,then switch off the resitor,then connect the microphone and do a final measurement/adjustment of the B+.
In my case I even did not use a switch,just a piece of solid core wire attached to 2 screw terminals which are labelled "test".



Also I'm having a real hard time finding a 14k 1w res. does this need to be a metal film res. or is there another more available type I could use.
I used 2 pieces of 28k in parallel,as far as  I can remember I found them at mouser....
This 14k is just a voltage divider together with the 12k to get the approx. +48vdc from the B+ to drive the relay and nothing else.

O.K.,did a quick search at mouser,found them:
http://de.mouser.com/ProductDetail/Vishay-Dale/CPF128K000FEB14/?qs=sGAEpiMZZMukHu%252bjC5l7YcnhMAGkDTDNt9nRJOdArgk%3d

Hope to have helped,

Udo.
Title: Re: [BUILD] MK47 tube mic kit - new batch @ white market
Post by: mrvision on March 12, 2012, 01:52:05 PM
For the 14K resistor I used a 12K + 2K in series, both 1W.

bought two 12K and one 2K from Mouser:

(1) 2K:     660-MO1CT52R202J
(2) 12K:   660-MO1CT52R123J

Title: Re: [BUILD] MK47 tube mic kit - new batch @ white market
Post by: mrvision on March 12, 2012, 02:11:36 PM
Also the 2.3K Test Resistor can be a little confusing. Specially for those of you initianting in electronics or DIY.
In the original schematic the 2.3K "test" resistor is shown inside the circuit, I personally did not include it in the circuit because the resistor has shown a little discrepancy of about 3-4 volts, If you read the thread there are some others that also found different readings with the real load, The 2.3K only tells you if the PSU is giving the juice is suppose to give and also gives you a close voltage to the one needed by your microphone.

I also recommend taking the time to read the thread, there is a lot of information already there. When you find a problem you already have an idea where to find some troubleshooting information  :)

The schematic below shows the 2.3K taken out of the circuit and used externally during test.
Title: Re: [BUILD] MK47 tube mic kit - new batch @ white market
Post by: 0dbfs on March 12, 2012, 02:14:58 PM
I'm pretty sure I left this feature out when I did mine. You need to tweak/fine-tune it with mic in-circuit anyway.

Plus, what are you going to fry in the mic? Some resistors, the tubes? If you are worried about your capsule, put in a couple capacitors until you have voltages and things all tweaked.

Cheers,
jb
Title: Re: [BUILD] MK47 tube mic kit - new batch @ white market
Post by: kante1603 on March 12, 2012, 02:22:31 PM
Also the 2.3K Test Resistor can be a little confusing. Specially for those of you initianting in electronics or DIY.
In the Schematic is shown inside the circuit, I personally did not include it in the circuit because the resistor has shown a little discrepancy of about 3-4 volts, If you read the thread there are some others that also found different readings with the real load, The 2.3K only tells you if the PSU is giving the juice is suppose to give and also gives you a close voltage to the one needed by your microphone.

I also recommend taking the time to read the thread, there is a lot of information already there. When you find a problem you already have an idea where to find some troubleshooting information  :)
+1! ;)
Title: Re: [BUILD] MK47 tube mic kit - new batch @ white market
Post by: Songguy on March 13, 2012, 09:07:50 AM
Thanks for the clarification. I have read the thread and bookmarked various posts and replys. I just require a little assistance understanding who the sum of the parts work together as a whole.
Thank you for your patience and sharing your experiences with me.
Chris
Title: Re: [BUILD] MK47 tube mic kit - new batch @ white market
Post by: Songguy on March 13, 2012, 07:57:21 PM
Ok guys, I need one more piece before I put this psu together. Does anyone have any preferences when it comes to a pattern switch? Rudimentery question but curious none the less.
Title: Re: [BUILD] MK47 tube mic kit - new batch @ white market
Post by: wave on March 13, 2012, 10:13:04 PM
Ok guys, I need one more piece before I put this psu together. Does anyone have any preferences when it comes to a pattern switch? Rudimentery question but curious none the less.

I used this just because it's big and awesome

http://www.mouser.com/Search/ProductDetail.aspx?R=S2B-ROvirtualkey63300000virtualkey633-S2B-RO

Dave
Title: Re: [BUILD] MK47 tube mic kit - new batch @ white market
Post by: Songguy on March 13, 2012, 10:17:49 PM
An excellent choice Dave. I just placed an order for the same one. looks like one substantial switch.
Title: Re: [BUILD] MK47 tube mic kit - new batch @ white market
Post by: wave on March 14, 2012, 12:46:41 AM
An excellent choice Dave. I just placed an order for the same one. looks like one substantial switch.

It's beefy. That's a quarter!

Dave
Title: Re: [BUILD] MK47 tube mic kit - new batch @ white market
Post by: Leonardo_007 on March 15, 2012, 06:55:06 AM
can someone build the pcb for the ps for me, please?

i've never build a circuit board and am not able to read schematics...

Title: Re: [BUILD] MK47 tube mic kit - new batch @ white market
Post by: zayance on March 15, 2012, 07:41:30 AM
can someone build the pcb for the ps for me, please?

i've never build a circuit board and am not able to read schematics...

I did an order to fab the PSU PCB, i'll have extra boards, should be here soon, i'll keep posted here...
Title: Re: [BUILD] MK47 tube mic kit - new batch @ white market
Post by: Leonardo_007 on March 15, 2012, 10:19:54 AM
can someone build the pcb for the ps for me, please?

i've never build a circuit board and am not able to read schematics...

I did an order to fab the PSU PCB, i'll have extra boards, should be here soon, i'll keep posted here...

thanks zayance!

i'll definitely take one!
Title: Re: [BUILD] MK47 tube mic kit - new batch @ white market
Post by: wave on March 15, 2012, 12:54:08 PM
can someone build the pcb for the ps for me, please?

i've never build a circuit board and am not able to read schematics...

I have to comment on this. I wanted to have a PCB for my PSU as well and I don't read schematics to save my life.
I have never etched my own board before and I thought it was going to be hard. Zayance had posted an etch file earlier in the thread and I tweaked it and made my own board. It was easier than I thought and I learned a lot from the process.
Many thanks to Zayance  for doing the leg work on that file!

Here is a shot of my board after etching before drilling and removal of the resist. I used the presensitized board with a transparency I had printed a Staples. I had never attempted any of this and it worked great on my first try. Having the etch file Zayance made really helped to understand the layout from schematic to PCB. I tweaked mine to have the test load on the board using 1K and 1.3K resistors in series with the test switch mounted on the board.

Dave
Title: Re: [BUILD] MK47 tube mic kit - new batch @ white market
Post by: zayance on March 15, 2012, 01:19:28 PM
Nice  8).

For the one i sended to fab, it is a little different than my etch file..
A little longer, about 155 x 78mm, and accepts on board until 10W wirewound resistors,
And Caps  25mm Max Diameter but i ommited the 5mm pitch, and just went for 7.5mm pitch and 10mm SnapIn footprint.

Sneak pic:

(http://img20.imageshack.us/img20/3429/mk47psuza.jpg)
Title: Re: [BUILD] MK47 tube mic kit - new batch @ white market
Post by: Songguy on March 15, 2012, 01:31:26 PM
What are the dimensions of that nice PCB.
Chris
Title: Re: [BUILD] MK47 tube mic kit - new batch @ white market
Post by: zayance on March 15, 2012, 01:38:28 PM
What are the dimensions of that nice PCB.
Chris

It's on my previous post, but i edited right after so maybe while you were replying..

And as for the test Load on board, as it was stated before from Kingston, it's not very useful i think, and i didn't needed that, saves space as well..., a nice big dummy load at the output connector when testing and you're done with it...
Title: Re: [BUILD] MK47 tube mic kit - new batch @ white market
Post by: wave on March 15, 2012, 04:01:08 PM
What are the dimensions of that nice PCB.
Chris

It's on my previous post, but i edited right after so maybe while you were replying..

And as for the test Load on board, as it was stated before from Kingston, it's not very useful i think, and i didn't needed that, saves space as well..., a nice big dummy load at the output connector when testing and you're done with it...

I did read that whole part of the thread. The reason that I included it was mainly just to stick something on the board for practicing my schematic to board layout skills. I don't use Eagle or any PCB software, I just draw it in Illustrator  :)

EDIT: That's a nice PCB you got there Zayance!

Dave
Title: Re: [BUILD] MK47 tube mic kit - new batch @ white market
Post by: zayance on March 16, 2012, 03:46:25 AM
What are the dimensions of that nice PCB.
Chris

It's on my previous post, but i edited right after so maybe while you were replying..

And as for the test Load on board, as it was stated before from Kingston, it's not very useful i think, and i didn't needed that, saves space as well..., a nice big dummy load at the output connector when testing and you're done with it...

I did read that whole part of the thread. The reason that I included it was mainly just to stick something on the board for practicing my schematic to board layout skills. I don't use Eagle or any PCB software, I just draw it in Illustrator  :)

EDIT: That's a nice PCB you got there Zayance!

Dave


I wasn't criticising your choice, but saying again why it was done so on the etching file and on this PCB as well.
And Sure whatever feets your bag of tools, actually i've seen great stuff done with illustrator, and some folks here like ti better than those "chunky" PCB programs, well that's what they were saying about it haha, but i can understand that, as Eagle is a little chnuky on some things, but anyway all programs have their pros and cons as always...
Depends on your skills and what you want to do with it also, i don't see triple layer done on illustrator, but again depends on skills...
Anyway nice job, nice thinking, and nice result, learning by doing is always better....

Thanks for the kind words, yes i like it also haha, had fun with it, there is very few components so... Zen garden style, do you hear those birds? lol.....
Title: Re: MK47 assembly - more pics added
Post by: Monoklang on March 16, 2012, 06:16:53 AM
Here is a pic of my mounting I've used it twice now worked great


How deep did you dare to drill those holes? I'm about to do the same thing here, is 5mm too much?

/ John
Title: Re: [BUILD] MK47 tube mic kit - new batch @ white market
Post by: jrasia on March 16, 2012, 12:26:25 PM
Hey can someone provide some quick tech support?

Finally finished my build with a Thierch M7 capsule.

Fired her up and it didn't fry :)

Cardioid sounds good, but when I switch to omni on the PSU I get a loud buzzing sound that stays.  I can however still hear it pass audio underneath all the buzzing.

Seem like I also need a fair amount of gain on my preamp (cardioid), about 35db on my AEA TRP preamp.  Is that normal?  I always had the impression the u47 is a very high output mic.

It is also rather warm to the touch on the body of the mic. Is that normal?  Never played with u47 before

Thanks

Jason
Title: Re: [BUILD] MK47 tube mic kit - new batch @ white market
Post by: david-p on March 16, 2012, 05:55:10 PM
Cardioid sounds good, but when I switch to omni on the PSU I get a loud buzzing sound that stays.  I can however still hear it pass audio underneath all the buzzing.

Seem like I also need a fair amount of gain on my preamp (cardioid), about 35db on my AEA TRP preamp.  Is that normal?  I always had the impression the u47 is a very high output mic.

It is also rather warm to the touch on the body of the mic. Is that normal?  Never played with u47 before
Quick help, though I havent built this particular circuit.

Sounds like you have a problem with the relay, either in the power supply wiring, or in the mic.  Can you hear the contacts actually close when you put your ear up to the mike and operate the switch?  Check the wiring carefully.

I am assuming that you are using the standard PS circuit.  Do you have the dummy resistor selected in the other position?  In which case, there should definitely be no change in hum.

The resistor shown in the pic above will get warm.  This is normal for all U47s.

35dB of gain sounds OK.  The output from a U47 is comparable to most condenser mikes.

David
Title: Re: [BUILD] MK47 tube mic kit - new batch @ white market
Post by: jrasia on March 17, 2012, 11:12:11 AM
Thanks for trying.  I think after more problem solving the issue must be with the mic cable I made 
With only the audio xlr cable hooked up there is no noise.  Once I attach the mic cable (GAC 7) to the PSU, but not hooked up to the microphone, the buzzing issue with omni is there and passing through the audio. I'm at least glad its not the mic( I think).

I work in IT and deal with the ID ten T errors all the time, so I feel a little silly having to resort to such questions, but I  drew a diagram of what I did with the cable(See pics). I like pictures.  They help simpletons like me.  I'm by no means an electronics wiz.

The PSU (Scott Hamptone) is wired as follows.  Pins 3 + 4 are common ground.  Shield also goes there from the connector

1. audio+
2. audio-
3. Ground
4. Ground
5. +105vdc @ 50mA
6. Pattern

I wired my cable as follows.

XLR                                   TUCHEL

1(A+) ----------------------  1(A+)
2(A-) -----------------------  2(A-)
3                  empty          3
4(B-) --------blue-----------4(B-)
5(B+) --------red -----------5(B+)
6(P) ------------------------- 6(P)
Tab -----Cable Shield--------7 --- Bridged to Tab


Then inside the microphone on the male 7 pin binder I have the shield bridged to pin 4.  Pin 4 is then bridged to the mic rail.  Though, I'd like to confirm the wiring on the cable first before looking at the male binder.

Sorry for the long winded post.  Again, any help is appreciated.

Title: Re: [BUILD] MK47 tube mic kit - new batch @ white market
Post by: G-Sun on March 18, 2012, 12:49:27 PM
What size is needed to mount the pcb?
There, found it: "Assembled unit: main PCB is 86 x 44 mm"
Title: Re: [BUILD] MK47 tube mic kit - new batch @ white market
Post by: johnny dance on March 19, 2012, 09:55:12 AM
Hey,

currently building with a EQu47 body and a Thiersch caplsule (very slowly)

any one have any idea on where to get a binder 691 connector for the mic cable to mic ?

I think someone only used zip tags to hold the M47 in the case... any photos?
Title: Re: [BUILD] MK47 tube mic kit - new batch @ white market
Post by: david-p on March 19, 2012, 10:55:17 AM
any one have any idea on where to get a binder 691 connector for the mic cable to mic ?
www.binder.com in the USA.

David
Title: Re: [BUILD] MK47 tube mic kit
Post by: johnny dance on March 20, 2012, 11:49:21 AM
thanks ! ordered a set of them...

one last question: does any one have any closeup photos of the connections of the Capsule, to the PCB? Just wanted to make sure I was doing it right, but slightly confused by the glass bits, how to solder it etc...
Title: Re: [BUILD] MK47 tube mic kit
Post by: Ishi on March 22, 2012, 08:59:27 AM
I finished building MK47.

I used STC-700 for the body of the microphone. The microphone cable was created by NC7 FX-B of Neutrik XLR and Gotham.

But a connector does not separate from a microphone :'(
Is there any method of solving this?
Title: Re: [BUILD] MK47 tube mic kit
Post by: Leonardo_007 on March 23, 2012, 12:51:27 PM
any news on the fab psu pcb's, zayance?

Title: Re: [BUILD] MK47 tube mic kit
Post by: Volume11 on March 24, 2012, 06:57:27 PM
Hey guys, I am having trouble getting 48v, and 105v with the mic hooked up. The most I can get is 45v and 99.8 v with the pot turned fully clockwise. Do I need to lower a resistor value somewhere before the pot? I want to test this myself with trial and error, but I want to use the mic tomorrow, so I'd hate to mess something up before then. It works without any problems and sounds good. I read somewhere back in this thread that the incorrect voltage values could possibly lower the lifetime of the capsule, so I am a bit worried. Any advice will be greatly appreciated.
Thanks
Title: Re: [BUILD] MK47 tube mic kit
Post by: david-p on March 24, 2012, 09:02:32 PM
Hey guys, I am having trouble getting 48v, and 105v with the mic hooked up. The most I can get is 45v and 99.8 v with the pot turned fully clockwise. Do I need to lower a resistor value somewhere before the pot? I want to test this myself with trial and error, but I want to use the mic tomorrow, so I'd hate to mess something up before then. It works without any problems and sounds good. I read somewhere back in this thread that the incorrect voltage values could possibly lower the lifetime of the capsule, so I am a bit worried. Any advice will be greatly appreciated.
Thanks
Understood that you will want to eventually establish the design voltages, and others who have faced the same problem will tell you what to do about it; but using the mic with the voltages that you quote will pose no danger to either vacuum tube or capsule.

David
Title: Re: [BUILD] MK47 tube mic kit
Post by: Volume11 on March 24, 2012, 09:09:23 PM
Thanks David, I'll go back and read through the thread when I get the time and post any updates.
Title: Re: [BUILD] MK47 tube mic kit
Post by: diylan on March 25, 2012, 01:35:21 AM
So I finished building the PSU and in testing I'm getting some very odd voltages...

I'm using the Triad VPT230-110 and I'm getting over 300v off of the secondaries! I'm in the US so this is wired for 115v in (blue to violet, gray to brown) and 230v out (red to orange, black to one side of rectifier, yellow to the other).

Secondary 1: 336v (319v under load)
Secondary 2: 313v (299v under load)
Rectifier out: 805v (737v under load)
B+: 667v (241v under load)

Needless to say, I haven't brought the mic anywhere near this thing yet!

It's probably something obvious but I just can't figure out why the power transformer secondaries are putting out such high voltage. Any help would be much appreciated. Thanks!
Title: Re: [BUILD] MK47 tube mic kit
Post by: kante1603 on March 25, 2012, 09:07:05 AM
So I finished building the PSU and in testing I'm getting some very odd voltages...

I'm using the Triad VPT230-110 and I'm getting over 300v off of the secondaries! I'm in the US so this is wired for 115v in (blue to violet, gray to brown) and 230v out (red to orange, black to one side of rectifier, yellow to the other).

Secondary 1: 336v (319v under load)
Secondary 2: 313v (299v under load)
Rectifier out: 805v (737v under load)
B+: 667v (241v under load)

Needless to say, I haven't brought the mic anywhere near this thing yet!

It's probably something obvious but I just can't figure out why the power transformer secondaries are putting out such high voltage. Any help would be much appreciated. Thanks!
Hello,

have you measured the ac from the wall outlet?Did you check the batteries in your DMM (when batteries go weak DMMs show pretty "funny" things!).
Beside of that I´ve looked at the specs for your transformer (via mouser),your wiring seems to be correct.
But the measurements are completely out of spec:
If wiring is correct you should get something like 230vac on the secondaries if wall outlet is 115vac-under load.
After the rectifier you should get something like 322ish volts dc,again under load.
BTW:How did you load it (you wrote you "....haven´t brought the mic anywhere near this thing yet")?
If your mains ac is correct you should post some pics of the transformer wiring and of the rectifier(is it set up correct etc.).

Hope to have helped,

Udo.
Title: Re: [BUILD] MK47 tube mic kit
Post by: diylan on March 25, 2012, 11:51:35 AM
Wow, I'm a huge idiot over here... feel embarrassed about even posting, but it's pretty funny. I spent hours looking at the build next to the schematic trying to figure out what was going on (before posting), even swapped out the batteries in my dmm, and then I figured it out:

I accidentally had the dmm set to measure AC instead of DC.  ::)

Just goes to show that you really need to check every last detail.
Title: Re: [BUILD] MK47 tube mic kit
Post by: kante1603 on March 25, 2012, 12:04:01 PM
Cool to hear ;D
No need to feel bad,we all make our more or less stupid things,but stating it here is what counts!
Have fun with your microphone,you'll love it!

Cheers,

Udo.
Title: Re: [BUILD] MK47 tube mic kit
Post by: cfierik on March 25, 2012, 03:09:32 PM
Has anyone tried and had success with a U48 style build on these?
Title: Re: [BUILD] MK47 tube mic kit
Post by: micaddict on March 25, 2012, 03:56:23 PM
Has anyone tried and had success with a U48 style build on these?

In this long thread there were a couple of posts about the U48 variant.

grantlack asked a question about it in reply #504:
Quote
as i look at the u48 schematic, it appears that the fig8 pattern was accomplished by simply switching a 1nF cap into the signal path between the membranes.  any reason the same approach couldn't be taken in the mk47?  the execution would be simple enough, it's just a matter of whether it would behave the same.  i tend to find omni to be less useful in my day-to-day work.

to which mad.ax responded in reply #510:
Quote
If your plan is to make a MK48 (sacrifice the omni patern to favor a figure 8 ) it's doable.
Pay attention to the U48 schematic. It's not just a matter of adding a cap and a resistor, you also need to modify the voltage divider.
In the U47 the 2M/3M extract 60V from the 105V PSU in order to polarize the front of the capsule. If you'd polarize the back with 105V, you wouldn't get a real figure 8 pattern (cause you'd need 120V). So for the U48 they changed the voltage divider  to 3M/3M. That gives 52.5V to the front, and then 105V at the back is right.
You can do the same with the MK47. Just keep in mind that, just like with a real U48, you'll loose a bit of sensitivity because of the lower polarization voltage.

Axel

And following that logic, I asked this in reply #653:
Quote
"If you'd polarize the back with 105V, you wouldn't get a real figure 8 pattern (cause you'd need 120V)."

Does this mean that without the voltage divider modification you'd get either cardioid or hypercardioid?

I never got a reply to that one BTW.

Anyway, as a start, perhaps this helps.
Title: Re: [BUILD] MK47 tube mic kit
Post by: cfierik on March 25, 2012, 04:46:50 PM
I really appreciate the work quoting the text , and alas I have read the whole thread. Mostly wondering if anyone has had it work as a 48.
I will be building one regardless, but figure 8 would be far more useful to me.
Title: Re: [BUILD] MK47 tube mic kit
Post by: mad.ax on March 25, 2012, 06:50:03 PM

And following that logic, I asked this in reply #653:
Quote
"If you'd polarize the back with 105V, you wouldn't get a real figure 8 pattern (cause you'd need 120V)."

Does this mean that without the voltage divider modification you'd get either cardioid or hypercardioid?

I never got a reply to that one BTW.

Kinda...
If you keep the 3M/2M voltage divider which gives 60V for the front, then 105V means a difference of 45V (105-60) to polarize the back. The sensivity of the membranes would then be different... The end result would be somewhere between cardioid and Fig8... Super or hyper cardioid...

Axel
Title: Re: [BUILD] MK47 tube mic kit
Post by: micaddict on March 26, 2012, 01:16:35 AM
Thanks, Axel!


Henk
Title: Re: [BUILD] MK47 tube mic kit
Post by: Studio Mollan on March 29, 2012, 07:01:02 AM
Hi guys!
Does anyone know if one PSU can power two microphones? Possible drawbacks on this?
It could be a money saver if it's possible.
Great work on this thread!!
/
Emil
Title: Re: [BUILD] MK47 tube mic kit
Post by: nashkato on March 29, 2012, 08:37:49 AM
i guess so , if you account for the higher power needed.
but , if i understand it correctly , you could not power only one mic at this PS.
less current draw from one mic => less voltage drop across resistors => higher voltage at output.
Also you would have to use quite higher wattage resistors than already used .
current drawn from two mics is doubled => P=I to the square * R => P= over 8 Watts ! at the 1K resistors.  Thats quite some heat.

so i guess building one PS for two mics would be siginificantly more expensive than building 2 PS , one for each.

i hope i´m right with my calculations and assumptions
Title: Re: [BUILD] MK47 tube mic kit
Post by: zayance on March 29, 2012, 09:09:28 AM
Hi folks,

I received the PCB's for the PSU, i remember having some folks that wanted me to help them by etching some,
i accidently erased PM's so feel free to contact me, not much was ordered so....

Thanks

PS: Thanks to Volker (not Silent Arts) for helping me clarify some obscure points for sending the boards to fab.



(http://img406.imageshack.us/img406/2581/pcbmk47psu.jpg)

Title: Re: [BUILD] MK47 tube mic kit
Post by: Studio Mollan on March 29, 2012, 09:24:21 AM
i guess so , if you account for the higher power needed.
but , if i understand it correctly , you could not power only one mic at this PS.
less current draw from one mic => less voltage drop across resistors => higher voltage at output.
Also you would have to use quite higher wattage resistors than already used .
current drawn from two mics is doubled => P=I to the square * R => P= over 8 Watts ! at the 1K resistors.  Thats quite some heat.

so i guess building one PS for two mics would be siginificantly more expensive than building 2 PS , one for each.

i hope i´m right with my calculations and assumptions

You've got a point there. That's ruled out then. Thanks!
/
Emil
Title: Re: [BUILD] MK47 tube mic kit
Post by: muffy1975 on March 29, 2012, 03:12:33 PM
Hi team,

people have mentioned connecting a mica capacitor in place of the capsule so to be able to test the microphone circuit.

How many mica capaciotors will i need to do the job and where should i connect them?

I presume i will need two 39pf caps.One cap will connect between the front tab and the back plate tab and the other will connect between the back plate tab and the rear tab.

is this correct?

michael
Title: Re: [BUILD] MK47 tube mic kit
Post by: david-p on March 29, 2012, 10:59:09 PM
Hi team,

people have mentioned connecting a mica capacitor in place of the capsule so to be able to test the microphone circuit.

How many mica capaciotors will i need to do the job and where should i connect them?

I presume i will need two 39pf caps.One cap will connect between the front tab and the back plate tab and the other will connect between the back plate tab and the rear tab.

is this correct?

michael

Presumably you want to measure the gain of the circuit, or just to see that it is working properly.  This means that instead of connecting the capsule to the vacuum tube, you attach a sine wave from a generator THROUGH a capacitor, which can be as large as 80 pF, to the grid of the valve.  Then you measure the output of the amplifier and vary the frequency to see that it is all working and not distorting.  You will have to have the body of the mic closed in order not to pick up hum.

David
Title: Re: [BUILD] MK47 tube mic kit
Post by: muffy1975 on March 30, 2012, 12:00:38 PM
hey there,

yeah i want to turn on the microphone and 'burn it in' and test the voltages before connecting the capsule.

i want to be able to check if the circuit is all fine so that i'm not panicking and desoldering stuff once the capsule is connected etc

do i need one or two capacitors and where do i connect them? i won't be using a sine wave generator, just listening to the circuitry.

where is the valve grid? do i  need to know where this is????

can i turn on the microphone without the capsule or the capacitors in it's place?

thanks in advance

michael
Title: Re: [BUILD] MK47 tube mic kit
Post by: david-p on March 31, 2012, 11:11:03 PM
hey there,

yeah i want to turn on the microphone and 'burn it in' and test the voltages before connecting the capsule.

where is the valve grid? do i  need to know where this is????

can i turn on the microphone without the capsule or the capacitors in it's place?
You can certainly turn the mic on with impunity without a capsule connected.  You probably cannot measure all the voltages, but the anode and cathode voltages should be measurable.

If you do a google search for the data on the valve you use, it will tell you which pin is which electrode.  The grid is the electrode to which the capsule is connected.

I cannot say more, as I dont have the circuit schematic in front of me.
Title: Re: [BUILD] MK47 tube mic kit
Post by: wave on April 01, 2012, 04:30:57 PM
So... My wall voltage is a little high and because of that, I'm measuring 280 VAC off the transformer sec. I have the 230 VAC Triad.
My circuit is working correctly and I'm able to dial in 105 VDC with the test load engaged.
My question is, since my wall voltage is high and conversely my trafo secondary is high, will that make my resistors work harder?
I'm asking because I used 7 watt resistors in the circuit (10 watt in the test load portion) and man they are getting very hot. So hot I can't touch them for more than a half second.
IS it normal for them to get pretty hot?

Dave
Title: Re: [BUILD] MK47 tube mic kit
Post by: zayance on April 02, 2012, 03:16:13 AM
Yes it's normal for them to get hot, on the safety note i attached to the Etching file i was pointing that out,
by saying "...solder those Hot resistors over the PCB a little to allow some air flow, and save the PCB overtime..."
For some numbers, my 7W resistors were getting to about 90 to 95°C after a minute or two, and that's a point
were you can't touch for more than a sec. Mine were rated to max 275°C iirc, so all good.
Title: Re: [BUILD] MK47 tube mic kit
Post by: wave on April 04, 2012, 08:22:41 PM
Thanks Zayance. I guess at some point I did read that note b/c I soldered the resistors a little above the board like you stated.

Next question:
I'm wiring my 7 pin connector to the MK47 board and while I was testing my connections, I found continuity between the A+ and A-.
I lifted the A+ off the board and there is still continuity between A+ and A- on the board. Is that correct?

Thanks,
Dave
Title: Re: [BUILD] MK47 tube mic kit
Post by: nashkato on April 05, 2012, 03:13:26 AM
Quote
  I lifted the A+ off the board and there is still continuity between A+ and A- on the board.
depends on where you measure , and what connection you lifted .
but generally A+ and A- is the secondary of the audiotransformer and therefor you measure continuity.
Title: Re: [BUILD] MK47 tube mic kit
Post by: funkymonksf on April 13, 2012, 10:41:54 AM
Have any of you had any luck with other mic bodies. Besides the t.bone sct-700, alctron, nady 1050, etc... Any mxl, or other cheap donors that work will work, even with a little work. I ordered a t.bone sct-700 and it may be the ugliest damn thing I've ever seen, plus had to return it because the headbasket was extremely crooked.

Any advice would help!
Title: Re: [BUILD] MK47 tube mic kit
Post by: wave on April 13, 2012, 10:53:01 AM
Have any of you had any luck with other mic bodies. Besides the t.bone sct-700, alctron, nady 1050, etc... Any mxl, or other cheap donors that work will work, even with a little work. I ordered a t.bone sct-700 and it may be the ugliest damn thing I've ever seen, plus had to return it because the headbasket was extremely crooked.

Any advice would help!

Ugly in what way? I got a t-bone and after I filled in the engravings and threw some paint on it, it's a much better looking mic body.
My headbasket isn't crooked tho.

Dave
Title: Re: [BUILD] MK47 tube mic kit
Post by: micaddict on April 13, 2012, 03:12:02 PM
A little "chrome" goes a long way.


(http://www.gearslutz.com/board/attachments/low-end-theory/262591d1321149701-anyone-got-new-stellar-cm5-yet-cm5.cm6.jpg)
Title: Re: [BUILD] MK47 tube mic kit
Post by: funkymonksf on April 14, 2012, 05:10:28 PM
I love the look of those stellar bodies! Sexy. Pricey! Know of a good cheap source for them?
Title: Re: [BUILD] MK47 tube mic kit
Post by: Monoklang on April 15, 2012, 03:59:21 AM
I've been looking at a lot of MK47 pictures in the Group DIY MK47 build thread. And when it comes to how to wire the capsule, it seems like there is a few differences.
I soldered my wires directly on the leads, "above the glass tubes", and front wire to "front", rear wire to "rear" and then this wire from the capsule side goes to the "backplate", is that correct?
I think I've seen people who put the rear to the backplate?

And some solder the wires to the leads under the glass tubes, and some don't, and some directly to the relay pins... Is there a right or wrong? I did my "glass tube leads" exactly a little bit too short to be able to solder anything on them... And I rather don't want to take that structure apart...

Best regards

John
Title: Re: [BUILD] MK47 tube mic kit
Post by: micaddict on April 15, 2012, 02:49:48 PM
Quote
I love the look of those stellar bodies! Sexy. Pricey! Know of a good cheap source for them?

Actually, the Stellar CM-5 and CM-6 are pretty good value for pre-modded/upgraded multipattern tube mics.

But if the question is where to get the shells only but with the chrome, then.......um...................er...............ah.......... ::)
....... :-\............................good question!
Title: Re: [BUILD] MK47 tube mic kit
Post by: wave on April 15, 2012, 04:33:19 PM
I've been looking at a lot of MK47 pictures in the Group DIY MK47 build thread. And when it comes to how to wire the capsule, it seems like there is a few differences.
I soldered my wires directly on the leads, "above the glass tubes", and front wire to "front", rear wire to "rear" and then this wire from the capsule side goes to the "backplate", is that correct?
I think I've seen people who put the rear to the backplate?

And some solder the wires to the leads under the glass tubes, and some don't, and some directly to the relay pins... Is there a right or wrong? I did my "glass tube leads" exactly a little bit too short to be able to solder anything on them... And I rather don't want to take that structure apart...

Best regards

John

John,
I was wondering what you think of your Q47-D Capsule?

Thanks,
Dave
Title: Re: [BUILD] MK47 tube mic kit
Post by: Monoklang on April 16, 2012, 02:35:41 AM
Dave,

I'm waiting for a couple of missing parts for the Psu. Then I will built it, but then I will tell you how it sounds. So until then I have no clue how it sounds. But do you the answers to my questions above? The thing about soldering the capsule wires above the glass tubes?

Regars

John
Title: Re: [BUILD] MK47 tube mic kit
Post by: wave on April 16, 2012, 11:32:29 AM
Dave,

I'm waiting for a couple of missing parts for the Psu. Then I will built it, but then I will tell you how it sounds. So until then I have no clue how it sounds. But do you the answers to my questions above? The thing about soldering the capsule wires above the glass tubes?

Regars

John

John,
Honestly I can't see why it would matter but if it does maybe Max will chime in. Maybe the glass isolators are just there to give stability to the ends of the pins and keep them from touching the board. I can't see what the difference is in soldering on the top or bottom.

Dave
Title: Re: [BUILD] MK47 tube mic kit
Post by: electrisizer on April 17, 2012, 03:00:15 PM
unfortunately my mic still dosent work...

i put it on scope feeding the lead of the "front" input and there is no problem. the amplifier gives a clean amplified sinus.

the problem is in the capsule part. neither the beez neeez capsule nor the original behringer sct700 capsule seem to have the right voltage. i just get a very low signal with some distortion...

the last measuring i can take is before the 100M resistor. there is 53V. is this ok? dosent the 100M resistor followed by the 10nf cap reduce the voltage?

any help would be nice.
Title: Re: [BUILD] MK47 tube mic kit
Post by: david-p on April 18, 2012, 12:04:15 PM
It should work with 53v, although 60 is more optimal.  There should be no voltage drop across the 100M resistor.

David
Title: Re: [BUILD] MK47 tube mic kit
Post by: electrisizer on April 19, 2012, 08:08:21 AM
It should work with 53v, although 60 is more optimal.  There should be no voltage drop across the 100M resistor.

David

ok i can trim it to 60v (trimable voltage resitor in psu)...

AFTER the 100M i have exactly 5,1V - some say its impossible to measure because of the high impedance. but my meter seems to have no problem. when i trim the voltage bit up or down - this voltage also goes up and down...

and i think thats the way the mic/capsule behaves: 5v polarisation voltage - very low output/sensitivity  :'(

is there any clue for this problem?
Title: Re: [BUILD] MK47 tube mic kit
Post by: david-p on April 19, 2012, 10:11:36 AM
is there any clue for this problem?

Yes.  What is the resistance of your meter?

David
Title: Re: [BUILD] MK47 tube mic kit
Post by: mrvision on April 19, 2012, 10:48:32 AM
If you suspect low voltage at the node where backplate, 100M resistor and the 10nf capacitor meet, you may have some sort of short path to ground. Try checking building problems first, like wires, connections, removing flux residue, overflooded Soldering points, etc. if everything looks fine then try swapping the 10nf (0.01uF) cap.
Title: Re: [BUILD] MK47 tube mic kit
Post by: muffy1975 on April 19, 2012, 07:34:45 PM
Guys,

sorry for asking a stupid question but......

In the PSU, where do you connect the orange and red centre tap wires of the TRIAD Xformer to? Do you just connect them to one another and leave them floating and insulted? Or, do you connect them to 0V which is the star ground point?

Kind regards and thanks

michael
Title: Re: [BUILD] MK47 tube mic kit
Post by: electrisizer on April 23, 2012, 08:31:43 AM
is there any clue for this problem?

Yes.  What is the resistance of your meter?

David

its > 7.8 Mohm

build looks clean. perhaps i have to change the caps. the 10nf seems to be ok if cap testing with the multimeter is trustable...
Title: Re: [BUILD] MK47 tube mic kit
Post by: wave on April 23, 2012, 01:26:47 PM
Guys,

sorry for asking a stupid question but......

In the PSU, where do you connect the orange and red centre tap wires of the TRIAD Xformer to? Do you just connect them to one another and leave them floating and insulted? Or, do you connect them to 0V which is the star ground point?

Kind regards and thanks

michael

Hi Michael,

Yes you connect them to each other and insulate the end. Definitely DO NOT connect it to 0V

Dave
Title: Re: [BUILD] MK47 tube mic kit
Post by: Rob Flinn on April 24, 2012, 10:16:10 AM
Dave,

I'm waiting for a couple of missing parts for the Psu. Then I will built it, but then I will tell you how it sounds. So until then I have no clue how it sounds. But do you the answers to my questions above? The thing about soldering the capsule wires above the glass tubes?

Regars

John




John,
Honestly I can't see why it would matter but if it does maybe Max will chime in. Maybe the glass isolators are just there to give stability to the ends of the pins and keep them from touching the board. I can't see what the difference is in soldering on the top or bottom.

Dave

I think that the glass isolators are there because that part of the circuit is the high impedance part.  At the impedances that we are talking normal insulating materials are sometimes not insulation.  I believe that is why Max has chosen to float that part of the circuit in mid air & has told you to make sure that certain valve base pins are not touching the pcb.  So ..... it might make a difference !
Title: Re: [BUILD] MK47 tube mic kit
Post by: wave on April 24, 2012, 01:09:20 PM
Rob,
I believe I remember reading that before too.

Thanks,
Dave
Title: Re: [BUILD] MK47 tube mic kit
Post by: david-p on April 24, 2012, 01:15:51 PM
is there any clue for this problem?

Yes.  What is the resistance of your meter?

David

its > 7.8 Mohm


This is not high enough for you to measure the polarizing voltage AFTER the large resistor and across the capsule.  For this reason, you get a lower reading than the truth.

David
Title: Re: [BUILD] MK47 tube mic kit
Post by: funkymonksf on April 27, 2012, 11:47:01 AM
The power supply leaves me with two questions. The two resistor sections: 1k/choke and the 680r/330r. Do attach both of the choke and the 1k or just one. Same goes for the 680r/330r, do I solder them both or just choose which one value to use. And if the latter how do I choose whether to use 330r or 680r.
Title: Re: [BUILD] MK47 tube mic kit
Post by: dissonantstring on April 27, 2012, 12:38:13 PM
hi funkymonksf,
you only need one of the options in each section your question is referencing.  either use a 1K resistor or the choke.  either use the 680R or the 330R.  the choke will provide less noise and the 680R or 330R really depends on your power transformer output.
with my build i used the choke and ended up using the 680R and was able to adjust the B+ to 105V exactly with the 500R pot (under load).  if you find that your voltage is too low under load you could try the 330R.  hope this helps.
best regards,
grant
Title: Re: [BUILD] MK47 tube mic kit
Post by: funkymonksf on April 27, 2012, 01:31:45 PM
thanks grant i appreciate the help. Have you finished your build? If so have you posted pictures? I would love to see more completed microphones.

Brice
Title: Re: [BUILD] MK47 tube mic kit
Post by: dissonantstring on April 27, 2012, 03:45:28 PM
hi brice,
yes, my MK47 is finished and burned in, but no real studio tests yet.  going to finish my MK7 build first and test both in studio.
sorry, no time for pics...my 2 year old and 2 month old are taking all my time right now.  psu built on perfboard and in a little enclosure i got cheap and powder coated at home.  all works great and sounds great though.  mic is in a EQU47 body.

forgot to give a great big thank you to max for the project!  max you are generous and design some great mic projects - THANK YOU sir!

kindest regards,
grant
Title: Re: [BUILD] MK47 tube mic kit
Post by: ioaudio on April 28, 2012, 08:01:30 AM
grant,

thanks for your kind words - just came in at the right time!

-max
Title: Re: [BUILD] MK47 tube mic kit
Post by: micaddict on April 28, 2012, 03:12:41 PM
You were not planning on leaving, were you?  :o
Title: Re: [BUILD] MK47 tube mic kit
Post by: ioaudio on April 28, 2012, 03:27:00 PM
no, not at all! It was just one of those days...

-max
Title: Re: [BUILD] MK47 tube mic kit
Post by: kante1603 on April 28, 2012, 04:39:24 PM
Good to hear Max.

Udo.
Title: Re: [BUILD] MK47 tube mic kit
Post by: micaddict on April 29, 2012, 06:43:45 AM
Quote
no, not at all!

Good!

Quote
It was just one of those days...

Yeah, I guess everybody has 'em from time to time.
Next time, just remember you've got a couple of friends here who like what you're doing.  :)
Title: Re: [BUILD] MK47 tube mic kit
Post by: david-p on April 30, 2012, 11:58:09 AM
either use a 1K resistor or the choke.  either use the 680R or the 330R.  the choke will provide less noise
Actually, the advantage of the choke is not a noise issue. Being largely inductive, it will reduce the ripple without getting as hot as the resistor.

David
Title: Re: [BUILD] MK47 tube mic kit
Post by: wave on April 30, 2012, 01:18:33 PM
Brice,
Which transformer are you using for the mains in your PSU?

Dave
Title: Re: [BUILD] MK47 tube mic kit
Post by: dissonantstring on April 30, 2012, 02:26:26 PM
max,
i do hope things are better and brighter.   we do enjoy your ideas, projects and participation in this forum - you are appreciated.  please be well.


Actually, the advantage of the choke is not a noise issue. Being largely inductive, it will reduce the ripple without getting as hot as the resistor.

David

david of course you are correct...thank you for that correction.   

Title: Re: [BUILD] MK47 tube mic kit
Post by: funkymonksf on May 01, 2012, 05:16:05 PM
I am using the antek AS 05T200. It seems to be a good canadate. I do however hate unneeded coils. It always makes me nervous simply tying them off. Especially 180 volts!
Title: Re: [BUILD] MK47 tube mic kit
Post by: 0dbfs on May 01, 2012, 05:33:09 PM
Isn't there a 6.3V on there that you can use for a jewel lamp?

I went with the LED method but may order a jewel lamp (fender gtr amp style I think) at some point since the transformer has the tap and it would be easy-squeezy.

Cheers,
jb

Title: Re: [BUILD] MK47 tube mic kit
Post by: wave on May 01, 2012, 05:51:32 PM
I am using the antek AS 05T200. It seems to be a good canadate. I do however hate unneeded coils. It always makes me nervous simply tying them off. Especially 180 volts!

Brice,
Just cut it and insulate the end with some shrink tube and it will be fine. I believe you will need to put the 680 and 330 resistors in parallel.
You can use the second 6.3VAC tap for a fender style jewel lamp.
You can use the layout I made for the Poor mans pultec PSU as a guide. The AN-5200 and AN-5240 have the same wire color pinout.
In this case you would use 1- 6.3VAC for the jewel lamp and the other 6.3V (blue+green) would be capped off like the grey 180V line.

Also, I know you like pics so..

(http://farm9.staticflickr.com/8158/6987373742_1b236b40f3.jpg) (http://www.flickr.com/photos/wavedealer/6987373742/)

Dave
Title: Re: [BUILD] MK47 tube mic kit
Post by: dissonantstring on May 02, 2012, 09:01:38 PM
dave,
very nice PSU build and homemade pcb no less.  great job!  what enclosure is that pictured?  do you have a pic of the outside?
best regards,
grant
Title: Re: [BUILD] MK47 tube mic kit
Post by: wave on May 02, 2012, 11:22:39 PM
Grant,
Thanks for the kind words!
I used this Hammond enclosure

http://www.mouser.com/Search/ProductDetail.aspx?R=1454Pvirtualkey54600000virtualkey546-1454P

Drilled it, epoxied logo on, masked that off, sprayed with primer then hit with about 4 coats of hammered.

This pic my pattern switch wasn't in yet. I ebded up going with 7 pin Amphenol connectors for the mic as opposed to Binder.
I wanted the reliability of having the cable screwed to the jack and the Amphenol made sense financially as well as it was much easier to modify the T-Bone for the male panel end


(http://farm8.staticflickr.com/7132/7137652923_0958445b6e.jpg) (http://www.flickr.com/photos/wavedealer/7137652923/)


Also here is a photo of my board right out of the etching bath


(http://farm8.staticflickr.com/7217/7137654703_26d1c84b96.jpg) (http://www.flickr.com/photos/wavedealer/7137654703/)

Gotta give credit to Zayance for his original etch file that I modified slightly for my needs!
Dave
Title: Re: [BUILD] MK47 tube mic kit
Post by: david-p on May 04, 2012, 11:45:33 AM
The whole thing looks great!  I see you use the box the other way up from the Hammond pictures!

Thanks for the heads up on the transformer: I have ordered a couple for my PSUs.  Which choke are you using? What do you use for the pcb blanks?

Thanks for answers when you have time,

David
Title: Re: [BUILD] MK47 tube mic kit
Post by: wave on May 05, 2012, 02:06:20 AM
The whole thing looks great!  I see you use the box the other way up from the Hammond pictures!

Thanks for the heads up on the transformer: I have ordered a couple for my PSUs.  Which choke are you using? What do you use for the pcb blanks?

Thanks for answers when you have time,

David

Hi David,
I am using the Triad 533-C-3X

This is the board that I used

http://www.mouser.com/Search/ProductDetail.aspx?R=603virtualkey59020000virtualkey590-603

Went to Staples and had them print a transparency. Exposed the board for about 9 min with a "25W" CFL bulb.
First time I ever did a photographic development style and only my second board etch!

I appreciate the compliments  :)

Dave
Title: Re: [BUILD] MK47 tube mic kit
Post by: muffy1975 on May 05, 2012, 07:30:00 AM
feels like i"m carpet bombing this thread.

Here you can see one of the tubes is pulled slightly. Just doing that at the mo to test for continuity and the like.

Doesn't my workjust look amazing. So clean...... ::)

So why doesn't it frickin wirk :-[

I heard the male equivalent pain wise, of giving birth to a baby is like passing a pineapple out your  urethra or whatever. can that be right? Surely the equivalent is actually to give birth yourself.

Well i feel like I'm doing this with the MK47.

Been up all night working on it. feeling grouchy, slightly tripping and feel really sleepy yet wired!

I've spent nearly £1000 and all i want to hear is this microphone. REALLY! :'(

Thanks for your help in advance

`Yes and the diode is around the right way.
Title: Re: [BUILD] MK47 tube mic kit
Post by: 0dbfs on May 05, 2012, 08:43:04 AM
Did you mention there was no voltage at the plate?

"that" would make it not-work. if that's the case I would start troubleshooting that problem.

Cheers,
jb
Title: Re: [BUILD] MK47 tube mic kit
Post by: muffy1975 on May 05, 2012, 09:14:24 AM
How can there be no voltage at the plate when my heater voltage is there? my B+ is rocking 105v!

Does the plate connect to the output cap? It's this voltage that's missing ie: 0V on the output cap.

Is the plate the 2/3 pin of the left hand tube when looking down on the pcb in my 1 or 2 photo?

Pin four has the 36V on the left hand tube?

Thanks 0DBFS

Title: Re: [BUILD] MK47 tube mic kit
Post by: abechap024 on May 05, 2012, 09:25:48 AM
Here's photo 3

Showing you from every angle this beautiful microphone that for no good reason will not work

Good gosh!

There is always a reason. Remember that when you get frustrated. Believe me I'm sure everyone here feels your pain, or at least has been in your shoes. Sometimes its good to give it a break come back to it in a day or two, probably easier said then done when you have some much time/money invested.

But its always something.

I haven't built this microphone (yet) but I couldn't read all your posts without trying to offer some advice.

Check for shorts. Check your wiring. Check your soldering. Clean you PCB with High grade alcohol. And especially watch around the high impedance parts, even oil from your fingers in the wrong spot could cause bad performance/no performance. Switch out your tubes. Check the tube sockets, make sure all the pins are connecting.

Do these things till you find whats wrong. Its usually simpler than you think and it ALWAYS is something.

Oh PS probably not the caps going bad, unless you got the polystyrene cap with alcohol, then you might need to replace it. (the capsule coupling cap)

Good luck!

Title: Re: [BUILD] MK47 tube mic kit
Post by: 0dbfs on May 05, 2012, 09:27:58 AM
Well, there are two resistors (100k & 30k) between B+ and plate connection. Check all of those nodes/solder-points for voltage. While you're at it check every node and write your voltages on a printout of the schematic (good for your reference/documentation). Schematic is on page 1 of this thread. You could have a bad solder joint or perhaps either the 100k or 30k has failed or something.

Be careful poking around in there!

Best luck! These mic's are great and there are very few parts so should not be hard to troubleshoot and get going.

-jb
Title: Re: [BUILD] MK47 tube mic kit
Post by: 0dbfs on May 05, 2012, 09:33:41 AM
I would also download the datasheets for the tube so you have the pinout and other tube data to reference. Also good to have in your documentation for your mic along with any notes you might make. The schematic shows one tube but there are obviously two of them. I believe the Plates, Grids, Cathodes are in parallel while heaters are in series.

Cheers,
jb

Title: Re: [BUILD] MK47 tube mic kit
Post by: electrisizer on May 05, 2012, 09:35:28 AM
hey muffy youre not alone...

my mic doesnt work too. everything soldered like supposed. volteges are right  :'(

does your mik produce any sound? even some wind noise or something else?

you can put it on a scope feeding the "front" input with a sinus and look if something coming trough...

PERHAPS the tubes (even if marked as nos tubes) are different from ioaudios tubes? i have tubes from an ebay seller because unfortuately one of ioaudios tubes broke? but i really dont know what else to do with this mik.
Title: Re: [BUILD] MK47 tube mic kit
Post by: Rob Flinn on May 05, 2012, 09:55:57 AM
Without wanting to sound condescending, which I'm definitely not trying to do.

I find when I build something & it doesn't work it's better to not assume that "I've wired everything up right".  It normally works better for me to think on the lines that I have probably done something wrong.

Either way I either have done something wrong or I have a duff component.  In my experiences building stuff with new parts it's not too often the latter......

Anyway if you have no HT present it's extremely unlikely that you have blown every capacitor in the mic.   

One thing I have noticed on this thread is people saying they were supplied with a shorted polystyrene cap.    This is probably unlikely.  It is more likely that the short developed through overheating whilst soldering.  Polystyrene caps don't like a lot of heat.
Title: Re: [BUILD] MK47 tube mic kit
Post by: muffy1975 on May 05, 2012, 10:07:17 AM
Hi there gang,

thanks so much for your advice.

i've soldered tens of polystyrene caps before when building 1290's. I've replaced it, but that's not gonna be the problem.

I've switched tubes now quite a few times. The pins seem fine.

I've switched out all the caps now and the problem remains with the temporary replacements so i've switched back. Think they are all OK.



I've built Marshall Plexis from scratch with no pre made PCBS. I've built loads of PSUs including this one. Built 1176 reva revd, igors 2254 and pultec, built 10 silly G1176s. A few pultecs, a few eqs including igors Sontec, built Great River Mp2s, built all kinds of stuff but this problem has me scratching my head. I'm SO methodical with this stuff you know?

I'm gonna keep looking.

Thanks for your support.?

Michael
Title: Re: [BUILD] MK47 tube mic kit
Post by: muffy1975 on May 05, 2012, 10:38:59 AM
GOT IT.

it wasn't my fault.

This PCB is not the highest quality. The traces sometimes look cool but aren't.

My problem was the join between the 30K and 100K resistor .........of course. It looked like it was there but wasn't somehow.

Thanks team

Michael
Title: Re: [BUILD] MK47 tube mic kit
Post by: muffy1975 on May 05, 2012, 11:08:24 AM
FUCX

this microphone sounds gorgeous. Not having any valve warm up issues yet either.

Will post u47 v TLM103 v SE Gemini very very soon.

God love you all or is that just me  ;D

Michael 8)
Title: Re: [BUILD] MK47 tube mic kit
Post by: gary o on May 09, 2012, 07:49:11 AM
Anyone know where I can get the 1uf oil capacitor.......mine has always leaked & stinks rotten horrible smell........thanks
Title: Re: [BUILD] MK47 tube mic kit
Post by: mrvision on May 09, 2012, 10:19:29 AM
here:

http://www.ebay.com/itm/1uF-300V-1-0uF-MBGO-2-CAPACITOR-LOT-OF-6-NEW-CAPACITORS-NOS-/330708284551?pt=Vintage_Electronics_R2&hash=item4cffbff487
Title: Re: [BUILD] MK47 tube mic kit
Post by: Monoklang on May 12, 2012, 07:15:46 AM
Hi! I'm finally putting my PSU together. But now when I should connect the trafos sec. 6,3 V to the jewel lamp, I can't get any solder on those leads. What should I do instead of soldering them?

And one more thing: Everything but the xlr, binder and the pattern switch are connected and I have measured it. But the values are "walking" between
104,91-105,12 V. Is that a problem or is that what it's suppose to do? I'm using a choke.


Thanks!
John
Title: Re: [BUILD] MK47 tube mic kit
Post by: wave on May 12, 2012, 01:21:44 PM
Do you have any crimp terminals like people use for speaker wiring? That could work.

Dave
Title: Re: [BUILD] MK47 tube mic kit
Post by: Monoklang on May 12, 2012, 03:00:46 PM
Yes, I can see if I find something... I already tried with some kind of "crimps things" (for IEC) but that didn't work. And now when I'm measuring between those two green sec. 6,3 V cables I only get like 0,18 V-0.00.
It should be DC right?

So is the trafos sec not working or am I doing something wrong here. A couple of hours ago, I put them on the lamp with "crocodiles", and the lamp worked. But now I don't get it to work.

The microphone is working and sounds incredible!!

So it's just the light left... If the trafos sec are faulty, is there another way to get 6,3v from that PSU?
Title: Re: [BUILD] MK47 tube mic kit
Post by: wave on May 12, 2012, 03:44:37 PM
What kind os transformer is it? The 6.3V secondary is AC not DC so measure accordingly.

Dave
Title: Re: [BUILD] MK47 tube mic kit
Post by: Monoklang on May 12, 2012, 04:12:53 PM
This is the transformer I'm using:

http://www.tube-town.net/ttstore/product_info.php/info/p2192_Torodial-30VA.html

And the lamp is this one:

http://www.tube-town.net/ttstore/product_info.php/info/p465_Fender-Pilot-Light-Assemply---Lamp-Holder.html

I will measure it again tomorrow. (in AC...)
Thank you!
Title: Re: [BUILD] MK47 tube mic kit
Post by: wave on May 12, 2012, 04:35:05 PM
I've been thinking about your solder issue and maybe the heat is being dissipated down the wire into the coil of the transformer. What wattage/heat are you soldering at generally?

You are wiring it correctly and if you saw the lamp light then it was working. You should def measure it and check the voltage. If you do have 6.3VAC at the secondary, maybe somehow the actual bulb went bad? Do you have any extras?

Just have to figure out why the solder isn't taking. I'm sure you can use some small crimp ends and solder those to the lap housing

Dave
Title: Re: [BUILD] MK47 tube mic kit
Post by: barney on May 12, 2012, 08:40:39 PM
You may need to scrape the clear coating (usually enamel) off the wire with a blade to make a good connection for soldering to on the transformer wires. 
Title: Re: [BUILD] MK47 tube mic kit
Post by: wave on May 12, 2012, 10:37:38 PM
You may need to scrape the clear coating (usually enamel) off the wire with a blade to make a good connection for soldering to on the transformer wires.

Excellent point barney. Didn't think of that myself!

Dave
Title: Re: [BUILD] MK47 tube mic kit
Post by: Monoklang on May 13, 2012, 04:14:47 AM
Thank you!

I scrapped the wires, soldered them to the lamp without any problems. The voltage measures to 7,3 V but the lamp works. That is ok, right?

When I switch between CARD/OMNI, it makes a pop. Is that the way it's suppose to be?

If that is suppose to happen, I'm finished! :) Thank you all for guiding me towards this build.
Title: Re: [BUILD] MK47 tube mic kit
Post by: Monoklang on May 13, 2012, 04:16:00 AM
And the whole package!
Title: Re: [BUILD] MK47 tube mic kit
Post by: Monoklang on May 13, 2012, 07:33:01 AM
One last stupid question through...

When measuring the PSU voltage I had the multimeter at DC. Was that right?
When Dave said that the sec. 7,3v where AC it got me thinking. Then would the 200v sec. also be AC. And in that case, I don't know why The DIMM could show me the right current in DC mode.

But since I am measuring between 105v and 0. I suppose there's no way that it could be DC. I am a total newbie when it comes to this sorts of electronics.

John
Title: Re: [BUILD] MK47 tube mic kit
Post by: wave on May 13, 2012, 01:01:17 PM
The 6.3V Sec is AC
The 200V Sec is AC
The 105V B+ is DC

If your wall voltage is a little high, that will translate through the transformer and produce higher secondary voltages.
The point of the PSU is to convert the 200VAC to the useable 105VDC.

That small drift you were getting (104.9 - 105.12) could be from drifting wall voltage. Those numbers you were seeing were pretty close to 105 so I wouldn't worry about it.

Dave
Title: Re: [BUILD] MK47 tube mic kit
Post by: barney on May 14, 2012, 12:34:03 AM
Glad you got it working, looking good.  Now I need to get onto finishing mine.
Title: Re: [BUILD] MK47 tube mic kit
Post by: Monoklang on May 14, 2012, 02:14:44 AM
Thanks!

I'm very proud of it. And it sounds amazing.
Yesterday I sat and played guitar in front of it for over 3 hours.
I didn't record anything, just listened meanwhile the tubes burns in. I havn't even heard any crackle, sparks or pops during the burn in. :)

Good luck with yours.

John
Title: Re: [BUILD] MK47 tube mic kit
Post by: electrisizer on May 14, 2012, 10:44:58 AM
mine is working now too ;D ;D ;D ;D with beez neez capsule and t bone houseing. its veeery quiet.

the mistake i made is really toooooo embrassing to report ::)

soundwise im in test phase. recorded a violin jesterday - well - i think i miss some highs. perhaps not the best application for that mik. today i made some gitar amp recordings and it seems a nice addition to a direct amp microphone like the shure sms. unfortunatley my female singer was ill so i cant go on this... (thats what i build the mik for)

whats your favored application for the mik?
Title: Re: [BUILD] MK47 tube mic kit
Post by: Monoklang on May 14, 2012, 12:53:19 PM
Well I have just tried it with acoustic guitar and vocals. And it owns every other microphone I got.

But I have been watching how much the voltage are pendling. And it seems to be more than I thought. When DIMM in DC mode it measures from like 103,5-106,3 V.

And if the DIMM is in DC True RMS it's more stable like between 104,8-105,6 V

I measured the the walls AC, and it drifts about 2,9 V so... that explain the drift but can it harm the microphone? Or is that ok?

John
Title: Re: [BUILD] MK47 tube mic kit
Post by: 0dbfs on May 16, 2012, 08:09:02 AM
I have seen numerous comments about b+ drifting. I have noticed this drift too over xx number of hours.

I had mine on the bench for several days recently. It was a week if it was a day.

Anyway, I monitored the b+ over several days of continuous use and once I would cal it to 105, it would drift within an hour or two. Came back one morning and it was up to 110. I'm thinking the stock 1k5 sand/power resistor may not be linear wrt heat.

In any case, I see significant drift. Well 5V up or down. That's not too bad in context I guess but a more stable b+ would be nice for consistency.

I see this on 2 mic's.

I may install bananas and a cal-pot to psu chassis to facilitate calibration before / during a session or as needed.

Any other thoughts / observations / comments with drifting b+ ?

BTW, I had one in service on-air 24/7 for a couple weeks under these conditions and it sounded great. I did not monitor b+ during that time though I did receive good feedback from users regarding sound.

Cheers,
JoBu
Title: Re: [BUILD] MK47 tube mic kit
Post by: abechap024 on May 16, 2012, 11:18:58 AM
Couldn't you place a Zener at the end of the b+ voltage rail in the PSU to keep the voltage fairly constant without too much fuss? Then again Zeners drift too... :o
Title: Re: [BUILD] MK47 tube mic kit
Post by: 0dbfs on May 16, 2012, 11:32:11 AM
Probably could but don't those generate noise which we don't want in the heater/cathode ckt (fixed bias)? These things are mostly fine in a cathode/self bias situation though.

Anyway, I'm thinking that the main heater dropping resistor in the mic may be drifting in value as it heats/cools thus changing current draw and Vdrop. I noticed that several people appear to have used the chassis-mount encased style resistors in the 1k5 heater dropper position (attached to the bell) and was hoping that others could test/measure for b+ variance over hours of time or longer...

Mains AC is measured constant 122 in this case.

Cheers,
jb

Title: Re: [BUILD] MK47 tube mic kit
Post by: gevermil on May 19, 2012, 10:53:57 PM
These mics sound good , nice top end detail with the Bees knees cap .
As soon as I get my M7 holder Ill post a comparison of a dale and a BK
Title: Re: [BUILD] MK47 tube mic kit
Post by: johnny dance on May 30, 2012, 06:39:33 AM
Hey quick q'n how is everyone mounting the pot inside the case? any brakets  Ican buy? or are people making their own?
Title: Re: [BUILD] MK47 tube mic kit
Post by: wave on June 03, 2012, 12:37:50 PM
I made my own. I bought a little aluminum warning tag from the hardware store and drilled it then bent it to hold the pot facing up so I could turn it easily.
Title: Re: [BUILD] MK47 tube mic kit -- new batch in!
Post by: Melodeath00 on June 07, 2012, 06:51:56 PM
Hey everybody! I'm considering building the MK47, but I really want a U47 body for it, and Equinox is out of stock. AMI has bodies, but they use a three-rib system, as opposed to two like the Equinox. Would the MK47 fit anyway? There's also Flea, but it's very expensive, and I have no idea if it's two-rib or three.  Thanks!
Title: Re: [BUILD] MK47 tube mic kit -- new batch in!
Post by: muffy1975 on June 09, 2012, 02:10:11 PM
hey there,

i wonder the same about the ami body too. Will the mk47 fit? i'm sure it can be made to fit. the ami body is far superior to the equinox.

Big question for the MK47 team

Will the cheaper RK47 from http://microphone-parts.com/rk47-microphone-capsule/ work with this mk47 design???? :o

the reason i ask is cos i'm trying to fit one and there is no bass to the signal. like there a severe high pass filter on the whole time.

Thanks for any thought

Michael
Title: Re: [BUILD] MK47 tube mic kit -- new batch in!
Post by: wave on June 09, 2012, 03:09:29 PM
The capsule does work with the design.
Are you sure that your power supply has the cardiod/omni switch in the cardio position?
When I first tested mine my switch was in omni and the mic sounded terrible. I know it's probably not the answer you're looking for but you should try to throw it and see what the other position sounds like. We can then work from there.

Also, what body are you using now?

Dave
Title: Re: [BUILD] MK47 tube mic kit -- new batch in!
Post by: kante1603 on June 09, 2012, 03:13:49 PM

Also, what body are you using now?

Dave
Dave! What are you talking about.....oh wait...you meant for the microphone?
(Excuse me,couldn´t resist ;D)
Title: Re: [BUILD] MK47 tube mic kit -- new batch in!
Post by: wave on June 09, 2012, 04:08:33 PM
Good one Udo! :D
Title: Re: [BUILD] MK47 tube mic kit -- new batch in!
Post by: muffy1975 on June 12, 2012, 08:26:14 AM
Guys,

if the 1uf capacitor connected to the output xformer is changed, is it important that the voltage of this capacitor is close to 250V?

If the voltage is higher, does it act as an HPF?

Also, what is the ratio of the transformer in Mk47? Is it 6:1 or 12:1? What is the output impedance too?

Kind regards and thanks for any help

Michael de A
Title: Re: [BUILD] MK47 tube mic kit -- new batch in!
Post by: LHS on June 13, 2012, 01:40:57 AM
Finally got my build finished and the mic works beautifully. How do you guys find it compares to an actual U47? It seems to be more dependent on placement then most U47s I've used. The top end seems to drop off during vocal tracking when the singers shifts their heads even very slighty. 47s certainly aren't overly bright but the drop seems more drastic on these. (using the Dale M7 capsule by the way).
Title: Re: [BUILD] MK47 tube mic kit -- new batch in!
Post by: david-p on June 13, 2012, 09:50:20 AM
Guys,

if the 1uf capacitor connected to the output xformer is changed, is it important that the voltage of this capacitor is close to 250V?

If the voltage is higher, does it act as an HPF?

The value of the C changes the bass response: 2µF will pass signal an octave lower than 1µF will.  The voltage rating can be higher, but not lower: this does not affect the frequency response, but rather the point at which the capacitor breaks down permanently, and it's value is determined by the high DC voltage on the anode.

David
Title: Re: [BUILD] MK47 tube mic kit -- new batch in!
Post by: bobine on June 13, 2012, 10:21:07 AM
Finally got my build finished and the mic works beautifully. How do you guys find it compares to an actual U47? It seems to be more dependent on placement then most U47s I've used. The top end seems to drop off during vocal tracking when the singers shifts their heads even very slighty. 47s certainly aren't overly bright but the drop seems more drastic on these. (using the Dale M7 capsule by the way).

My M7 (Chuck D) is darker than my Beez Neez K7.  Both are in MK47s and EQ bodies.  I haven't noticed a placement issue, though. I prefer the K7 for lead vocals...astounding presence but never shrill.  The M7 can be beautiful, too, in the right setting.
Title: Re: [BUILD] MK47 tube mic kit -- new batch in!
Post by: dandeurloo on June 13, 2012, 06:33:07 PM
Guys, I have kind of a dumb question.  When building up my Cable for the tube mic to the PSU should I connect the shielding from the cable to the ground point on the Binder connection on my PSU?  I am assuming that at least one end of the shield should be connected to ground and it seems to make the most sense to do it at the PSU but I could be completely wrong.

Thanks as always.
Title: Re: [BUILD] MK47 tube mic kit -- new batch in!
Post by: 0dbfs on June 13, 2012, 07:00:09 PM
Guys, I have kind of a dumb question.  When building up my Cable for the tube mic to the PSU should I connect the shielding from the cable to the ground point on the Binder connection on my PSU?  I am assuming that at least one end of the shield should be connected to ground and it seems to make the most sense to do it at the PSU but I could be completely wrong.

Thanks as always.

Dan, I had my shield floating on the mic side with a conductor connected to mic-body and both shield and GND conductor connected to the star gnd point. That was fine until I was in a high RF environment where I got radio on the mic instead of mic on the radio.

So to fix it I ended up remaking my cables and connecting shield to star-gnd on the psu side and the GND/0V conductor (heater return) to the minus side of the last filter cap in the PSU. Quiet as a broken mic now :)

GND plane on the mic PCB is connected to mic-body through the body-rails.

Shield is connected to binder/chassis on both sides.

Cheers,
j

hmm.. I'll have to look in the PSU. I may not have a connection to star point from the shield on the PSU side but thought I did. The RF problem went away though.
Title: Re: [BUILD] MK47 tube mic kit -- new batch in!
Post by: dandeurloo on June 13, 2012, 07:17:55 PM
so basically connect the shield on both sides to the ground on both sides.

My PSU has everything going back to a star ground point so this makes sense that it would all really just be connected to one point then. 
Title: Re: [BUILD] MK47 tube mic kit -- new batch in!
Post by: 0dbfs on June 13, 2012, 07:59:10 PM
I believe that you want the body, the shield, and the PSU chassis all connected to the safety earth so if anything shorts no-one get's zapped. I did that by connecting shield to the binder connector on the little solder tab inside the binder on both sides.

Then, 0V on the mic PCB goes back via a conductor to the negative side of the last filter cap in the PSU. My 0V on the mic PCB is also connected to the mic-body through the screws that attach it to the rails. I'm thinking that creates a so-called gnd loop but it works well in practice over here. I would think that if you had some plastic or fiber washers you could have the PCB 0V float in the body and only have one path back to the last filter cap/0V.

The 0V side of the bridge rectifier in the PSU is also connected to the star gnd.

I also have pin1/shield of the XLR connected to star-gnd & XLR chassis-connector.

There is no more RF or ground hum. I did have RFI when I had the shield disconnected from the mic-end of the binder connector/chassis.

Does that help?

Cheers,
jb
Title: Re: [BUILD] MK47 tube mic kit -- new batch in!
Post by: dandeurloo on June 13, 2012, 10:22:53 PM
Yep!  Thanks
Title: Re: [BUILD] MK47 tube mic kit -- new batch in!
Post by: dandeurloo on June 14, 2012, 10:46:11 PM
So, I got the mic powered up and about ready to do an audio test with my crappy Chinese test capsule.  I figured if anything goes bad I would rather it happen to that capsule then my blue line.

Anyway, most all my voltages look good.  I am getting pretty low voltage however at the 2M/3M/100M point.  I get 28.6 volts.  Does that seem correct?  I thought it should be twice that.
Title: Re: [BUILD] MK47 tube mic kit -- new batch in!
Post by: ioaudio on June 15, 2012, 07:34:41 AM
should be approx. 60vdc - re-check resistor values?
Title: Re: [BUILD] MK47 tube mic kit -- new batch in!
Post by: zayance on June 15, 2012, 09:04:41 AM
I'll have some more PSU PCB's for if interested.


T.
Title: Re: [BUILD] MK47 tube mic kit -- new batch in!
Post by: kante1603 on June 15, 2012, 12:04:48 PM
I'll have some more PSU PCB's for if interested.


T.
Will be in for two-if I may!

Udo :)

P.S.:Pm sent!
Title: Re: [BUILD] MK47 tube mic kit -- new batch in!
Post by: dandeurloo on June 15, 2012, 12:12:25 PM
should be approx. 60vdc - re-check resistor values?

OK, I will check.  It seems to sound fine.  I get a little wind noise and when I record the noise it to my DAW it shows up as a littel 120hz peak that comes and goes.  Maybe that is ripple?

Taking it apart again now to triple check resistor values.
Title: Re: [BUILD] MK47 tube mic kit -- new batch in!
Post by: dandeurloo on June 15, 2012, 12:28:50 PM
The resistors are all correct.  I have read that it isn't possible to read the voltage at the capsule because of the high impedance.  Is this the same for measuring at the Node point of the 3M/2M/100M resistor?  Could it be the mic is fine?
Title: Re: [BUILD] MK47 tube mic kit -- new batch in!
Post by: madreza on June 16, 2012, 05:27:23 AM
Hi guys,
I 'm having an issue with my mics ( all of them )
the mics can work fine for hours or days, and suddenly that nois :
https://dl.dropbox.com/u/56011166/Mic%20noise.wav
any idea of what it can be ?
I've changed the PSU caps .....
wondered if this can be the 1K5 Resistor inside the mic , not being cooled well
in the PSU , I Also have a 1K5 Resistor that's heating much..... how can I cool it ?

Thanks Guys,

CHEERS
Title: Re: [BUILD] MK47 tube mic kit -- new batch in!
Post by: zayance on June 16, 2012, 05:58:25 AM
Those cracklings/sputterings Sounds like bad tubes, now if it's on all of them, then i guess that's bad luck?
Or tube socket bad solder joint maybe? Flux etc....
I don't think changing the caps would have done something here, well if these are brand new and within specs.
Try to get some new tubes and check it out...
Title: Re: [BUILD] MK47 tube mic kit -- new batch in!
Post by: spyder_hobo on June 16, 2012, 11:21:23 AM
I'll have some more PSU PCB's for if interested.


T.
I'll take one.
Title: Re: [BUILD] MK47 tube mic kit -- new batch in!
Post by: dandeurloo on June 16, 2012, 11:50:12 PM
The Mic sounds wonderful!

Be sure to connect the shield from the cable on both ends to the PSU star ground and to the mic ground.  I had noise in some places and not in others until I did that. Thanks everyone now to finish my second one.

Oh, anyone find good wood boxes that hold Skylars bodies?
Title: Re: [BUILD] MK47 tube mic kit -- new batch in!
Post by: david-p on June 17, 2012, 12:45:28 PM
anyone find good wood boxes that hold Skylars bodies?
Hobby Lobby for around $5.

David
Title: Re: [BUILD] MK47 tube mic kit -- new batch in!
Post by: dandeurloo on June 17, 2012, 07:51:10 PM
Thanks I will go check them out!
Title: Re: [BUILD] MK47 tube mic kit -- new batch in!
Post by: Sredna on June 22, 2012, 01:55:47 PM
Hi guys,
I 'm having an issue with my mics ( all of them )
the mics can work fine for hours or days, and suddenly that nois :
https://dl.dropbox.com/u/56011166/Mic%20noise.wav
any idea of what it can be ?

Yes, sounds like bad tubes. I had this as well and had to swap a couple of times before I found a quiet pair. Let the tubes burn in at least 24 hours.
Also check for microphonics, one tube gave an audiable "ping" when I turned the mike over.

Title: Re: [BUILD] MK47 tube mic kit -- new batch in!
Post by: zayance on June 25, 2012, 08:02:04 AM
PSU Boards are IN, if interested?


T.
Title: Re: [BUILD] MK47 tube mic kit -- new batch in!
Post by: Rob Flinn on June 25, 2012, 08:16:51 PM
How much are these PSU boards ?
Title: Re: [BUILD] MK47 tube mic kit -- new batch in!
Post by: zayance on June 25, 2012, 08:29:33 PM
Answerd on PM, as i don't want th support thread to be a selling place.
These boards were ordered because some were asking for them, and the spares i have are according to what Ioaudio still sells.
I was just making a call for who could be interested "as future kit buyers" and if these can help their builds.
Title: Re: [BUILD] MK47 tube mic kit -- new batch in!
Post by: David R. on July 02, 2012, 01:57:36 PM
anyone find good wood boxes that hold Skylars bodies?
Hobby Lobby for around $5.

David

David, I have searched their site and not found it.  Can you post a link? 

Thanks,

-David R.
Title: Re: [BUILD] MK47 tube mic kit -- new batch in!
Post by: david-p on July 04, 2012, 03:53:49 PM
David:

LOL.  I went straight to it by searching on wood box:

http://shop.hobbylobby.com/store/item.aspx?ItemId=165037 (http://shop.hobbylobby.com/store/item.aspx?ItemId=165037)

Cheers,

David
Title: Re: MK47 tube mic kit - build thread
Post by: withnail on July 08, 2012, 11:04:56 PM
Hi all - I just got Dan @ Collective Case's excellent PSU case and ordered the PCB from Tony (zayance).  Does anyone have recommendations on a PT which is suitable for both 115/230V?
Title: Re: MK47 tube mic kit - build thread
Post by: wave on July 09, 2012, 04:10:12 PM
The Antek AN-05T200 is a good choice

http://www.antekinc.com/details.php?p=603

It works on 115/230 and has a 200V sec as well as (2) 6.3V sec (for a nice fender jewel lamp etc).

Dave
Title: Re: MK47 tube mic kit - build thread
Post by: withnail on July 09, 2012, 04:30:37 PM
The Antek AN-05T200 is a good choice

http://www.antekinc.com/details.php?p=603

It works on 115/230 and has a 200V sec as well as (2) 6.3V sec (for a nice fender jewel lamp etc).

Dave

Thanks, Dave!
Title: Re: MK47 tube mic kit - build thread
Post by: jandoste on July 22, 2012, 02:52:40 PM
Hey guys,
I just received my 4 tubes that I bought them on ebay but they all have 9 pins :(  2x EF86= 9 Pins and 2xPF86 = Pins
so what the next step?  I am missing something with these Tubes?
Thanks for any advice!
Cheers
Title: Re: MK47 tube mic kit - build thread
Post by: Sredna on July 22, 2012, 03:04:13 PM
Wrong tubes for the MK47, they would suit the MK7 on othe other side! ;o)

For MK47 you should look fore these: http://www.ebay.de/itm/6028-408A-Philips-ECG-USA-Tube-Lot-of-10-Pcs-/380384374928?pt=UK_Sound_Vision_Valves_Vacuum_Tubes&hash=item5890acf090
Title: Re: MK47 tube mic kit - build thread
Post by: jandoste on July 22, 2012, 03:29:11 PM

Hey Sredna,
Thanks for the link! I get 10 pcs from your link and I don't know what I will do with the "EF86" tubes :) :) :)
cheers


Wrong tubes for the MK47, they would suit the MK7 on othe other side! ;o)

For MK47 you should look fore these: http://www.ebay.de/itm/6028-408A-Philips-ECG-USA-Tube-Lot-of-10-Pcs-/380384374928?pt=UK_Sound_Vision_Valves_Vacuum_Tubes&hash=item5890acf090
Title: Re: MK47 tube mic kit - build thread
Post by: zayance on July 22, 2012, 04:58:44 PM
You can get them here as well

http://www.audiophonics.fr/jan-philips-6028408a-tube-qualite-militaire-p-6168.html
Title: Re: MK47 tube mic kit - build thread
Post by: jandoste on July 22, 2012, 05:28:11 PM
You can get them here as well

http://www.audiophonics.fr/jan-philips-6028408a-tube-qualite-militaire-p-6168.html

You are the best Zayance!
Thanks,
Title: Re: MK47 tube mic kit - build thread
Post by: Sredna on July 22, 2012, 06:04:57 PM
... and I don't know what I will do with the "EF86" tubes :) :) :)

Give them to me! ;o)

Or build a MK7 or a U67 or a G7 or a REDD47 or a ......
Title: Re: MK47 tube mic kit - build thread
Post by: jandoste on July 25, 2012, 06:07:38 PM
Hey Guys,
I finished my build but just got a small problem  :D
the mic sound is too low :o The Psu is awesome[ thanks Zayance]! I got all right voltages! maybe the tubes are bad or my wire connexion is bad?
I used this one;
(http://i1236.photobucket.com/albums/ff442/jandoste/MK47_PSU_wiring_1_a.jpg)

Any idea?
regards
Title: Re: MK47 tube mic kit - build thread
Post by: Sredna on July 25, 2012, 08:12:36 PM
Have you checked the voltages inside the mike?

Are both tubes working?

Title: Re: MK47 tube mic kit - build thread
Post by: jandoste on July 26, 2012, 04:02:21 AM
Have you checked the voltages inside the mike?

Are both tubes working?

Hey Sredna,
thanks.... Yes, I have checked the voltages and I got 102V for B+ and the tube pins have the same voltage but they are not very brilliant  :D :o
cheers
Title: Re: MK47 tube mic kit - build thread
Post by: David R. on August 18, 2012, 12:48:35 AM
OK, build of 2 MK47 mics done, and they look beautiful.  Not crazy about the sound yet.  One sounds very nice, yet dark, and the other is completely lacking low end.  I will look at the connectors first, then grounding second.  Would the tubes be suspect?  Any tips for troubleshooting?

I used Skylar's body and capsule.  The psu board from Zayance.  Made the cables.  Swapped cables and psu's to verify it is the mic and not the supply or cable.

Title: Re: MK47 tube mic kit - build thread
Post by: david-p on August 20, 2012, 11:49:54 AM
OK, build of 2 MK47 mics done, and they look beautiful.  Not crazy about the sound yet.  One sounds very nice, yet dark, and the other is completely lacking low end.  I will look at the connectors first, then grounding second.  Would the tubes be suspect?  Any tips for troubleshooting?
I should have thought it was very unlikely to be the tube.  I would suspect the input or output capacitor or the o/p txfr.  In the absence of serious test gear, having inspected everything for any obvious differences, the best way would be to swap components from one mike to the other.  I would begin with the tube, as that is easy to change.  Then the transformer.  Then the capsule... Identify the mics clearly and keep a written log of every change and test.  These things can take time to nail down.

David
Title: Re: MK47 tube mic kit - build thread
Post by: David R. on August 21, 2012, 02:39:18 PM
Thank you, David P.
Title: Re: MK47 tube mic kit - build thread
Post by: jandoste on September 02, 2012, 06:00:50 PM
Great Sound! Amazing Mic :o! everything works here!
Thanks Max and Zayance for the PSU!
Cheers


Have you checked the voltages inside the mike?

Are both tubes working?

Hey Sredna,
thanks.... Yes, I have checked the voltages and I got 102V for B+ and the tube pins have the same voltage but they are not very brilliant  :D :o
cheers
Title: Re: MK47 tube mic kit - build thread
Post by: Myc on September 06, 2012, 11:14:01 AM
Forgive me if I missed this in my scour of this thread plus some selective searching but I'm looking for informed opinion on wiring the tube town 30va toroid. Four wires for the primary, which are live and which are neutral?  Thanks for any help and for the great kit and psu pcb M and Z.
Title: Re: MK47 tube mic kit - build thread
Post by: nashkato on September 06, 2012, 11:40:50 AM
my short (5 seconds ) search brought this up

Pri: 0 - 220 - 230 - 240 V (schwarz-gelb-lila-rot / black-yellow-purple-red)
Sec 1: 200 V @ 0,1 A (red / rot)
Sec 2: 6,3 V @ 1,5 A (green / grün)

from the tubetown website .
hope that makes it clear ?


Title: Re: MK47 tube mic kit - build thread
Post by: Myc on September 06, 2012, 11:48:02 AM
Sorry, no it doesn't. What does that mean? I had the info before (its in the outside of my transformer) and an opinion as to what it meant but I kept it to myself to avoid misinterpretation and get an opinion from someone who'd wired one. The secondary is clear but which wires go where for the primary? Again I have an opinion but I want to hear from someone who knows.  Thanks for your attempt.
Title: Re: MK47 tube mic kit - build thread
Post by: nashkato on September 06, 2012, 12:44:46 PM
i doesn´t really matter which is neutral and which is live.
there´s no right direction to plug the IEC into the outlet (0 degree or 180 degree and N/L are swapped)

the right colout code would be
here in Austria blue is Neutral = 0
                       brown is Live = 220-240V

the only effect if you do it reverse is the phase will be 180 degree , but additionally there´s no guarantee that the colours coming from your wall are correct. besides that try to measure the voltages in your house in the morning , midday , and evening . you´ll see they vary depending on the usage of power in your area.

if every household in an area would decide to turn on their oven and/or washing maching machine simultaneously , the fuse at the power plant would fall , cause the lines wouldn´t be able to handle the power.

Title: Re: MK47 tube mic kit - build thread
Post by: kante1603 on September 06, 2012, 01:13:27 PM
@myc:

You just pm'ed me for info on this.
Thought it might be important for others too,that's why the answer is here.
The question was about colour codes on the primary of the tubetown-transformer.

At first the translation german to english:

SW= Schwarz=Black
GE=Gelb=Yellow
VIO=Violett=Violet
RT=Rot=Red

SW is the start of winding.
The other colours are different taps off it.
So in either case you need SW plus the colour you need,I wired mine for 230vac operation meaning SW & VIO.

Isolate the leftover wires with some shrink tube or so.

Hope to have helped,

Udo.
Title: Re: MK47 tube mic kit - build thread
Post by: Myc on September 06, 2012, 01:40:10 PM
Thank you both.  Very much appreciated, my opinion had been Black Red for uk 240v but I had a creeping doubt that it might have been incremental...  Thanks again both of you, you've helped me out more than it would seem.
Title: Re: MK47 tube mic kit - build thread
Post by: kante1603 on September 06, 2012, 01:53:19 PM
You're welcome,maybe you should put in your location in your profile.Helps a lot when it comes to questions about psu stuff.

Cheers,

Udo.
Title: Re: MK47 tube mic kit - build thread
Post by: Treelady on September 20, 2012, 01:35:07 PM
Has anyone used "audiophile" caps in the power supply?  I've read some arguments that they make a difference.   Any opinions here?
Title: Re: MK47 tube mic kit - build thread
Post by: zayance on September 20, 2012, 02:02:41 PM
Don't think you'll find any "Audio Grade" at that voltages, i might be wrong.
I think it's useless, get some good high temp Caps, Snap In or leaded, and you'll be good.


T.
Title: Re: MK47 tube mic kit - build thread
Post by: Treelady on September 22, 2012, 06:16:34 PM
Just got my Power Supply boards from Zayance. 

I'm embarrassed that I was going to try turret boarding when these first-class PCBs are available.   People, these are very very nice.  I have no reservations about tell you to use them (but let me order more first)!

Title: Re: MK47 tube mic kit - build thread
Post by: ioaudio on September 27, 2012, 11:08:43 AM
Just a quick reminder for those who have been interested in kits, only 9 left in my WM thread.
Title: Re: MK47 tube mic kit - build thread
Post by: chunger on October 01, 2012, 04:12:07 AM
Thanks, ioaudio. . . this fantastic kit was a treat to build!

(http://studio939.zenfolio.com/img/s2/v58/p1158785206-5.jpg)
Title: Re: MK47 tube mic kit - build thread
Post by: EvLoutonian on October 01, 2012, 08:26:28 AM
Tidy work, chunger! 
Very nice.

Timely inspiration for myself, also, as I'm just about finished building the PSU and getting set to move on to the mic circuit.

(https://fbcdn-sphotos-e-a.akamaihd.net/hphotos-ak-snc6/199530_10152137196500282_68066638_n.jpg)
(Supply tests well with 105v on the test circuit).

Gotta wire up the panel sockets now.
How much ventilation is needed for the enclosure?
Mine only has a few unused screw holes, but nothing like the amount on the original Neumann units.
Will this be OK?
Title: Re: MK47 tube mic kit - build thread
Post by: EvLoutonian on October 01, 2012, 08:49:04 AM
Painted up my PSU in hammertone - only way to go!

(https://fbcdn-sphotos-a-a.akamaihd.net/hphotos-ak-ash4/389923_10152131059430282_1436519320_n.jpg)
Title: Re: MK47 tube mic kit - build thread
Post by: ioaudio on October 01, 2012, 12:23:11 PM
nice work, chunger!
EvLoutonian, your psu housing should be fine - add holes if you experience too much heat after a long session.
Title: Re: MK47 tube mic kit - build thread
Post by: EvLoutonian on October 01, 2012, 05:23:17 PM
Thanks Max!
(:
Title: Re: MK47 tube mic kit - build thread
Post by: Treelady on October 02, 2012, 04:10:33 PM
Power Supply test question.

Using the suggested R values for 1 - 4, I was getting 68 vDC. 
Jumpering R4 I got to 80 vDC.   
Chaging R3 and R4 to from 1k Ohms to 500 Ohms got me to 97 vDC.   

Can I jumper R3?  Or do I need something in there?  I don't want to burn up something.

Trying to get to 105 - 110 vDC.

Thanks!


Title: Re: MK47 tube mic kit - build thread
Post by: zayance on October 02, 2012, 05:17:25 PM
That looks too low.
For a better view of the prob, please specify the power transformer you use, how you hooked it up etc... EDIT: AND measure the Mains you got where you've tested the PSU, probe inside the Mains hole, DMM set to AC.
And i assume that these values are when you test the PSU with a Dummy load of about 2.2K right? Not with the Mic attached.
We need to test the PSU before connecting to the Mic as previously mentionned here and on the Safety instruction i forwarded with the PSU.
Title: Re: MK47 tube mic kit - build thread
Post by: Treelady on October 02, 2012, 05:38:27 PM
This is with a dummy load attached, using a Zayance PC board.

I'm located in the US.
I used the  TRIAD VPT230-110 wired on the primary/input side in SERIES.   Maybe I should have wired it in parallel??
for the Choke I used: TRIAD C-3X Choke
Title: Re: MK47 tube mic kit - build thread
Post by: zayance on October 02, 2012, 05:45:57 PM
This is with a dummy load attached, using a Zayance PC board.

I'm located in the US.
I used the  TRIAD VPT230-110 wired on the primary/input side in SERIES.   Maybe I should have wired it in parallel??
for the Choke I used: TRIAD C-3X Choke

You mean on the Secondary right?
I've also forwarded a Power transformer wiring scheme, that you could have used for giving you an idea.
BUT this power transformer clearly states on the Technical documentation that

Primary  beeing Blue/Gray - Violet/Brown (check on the Toroidal itself to be sure about colours)

Series gives 230VAC
Parralel gives 115VAC (That's the MAINS you need beeing in the US.)


Secondary Black/red - Orange/Yellow (Check again)

Series gives 230VAC @0.11A (that's what you'd wire to the board)
Parralel gives 115VAC @ 0.22A won't use that configuration
Title: Re: MK47 tube mic kit - build thread
Post by: Treelady on October 02, 2012, 06:55:17 PM
Here is how I have it wired NOW.   

These colors in the graphic match the legend printed on the side of my transformer, so the colors are correct for THIS discussion (and only this discussion unless you have the same exact transformer and are working in the US).

I have black and yellow going to board.  Red and Orange tied together.  I always had that, and I think that's fine.

Now I have Blue / Violet going to the load / power switch (I say load because there is a fuse in there...for safety).
The Grey and Brown are tied to the Neutral.

Thanks so much.  And Chunger did the graphic!
Title: Re: MK47 tube mic kit - build thread
Post by: Treelady on October 02, 2012, 09:31:19 PM
Working now.   You need to add "if you do not sleep, do not try to wire the power supply..." to your notes.
Title: Re: MK47 tube mic kit - build thread
Post by: late on October 03, 2012, 04:16:19 PM
Anyone have used ami body?
Title: Re: [BUILD] MK47 tube mic kit - new batch @ white market
Post by: EvLoutonian on October 07, 2012, 09:30:27 AM
The PSU (Scott Hamptone) is wired as follows.  Pins 3 + 4 are common ground.  Shield also goes there from the connector.

1. audio+
2. audio-
3. Ground
4. Ground
5. +105vdc @ 50mA
6. Pattern


I wired my cable as follows:

XLR                                   TUCHEL

1 (A+) ----------------------  1 (A+)
2 (A-) -----------------------  2 (A-)
3                 empty             3
4 (B-) --------blue----------  4 (B-)
5 (B+) --------red ---------- 5 (B+)
6 (P) ------------------------- 6 (48v pattern)
Tab -----Cable Shield-------- 7    ---    Bridged to Tab


Then inside the microphone on the male 7 pin binder I have the shield bridged to pin 4.  Pin 4 is then bridged to the mic rail.  Though, I'd like to confirm the wiring on the cable first before looking at the male binder.

Did you end up getting this all working satisfactorily, jrasia?
I was thinking of using your scheme above (and your attached graphic on page 36 of this thread) as a guide to work from..

Also, are people generally ending up with one pin spare (unconnected) in their 7 pin cable?


Thanks!
Evan.
Title: Re: MK47 tube mic kit - build thread
Post by: wave on October 08, 2012, 09:17:38 AM
Evan,
Yes one pin will be unused in the 7 conductor cable.

Dave
Title: Re: MK47 tube mic kit - build thread
Post by: EvLoutonian on October 08, 2012, 09:57:41 AM
Thanks for confirming this, Dave.

Would I be stretching the laws of reality in then thinking that perhaps, in this case, if I also had another U47 clone mic, but based around an EF80 tube (which additionally requires approx 6v. filament heater voltage) that I should select this unused pin for the filament voltage, making it safer if I should accidentally plug the wrong mic into the wrong supply?

Presumably the audio pins and B+ pins would be compatible between these two mic's I intend to build, but the heater voltage is a separate requirement on the EF80 circuit, and the 48v. pattern switch on the MK47 is something else I'd need to look at, as the EF80 circuit may simply have a mechanical switch on board, or alternatively variable pattern voltage supplied from the PSU.  So that's another thing to figure out what can be done.

I'm trying to think of a safe way to connect my cables up, in the (hopefully unlikely) event of this mis-match between PSU and mic happening, maybe something will not work quite right, but basically nothing dangerous or bad will happen.


I do intend to make both an EF80 type mic, based on the AMI circuit, as well as my MK47 - both using Skylar's Equinox body kit, and each will have the same Binder 7 pin connector at the base, so it's a real concern.

Has anyone encountered this same situation?

I'm hoping there's a way to connect up my pins on each supply / cable / mic, so that nothing would get damaged in the case of myself (or anyone else) getting this mixed up.  I'm not sure if there's enough pins available to achieve this, though.  Am I dreaming?


 
Title: Re: MK47 tube mic kit - build thread
Post by: HellfireStudios on October 08, 2012, 11:20:04 AM
Thanks for confirming this, Dave.

Would I be stretching the laws of reality in then thinking that perhaps, in this case, if I also had another U47 clone mic, but based around an EF80 tube (which additionally requires approx 6v. filament heater voltage) that I should select this unused pin for the filament voltage, making it safer if I should accidentally plug the wrong mic into the wrong supply?

Presumably the audio pins and B+ pins would be compatible between these two mic's I intend to build, but the heater voltage is a separate requirement on the EF80 circuit, and the 48v. pattern switch on the MK47 is something else I'd need to look at, as the EF80 circuit may simply have a mechanical switch on board, or alternatively variable pattern voltage supplied from the PSU.  So that's another thing to figure out what can be done.

I'm trying to think of a safe way to connect my cables up, in the (hopefully unlikely) event of this mis-match between PSU and mic happening, maybe something will not work quite right, but basically nothing dangerous or bad will happen.


I do intend to make both an EF80 type mic, based on the AMI circuit, as well as my MK47 - both using Skylar's Equinox body kit, and each will have the same Binder 7 pin connector at the base, so it's a real concern.

Has anyone encountered this same situation?

I'm hoping there's a way to connect up my pins on each supply / cable / mic, so that nothing would get damaged in the case of myself (or anyone else) getting this mixed up.  I'm not sure if there's enough pins available to achieve this, though.  Am I dreaming?


 

Is there a 6-pin Binder connector out there? If so, putting the 6-pin on the MK47 would solve the problem of mismatching mics and power supplies. You could even have one with Binder one with XLR. Then, they could both be 7-pin.

-James-
Title: Re: MK47 tube mic kit - build thread
Post by: ioaudio on October 08, 2012, 04:26:21 PM
agreed, i'd use different connectors.
Title: Re: MK47 tube mic kit - build thread
Post by: electrisizer on October 10, 2012, 02:06:53 PM
hello there,

ive used the mk47 in different productions till now and really like what it does! espacially on male voices this mik shines...

theres one thing i would like to change. it has not very much highs! even if the highs sound good and smooth when eq is boosting the dedicated frequencies (in contrast to most cheap miks)... i would like to have the highs right there after recording :)

is there a resistor determining the highs in this circuit???
Title: Re: MK47 tube mic kit - build thread
Post by: chunger on October 10, 2012, 02:14:27 PM
Which capsule is being used in your build?


hello there,

ive used the mk47 in different productions till now and really like what it does! espacially on male voices this mik shines...

theres one thing i would like to change. it has not very much highs! even if the highs sound good and smooth when eq is boosting the dedicated frequencies (in contrast to most cheap miks)... i would like to have the highs right there after recording :)

is there a resistor determining the highs in this circuit???
Title: Re: MK47 tube mic kit - build thread
Post by: ioaudio on October 17, 2012, 04:57:18 PM
ive used the mk47 in different productions till now and really like what it does! espacially on male voices this mik shines...
theres one thing i would like to change. it has not very much highs! even if the highs sound good and smooth when eq is boosting the dedicated frequencies (in contrast to most cheap miks)... i would like to have the highs right there after recording :)
is there a resistor determining the highs in this circuit???

no,  in the u47 circuit everything's quite linear in the upper frequency domain - the presence should come from the capsule itself.

-max
Title: Re: MK47 tube mic kit - build thread
Post by: chunger on October 17, 2012, 07:13:20 PM
Hi ioaudio,

I'm experiencing a bit of hiss in my mic build detailed in the "newbie builds" thread.  I have burned in tubes overnight and the issue remains.  Issue also persists with all of the 7 tubes I switched in (searching for least microphonic tubes in the batch).  The general sonic characteristic of the microphone seems good across frequencies, there is just an underlying hiss that is louder than I am comfortable with.

I'm checking in to see if you could walk me through a few diagnostic steps to try and isolate the problem.  I do not have my final capsule in hand yet so this is operating on a stock Alctron GT-2B capsule.

PSU is set to delivery 105.1V at B+.  I am not experiencing hum that i can detect, this is a low-level hissing that ramps up at power-up as the tubes come online it seems.  The grounding scheme is as follows:

at PSU:

PSU grounding bus to star ground
PSU 3 pin xlr pin1 to star ground
PSU 7 pin "audio ground" (pin 4 on my setup) to star ground
PSU 7 pin "ground" (pin 7 on my setup) connected to shield in cable and connect to star ground

in microphone:

B- connected to "ground" (pin 7)
"ground" (pin7), "audio ground" (pin 4), and chassis contact tab tied together at XLR jack.
Solid contact is made via screw between PCB and frame rail.

Cable is Gotham 7 conductor, but also tested with stock Chinese 7 pin cable with same result.  Pin 7 (ground) on my cable is connected to shield at both ends as well as one of the internal wires.
Title: Re: MK47 tube mic kit - build thread
Post by: dandeurloo on October 17, 2012, 11:06:13 PM
I had noise at first as well.  I didn't have great connection of the mic Body back to the star ground.  Make sure that is happening properly. 
Title: Re: MK47 tube mic kit - build thread
Post by: ioaudio on October 18, 2012, 07:44:08 AM
'chung,

it's probably capsule related as well: the capsule you use now might have a low output, expecially if it's designed to run on 80VDC polarisation (and now running on 60VDC)
Other than that, tubes often want a long burn in period (leave it turned on for three days at a 110VDC coming from the Psu)

-max
Title: Re: MK47 tube mic kit - build thread
Post by: chunger on October 19, 2012, 09:06:01 PM
Thanks,

another forum member also recommended the following test:

"Here is a brute force test you can do:  disconnect the front diaphragm of the capsule, so that the only connection to the tube grid is the 100M pull-down resistor.  The mike should be dead quiet in this configuration
provided the tube itself is quiet.  Then, ground the grid of the tube directly to ground.  If the hiss goes away, you have grid current flowing through the 100M resistor and need to check to make sure there is no contact anywhere on
the PCB."

I'm hoping to implement this test later on tonight but need to know which pin is the grid on the 6028 tube?

Title: Re: MK47 tube mic kit - build thread
Post by: ioaudio on October 19, 2012, 09:12:49 PM
The grids are tied together directly on the tube socket fed throught the holes on the pcb (going to the "front" connection to the capsule)

Title: Re: MK47 tube mic kit - build thread
Post by: chunger on October 19, 2012, 10:43:32 PM
Thanks. . . this would be pin one I presume.  The one with the through holes.

I ran the test as described and did not hear a significant decrease in the base noise (hiss) with the front capsule disconnected and with the grid grounded.  I should probably test again and actually measure the differences but do not have a DAW setup at home currently, but based on this result, it appears what I am hearing is tube noise and the remedy may be to burn the tubes in for another 48 hours and re-check.  Alternately, a proper capsule designed for the circuit's lower-than-stock-Alctron polarization voltage should yield higher output which will further mitigate the base noise issue (if in-fact it is an issue).

Capsules have been ordered and I am awaiting shipping of K7 and M7 from Beesneez.

In the meantime, I will go back and review my build pictures to verify that I have not made a component value error during the build.

UPDATE: There was nothing wrong with the mic.  In the studio listening environment, it is extremely quiet.  My junk listening setup at home must have been acting up.  The noise that was present was very normal, low-level tube noise.
Title: Re: MK47 tube mic kit - build thread
Post by: tonycamp on October 23, 2012, 12:58:59 AM
Hey Chung,

I just built 4=7th circle audio pre's a while back, i was having an issue with one of the api's. I tested everything, measured this and that, carefully compared to my other functioning api, ordered replacement Ics and caps, none of it worked. As a last resort and completely frustrated, i flipped the pcb over and started touching my iron and rewetting all my solder points, plugged her back in and.......
you can guess the rest. By all outward appearances, a flawless solder job, that wasnt so flawless.

good luck
Title: Re: MK47 tube mic kit - build thread
Post by: electrisizer on October 23, 2012, 07:31:28 AM
Which capsule is being used in your build?


hello there,

ive used the mk47 in different productions till now and really like what it does! espacially on male voices this mik shines...

theres one thing i would like to change. it has not very much highs! even if the highs sound good and smooth when eq is boosting the dedicated frequencies (in contrast to most cheap miks)... i would like to have the highs right there after recording :)

is there a resistor determining the highs in this circuit???

hey was away for some days sorry for late answering.


its a beezneez capsule from first group buy... a K7
Title: Re: MK47 tube mic kit - build thread
Post by: Pliplo on October 24, 2012, 09:40:17 AM
I was about to buy my Thiersch STW7 blue line capsule but a new variable appeared. Capsule holder size...

I got this from Thiersch:

"The outer diameter of STW7 is 32 mm. The original Neumann K67 has got a
> diameter of 34 mm so that a holder that is used for K67 cannot be used for
> M7 or STW7. Maybe you'll also need another holder for your project?"

Anyone knows what capsule holder i should order? (Altran 2b donor body)

thx
Title: Re: MK47 tube mic kit - build thread
Post by: chunger on November 03, 2012, 02:38:02 AM
PSU 1:

(http://studio939.zenfolio.com/img/s2/v53/p494854831-3.jpg)

(http://studio939.zenfolio.com/img/s4/v62/p1142866980-3.jpg)

PSU 2:

(http://studio939.zenfolio.com/img/s2/v72/p1236400998-3.jpg)

(http://studio939.zenfolio.com/img/s4/v69/p1236403938-3.jpg)

(http://studio939.zenfolio.com/img/s2/v70/p1236405074-3.jpg)

Both running easy and completely cool to the touch :)  What a bit of DIY fun!  Learning lots along the way.
Title: Re: MK47 tube mic kit - build thread
Post by: ioaudio on November 05, 2012, 09:07:00 AM
Looking great, 'Chung!
Once more the link for chunger's fantastic build thread http://www.groupdiy.com/index.php?topic=47112.0
Title: Re: MK47 tube mic kit - build thread
Post by: Enchilada on November 20, 2012, 09:56:33 PM
Hey guys.

While I'm waiting to buy a PCB I'm going to have a crack at building this point-to-point just for fun. I've got a quick question about the schematic. It shows g2 and g3 tied to a but the 6028 has an internal connection between g3 and k.

How is the tube actually connected?

I've read here that the heaters are in series and the grids/a/k are all in parallel but I can't find anything about the internal g3 and k connection.

Thanks,

Kris
Title: Re: MK47 tube mic kit - build thread
Post by: My3gger on November 21, 2012, 09:47:45 AM
I guess you are looking at first schematic with VF14 tube, not 6028. VF14 doesn't have G3 connected to cathode and 6028 has. This is why it is possible to connect VF14's G2 and G3 to anode. Another example is EF86, G3 is not connected to cathode.
I'm also interested in knowing how 6028 is connected here. Preferred method is connecting G2 to anode and G3 to cathode. I don't think there are other choices with 6028. It's probably connected this way (maybe some resistors are added to grids) and two tubes paralleled like they say.
'
Title: Re: MK47 tube mic kit - build thread
Post by: Enchilada on November 22, 2012, 06:08:37 AM
I guess you are looking at first schematic with VF14 tube, not 6028.
The schematic on page 1 of this thread, as noted in the lower left corner, is for the MK47, not the U47. There are a few differences including the tube being labeled as VF14r. No such tube exists, it is the name given to the Vf14 emulation provided by paralleling 2 x 6028 tubes.

However, the question still remains. How are the g3 and k connected?
Title: Re: MK47 tube mic kit - build thread
Post by: My3gger on November 25, 2012, 07:07:17 AM
You are right about VF14r, no such tube exists, it's drawn as a replacement for VF14 made out of two 6028 tubes in parallel. Sorry for misinformation, i thought i was looking at redrawn U47 schematic...
G3, cathode and shield are connected together inside the tube, so there can't be any other connection for G3 than this.
http://tubedata.milbert.com/sheets/185/6/6028.pdf
http://www.westernelectric.com/spec_sheets/408A.pdf
I think better question is if G2 is directly connected to anode. Looking at datasheets i don't think you will ruin your tubes by connecting G2 directly to anode. Pictures are good and you might see correct connections from them.
Title: Re: MK47 tube mic kit - build thread
Post by: Enchilada on November 25, 2012, 11:41:58 PM
You are right about VF14r, no such tube exists, it's drawn as a replacement for VF14 made out of two 6028 tubes in parallel. Sorry for misinformation, i thought i was looking at redrawn U47 schematic...
G3, cathode and shield are connected together inside the tube, so there can't be any other connection for G3 than this.
http://tubedata.milbert.com/sheets/185/6/6028.pdf
http://www.westernelectric.com/spec_sheets/408A.pdf
I think better question is if G2 is directly connected to anode. Looking at datasheets i don't think you will ruin your tubes by connecting G2 directly to anode. Pictures are good and you might see correct connections from them.

It shows g2 and g3 tied to a but the 6028 has an internal connection between g3 and k.
You're not giving me anything I haven't already stated. My question was not "how is g3 connected" my question was "how is the tube actually connected?" I was asking the question in reference to my previous comment outlining that the schematic has g2 and g3 to a and k to -f but this cannot be correct because, as I previously stated, there is an internal connection between g3 and k.
Title: Re: MK47 tube mic kit - build thread
Post by: 0dbfs on November 26, 2012, 11:20:27 AM
I don't have my mk47's with me at the moment to beep it out and confirm but if you look at a 6028 datasheet there is no dedicated pin for the suppressor grid. Pin 2 and Pin 7 on the 6028 datasheet that I have are labeled as Cathode, Suppressor Grid, and Internal Shield. If you inspect Max's example photo's you will see that pin 2 is floating (ie; no connection) while pin 7 is connected to the cathode portion of the circuit. I do have some 6028's here though and pin 2/7 measure zero ohms so I can confirm that pins 2/7 are internally connected on the 6028's.

The VF14 is an eight pin tube and the control, suppressor, and screen grids are broken out to different pins as well as the cathode.

Cheers,
jonathan
Title: Re: MK47 tube mic kit - build thread
Post by: micaddict on November 27, 2012, 10:56:44 AM
Lots of circuit tech talk here, as is to be expected on an electronics DIY forum, especially in a dedicated build thread.

But now that we're three years past the announcement of the MK47, there should be quite a few specimens in the field actually transducing artistic sounds from human throats and musical instruments. So I'd like to ask members if they could post more sound samples.
Since this would be more about the finished product rather than the build, I could also start a new thread for it if that is preferred.
Max?

Also, what is the experience on the slightly longer term. Like how have the parallel tubes been holding out?
And what are the experiences with the various M7/K47 capsules? Are they just right for the circuit, or maybe a little dark to some, somewhat midrangey? Etc. etc.
Have some changed out caps and such to alter tone?
Questions like that. (Those questions perhaps stay closer to the relevance of a build thread, and some may have been answered to some extent.)

I know the journey is often more fun than reaching the destination, but I think it'd be nice to read and hear some more feedback about the actual finished microphone. Or am I alone in this? If so, please forget I posted this.  :)
Title: Re: MK47 tube mic kit - build thread
Post by: tonycamp on November 27, 2012, 11:13:43 AM
I am with micaddict, i've built the mk47, waiting on Chungers donors to come in, i am leaning toward the theirsch M7 blue line, but the beezkneez k7 has been revered. So more verbiage and samples would be great :)
Title: Re: MK47 tube mic kit - build thread
Post by: guitar4444 on November 30, 2012, 05:10:52 AM
I'm just putting together my MK47 kit and thinking I wouldn't mind a fig 8 option. I thinking about trying an internal switch for making the mic either a U47 or U48.
Anyone else tried a fig 8 with the IOaudio kit?

cheers  Greg
Title: Re: MK47 tube mic kit - build thread
Post by: JW on December 07, 2012, 06:13:48 PM
Hey folks,

So I think I've finally figured out what's wrong with my MK47 mic. I have a couple questions though.

A little background: I've been having some intermittent ocean noises ever since I built this mic.  I know this is something that probably should have been done a long time ago, but I finally started checking voltages around the tubes.

Luckily, I have a second MK47 that's working flawlessly (why don't we call this one #2 to delineate from the non-functioning one, which we'll call #1) Anyhow, makes for easier troubleshooting.

So, on both #1 and #2, I'm getting 90V after the 30K resistor that is in series with the B+ voltage.
However, when I measure after the 100K resistor that is in series with the 30K resistor, I'm getting two very different voltages.

On #2, the functioning mic, I'm getting 54V
But on #1, I'm getting 41V

I thought this might clearly point to a bad 100K resistor in mic #1? However, the 100K resistor measures 102K 'in circuit' in both mics, which has me puzzled. What else could it be? Tubes drawing too much voltage/current? I bought 10 of the tubes when I first started building these mics, and I've swapped many in and out of this mic, burning them all in for hours, and it hasn't made any difference.

BTW, this is an aside, but I have a Beez Neez K7 in the functioning mic, which sounds great. And I have a Thiersch blue line on the way, which will go in the other mic, but I need to fix this problem first, so I can provide y'all with some samples.
Title: Re: MK47 tube mic kit - build thread
Post by: EvLoutonian on December 07, 2012, 08:56:01 PM
Also love to hear sound samples and results / feedback from people who've completed the mic.
Title: Re: MK47 tube mic kit - build thread
Post by: JW on December 11, 2012, 07:13:51 PM
Can somebody tell me what the plate voltage should be? Actually, I'm unsure whether this is the plate or grid #2 (according to 6028 data sheet) and because pins 5 and 6 are connected together on both tubes, but anyway, what is a good voltage here? (at intersection of the 1uF output cap, the 100K resistor, and pins 5 and 6 on both tubes)
Title: Re: MK47 tube mic kit - build thread
Post by: ioaudio on December 11, 2012, 07:17:51 PM
41v should be fine - #2 the working mic is on the high side.
Re-check the HighZ portion of the mic carefully.

-max
Title: Re: MK47 tube mic kit - build thread
Post by: JW on December 11, 2012, 07:53:25 PM
Thanks Max,

Okay, so if 41 VDC is good, what's the high and low of the acceptable range for this spot in the mic?

I pulled the tubes from the working mic, and put them in the mic with ocean noises, and surprise, it works fine now.
I really didn't think it was the tubes because I had thought I tested (and burned in) all of the other tubes from the ubiquitous Phillips 10 pack ebay source. That is a lot of non functioning tubes.

Anyway, despite the ocean noises apparently solved with the tube swap, the high voltage issue follows those (good?) tubes as well. Hmmmmm

I think I'm gonna look for another brand of tubes. 408A I presume are okay as well as 6028?
Title: Re: MK47 tube mic kit - build thread
Post by: micaddict on December 12, 2012, 06:44:23 AM
Anyone here using his MK47 on a regular basis?
Please chime in.
Title: Re: MK47 tube mic kit - build thread
Post by: ioaudio on December 12, 2012, 08:36:26 AM
I'm sure there are some reviews in this thread.
There have been some threads on gearslutz as well, just can find this one atm http://www.gearslutz.com/board/high-end/550966-so-im-building-u47-clone-7.html by user JMc (i found this by google-ing ioaudio mk47 )

JW,

i'm not sure where to find good 6028 tubes these days, hopefully other users will chime with their experience.
Some tubes need 48hours+ burn in before they settle.
Title: Re: MK47 tube mic kit - build thread
Post by: micaddict on December 12, 2012, 09:06:48 AM
Quote
I'm sure there are some reviews in this thread.

Yes, but not much news lately.
Anyway, it'd be nice.  :)


Quote
i'm not sure where to find good 6028 tubes these days, hopefully other users will chime with their experience.

I bought two dozen here:
http://www.tubezone.net/6028-408A-Philips-ECG-USA-Tube_p_169.html (http://www.tubezone.net/6028-408A-Philips-ECG-USA-Tube_p_169.html)
Well, at their UK branch actually:
http://www.tubezone.co.uk/6028-408A-Philips-ECG-USA-Tube_p_177.html (http://www.tubezone.co.uk/6028-408A-Philips-ECG-USA-Tube_p_177.html)

Title: Re: MK47 tube mic kit - build thread
Post by: JW on December 15, 2012, 04:09:26 PM
Still wondering what an appropriate range is for the plate voltage. ??

As it stands right now, I've got one mic with 43V at the plate, and another with 47V.

Concerning the tubes, micaddict, those are the same tubes I'm using, though sourced from ebay, 10 piece lot.

I went back to some of the tubes that never seemed to settle, after burning them in for 36 hours or so, and burned them in for 72 additional hours, and that seems to have helped a lot, though, there's still a couple little pops on one mic.

One tube was the culprit in the mic with the high plate voltage (56VDC), and another was the culprit in an additional recent problem: I got all set up to burn in tubes for a long period of time, tested voltages, got a similar reading to what I have now, around 44VDC at the plate, let them burn, came back three days later, to find the B+ up at 300VDC!
The mic seems okay, after having identified another bad tube that was obviously causing the mic to not load down the power supply.

For readers of this thread, who've yet to order tubes, beware that these Phillips tubes can take a LONG time to burn in. A week? Maybe. And count on purchasing a few of them.

I'm thinking about maybe looking at some RCA 408A's, or the Western Electric affiliated ones that are in Canada that I see a lot of on ebay.
Title: Re: MK47 tube mic kit - build thread
Post by: Joelv on December 29, 2012, 02:10:36 PM
Hey, I was wondering if someone could clear up a few things regarding my PSU for the MK47.

I am located in Canada and the transformer I am using is the AN-05T200 (http://www.antekinc.com/pdf/AN-05T200.pdf)

The question I have is how should I be wiring the primary wires? Should I only use one set (black - red), wire in parallel (black/black - red/red), or should I wire in series (black/red - black/red)?


Thanks in advance.
-Joel
Title: Re: MK47 tube mic kit - build thread
Post by: wave on December 29, 2012, 02:39:32 PM
Hi Joel,
I made this for the Poor man's Pultec thread but it applies to this as well.

Dave
Title: Re: MK47 tube mic kit - build thread
Post by: poctop on December 29, 2012, 08:03:12 PM
Hi Joel,
I made this for the Poor man's Pultec thread but it applies to this as well.

Dave

Nice Work Wave ,
Super nice drawing ,
That is great help for everyone,
Dan,
Title: Re: MK47 tube mic kit - build thread
Post by: zayance on December 30, 2012, 05:20:59 AM
Well it's nice to have a drawing for how to wire the mains.
BUT
It's still very important to understand why it is wired like this and how it applys on other power transformer and build etc...
Title: Re: MK47 PCB tube mic kit - build thread
Post by: ioaudio on January 07, 2013, 07:58:20 AM
FYI: small batch of new kits available at the WM
Title: Re: MK47 PCB tube mic kit - build thread
Post by: burglar on January 20, 2013, 03:48:12 PM
Hi folks.  Forgive my cluelessnes but i'm struggling to figure out what power transformer i need for the psu.  i'm in the uk so i need a 240v primary.  I unsure what voltage the secondary needs to be? what V do i want to be hitting the bridge rectifier with in order to be somewhere near 105v at the end? does it need to be single primary and secondary?

 i can read the layout of the schematic but i dont know how to wire the IEC to the transformer?  i'm unsure of parallel / series wiring.  Any chance some of you guys could explain in laymans terms where i should start with this. pm probably best.

Cheers

B
Title: Re: MK47 PCB tube mic kit - build thread
Post by: wave on January 20, 2013, 07:26:41 PM
You want to use a power transformer with a 200VAC secondary. If you use this voltage you don't have to change out components on the PSU.
Some of us use a Triad VPT230 which will output 230VAC on the secondry. Using this transformer necessitates changing a few resistors and the pot.

Here is a Mouser link to the Triad which can be used in both 115 and 230 mains voltage configs

http://www.mouser.com/Search/ProductDetail.aspx?R=VPT230-110virtualkey55310000virtualkey553-VPT230-110

Also this is a great transformer which outputs a 200VAC secondary and can be used for 230V mains and has a couple 6.3 VAC secondaries that you can use to power a nice Fender style jewel lamp

http://www.antekinc.com/details.php?p=603

There is also a power transformer that European users have used in the build. I think it was this one:

http://www.tube-town.net/ttstore/product_info.php/info/p2192_Toroidal-30VA.html

Read the build thread to find out (seems that asking this question means you didn't read the build thread and you should!)  :)

Also, if you figure out which power transformer you will be using then I can help you with the series/parallel wiring question

Dave
Title: Re: MK47 PCB tube mic kit - build thread
Post by: burglar on January 21, 2013, 08:11:09 AM

Thanks for your post Wave,

I have scanned through the thread and picked a few bits up here and there but I didn't really know what I was looking for regarding the transformer.  I did a bit of reading last night.

It looks like the tube-town transformer is best suited for me.  Can you verify: 

From the IEC the earth goes to the chassis, neutral goes straight to the 240v primary?, live goes to a fuse (value?) and then to the on/off switch, then to the primary?  The 200v secondary then goes to the bridge rectifier? 

Looking at Chungers build doc the best place to tap star point ground is off the 2nd cap?   

I am unsure on the pattern select switch wiring.  I have found two diagrams which are different.  One suggests that the 3rd leg of the switch goes to pin 6 of the 7 pin xlr and the other one  suggests that the 3rd leg of the switch goes to the 48v?   

Title: Re: MK47 PCB tube mic kit - build thread
Post by: burglar on January 21, 2013, 08:12:13 AM

Here's the other wiring diagram
Title: Re: MK47 PCB tube mic kit - build thread
Post by: leitrim_lad on January 21, 2013, 08:45:19 AM
Hey there, just wondering if you could help me out. I bought a mk47 and power supply second hand. The mic worked for about a week but now it pops when tryin to record sometimes. When it started happening if I turned off power supply, plugged out mic, plugged it back in and turned on power supply it seemed to clear the pops for awhile. However now it seems to be happening the minute I turn it on. Any help would be greatly appreciated

Title: Re: MK47 PCB tube mic kit - build thread
Post by: wave on January 21, 2013, 03:38:08 PM
Burglar,
It's the same difference between the 2 diagrams. If you look you will notice that on the second there is nothing else connected to the pattern "turret" so in theory you could just wire the switch to the 7 pin connector pin 6. Does that make sense?

Your description of how to wire the IEC sounds correct to me. I think I out a 250mA slo-blo fuse in mine. Make sure that if you use an SPDT switch that you wire the live line from the fuse to an outside pin and wire the center pin to your transformer. That will make sure that there is no voltage present on the other unused pin when the power is off

Leitrim-lad,
The first thing I would do with your mic is buy some more vacuum tubes. Those things are notorious for inducing noise and pops. Do you know if the original builder let the tubes burn in for a few days (i.e leave the mic plugged in and powered for 48 hours)?

Dave
Title: Re: MK47 PCB tube mic kit - build thread
Post by: burglar on January 21, 2013, 04:42:16 PM
Burglar,
It's the same difference between the 2 diagrams. If you look you will notice that on the second there is nothing else connected to the pattern "turret" so in theory you could just wire the switch to the 7 pin connector pin 6. Does that make sense

....sorry, i dont understand.  when the switch connects the 14k and 12k resistors together it sends 48v down the pattern pin and the mic relay selects omni?  When the 12k / 14k resistor connection is broken by the switch the rise in voltage going to the pattern pin causes the relay to switch to cardioid?

what i cant get my head around is that in neither diagram does the pattern 48v or the 2 turrets next to it go to the 7 pin mic cable, or connect with anything for that matter?.  are they there purely to indicate what the switch is doing when it connects the 12k / 14k resistors?   

Thanks again for your help.

B
Title: Re: MK47 PCB tube mic kit - build thread
Post by: wave on January 22, 2013, 01:15:51 AM
No. The switch is either taking the voltage from the 14K resistor and sending it to the pattern pin 6 in the 7 pin XLR or its sending it to the 12K resistor and on to 0V. So you have 2 positions:
1. Voltage coming into the switch from the 14K resistor and then going out to pin 6 of the cable
2. Voltage coming into the switch from the 14K resisotr and then going out to the 12K then on to 0V

So when you wire up the switch you would take a wire from the turret the 14K resistor is on to the center pin of the switch then one of the outside pins of the switch would go to the XLR pin 6 and the other outside switch pin would go to the turret that the 12K resistor is strapped to.
It's a bit easier to understand of you look at Zayance's PSU PCB maybe. I found it back on page 19

(http://farm9.staticflickr.com/8471/8404922964_4648805534.jpg) (http://www.flickr.com/photos/wavedealer/8404922964/)

Zayance if you want me to take this down, please let me know!

Hope this helps,
Dave
Title: Re: MK47 PCB tube mic kit - build thread
Post by: EvLoutonian on January 22, 2013, 04:15:38 AM
Hey, thanks for these recent questions - AND ANSWERS - re. specifics on wiring for PSU and polarity switching etc. 
I'm finding it illuminating also.  Just thought I'd say so.  Cheers.
(~:
Title: Re: MK47 PCB tube mic kit - build thread
Post by: leitrim_lad on January 22, 2013, 04:32:14 AM
Hey wave, cheers for the reply. I'm not sure if he let the tubes burn in to be honest. It didn't seem to be popping for a few weeks when i got it but its getting extremely bad now. I measured the voltage I was getting from the power supply and it was 117 volts. Is this far to high? Would this be causing the pops?
Title: Re: MK47 PCB tube mic kit - build thread
Post by: wave on January 22, 2013, 10:29:21 AM
Hey wave, cheers for the reply. I'm not sure if he let the tubes burn in to be honest. It didn't seem to be popping for a few weeks when i got it but its getting extremely bad now. I measured the voltage I was getting from the power supply and it was 117 volts. Is this far to high? Would this be causing the pops?

Maybe. Like I said those tubes can def cause some noise and pops and hitting them with 117V might be the cause. There should be a pot in the PSU that you can use to adjust the voltage to 105.
With the mic connected you should try to adjust it.

Dave
Title: Re: MK47 PCB tube mic kit - build thread
Post by: burglar on January 22, 2013, 03:50:48 PM

Thanks Wave.  I think i get it now.  It'll sink in once i read your posts a couple more times. 

You've been a great help.  Thanks again!

B
Title: Re: MK47 PCB tube mic kit - build thread
Post by: wave on January 22, 2013, 07:29:07 PM

Thanks Wave.  I think i get it now.  It'll sink in once i read your posts a couple more times. 

You've been a great help.  Thanks again!

B

No Problem B!
Are you doing a point to point or PCB build for your power supply?

Dave
Title: Re: MK47 PCB tube mic kit - build thread
Post by: burglar on January 22, 2013, 09:35:29 PM

At first i planned to use the PCB but i've decided to do point 2 point.  I was given a load of turrets & G10 + I'll learn more this way.  I just hope that by the time I'm finished the MK47 kits are still available!

The PSU will be my first non-kit project.
Title: Re: MK47 PCB tube mic kit - build thread
Post by: wave on January 22, 2013, 11:05:24 PM

At first i planned to use the PCB but i've decided to do point 2 point.  I was given a load of turrets & G10 + I'll learn more this way.  I just hope that by the time I'm finished the MK47 kits are still available!

The PSU will be my first non-kit project.

Have you had a look at Chunger's build guide for the MK47? He did a P2P and he always has great photos to look at!

Dave
Title: Re: MK47 PCB tube mic kit - build thread
Post by: chunger on January 23, 2013, 12:59:30 AM
Just don't mess up the layout like I did on my 1st go at it  :o .  I think I have a PDF posted that you can print for my board layout. .. . which isn't the most space efficient, but gets the job done.  I enjoyed building the psu both ways (turret board and Zayance pcb).

I believe ioaudio is committed to keeping the mk47 kits available.  Demand for them comes and goes but I'm sure you will be able to get one when you are ready.
Title: Re: MK47 PCB tube mic kit - build thread
Post by: EvLoutonian on January 23, 2013, 04:06:44 AM
.. I enjoyed building the PSU both ways (turret board and Zayance PCB).

How did you go with your MK47's so far, Chunger?
Did you make a matching pair, or variances in each?
I'd love to hear some audio samples!

Ev.
Title: Re: MK47 PCB tube mic kit - build thread
Post by: chunger on January 23, 2013, 07:33:04 AM
Still waiting for Beesneez capsules to ship so my mic still has the stock (not quite appropriate) Alctron GT-2B capsule.  Looks like a lot of folks got in line ahead of me on this M7 and K7 capsule offer here on the white market :)  I have been busy lately and not had a chance to build up the 2nd mic, but i have an interesting donor body for mic #2 and should be able to resume building soon.  Audio samples will be forthcoming shortly after build completion, but for now, my timeline is dependent on the capsule backlog at Beesneez.

But, mic #1 is functioning just fine on the temporary capsule.
Title: Re: MK47 PCB tube mic kit - build thread
Post by: EvLoutonian on January 23, 2013, 07:38:04 AM
Oh, great!  I'll look forward to more updates..

I just ordered 10 backup 6028/408a tubes from 'triodeel' on eBay UK, as it sounds like a lot of people are having to cycle through quite a few tubes to get quiet ones.

Seems like a good idea to have some spares up my sleeve, either way.

Title: Re: MK47 PCB tube mic kit - build thread
Post by: Majestic12 on January 24, 2013, 03:48:40 PM
Has anybody tried to make the power supply regulated? A simple TL783 could be used to stabilize the B+ on exactly 105V without having to worry about mains voltage drifts.
Title: Re: MK47 PCB tube mic kit - build thread
Post by: ioaudio on January 26, 2013, 01:44:21 PM
The kit was assembled in varying configurations over the last two years.
Some users went with ready-made regulated Psu's (made by Grosser, Drefahl, Hamptone etc.)
Those use adequate circuits to provide for clean well-filtered power.

Depending on your needs the TL783 solution might be too noisy, but one of my costumers went with it and thinks it's perfectly fine.

I once made a tl783 psu and put a lowDCR choke + cap after the regulator to clean up, was fine too.
Another costumer modified a old regulated tube lab supply, nice and heavy.
On the other side i have seen attempts to use finely filtered switched power supplies with modern parts only.

105V @ 0.05A is needed on one or the other way. I still like the original passive Psu most, especially with a split choke like the first original Neumann U47 PSU.
Add a check switch and a voltmeter permanently mounted into the PSU housing if mains voltage drift is a problem.

EvLoutonian,

yes, and do not underestimate the effect of giving the tubes some time to burn in, sometimes it's days before the noise settles.

'chung,

Yes kits will remain on the plate - i still wind and make the transformers by hand, and i rather do that in small batches.
Looking forward to your completed build. I sent you the pcb yesterday.

Waves,

thanks for chiming in!

-max





Title: Re: MK47 PCB tube mic kit - build thread
Post by: ioaudio on January 27, 2013, 09:43:34 AM
A new batch is available at the white market.
Title: Re: MK47 PCB tube mic kit - build thread
Post by: laddie.music on February 05, 2013, 06:06:35 PM
Could anybody point me in the direction for a power transformer for the U47 PSU by zayance???

i'm in the USA therefore his BOM is not relevant for the power transformer for PSU, and i'm not sure which to buy?

I'm guessing the Choke will be compatible either way, the one listed in the BOM?
Title: Re: MK47 PCB tube mic kit - build thread
Post by: zayance on February 05, 2013, 07:01:36 PM
Could anybody point me in the direction for a power transformer for the U47 PSU by zayance???

i'm in the USA therefore his BOM is not relevant for the power transformer for PSU, and i'm not sure which to buy?

I'm guessing the Choke will be compatible either way, the one listed in the BOM?

This one will do: http://fr.mouser.com/ProductDetail/Triad-Magnetics/VPT230-220/?qs=sGAEpiMZZMvwUzoUXIIvyTw34uqMHR%252budKXefz75NmY%3d
 the one Chunger seems to use, BUT you won't have a Jewel lamp voltage as seen on other builds.
Beware on the primary and secondary connection, check the pdf of the part, and also the transformer wiring diagram that was sended with the other files, and wire going with the color code marked ON the Toroidal, you never know, they may screw up on a batch, and people will follow pdf :/.

Antek, is another dealer for Toroidal in the US, seems to be out of stock for the ones needed for the PSU, AN-05T200 to be more precise.

And one last thing, i advise you to read through this thread and Chunger's, as this will help you find a lot of things that may help you threw the build, something that i noted on the Safety note pdf that i sended to you also.

Some of your questions points to a lack of searching around and some Electronic knowledge as well (i could be wrong), so i would be more than carefull dealing with my PSU and HT, without reading some things around, and getting a better view of the things to know first before jumping in, my Safety note gives some "notes" about it, but anyway, all is possible, but better be safe than sorry, as always.

Good Luck



T.
Title: Re: MK47 PCB tube mic kit - build thread
Post by: wave on February 05, 2013, 07:11:47 PM
Laddie,
I used the Triad that Zayance listed and you will have to change a few values in the components of the PSU if you go with that trafo.
There is an option for a jewel lamp as Mouser does stock a #47 bayonet lamp that works right off the IEC in. The bulb takes 130VAC so in the US we can use this in our PSUs with a jewel lamp holder (the kind at tube depot).
We have successfully done this over on the DU67 thread. I'll give you the necessary links if you wish to have a jewel lamp.

Dave
Title: Re: MK47 PCB tube mic kit - build thread
Post by: laddie.music on February 05, 2013, 08:00:31 PM
Thanks Zayance, really appreciate it,
i will definately do that,  and yes lack of knowledge on my behalf... i'm good with a solder,  but the PSU will absolutely be built by my friend who is a proper tech.
I will just pass on the parts and information I find through the thread...

Title: Re: MK47 PCB tube mic kit - build thread
Post by: braeden on February 07, 2013, 10:44:29 PM
Received my MK47 kits today, thanks ioaudio!

Also, I know this question has been asked in this thread before but I couldn't really find a definitive answer.

How does one modify the MK47 circuit for a Figure Of 8 pattern instead of the Omnidirectional as standard? (i.e. U47 to U48 conversion)?

I've compared the U47 and U48 schematics but unfortunately my electronics knowledge is lacking at the moment, especially when I am risking a lot of money.

I know there is a difference in the voltage divider resistor values, (3M/3M) as opposed to (3M/2M) as well as the addition of a capacitor from a relay pin, but I'm not sure whether this applies to the 6028.

Could anyone that's actually tried this confirm what modifications are to be done?

Thanks a lot,
Braeden
Title: Re: MK47 PCB tube mic kit - build thread
Post by: ioaudio on February 08, 2013, 05:51:42 PM
Not much harm can be done, just follow the original U48 schematics.
The tube type has nothing to do with the polarisation of the capsule.
Note that the modification provides only 50V polarisation per side.

-max
Title: Re: MK47 PCB tube mic kit - build thread
Post by: braeden on February 08, 2013, 11:52:49 PM
Not much harm can be done, just follow the original U48 schematics.
The tube type has nothing to do with the polarisation of the capsule.
Note that the modification provides only 50V polarisation per side.

-max

Thanks for the reply.
Title: Re: MK47 PCB tube mic kit - build thread
Post by: braeden on February 10, 2013, 03:36:29 AM
(http://i.imgur.com/dZ1Rp2p.png)

Here it is, or isn't for that matter. A 'MK48' schematic.

Any advice is welcome, I don't actually know how correct this is, especially in regards to component values.

Thanks
Title: Re: MK47 PCB tube mic kit - build thread
Post by: ioaudio on February 10, 2013, 06:26:49 AM
looks fine.
Title: Re: MK47 PCB tube mic kit - build thread
Post by: micaddict on February 10, 2013, 02:00:14 PM
Those interested in doing this (or with a twist) may also want to check replies #727 and #729 of this thread.
Title: Re: MK47 PCB tube mic kit - build thread
Post by: Kathode on February 19, 2013, 03:07:11 PM
Hello everyone!
Thanks for this threat. I got so much information by reading it.

I will start building this kit and psu next days and i own to telefunken 6922. Is it possible to use them, or to mod the kit?

Title: Re: MK47 PCB tube mic kit - build thread
Post by: micaddict on February 19, 2013, 06:19:13 PM
Welcome!
Title: Re: MK47 PCB tube mic kit - build thread
Post by: ioaudio on February 20, 2013, 06:50:46 AM
I will start building this kit and psu next days and i own to telefunken 6922. Is it possible to use them, or to mod the kit?

Hi again!
No the circuit needs 6028 / 408a tubes to work correctly.

Title: Re: MK47 PCB tube mic kit - build thread
Post by: Kathode on February 21, 2013, 03:44:21 PM
Ok. thank you!
Title: Re: MK47 assembly - more pics added
Post by: EvLoutonian on February 26, 2013, 06:34:35 PM
PSU gut shot

Hi James,

Do you mind posting a nice detailed photo of just the wiring in the back of your connectors, at PSU end?
I'm trying to get my head around the wiring of the 7 pin connector, including paths across to XLR output etc.

Much appreciated!
Evan.
Title: Re: MK47 PCB tube mic kit - build thread
Post by: wave on February 27, 2013, 04:06:38 AM
Evan,
Here is a pic of my wiring. I etched my own board so it might look a little different than a P2P build but the wiring is still the same

(http://farm9.staticflickr.com/8386/8512792180_2918fed81b.jpg) (http://www.flickr.com/photos/wavedealer/8512792180/)


If it helps you then that is my goal!

Dave
Title: Re: MK47 PCB tube mic kit - build thread
Post by: EvLoutonian on February 27, 2013, 04:31:23 AM
Thanks Dave - That's awesome!

I have to wire up all of this section next, and I'm just going through all the wiring info I can find in the thread to make sure I have the best overview I can figure out. 
Pictures sometimes really do tell a thousand words though, in these cases.
(:

Much appreciated.
Evan
Title: Re: MK47 PCB tube mic kit - build thread
Post by: EvLoutonian on February 27, 2013, 06:17:41 AM
Here is a pic of my wiring ...
If it helps you then that is my goal!

One more question.. Do I strictly need the two 0v conductors (pins 3 & 7 indicated on your picture), or can one suffice?

Thanks again,
Ev.
Title: Re: MK47 PCB tube mic kit - build thread
Post by: wave on February 27, 2013, 12:57:52 PM
Evan,
IIRC, you do need both. It's been a while since I had it open tho. There was a diagram floating around the build thread that I based my wiring on and I have no noise issues.

Dave
Title: Re: MK47 PCB tube mic kit - build thread
Post by: braeden on February 27, 2013, 11:25:29 PM
Speaking of PSUs, I finished mine recently... I just have to wire up the output/input connectors.

(http://i.imgur.com/4uuTMgG.jpg)

I'm getting 105V with the 2.3K load resistor when the pattern switch is off, and 110V when it's on (voltage is being supplied to the relay). Is this normal? (I might be asking in the wrong thread).

By the way, for the U48 set up, the film capacitor is connected in series with the lead going to the back of the capsule correct?

Thanks,
Braeden
Title: Re: MK47 PCB tube mic kit - build thread
Post by: The Frizzle on March 03, 2013, 04:58:15 PM
I couldn't source a 5W 500 Ohm trim pot in Germany.
But i got this 4W 1K pot: http://www.conrad.de/ce/de/product/444820/TT-Electronics-AB-4-Watt-Drahtdrehwiderstaende-Linear-1-k-4-W-10- (http://www.conrad.de/ce/de/product/444820/TT-Electronics-AB-4-Watt-Drahtdrehwiderstaende-Linear-1-k-4-W-10-)
So i need 5W and it only has 4W.
My Question is: Can i put a resistor in parallel to the pot so half the current flows through the resistor and i don't need 5W anymore?
I need 325 Ohm to get 105V, so i would use a 680 Ohm Resistor in parallel to the pot which then needs to have 623 Ohm.
So I'll have 680 Ohm with 623 Ohm in parallel.
Title: Re: MK47 PCB tube mic kit - build thread
Post by: Majestic12 on March 04, 2013, 01:20:57 AM
My Question is: Can i put a resistor in parallel to the pot so half the current flows through the resistor and i don't need 5W anymore?
I need 325 Ohm to get 105V, so i would use a 680 Ohm Resistor in parallel to the pot which then needs to have 623 Ohm.
So I'll have 680 Ohm with 623 Ohm in parallel.

Sure, no problem.
Title: Re: MK47 PCB tube mic kit - build thread
Post by: tonycamp on March 04, 2013, 10:53:22 AM
Hey Fella's,

I've been following this thread for a looooong time, regarding capsules for the mk47, i've read about the majestic sound of the Beezneez K7, and it's on it's way. I am going to be purchasing a M7 today!(i hope), my quandary is choosing between the REDLINE/BLUELINE from Thiersch?? All my nostalgic nerves are screaming BLUE and my practical side is saying RED and save a couple $'s, I haven't heard these 2 in person (that i know of), anyone have some feedback for me? Help me please! I'll be your best friend :-\

one way, or the other, the "pay now" button will be depressed shortly

Thanx Fella's
T
Title: Re: MK47 PCB tube mic kit - build thread
Post by: micaddict on March 04, 2013, 11:36:19 AM
Tony, you may or may not have seen/heard this:

http://www.panphonic.com/M7/tellme.html (http://www.panphonic.com/M7/tellme.html)

The corresponding graphs were posted on several fora, including ours:

http://www.groupdiy.com/index.php?topic=29254.0 (http://www.groupdiy.com/index.php?topic=29254.0)

This was before the BeesNeez K7 and M7 were available.

http://repforums.prosoundweb.com/index.php/topic,33278.0.html (http://repforums.prosoundweb.com/index.php/topic,33278.0.html)




Henk
Title: Re: MK47 PCB tube mic kit - build thread
Post by: tonycamp on March 04, 2013, 07:59:59 PM
Thanx addict,

The Thiersch is a no brainer in those tests to my ears, seemed the mylar capsule had more bass than the reskinned pvc? Wish there was a comparison between a straight up redline and blueline. I decided to go with the blueline. I requested an invoice, but they haven't sent it yet, probably not till tomrw, so?... still time to vacillate ::)

T
Title: Re: MK47 PCB tube mic kit - build thread
Post by: bubbi on March 19, 2013, 12:15:32 PM
Hey guys,
is mounting the 1.5K resistor like this a bad idea?
Title: Re: MK47 PCB tube mic kit - build thread
Post by: baol on March 20, 2013, 06:34:03 PM
Hi all you guys, I finished today to assemble my mk47 and psu well... I have 105v on the ouput but when I connect the mic there's no signsl at all, just a few pop sometime. Any idea of what to check again? thank you a million.

Andrea
Title: Re: MK47 PCB tube mic kit - build thread
Post by: HellfireStudios on March 20, 2013, 06:57:40 PM
Hi all you guys, I finished today to assemble my mk47 and psu well... I have 105v on the ouput but when I connect the mic there's no signsl at all, just a few pop sometime. Any idea of what to check again? thank you a million.

Andrea

There are too many places to recommend a good starting point. Pictures of your mic and circuit will help us with solving your problem (obvious wiring mistakes). As always, double check your wiring and solder joints. A lot of times it is simply a cold soldered joint. Do you have another tube to try in the mic?

-James-
Title: Re: MK47 PCB tube mic kit - build thread
Post by: baol on March 20, 2013, 07:21:39 PM
Hi hellfire, I only have the 2 tubes sent with the kit. I checked the signals from each of the 7 pin on the  psu xlr, to the mic board (A-, A+, B+ etc...) and there's continuity. the tubes get red but there's no sound. I don't know what to check more than B+ and Pattern values... Here a few pics
Title: Re: MK47 PCB tube mic kit - build thread
Post by: baol on March 21, 2013, 12:47:33 PM
...and here the mic
Title: Re: MK47 PCB tube mic kit - build thread
Post by: mrvision on March 21, 2013, 02:39:17 PM
Make sure the bracket extensions under the tubes are not touching a tube pin, a trace or another component soldering. make sure there are no shorts due to the aluminum bracket.
Also double check component placements and resistor values.
Title: Re: MK47 PCB tube mic kit - build thread
Post by: dmp on March 21, 2013, 03:50:29 PM
Wow, baol, your psu is a nice DIY build.

I haven't built one of these (warning), but you could check the voltage drop across the 100k plate resistor. That will tell you if the tube(s) is conducting.
And check the voltage where the 2M and 3M meet and see if the capsule bias is getting set. Should be somewhere near 35v with a typical dmm.
Title: Re: MK47 PCB tube mic kit - build thread
Post by: leitrim_lad on March 22, 2013, 11:10:43 AM
Hey there, im having problem with my mk47.. It keeps making popping sounds.. Iv changed the tubes but it still is making these sounds. Im just wondering would anyone have any idea of what might be wrong? Ive included a linkto a recording of the pops for you to have a listen.

Regards

https://dl.dropbox.com/u/12155948/Output%201-2.mp3
Title: Re: MK47 PCB tube mic kit - build thread
Post by: idylldon on March 22, 2013, 11:15:01 AM
Hey there, im having problem with my mk47.. It keeps making popping sounds.. Iv changed the tubes but it still is making these sounds. Im just wondering would anyone have any idea of what might be wrong? Ive included a linkto a recording of the pops for you to have a listen.

How long have you burned in the tubes?  Mine was making the same sounds with the tubes that were included in the kit after countless hours of burning in, so I bought a bunch and put in another pair.  After a few days of burn in, the mic is dead quiet.  I know you've changed the tubes, but you might have to go through a few pairs to find ones suited for mic use.  Luckily, they are cheap and plentiful.

Cheers,
--
Don
Title: Re: MK47 PCB tube mic kit - build thread
Post by: leitrim_lad on March 22, 2013, 11:52:51 AM
Cheers don, was it the same kind of noise yours was making? The mic used to be dead quiet then started making the noise. I've only changed the tubes a couple of hours ago and have been burning in since !
Title: Re: MK47 PCB tube mic kit - build thread
Post by: micaddict on March 22, 2013, 11:57:28 AM
Quite a few have mentioned the popping noise, so this likely is more than coincidental. Tube burn in has helped some but not all. And most are using the JAN Philips 6028 that come with the kit.

A while ago I read a post by Oliver Archut, about JAN tubes and noise. Random noise was mentioned, too.
Here's a quote:

"JAN tubes, Join Army Navy tube key, specialty tubes made for military use. Most of them were upgraded industrial tubes, with the one purpose to insure function under very heavy-duty circumstances. Their construction was designed to insure the minimal function over a long period of time. To put it into better terms, there were pre tested on the edge of their rating to sort out early failing ones. It doesn't mean that they were tested for audio, and most of those tubes are very noisy, not microphonic but a lot of random and white noise. In circuits like the U67 most of it is suppressed because of the HF cut off feedback as you pointed out. The higher noise relates to the cathode construction, some of them used sintered ones others a double layer coating design, the first layer is fast activated at the factory, the second one starts activating over a long period of time. *This process was patented by Sylvania and use for most JAN tubes after 1963* That is what generates the higher noise floor if used for audio. Sure they nearly live forever with hardly no microphonics, but gain structure is quite different, most of them sound quite harsh. In the last few years so many JAN tubes were decommissioned and entered the audio market, but for my personal taste a standard RADIO GRADE or some industrial tubes are more desirable. Of course there are some exception, like the JAN tubes than were special made for audio use."

I've wondered if the JAN Philips 6028 (seventies era tubes if I'm not mistaken) could have had the treatment Oliver is talking about.
Just to be sure I bought some pre '63 6028s for my build.
Title: Re: MK47 PCB tube mic kit - build thread
Post by: idylldon on March 22, 2013, 11:57:44 AM
Yes, the noise was pretty much the same, but mine would do it in short bursts and not in such a random fashion as yours.  When I first powered up the mic with the included tubes, it was quiet but then developed these "pops."  I put a new set of tubes in, burned them in for a few days, and, like I said, it's dead quiet now.  I used it on sessions this past weekend and was extremely pleased by its performance.  Like someone else mentioned earlier in this thread, not all tubes are up to the performance level required in a mic circuit so you might have to go through some pairs to find just the right ones.  Once you get a good pair, though, they'll probably last a lifetime.

Cheers,
--
Don
Title: Re: MK47 PCB tube mic kit - build thread
Post by: Volume11 on March 22, 2013, 03:42:01 PM
Yes, the noise was pretty much the same, but mine would do it in short bursts and not in such a random fashion as yours.  When I first powered up the mic with the included tubes, it was quiet but then developed these "pops."  I put a new set of tubes in, burned them in for a few days, and, like I said, it's dead quiet now.  I used it on sessions this past weekend and was extremely pleased by its performance.  Like someone else mentioned earlier in this thread, not all tubes are up to the performance level required in a mic circuit so you might have to go through some pairs to find just the right ones.  Once you get a good pair, though, they'll probably last a lifetime.

Cheers,
--
Don

I had the same issue a few months back. I ordered a set of ten nos tubes off of someone on eBay, popped them in and let them burn in. Mic has been perfect ever since. I was getting the same random pops and noise.
Title: Re: MK47 PCB tube mic kit - build thread
Post by: baol on March 23, 2013, 02:18:41 PM
Hi, so once I have my 105 volts on the psu output it means that the psu it’s ok, the problem is in the mic, isn’t it?
Well, the connections seems to be ok because there’s continuity between psu and the wires arriving at the microphone. DMP told me to check the voltage drop across the 100k plate resistor but I don’t really have understood what he means, I checked between ground and both 100K rheophores but I found something like a 0.30 volts, than I checked between 2M & 3M res and ground and I found 61 volts… May someone suggest me where and what (and maybe how) to chek on the mic? What kind of values should I have?
Title: Re: MK47 PCB tube mic kit - build thread
Post by: leitrim_lad on March 23, 2013, 05:01:53 PM
Iv been letting them burn in for nearly 20 hours on and off now and the pops have slowed down a good bit but are still popping every 30 seconds or so .. is this normal for the burning in process or do you still think my new tubes are jacked as well? 

Regards
Title: Re: MK47 PCB tube mic kit - build thread
Post by: idylldon on March 23, 2013, 05:39:22 PM
Iv been letting them burn in for nearly 20 hours on and off now and the pops have slowed down a good bit but are still popping every 30 seconds or so .. is this normal for the burning in process or do you still think my new tubes are jacked as well? 
Regards

I'd leave it on at least 48 hours continuously and then check.  If they're still popping after that, I would most likely try another pair.

Cheers,
--
Don
Title: Re: MK47 PCB tube mic kit - build thread
Post by: Studio Mollan on March 24, 2013, 03:48:56 PM
Hi again.
I'm hearing a bit of hissing but will wait a couple of days to let the tubes burn in thoroughly before pursuing that.
Is anyone else experiencing a clear high freq ringing when tapping and handling the microphone? Haven't heard any random noise yet. I still have only listened to my own voice through an mbox with headphones but it seems to be a killer sounding microphone! Thanks for this Max!
/
Emil
Title: Re: MK47 PCB tube mic kit - build thread
Post by: baol on March 24, 2013, 04:38:14 PM
Hi, so once I have my 105 volts on the psu output it means that the psu it’s ok, the problem is in the mic, isn’t it?
Well, the connections seems to be ok because there’s continuity between psu and the wires arriving at the microphone. DMP told me to check the voltage drop across the 100k plate resistor but I don’t really have understood what he means, I checked between ground and both 100K rheophores but I found something like a 0.30 volts, than I checked between 2M & 3M res and ground and I found 61 volts… May someone suggest me where and what (and maybe how) to chek on the mic? What kind of values should I have?
Title: Re: MK47 PCB tube mic kit - build thread
Post by: Studio Mollan on March 24, 2013, 05:43:52 PM
Also I have a question about the 6028 tube. I just bought 10pcs of the tube made by an old swedish telephone company LM Ericsson. Anyone tried these or have any preferences for the tubes? Searching eBay gives you quite a selection incl expensive gold pin versions. Any thoughts?
/
Emil
Title: Re: MK47 PCB tube mic kit - build thread
Post by: Studio Mollan on March 24, 2013, 07:02:41 PM
I notice I have some electrical noise, sounds like ground hum, low but audible when in cardoid mode. Omni is dead quiet.
Anybody have any experience on this?
/
Emil
Title: Re: MK47 PCB tube mic kit - build thread
Post by: Andy Meyer on March 24, 2013, 08:06:48 PM
I built this kit 2 years ago and I had issues with the tubes. After 3 pairs I found some good ones. Shortly after, the popping came back. I swapped out the 5W resistor and it has been perfect ever since.
Title: Re: MK47 PCB tube mic kit - build thread
Post by: Studio Mollan on March 24, 2013, 08:27:22 PM
Actually the 1k5 resistor is a new one as the one with the kit could not be removed from a different donor body which I ended up rejecting. I think it might be an issue with the relay or the 48v to it. Seems reasonable looking through the schematics. It's really not loud but with headphones on its clearly audible and will be a problem after compression. Any help on this is greatly appreciated!
/
Emil
Title: Re: MK47 PCB tube mic kit - build thread
Post by: Songguy on March 25, 2013, 12:54:55 PM
Hi all,
I have a question on 7 pin gotham cable wiring..
I have been reading a few posts on how to wire the mic/mic body to the psu using the 7 pin connectors. It seems that there are a few different ways to this when it comes to ground wiring ie pin 3/4 and bridging of pins.
I would be grateful if someone could let me know what seems to be the best way to wiring the grounding regarding mic body and 7 pin connector.

Many thanks,
Chris
Title: Re: MK47 PCB tube mic kit - build thread
Post by: maq3396 on March 26, 2013, 09:09:39 AM
Slightly different aspect of the MK 47b build here...

I would like to use the Beez Neez U47 body.

Ben and Veronica have two styles-a three rail with tapered base and a two rail with a flat base.

The current builds seem to be based on a two rail system but I am partial to the other body style.

Has anyone tried the kit using a three rail body?

Thanks
Mac
Title: Re: MK47 PCB tube mic kit - build thread
Post by: North on March 30, 2013, 02:21:43 AM
Hi guys, First time caller - long time listener. In order to get to 105v using a VPT30-110 I had to add about 1.5k ohms resistance to the recommended layout of two-1k's, 1-680, 1-Triad 553-c-3x choke and 1-500r pot. I basically pulled the 680 and replaced it with a 2.2k resistor. Without doing that I land on about 118v with little room for adjustment. Has anyone else had to add that much resistance or does something sound amiss? Thanks so much
Title: Re: MK47 PCB tube mic kit - build thread
Post by: ioaudio on March 30, 2013, 08:16:39 AM
You did the right thing - nor harm - add resistance if voltage is too high.
Title: Re: MK47 PCB tube mic kit - build thread
Post by: baol on March 30, 2013, 09:53:56 AM
Well, I tryed to measure some of my mic values (that it’s still completely mute, and I cannot understand why!). I took them between B- and the following points (may you tell me if it’s right?). And I was in cardioid mode.

1-   B+ 105VDC
2-   Heater (I read it on pins 3 & 4 on both tubes): left tube pin3: 19.5VDC; pin4:0 
                                                                                  right tube pin3: 1.27VDC; pin4:19.4VDC
3-   27R  1.26VDC
4-   Backplate 56VDC
5-   Output cap: wich cap is the output one (I cannot read the schematics!)? I read it on the 1k5 (is this the output?) and I get 37.5VDC

May a compassionate guy tell me if reading points were right (if values too) and if not what to do to fix them?
Thank you all and have a happy easter

Andrea
Title: Re: MK47 PCB tube mic kit - build thread
Post by: North on March 30, 2013, 11:12:22 AM
Thanks Max. I feel better relieved knowing this!
Andrea if I were further into the build I'd be more than happy to compare voltages. I'm just finishing up the PSU right now.
Chris
Title: Re: MK47 PCB tube mic kit - build thread
Post by: ioaudio on March 30, 2013, 08:06:58 PM
Andrea,
if you have a working and a non working mics try moving components to rule out the error - first easy things like tubes, capsule.
The output capacitor is the big rectengular one 1µF.
Recheck all solderings, wiring etc - go slowly and you surely find the problem.

Title: Re: MK47 PCB tube mic kit - build thread
Post by: baol on March 31, 2013, 04:45:15 AM
Hi ioaudio, I have only one mic, it's not working and it gives me the values I wrote before. I don't know where to check the heaters (I have so different values from the others I read in the group!), and I don't know if my values have an effect on its failure.
thank you

Andrea
Title: Re: MK47 PCB tube mic kit - build thread
Post by: North on March 31, 2013, 01:07:46 PM
I don't see an orientation on the vishay 1813 1uf cap, Does it matter which way? Thanks
Title: Re: MK47 PCB tube mic kit - build thread
Post by: baol on April 01, 2013, 02:27:28 PM
North, looking at the schematic it seems they're all NOT polarized caps so the way doesn't matter.
Title: Re: MK47 PCB tube mic kit - build thread
Post by: North on April 01, 2013, 10:15:51 PM
Yeah that's what I was thinking- however I should have read the schematic too LOL  :-[. Now I just need to figure out what to do with the microphones center pin 7 for audio ground- ,maybe screw it down on one of the side rails?
Title: Re: MK47 PCB tube mic kit - build thread
Post by: maq3396 on April 03, 2013, 06:23:07 AM
Can anyone comment on the Equinox vs Beez Neez body with regards to:
-Quality of construction
-Ease of mounting Mk 47 pcb board
-Sound quality

Thanks
Mac
Title: Re: MK47 PCB tube mic kit - build thread
Post by: micaddict on April 03, 2013, 09:30:23 AM
Can anyone comment on the Equinox vs Beez Neez body with regards to:
-Quality of construction
-Ease of mounting Mk 47 pcb board
-Sound quality

Thanks
Mac

-Quality of construction

Not many will have them side by side. But BeesNeez has a reputation when it comes to the hardware quality of the Producer/Tribute Series bodies. Heavy gunmetal (bronze) for the sleeve is one example. The Equinox uses aluminum, like most U47s. But the earliest U47s actually did use gunmetal bronze.
I did read a couple complaints about the quality of the Equinox. What the Equinox body has going for it is that (on the outside) it looks a little more like an original U47, for those who are sensitive to that.
A BeesNeez extra is the option of various colors.


-Ease of mounting Mk 47 pcb board

Unlike an original U47, the Equinox has two rather than three rails. For the MK47 PCB this is an advantage.
BeesNeez normally have three rails (so on the inside this is closer to the original), but especially for us, BeesNeez offers a two-rails version.


-Sound quality

Not everyone will swallow this, but the theory goes that a sturdier, weightier, more solid body benefits sound.


HTH


Henk
 

Title: Re: MK47 PCB tube mic kit - build thread
Post by: micaddict on April 03, 2013, 09:36:18 AM
And of course Max himself is working on a bronze/brass body. This one will have three rails, for a point-to-point build.

http://www.groupdiy.com/index.php?topic=50694.0 (http://www.groupdiy.com/index.php?topic=50694.0)
Title: Re: MK47 PCB tube mic kit - build thread
Post by: wave on April 03, 2013, 01:31:01 PM
I haven't handled an Equinox body but Ben himself showed me one of his mics when he was here in Chicago and I can say his build quality is amazing. The parts are very heavy duty and the mic exhibits no resonance in the body whatsoever.

His stuff is top notch! I am going to get one of his bodies to make my Ela M251.
Dave
Title: Re: MK47 PCB tube mic kit - build thread
Post by: maq3396 on April 03, 2013, 08:17:18 PM
Thanks for the help!

Cheers
Mac
Title: Re: MK47 PCB tube mic kit - build thread
Post by: North on April 03, 2013, 10:43:43 PM
Hi Mac, I have an Equinox body and I'm totally happy with it. The grill is high quality and the whole setup looks fantastic. I'm using mine for the MK47 and the two rail system is way preferred for this pcb mount. If you're going for authenticity, you would  want an oem type body as you would want an under set transformer, room for resistor stacks, a floating tube mount, grill mounted pattern switch and point to point wiring. There are two types of builds in my opinion. There is the do it yourself U47 build and there is the U47 reproduction build and of course there will be corresponding price points. Depending on your budget and what your going to use it for, The Equinox is solid and a great bargain.
Title: Re: MK47 PCB tube mic kit - build thread
Post by: micaddict on April 04, 2013, 03:35:02 AM
Yep, there are a several options and and various price points. And there's more to come. I already mentioned the new body Max is working on and fellow member Spencerleehorton seems to be up to something, too. The first I hope will be in the BeesNeez price ballpark, the second will be in the Equinox territory I guess.
If we look at what's currently available and arguably appropriate I come up with the following, more or less from top to bottom price wise:

- Flea. Relatively expensive, but high quality and a very close replica, especially since the headbasket was improved. The number one choice for a reason.

- Ami (was Flea actually*, last time I checked).

-Telefunken USA. They make their own bodies now. There have been some remarks about the quality of the metal work and plating in particular. It's a reasonably convincing copy, though, with pattern switch and all.

- BeesNeez. Lower in price point than all of the above and sturdier to boot. And with the current discount it's actually not so very much more than the Equinox.
Not an ultimately close copy with pattern switch and such. A little more personality, so to speak, especially when a different color is chosen (standard BeesNeez colors at no upcharge).

-Equinox. No pattern switch, but a pretty convincing looking 47 actually. Though not quite of  Flea quality IMO, e.g. the headbasket does look smoother than the more expensive Telefunken.

-Alctron GT-2B/Nady TCM1050/T-bone SCT700. This body is actually a complete microphone, but in this case it will be gutted. Price is about half the Equinox.
Some may not know and others may have forgotten, but the MK47 kit was made to fit this body.


Edit: *Not so sure anymore, for the (whole) U47 body that is. E.g. the AMI headbasket is a lot cheaper than the Flea.
Title: Re: MK47 PCB tube mic kit - build thread
Post by: useme2305 on April 05, 2013, 06:52:03 PM
i started finishing my PSU for this project today and noticed some anomalies in the 48V polar pattern voltage.

according to the schematic for the PSU there is a SPDT switch for enabling the 48V.

here's the bit for this from the original schematic again:
(http://i46.tinypic.com/2jeqkug.png)

it doesn't make much sense to me and i'm puzzling over why.but with a switch like this how are there 48V which i thought are derived from a voltage divider formed by the 14k and the 12k resistors. the chematic takes the 12k resistor completely out of the equation with the switch the way i read it, which is that it's a SPDT.

so why doesn't it use an on/off switch? this way there will be 48V the way i see it.
it would look like this:
(http://i46.tinypic.com/34htc9z.png)

am i totally off here? i can not see how some of you get the 48V with the original schematic. i tried it and it doesn't work. i haven't connected the mic yet. is that crucial? does the relay coil's resistance have something to do with this?
Title: Re: MK47 PCB tube mic kit - build thread
Post by: zayance on April 05, 2013, 07:12:10 PM
Stick to the original schematic.
Remember, relay's have resistance too, the reed one inside the mic is at 12K,
so no need to divide the voltage before.
Title: Re: MK47 PCB tube mic kit - build thread
Post by: electrisizer on April 06, 2013, 04:55:06 AM
hey there. ive done some 500 preamp testing/shoots with this mik and can provide some samples with a female singer demonstrating mik in action :)

lindell 6x-500: https://www.box.com/s/5toxdjosjpr1gih34pht

hairball lola: https://www.box.com/s/8g8yd6rjdaj4uxywd49u

there was (like always) a neve 1084 clone with a bit of mids at 3.2k in the recording chain too. AD was ssl alphalink mx
Title: Re: MK47 PCB tube mic kit - build thread
Post by: micaddict on April 06, 2013, 06:42:54 AM
Thanks!

Any more details, like capsule and body used?
Title: Re: MK47 PCB tube mic kit - build thread
Post by: braeden on April 06, 2013, 07:03:20 AM
I want my money back... these mics are too good.

Crystal clear, unexaggerated low-end, beautiful presence in the mids and just the right amount of highs.

I converted both of my MK47's to a U48 'style' successfully which involved removing one of the 2M resistors and replacing it with a 3M resistor.
I also had to add a few capacitors and resistors to ground from the rear diaphragm.

I originally had problems with a lack of 'proximity effect' or low-end (I guess) in one of the microphones. I believe this can be attributed to the fact that I accidentally wired the +/- audio outputs from the PCB in reverse.

Thanks max for the great project, at times it was a pain in the ass but worth it all the way. I'll hopefully post some samples later on.

Braeden

Edit: I thought I'd mention also that I am using the Thiersch M7 blue-line capsules  ::)
Title: Re: MK47 PCB tube mic kit - build thread
Post by: electrisizer on April 06, 2013, 02:15:18 PM
Thanks!

Any more details, like capsule and body used?

oh i forgot. its the t.bone body and beezneez capsule.

after some recordings i first wasnt sure if theres enough top end with this capsule/mik - so i turned the capsule and now i like the sound very much.
ive done some male voice (hard rock/metal) recordings too and the mik always wins in comparison to our other miks in midrange price field... by far!
exept a bit of midrange boost i dont need to add anything to the recording. it easily shines through the mix :)
thanks max again  :D
Title: Re: MK47 PCB tube mic kit - build thread
Post by: North on April 06, 2013, 02:27:14 PM
Hey Zayance can you tell me exactly how many volts the LED traces are supposed to be putting out on your PCB? I want to pickup an led for the XLR  side of the psu but Its showing 48 volts on the led traces. This seems to be about 45 too high isn't it? Thanks
Title: Re: MK47 PCB tube mic kit - build thread
Post by: micaddict on April 06, 2013, 02:43:49 PM
Quote
oh i forgot. its the t.bone body and beezneez capsule.

Thanks.  :)


Quote
after some recordings i first wasnt sure if theres enough top end with this capsule/mik - so i turned the capsule and now i like the sound very much.

That would mean both sides are not the same.
They should be.
Title: Re: MK47 PCB tube mic kit - build thread
Post by: Joelv on April 06, 2013, 06:10:45 PM
Hey guys,

So I just finished my U47 and when I power it up all I get is noise. It sounds like a grounding issue or possibly bad tubes, any idea on why this might be happening?

Here is a sound clip: https://soundcloud.com/joelv/u47 (https://soundcloud.com/joelv/u47)


Cheers,
-Joel
Title: Re: MK47 PCB tube mic kit - build thread
Post by: ioaudio on April 06, 2013, 06:30:10 PM
Joel,
it sounds like you tested the mic without the mic body/headbasket assembled.
Title: Re: MK47 PCB tube mic kit - build thread
Post by: Joelv on April 06, 2013, 06:43:08 PM
Yeah, I wanted to make sure nothing was burning up inside ;) Would not having the body on generate that amount of noise? I think I found my problem though, 0V wasn't connected to ground, so now everything seems to be working. I'm going to assemble it all first then report back with some pics.


Cheers,
-Joel
Title: Re: MK47 PCB tube mic kit - build thread
Post by: braeden on April 06, 2013, 07:56:24 PM
Yeah, I wanted to make sure nothing was burning up inside ;) Would not having the body on generate that amount of noise? I think I found my problem though, 0V wasn't connected to ground, so now everything seems to be working. I'm going to assemble it all first then report back with some pics.


Cheers,
-Joel

I noticed that as soon as I placed the head basket/grille over the capsule the noise would slowly start to disappear, when the head basket was actually bolted on the noise disappeared completely and the mic was silent.
Title: Re: MK47 PCB tube mic kit - build thread
Post by: HellfireStudios on April 06, 2013, 08:28:38 PM
All mic electronics need to be fully shielded to eliminate RFI/EMI. You can test the mic electrically with a DMM when it is exposed to the elements, but auditory testing should only take place when the mic is in its fully sheilded state (completely put together with all grounds connected and the ground hooked to the mic chassis and headbasket). This will most likely stop your noise issues.

-James-
Title: Re: MK47 PCB tube mic kit - build thread
Post by: maq3396 on April 06, 2013, 09:31:40 PM
Hello everyone

Just putting together the Mouser order for the PSU

Can someone please  recommend a mouser number for:

-On/off switch and
- test switch

Thanks
Mac
Title: Re: MK47 PCB tube mic kit - build thread
Post by: braeden on April 06, 2013, 10:41:48 PM
-On/off switch and
- test switch

Thanks
Mac

S6A from Nikkai, they're kinda expensive but they are a reliable and beautiful switch (has a knurled mounting nut for the front panel so it looks less ugly).
That particular part no. is a DPDT [ON/ON]

http://au.mouser.com/ProductDetail/NKK-Switches/S6A/?qs=sGAEpiMZZMuVJC7Vq%252bMl56bwffTaIvrQ

Remember to double check width & height clearances of the actual switch (where the contacts are) before you make your front/rear panels obviously.
 
chunger recommended this part for the test switch -
http://au.mouser.com/ProductDetail/CK-Components/7101SD9V3QE/?qs=sGAEpiMZZMsFqsQxqFp%252bdEaPJPZAMV%252b5

Any SPDT switch should be okay, just double check voltage ratings.

Braeden
Title: Re: MK47 PCB tube mic kit - build thread
Post by: EvLoutonian on April 07, 2013, 12:15:59 AM
Has anyone tried an MK47 build using an original Neumann PSU?
Title: Re: MK47 PCB tube mic kit - build thread
Post by: maq3396 on April 07, 2013, 12:08:40 PM
Thanks Braeden!

Cheers
Mac
Title: Re: MK47 PCB tube mic kit - build thread
Post by: useme2305 on April 08, 2013, 06:22:23 AM
hey everyone,

i just finished my build and everything seems to work fine.

some minor issues though. the output of the omni pattern is significantly lower than that of the cardioid pattern. this is normal i guess?
i'm still messing around with some grounding variants to eliminate the last bit of audible noise. does "burning in" the tubes get rid of the noise floor or is it just a slightly noisier mic? i must add that the noise i'm getting is already almost inaudible with reasonable amounts of gain.

i used this cable:
http://www.thomann.de/de/pro_snake_tpd_5.htm

does anyone think this is a bad idea?
i don't need more than four cores plus shield for B- and it seems to work just fine and it's very cheap. just a little stiff...not to bad  though.
i simply replaced the female end with the binder connecter.
Title: Re: MK47 PCB tube mic kit - build thread
Post by: EvLoutonian on April 08, 2013, 07:06:12 AM
..i don't need more than four cores plus shield for B- and it seems to work just fine and it's very cheap...

I'm still confused about the cable wiring and plug connections etc..
If it really is possible to wire it up correctly with just 4 core and a shield, that sounds encouraging.  Can you indicate what each connection is on your 7 pin plug? 
THANKS!
Title: Re: MK47 PCB tube mic kit - build thread
Post by: useme2305 on April 08, 2013, 07:13:36 AM
hm, what exactly is your question/problem?

you simply need four connections plus shield. audio+, audio-,  48v (Pattern Switch) and 105V (B+). ground (B- in this project) goes to shield. the 7 pin binder connecter has 3 empty pins in this project the way i wired it up.

how you connect them to each connector is up to you....you can shuffle it around how you like....you just have to make sure that each connection ends up at the right destination in the end between mic and psu.
Title: Re: MK47 PCB tube mic kit - build thread
Post by: braeden on April 08, 2013, 07:22:28 AM
I think what you're hearing is just the noise floor of the microphone, all you really want is an acceptable signal to noise ratio with no extraneous/intermittent noises/pops/crackles/hums.

I've had my two MK47s at around the 2 o'clock mark on my Tascam DM-3200 pres (not the greatest pre either) and there is some 'noise' but the signal is loud and clear in comparison (das heisst, the signal to noise ratio is pretty damn good).

Braeden
Title: Re: MK47 PCB tube mic kit - build thread
Post by: EvLoutonian on April 08, 2013, 07:23:46 AM
.. audio+, audio-,  48v (Pattern Switch) and 105V (B+). ground (B- in this project) goes to shield.

Thanks.. I guess what I wasn't too clear on is whether B- has its own core (or just travels on the shield), and whether audio ground also shares the same shield.  I got the impression some people have a separate individual core for some of these functions, but as I say, I wasn't sure one way or the other.
Title: Re: MK47 PCB tube mic kit - build thread
Post by: useme2305 on April 08, 2013, 07:28:23 AM
thanks for clearing that up braeden.

btw, does anyone know how to perfectly drill the two diagonal screw holes for D-series XLR chassis connections?
i ALWAYS seem to f**k them up.
yesterday i spent two 90mins routing and dremeling two perfect xlr holes for in-chassis mounting just to mess up the screw holes which i thought would be the easiest part. what's the trick?
Title: Re: MK47 PCB tube mic kit - build thread
Post by: HellfireStudios on April 08, 2013, 07:33:03 AM
thanks for clearing that up braeden.

btw, does anyone know how to perfectly drill the two diagonal screw holes for D-series XLR chassis connections?
i ALWAYS seem to f**k them up.
yesterday i spent two 90mins routing and dremeling two perfect xlr holes for in-chassis mounting just to mess up the screw holes which i thought would be the easiest part. what's the trick?

Make the holes a bit bigger than needed. Then, use bolts and nuts to secure the XLR. The larger holes will allow for some wiggle room with regards to placement/alignment.

-James-
Title: Re: MK47 PCB tube mic kit - build thread
Post by: useme2305 on April 08, 2013, 07:33:39 AM
.. audio+, audio-,  48v (Pattern Switch) and 105V (B+). ground (B- in this project) goes to shield.

Thanks.. I guess what I wasn't too clear on is whether B- has its own core (or just travels on the shield), and whether audio ground also shares the same shield.  I got the impression some people have a separate individual core for some of these functions, but as I say, I wasn't sure one way or the other.

well, as far as i understood it audio ground and B- are pretty much the same thing here...that is: ground.
from reading the thread i got the idea that some people seem to separate each and use 7 pin cables just to run into ground loop problems when they finish the project and detach either on the mic side of the cable. so i thought why not use a 5 pin cable.
Title: Re: MK47 PCB tube mic kit - build thread
Post by: useme2305 on April 08, 2013, 07:41:53 AM
thanks for clearing that up braeden.

btw, does anyone know how to perfectly drill the two diagonal screw holes for D-series XLR chassis connections?
i ALWAYS seem to f**k them up.
yesterday i spent two 90mins routing and dremeling two perfect xlr holes for in-chassis mounting just to mess up the screw holes which i thought would be the easiest part. what's the trick?

Make the holes a bit bigger than needed. Then, use bolts and nuts to secure the XLR. The larger holes will allow for some wiggle room with regards to placement/alignment.

-James-

yeah, unfortunately bigger holes are out of question here since i went for the mounting option from the inside of the chassis. which i find just looks neater.

see here:

(http://i47.tinypic.com/296c076.jpg)

notice how the screw holes are totally messed up?

i guess this thread is not the place for this type of question. i'm just not handy with the tools i have. i just thought there'd be a trick.
Title: Re: MK47 PCB tube mic kit - build thread
Post by: HellfireStudios on April 08, 2013, 08:03:42 AM
thanks for clearing that up braeden.

btw, does anyone know how to perfectly drill the two diagonal screw holes for D-series XLR chassis connections?
i ALWAYS seem to f**k them up.
yesterday i spent two 90mins routing and dremeling two perfect xlr holes for in-chassis mounting just to mess up the screw holes which i thought would be the easiest part. what's the trick?


Make the holes a bit bigger than needed. Then, use bolts and nuts to secure the XLR. The larger holes will allow for some wiggle room with regards to placement/alignment.

-James-

yeah, unfortunately bigger holes are out of question here since i went for the mounting option from the inside of the chassis. which i find just looks neater.

see here:

(http://i47.tinypic.com/296c076.jpg)

notice how the screw holes are totally messed up?

i guess this thread is not the place for this type of question. i'm just not handy with the tools i have. i just thought there'd be a trick.

Panel mounting XLR's is a real pain. I even tried finding a XLR template on google(no luck, though). Larger-headed bolts or finish washers could save the day, though. You could also paint the bolts/washers to match your panel for a clean look.

-James-
Title: Re: MK47 PCB tube mic kit - build thread
Post by: Sredna on April 08, 2013, 08:51:22 AM
The XLR connectors are the templates!  ;)

First make the big hole with preferably a greenle hole-punch then put the XLR connector in place with the flange on the outside and mark the small holes with a fine pen (CD-marker).
Use a pointy tool to make a dent exactly in the middle of the marking and either use a drill bit with a smaller diameter for a guide hole or start with the final diameter. Always measure twice!  ;)
Title: Re: MK47 PCB tube mic kit - build thread
Post by: useme2305 on April 08, 2013, 09:46:49 AM
yeah, that doesn't work. the xlr's shafts are too big for the holes.

EDIT:

sry, i meant they are too small for the holes...which means there too much room for them to wiggle.
Title: Re: MK47 PCB tube mic kit - build thread
Post by: Sredna on April 08, 2013, 09:52:23 AM
Not really, put more effort in it!  ;)
Title: Re: MK47 PCB tube mic kit - build thread
Post by: North on April 08, 2013, 10:14:00 AM
I just finished my build and tested last night and the mic is dead quiet with virtually no noise floor. I used Gotham GAC7 (could have gone with 6) for my cable and wired it as pins 1and 2 = A+ and A-, pin 3= B-, pin 4 =empty, pin 5 =B+, pin 6 =Pattern, pin 7 ground, tabs on cable connectors=shield. Pins 7 and 3 should be united at both ends to ground. I have always treated the shield as a separate entity and connect its beginning and end to the tabs on the male and female cable connector ends of whatever cable I am making. Then I connect the receptacle tabs to case ground in the power supply and in the mic. Pin 3 caries B- to the mic's pcb but I also use pin 7 as a chassis ground so I connect pin 7 to a mic rail and the mic rail to the B- pad. Therefore I have an electrical ground, chassis/case ground and a shield ground. The shield is always used as a cable wire encasement... "shield" for RF in that any RF that is introduced to the system is carried to ground. So far this has worked for me over decades. If you are experiencing a noticeable noise floor, I would look at the grounding scheme. This mic really is dead quiet :)
Title: Re: MK47 PCB tube mic kit - build thread
Post by: useme2305 on April 08, 2013, 11:22:50 AM
yup, it's dead quiet.....after some stressful building last night i just patched together some case grounding from the connectors with some alligator test cords. but i was already too tired to really judge the recordings i made with the mic last night cause i head some serious tidying ahead of me before i was going to go to bed. the build was a real mess.

i listened to the recordings from last night today and it's just a little ambient noise which i mistook for mic noise. the mic is perfectly quiet.

so now i firmly soldered all the ground wires and assembled the psu casing with all its screws and stuff and it's super quiet.
plus, the mic has a VERY high output. wow....not much gain needed at all for even quiet whispered singing.

btw, the thomann 5-pin dmx cable is good for this build if you need a cable quick and cheap get this, guys.
i might replace it with sommer tube mic cable some day...but i might also not.
Title: Re: MK47 PCB tube mic kit - build thread
Post by: braeden on April 08, 2013, 10:05:29 PM
The best way to drill those XLRs is to download Front Designer (from frontpanelexpress.com) or Schaeffer AG (Europe/Deutschland).

Measure the height & width of your drill surface, get the datasheets for all of your components (e.g. toggle switch, XLRs etc.) and draw them out in FrontDesign.

There are already 'macros' or pre-made XLR objects that can be dragged into your Front Design project. I know for a fact that the Neutrik D series is in there somewhere.

Then you just print it out (with reference points so you know where to centre punch & drill), glue it or tape it to your drill surface and go nuts.

As there isn't really any drill bit for the XLR cutout I use a stepped drill bit which goes to around 32mm I think. The XLR is around 25mm or something.

An M3 drill bit usually does the XLR holes quite nicely. If you want you can tap them by drilling a M2.5 hole first (I think anyway) then tap the thread with the correct plug.
Title: Re: MK47 PCB tube mic kit - build thread
Post by: EvLoutonian on April 10, 2013, 11:47:14 AM
...So far this has worked for me over decades...
Thanks for the nice detailed explanation of your cable wiring procedure, North.  This has been baffling me a bit for a while.
 
useme2305's system, using less strands, grabbed my attention, as I was hoping to find a way to make two cables compatible between two different mic's/PSU's, each using the Binder connector at the mic end, that will not harm either mic if it's plugged into the wrong supply. 

Both mic's will use the Equinox body, and I have the BINDER connectors to suit these now, so it would be fantastic if I could find a risk-free way to make up these cables to suit each of the mic's in question, but also not pose a risk to the other if muddled up.

The first mic is the MK47, of course, whilst the "other" mic will be an EF800 based "EF47" type mic, based on the AMI circuit.  Both have the same 105v B+ voltage (and of course audio +/-) but the EF800 circuit has the additional requirement of a separate 6v heater supply, and the variable capsule polarization is supplied directly from the PSU rather than the fixed 48v relay switching.
 
So, with the Mogami 3172 cable that I have (6 conductors plus shield) I have been grappling with how this precautionary compatibility could be achieved to avoid any nasty accidents happening to one or the other mic down the line one day..

I will be most grateful for some input on this, as the next thing I need to do is wire up these connections before completing my MK47 build!

I made up the table below to try to figure it all out:
(Based on the 7 pin connector scheme used on the Neumann M250)


PIN           MK47         (common)        EF800 / 'EF47'
1                                   Audio -
2                                   Audio +
3                                                        Pattern (variable 0-60v?)
4                                                        Heater 6v+
5                                   105v B+
6              Pattern 48v
7                                   0v, & chassis/ground


A few questions:

*Do I need a separate dedicated conductor in the "EF47" mic cable for low voltage filament (H-) ?

*Could it damage the MK47 relay if I accidentally fed it the 0-60v from the other mic supply (or vice-versa), or could these voltages safely be common on pin 3?  (which would free up one more pin for something else)

*Is it beneficial to have the B- on its own pin as well?  Or is it fine on the shield?

THANKS IN ADVANCE!
Evan



Title: Re: MK47 PCB tube mic kit - build thread
Post by: useme2305 on April 10, 2013, 03:45:13 PM
i think with a 7 core plus shield cord it's definitely doable.

one tip:
if you want to avoid an accidental mix up between the two mics' cables why don't you use a different connector on the psu side to avoid this. say, 5pin vs 7pin xlr.
plus, label your cables properly?
Title: Re: MK47 PCB tube mic kit - build thread
Post by: Treelady on April 10, 2013, 07:21:02 PM
Although you can wire the mic cable any way you want to, there is a "sort" of standard for the U47/tube mics:


Audio (+) = White
Audio (-) = Black
Ground = Thick blue
Heater = Thick Red
B+ = Yellow
0-120v (variable pattern) = Green
snip the remaining conductor (gray), and you are done
And make sure that you terminate shield on both connectors to ground and connector sleeves. [/i][/li][/list]


I want to state I got this from a post by Klaus Heyne, so I don't want to take credit for coming up with it or anything. 
Title: Re: MK47 PCB tube mic kit - build thread
Post by: EvLoutonian on April 10, 2013, 10:53:10 PM
  ..If you want to avoid an accidental mix up between the two mics' cables why don't you use a different connector on the psu side to avoid this?

Hehe.. thanks, UseMe..
 
I did think of this (and it seems to be an obvious solution)..
- but then of course the BINDER connectors at the mic end are still the same, so you could still plug the wrong mic into the wrong cable / PSU combo.

I will however make the plugs different on each power supply anyway, to distinguish one cable from the other..  But I want to make it foolproof, in case someone else is using the mic's one day, for example, or I make the mistake myself somehow..

I could put a label on each mic (and another hanging off the connector end of each cable) saying "WARNING: Check that this is mic UNIT 1, connecting to CABLE 1", etc.. but it will look pretty ugly if it's gonna be big enough to be effective!  Seems a shame to put a whopping big label on my lovely MK47 body if I don't need to.

If I can do it eloquently (and functionally) in the way that I make up the cables, that would be my preference.
Title: Re: MK47 PCB tube mic kit - build thread
Post by: North on April 11, 2013, 01:49:12 AM
Hi Ev, I'm not completely clear on what you want to achieve. If its cable pooling, I use mix and match cables all the time. You just want to be sure that all pins on the male cable end correspond with the same pins on the female end. Colors don't matter in a cable as long as they are not crossed. I never do pin jumping in my cable's connectors. I perform all "jumping" in my psu or my mic leaving only straight through wiring in my cables. I use Gotham cable but as far as the 2 larger gauged wires, I always use one for B+ and the other for B- as they are carrying the voltage and in my opinion is safer to do than using a smaller gauge for B- and a larger for heater. Some may think its a waste but B- is just as vital as B+ and I don't want to impede my electrical ground. I also connect ALL wires in my cables to pins. This way in one setup I can use for example pin 4 as heater but used in another setup, pin 4 is not connected in the psu so its unseen and therefore interchangeable. Now as far as accidentally mismatching psu's that's a good one. If you customize cable connections then they are no longer interchangeable and you are back to square one. The absolute safest thing to do is use different size and type Binder female ends on the power supplies and corresponding mating cable connectors so connecting to the the wrong psu's are impossible. Binder has a ton of options. hope this helps a little
Title: Re: MK47 PCB tube mic kit - build thread
Post by: EvLoutonian on April 11, 2013, 02:58:09 AM
Hi Ev, I'm not completely clear on what you want to achieve...

Thanks again for your on-the-point response, NORTH.
Much appreciated!

I wasn't referring to changing pin correlation at each end of the cable.

Perhaps a better way for me to explain my objective, in response to your points, is:

Can I set up the pin connections on my two different power supplies (one for MK47, the other for EF800 mic) so that neither mic will suffer if accidentally plugged in to the wrong supply?

You could therefore think of the table in my earlier post as simply referring to the PIN OUT on the PSU if you like. 

Each cable would be pretty much identical I guess - pin to pin straight through connections.

I would absolutely just use different connectors on the two mic's, if it were that easy, but the Equinox bodies I'm using (for both projects) are already so eloquently set up for (& supplied with) the BINDER 7 pin male connector.  And now I also finally tracked down the Binder female connectors to match.  So it seems a bit of a shame to hack one of the bodies and use a different type of connector, even if I could think of a way to do that.

I'm hoping there are enough pins available to share not only the common requirements, but also the separate requirements of each mic, between the 7 pins available, so that, as you say, if one or two pins are only to be used on one mic or the other, they can just remain disconnected at the input connection on the other mic.

Hmm, does that make more sense?  It's kind of harder to explain than I'd hoped. haha.

The way I see it is that I could simply interchange PSU's for these two mic's, except that the pattern voltage is different (MK47 48v vs EF-AMI 0-60v, I think), and the EF800 tube requires 6v heater pin(s), which would need to be unused in the MK47 mic itself.

Do I have enough pins that I can keep these discrepancies separated?
Title: Re: MK47 PCB tube mic kit - build thread
Post by: North on April 11, 2013, 10:11:11 AM
Not that I can tell. I may be overlooking something here but It looks like you will have at least one charged pin directed to the wrong mic if accidentally plugged in. Even if you use shield as a separate path you would still introduce noise at some point and would have to constantly be moving your cable around like an antenna to get away from it. One way to accomplish no accidents would be to use a male 7 pin receptacle on one of the power supplies. One of your cables would be the normal female and male ends while the other would have female and female connectors. That way its physically impossible to mismatch psu's?
Title: Re: MK47 PCB tube mic kit - build thread
Post by: EvLoutonian on April 11, 2013, 10:27:33 AM
That's the point I made earlier, which is that you could still plug the wrong mic into the (female) Binder connector of the "wrong" cable (no matter which PSU the other end is plugged correctly into).. if you know what I mean?

Is the 'antenna' effect you mentioned caused from B- being on the shield only?

Would it be an improvement to have the pattern voltages both on the same PIN, freeing up another PIN for the B-?

PIN           MK47         (common)        EF800 / 'EF47'
1                                   Audio -
2                                   Audio +
3              0 / 48v          Pattern          0 / 60v (?)
4                  -                                     Heater+ (6v)
5                                  B+ 105v
6                                  B-      0v
7                    Chassis/ground & 0v Heater-

In cardioid setting, would both mic's see 0v at the pattern select pin?
(might be the safest way to leave the PSU's when stored)

With my 6 core cable I realise also I literally don't even have another conductor available for an independent Heater- voltage (for the EF800 mic).  Is that a problem?  Or is it okay to have the H- shared on the B- pin &/or shield pin?

..hmmmm..  am I the only one with this issue?  Or have others tried to crack this nut too?
Title: Re: MK47 PCB tube mic kit - build thread
Post by: HellfireStudios on April 11, 2013, 12:52:45 PM
It is not a great idea to put a male jack on the power supply. High voltage is going to those pins. If someone were to turn it on without a mic attached, and touch one of the xposed pins, the results would be less than ideal (unless funeral planning is what you do for a living).

Another type of jack would be preferable in this application. I would use an XLR for one the power supply end of one cable. You could then use 6 pin for one cable, 7 pin for another, Binder for another, and so on...

-James-
Title: Re: MK47 PCB tube mic kit - build thread
Post by: 0dbfs on April 11, 2013, 01:28:14 PM
I would add that one should label each end of your cables, your mic's, and your psu's (serial #'s?).... That way when you have more than one similar mic-system, System-components can then be swapped to help troubleshoot "intermittent or sporadic" issues.

Cheers!
-jb
Title: Re: MK47 PCB tube mic kit - build thread
Post by: useme2305 on April 11, 2013, 04:19:52 PM
thought i'd post a pic of my finished duo. i'm so impressed that i ordered another mk47 kit.
it has chuck's M7 type capsule that sounds fantastic so far. the xlr connectors are amphenol which i think look slightly more vintage than the D-series neutriks. the pilot light is a fender tube amp one.

(http://i50.tinypic.com/2jb2tcx.jpg)
Title: Re: MK47 PCB tube mic kit - build thread
Post by: micaddict on April 11, 2013, 05:04:56 PM
Looking good.

Congrats!



Henk
Title: Re: MK47 PCB tube mic kit - build thread
Post by: North on April 11, 2013, 09:02:55 PM
the results would be less than ideal (unless funeral planning is what you do for a living). Well said.... LOL  ;D
Title: Re: MK47 PCB tube mic kit - build thread
Post by: North on April 12, 2013, 11:02:45 AM
Ev, what if you use different sized connectors at the PSU end like we discussed and on the MK47's mic cable there will be an empty pin unused. Remove that pin in the MK47' body male connector and squish up a piece of that hard steal stick epoxy and fill in the corresponding pin hole in the mic cable. It would mate perfectly with the MK47 but not at all with the other and then do the same with the other mic with a different pin.
Title: Re: MK47 PCB tube mic kit - build thread
Post by: North on April 12, 2013, 11:04:02 AM
Nice job useme - Looks great!!
Title: Re: MK47 PCB tube mic kit - build thread
Post by: Pip on April 17, 2013, 02:11:05 AM
OK! Almost there!!!

Microphone built. On to the PSU and away!

Equinox systems body Cathedral Pipes capsule.

Title: Re: MK47 PCB tube mic kit - build thread
Post by: useme2305 on April 17, 2013, 09:27:21 AM
hey Pip, nice work so far but for the sake of vintage conformity i suggest you find a way to use the acrylic plastic riser for the capsule mount.  ;)
i know, the cathedral pipes capsule mount is not compatible with the equinox body. what i did was i epoxied an M3 nut into the bottom piece of the cathedral pipes capsule mount after widening the existing thread with a drill. then you can use an M3 type screw which is a perfect fit for the equinox body.
one could also just widen the hole of the acrylic riser thingy but i wanted to keep the body in its original state for capsule options later on.

also, does anyone know if there's a swivel mount available for the binder connector? that would be so awesome. it's a pretty long shot i suppose?
Title: Re: MK47 PCB tube mic kit - build thread
Post by: dandeurloo on April 19, 2013, 09:33:12 PM
 ;D

(https://sphotos-a.xx.fbcdn.net/hphotos-ash3/529623_10200950713475686_1721371651_n.jpg)
Title: Re: MK47 PCB tube mic kit - build thread
Post by: EvLoutonian on April 20, 2013, 10:38:35 AM
Great photo, Dan.
which shock mounts do you have there?
I'm still hanging out (pun intended) for some affordable (yet genuine look & function) mounts for around the $30 ea price point..
Are there any out there?
Title: Re: MK47 PCB tube mic kit - build thread
Post by: dandeurloo on April 20, 2013, 11:16:49 AM
Two of the bodies are from Skylar and the shock mounts for them are from ChuckD and have Thiersch Red Line and a Blue Line capsules in them.  The other mic is a BeesNees body and shock mount and M7.  Honestly they all sound wonderful and I have no preference between them.  I was happily surprised.  I thought I would like one more than the others and then feel like I need to make them all like the one I prefer.  The only thing I can say is that the BN seems flatter across the spectrum while the Thiersch capsules seem to have a little more something but that isn't always a good thing.  I use any of them on anything and with confidence.  I just tried them on drum overheads and it was very nice.

Title: Re: MK47 PCB tube mic kit - build thread
Post by: late on April 21, 2013, 09:50:46 AM
Just finished my build. Max what i can get out of my psu with mic is +103v. Is that ok or do i need do something?
Title: Re: MK47 PCB tube mic kit - build thread
Post by: baol on April 21, 2013, 04:19:02 PM
Ok, I finally found out where the issue was, with a friend of mine and a strong dentist's magnifying glass I found one of the 100R lead wasn't well soldered. Everything it's all right now, I burned the tubes (I also have 2 rca tubes to test) and it sounds great (to me, sure). Now I gave it to a friend working in a studio waiting for a review from him that usually uses a lot of different mics. As soon as possible I will post the pictures, and maybe a take. Thank you everybody for the help and thank you max for the project.

Andrea
Title: Re: MK47 PCB tube mic kit - build thread
Post by: North on April 25, 2013, 09:38:25 AM
Would love to hear audio samples of MK47 against a real U47. Anyone have a link to any?
Title: Re: MK47 PCB tube mic kit - build thread
Post by: Pip on April 26, 2013, 09:52:38 PM
So she is done!

Rather than taking up more Space check it out here:

http://www.groupdiy.com/microphones/newbie-builds-ioaudio-mk47-microphone/msg665155/#msg665155
Title: Re: MK47 PCB tube mic kit - build thread
Post by: burglar on April 27, 2013, 05:07:03 AM

For the 14k resistor in the PSU, all I can source here in the UK is a 0.4 watt.  Will this be ok or no?
Title: Re: MK47 PCB tube mic kit - build thread
Post by: useme2305 on April 27, 2013, 05:10:19 AM
burglar, try to get the correct value by putting two resistors in series. say 12k plus 2k or whatever combination you can source.
Title: Re: MK47 PCB tube mic kit - build thread
Post by: burglar on April 27, 2013, 06:47:20 AM
Yes, I think I'll have to do that.  Might be a bit short of room.  Thanks for your response.
Title: Re: MK47 PCB tube mic kit - build thread
Post by: burglar on April 30, 2013, 03:19:12 AM

Hi Folks,

I powered up my PSU for the first time last night.  Initially it seemed that it was getting no power at all, so I changed the fuse in the IEC and powered up again.  This time it powered up and the fuse blew after a matter of seconds. 

The only thing I can think of that could be causing it is that I have possibly muddled up the primary and the secondary on the power transformer.  There is a blue/brown combo and a red/black combo.  Currently I have the blue/brown wired to the IEC/switch and the red/black going into e rectifier.

If anyone could shed any light on this I'd be very grateful.

Regards

B
Title: Re: MK47 PCB tube mic kit - build thread
Post by: zayance on April 30, 2013, 04:21:07 AM
Refer to the colors on the Toroidal!

(http://imageshack.us/a/img855/2450/powertransformerwiring.jpg)
Title: Re: MK47 PCB tube mic kit - build thread
Post by: burglar on April 30, 2013, 05:53:58 AM

Sorted, simple hook up error.  I did check for colours on the toroidal but there was no code.  Although I was 99% sure of the color scheme after googling I thought I'd post just in case.   As I turned out, I had accidentally wired the secondary- directly into the bottom 0v rail instead of the rectifier- .Cults.



Title: Re: MK47 PCB tube mic kit - build thread
Post by: burglar on April 30, 2013, 09:11:19 AM

Would just likr to run this by you all.  The combination of the 10H choke, two 1k resistors and a 680r only broght me to 106-107V so I put a 5R6 after the 680 which brought me within range with the 500R pot.  Is this normal or does it suggest a problem else where? 

I'm using a toroidal with 240V primary / 200V secondary. 

Also, when my + rail is reading 105v and I switch to omni.  I measure the voltage just before the 12k resistor and it's only 45v? 
Is this normal.  Where should I be getting my 48v reading from? 
Title: Re: MK47 PCB tube mic kit - build thread
Post by: North on April 30, 2013, 09:44:44 AM

Would just like to run this by you all.  The combination of the 10H choke, two 1k resistors and a 680r only brought me to 106-107V so I put a 5R6 after the 680 which brought me within range with the 500R pot.  Is this normal or does it suggest a problem else where?  "

Yes that is normal as I found out. I have around 123-127 volts coming out of my wall and I had to add a lot of resistance to mine beyond the standard build specs to bring it down to a 105 range. I also had a 3 volt fluctuation so I plugged the psu into my ups and only turned on exactly what I was going to be using for tracking with the mic (computer and rack preamp) and wait for the everything to reach its nominal range and then adjusted to 105. Seems to be doing ok there - until the A/C comes on  ???
Title: Re: MK47 PCB tube mic kit - build thread
Post by: burglar on April 30, 2013, 10:02:37 AM
Ok, great.  Can anyone lend some information on the 48v.  I'm not sure where I should be measuring from?  As I said, with -probe on 0v rail and +probe just before the 12k resistor I have 46.8 or there abouts when switched to omni.  Is this enough or do I need to change the 12k / 14k resistor to something else?
Title: Re: MK47 PCB tube mic kit - build thread
Post by: ioaudio on April 30, 2013, 11:06:21 AM
That's perfectly fine.
Title: Re: MK47 PCB tube mic kit - build thread
Post by: burglar on April 30, 2013, 11:20:04 AM
Spot on, thanks.  Something else that I wanted to check was, I have wired the input / output XLR's as per the diagram below but for A- ,  A+ and shield going from the 7 pin to the 3pin I have used separate cores cable tied together instead of mic cable.  Is this a problem?  Am I likely to having grounding problems this way. 

Also, the neutrik XLR's I have used have a tag on them.  Do I need to send these to ground as well?

(http://i1236.photobucket.com/albums/ff442/jandoste/MK47_PSU_wiring_1_a.jpg)
Title: Re: MK47 PCB tube mic kit - build thread
Post by: Songguy on April 30, 2013, 09:53:36 PM
Thanks for everyone's help! The mic is AWESOME!!
I let the tubes burn in for 2 days. When I attached the capsule and powered her up I couldn't believe how quiet the circuit was!
Title: Re: MK47 PCB tube mic kit - build thread
Post by: ioaudio on May 01, 2013, 06:27:23 AM
 :)
Title: Re: MK47 PCB tube mic kit - build thread
Post by: micaddict on May 01, 2013, 07:15:07 AM
Congrats!

What PSU do you use?
Title: Re: MK47 PCB tube mic kit - build thread
Post by: EEMO1 on May 03, 2013, 01:53:10 AM


 mine was quiet right off the bat without even burning in the tubes! congrats on your mic!


Thanks for everyone's help! The mic is AWESOME!!
I let the tubes burn in for 2 days. When I attached the capsule and powered her up I couldn't believe how quiet the circuit was!
Title: Re: MK47 PCB tube mic kit - build thread
Post by: North on May 04, 2013, 05:25:02 PM
 I also want to say thanks to:
Max for an awesome project and for making an affordable U47 possible.
Zayance for a low cost - high quality psu pcb.
Equinox for producing a body that is a treasure to behold.
Dan- Classic Cases for outstanding customer service and going above and beyond.
And to all on the board for all your help and input.

Now If I could just figure out how to post pics under 1024kb ???
Title: Re: MK47 PCB tube mic kit - build thread
Post by: Alexwfm on May 06, 2013, 06:20:39 PM
Hello everyone!

I'm Alex and month ago I got the Mk47 kit from Ioaudio,  today i did a first run.
I just moved to London so I have no tools aside soldering iron and drill, and I'm also poor so i tried to save a bit on not critical parts!
For example replacing the PSU circuit using the original little case that came with the mic PSU. But that was more pain in the """ than money saving.
At the first run i noticed couple of pops that disappeared 1 minute later. I used some used matched pair of 6028 that I slammed on the wooden floor while trying to unplug them.
 I can't notice any difference in noise floor with the microphone either unplugged or plugged with lots of gain :) . that's cool!

The original PSU came with a metal divider that was splitting the case in two. I used it as cooling sink for the 10W resistors and to separate the first ripply part of the circuit (diodes and first cap) from the second (all the rest after choke). Each part had own ground wire that was going to one spot.
The output voltage went to 350v when load-free, but 110v on load. I couldn't get down to 105v if I was on omni mode.

The mic is built in a Tbone SCT700 body. Instead of screwing the 5W resistor to the case I have applied some termal paste under it, and then while pressing it down I "epoxied" the two sides to keep it there. forever.
It sounds nice even with the stock chinese capsule, but I'm waiting for a RK-47 from microphone-parts.com

PSU inside (was actually small.)
(http://s7.postimg.org/ydc3ru5qv/IMG_0212.jpg) (http://postimg.org/image/ydc3ru5qv/)

If you were looking for the transformer and the choke:
[img=http://s7.postimg.org/t0n9dphuf/IMG_0214.jpg] (http://postimg.org/image/t0n9dphuf/)

Heater dropper fix:
[img=http://s15.postimg.org/4bp5vftd3/IMG_0180.jpg] (http://postimg.org/image/4bp5vftd3/)

Thanks Ioaudio and Chunger for parts and super detailed build tutorials. I once was dreaming of being 21 and rock star, but now I'm happy enough just building tube condenser mics :) .

YO.

Title: Re: MK47 PCB tube mic kit - build thread
Post by: micaddict on May 07, 2013, 04:14:04 AM
Welcome!

Good DIY story.

Poor? Well, at least you seem to have a passion (which is wealth by itself) and now basically a high-end (whatever that means) tube microphone to boot.  :)
Yes, do upgrade the capsule.
Did you have to skip meals?

Anyway, you done good.
And thanks for sharing.
Title: Re: MK47 PCB tube mic kit - build thread
Post by: Alexwfm on May 07, 2013, 01:22:30 PM
Did you have to skip meals?

I just did not have drinks that weren't the half priced ones in the bar where I work and I share my room with a crazy Dutch girl.
Both money and liver saving.

Not long ago I built an RM-5 ribbon mic and a INA217 preamp, they both are ok but much less budgety than the MK47.
I'm in the middle of making my bedroom studio and apparently filling it with equipment you made by own is a lot satisfying and, well.. bit cheaper!
Isn't it? :)




Title: Re: MK47 PCB tube mic kit - build thread
Post by: micaddict on May 07, 2013, 03:33:56 PM
Quote
I share my room with a crazy Dutch girl.

Hey, mine's Dutch, too.  :P

But this is is the MK47 build thread, so I'll leave it at that.
Title: Re: MK47 PCB tube mic kit - build thread
Post by: Alexwfm on May 09, 2013, 06:32:04 PM
 Still I have a question.

I noticed the voltage output from the PSU rising about 10v when I was switching in Omni mode (without mic plugged).
Is it because there's no load? I'm so scared that with mic plugged in it will make Vout to rise from 105v and probably damage the mic.

By the way, is there a "safe offset" of Vout that the mic would accept without breaking?

Thanks! :)
Alex
Title: Re: MK47 PCB tube mic kit - build thread
Post by: ioaudio on May 10, 2013, 06:01:20 AM
Hi Alex,

yes that's normal - voltage comes down when loaded by the relais when connected.

-max
Title: Re: MK47 PCB tube mic kit - build thread
Post by: ioaudio on May 12, 2013, 10:22:14 AM
New batch available in my white market thread.
Title: Re: MK47 PCB tube mic kit - build thread
Post by: maq3396 on May 16, 2013, 12:00:44 PM
Newb question:

Can someone please comment on the gauge of the wire(s) used in both the microphone and the psu?

Thanks
Mac
Title: Re: MK47 PCB tube mic kit - build thread
Post by: HellfireStudios on May 16, 2013, 01:16:53 PM
Newb question:

Can someone please comment on the gauge of the wire(s) used in both the microphone and the psu?

Thanks
Mac

I've been using 22-24 AWG for my mic builds. You might want something a bit thicker for high voltage and high current hookups (polarization voltage leads and ground respectively).

-James-
Title: Re: MK47 PCB tube mic kit - build thread
Post by: maq3396 on May 16, 2013, 03:28:08 PM
Thanks James

Time to warm up the soldering pen....

Cheers
Mac
Title: Re: MK47 PCB tube mic kit - build thread
Post by: late on May 18, 2013, 05:37:58 AM
Hi

Is it normal that with 2.3k test load i can get about 105v but with mic 103v. My mic resistance is 1.8k.
Title: Re: MK47 PCB tube mic kit - build thread
Post by: useme2305 on May 18, 2013, 06:42:41 AM
the test load gets you in the ballpark voltage so you do not damage the mic. readjust the voltage with the mic after the test load adjustment.
Title: Re: MK47 PCB tube mic kit - build thread
Post by: late on May 18, 2013, 07:20:45 AM
the test load gets you in the ballpark voltage so you do not damage the mic. readjust the voltage with the mic after the test load adjustment.

103v is the max what i can get with mic. Wondering why it is 103v with mic. Because it gives about 105v with 2.3k test load and mic resistance is 1.8k. So i need lower 680ohm little bit of psu. But how much if i want get 5v more?
Title: Re: MK47 PCB tube mic kit - build thread
Post by: useme2305 on May 18, 2013, 08:04:29 AM
don't you have the 5W pot in series with the resistors? if so, just get a 330ohms to replace the 680ohms resistor and lower the resistance of the pot by turning it. this will get you in the right ballpark with enough play for the pot.
Title: Re: MK47 PCB tube mic kit - build thread
Post by: late on May 18, 2013, 08:20:50 AM
don't you have the 5W pot in series with the resistors? if so, just get a 330ohms to replace the 680ohms resistor and lower the resistance of the pot by turning it. this will get you in the right ballpark with enough play for the pot.

Yes i have 500ohm pot. Ok, so 330ohms.
Title: Re: MK47 PCB tube mic kit - build thread
Post by: Woot on May 30, 2013, 06:04:26 AM
Hey Guys,

Just after a bit of n00b advice from anyone who has used a Beesneez body to build one of these... could you please let me know how you have installed the 7 pin xlr in the mic? Are you just using the insert and a grub screw (although that side screw hole doesn't look threaded).

I have had a bit of a play around with the insert of standard 7 pin xlr, but it's escaping me how this could be installed in a sturdy/reliable way.

Any advice welcome! Thanks!

Matt
Title: Re: MK47 PCB tube mic kit - build thread
Post by: tonycamp on May 31, 2013, 12:44:22 AM
Hi Fella's,

I've got my mk47 running with a couple 408a western electrics in it, and a blueline Thiersch M7. I had crackling for a bit, so i sat it in front of speakers and broke it in for around 4 days, the mic is now dead quiet, and sounds every bit as amazing as i ever hoped it would. I can't believe how beautiful it sounds! I'm really blown away ;D

thank you Max!, i will be ordering a second soon.

T
Title: Re: MK47 PCB tube mic kit - build thread
Post by: EvLoutonian on May 31, 2013, 05:26:26 AM
I'm hoping this is the right place to get an answer on this.. with regards to the Zayance PSU PCB set-up.

Will I run into trouble if I run three LED's off of the LED point?

I'm using a PSU enclosure which already had three lights mounted on the front panel, so, unless there's any reason not to, I was just going to hook them all up..

I even thought about having the top LED (next to pattern selector knob) just switch on in either cardioid or omni, as there are extra poles available on the switch.   

Also, I realised that I think the polarity switch I have installed here is a 'make-before-break' type.  Is that OK, or problematic?

THANKS!!
(can't hardly wait to switch this thing on)   ~gulp~
Title: Re: MK47 PCB tube mic kit - build thread
Post by: EvLoutonian on May 31, 2013, 05:27:32 AM
LED board (inside)
Title: Re: MK47 PCB tube mic kit - build thread
Post by: tonycamp on June 01, 2013, 01:12:27 AM
It may not matter, but i try to keep led's and their wiring away from my input, output and polar pattern knobs, I'd also use shielded wire just in case.

on my psi, i have the led away from the audio signal stuff, and behind a shield plate and showing through the top, it's as quiet as a mouse pissing on a cottonball :)(i'll post an inside pic also)


good luck
Title: Re: MK47 PCB tube mic kit - build thread
Post by: tonycamp on June 01, 2013, 01:14:19 AM
inside
Title: Re: MK47 PCB tube mic kit - build thread
Post by: EvLoutonian on June 01, 2013, 11:22:34 AM
Oh, that's interesting..
Maybe I should simply disconnect the LED's altogether..
I did notice, so far, my mic does have a slight background hiss, where-as others here describe their build as positively silent!
(which is obviously what we'd all love to achieve)
Could the LED wiring really cause such noise/interference?
Title: Re: MK47 PCB tube mic kit - build thread
Post by: Pip on June 04, 2013, 12:13:00 AM
Oh, that's interesting..
Maybe I should simply disconnect the LED's altogether..
I did notice, so far, my mic does have a slight background hiss, where-as others here describe their build as positively silent!
(which is obviously what we'd all love to achieve)
Could the LED wiring really cause such noise/interference?

The thing you have to watch for is the current draw of the LED's. You have to remember anything you add t o PSU draws current. I still haven't put any indicator light on my PSU as I didn't have one that drew very little current in stock.
Title: Re: MK47 PCB tube mic kit - build thread
Post by: EvLoutonian on June 04, 2013, 12:20:32 AM
My PSU has a 6.3v normal globe lamp, so I could just disconnect the LEDs I think..
Title: Re: MK47 PCB tube mic kit - build thread
Post by: Joelv on June 17, 2013, 09:35:04 PM
Finally finished! Sounds great! Hi-res pic can be viewed on my Flickr page: http://www.flickr.com/photos/louisstudios/
Title: Re: MK47 PCB tube mic kit - build thread
Post by: Marc Duchesne on June 29, 2013, 03:54:54 PM
For people looking for tubes, I just tried these...

http://www.nostubestore.com/2012/08/philips-miniwatt-ts62-6028-408a.html

Awesome tubes...
-marc
Title: Re: MK47 PCB tube mic kit - build thread
Post by: micaddict on June 29, 2013, 05:05:13 PM
Yup, I've got some, too, but haven't tested them, yet. (MK47 still in the works.)

What I can tell you all is that Koray is a great guy to buy tubes from.



Henk
Title: Re: MK47 PCB tube mic kit - build thread
Post by: ioaudio on June 30, 2013, 10:56:53 AM
Thanks marc, have to try those.
Title: Re: MK47 PCB tube mic kit - build thread
Post by: micaddict on June 30, 2013, 12:02:19 PM
When I got them, Koray had some slightly older, D-getters left, too.
Probably not much difference, but I got them anyway.  :P
Title: Re: MK47 PCB tube mic kit - build thread
Post by: cariocaman85 on July 01, 2013, 06:36:36 AM
Hi!

Do you know if this kit might fit in a t-bone sct2000 body? I know it's ok with a sct700 but I'm not sure they have exactly the same size...

What do you think?

Best,

Rémi
Title: Re: MK47 PCB tube mic kit - build thread
Post by: ioaudio on July 01, 2013, 11:33:14 AM
I think it's ok - i probably have seen a build with it? Not quite sure atm, better check the dimensions.
Title: Re: MK47 PCB tube mic kit - build thread
Post by: Winetree on July 01, 2013, 01:04:27 PM
Tried the 1950's  Miniwatt gold pin "D " getters.
Didn't like them.
Title: Re: MK47 PCB tube mic kit - build thread
Post by: MicDaddy on July 01, 2013, 02:19:56 PM
Hi guys, for anyone who has used the Binder 691 series connectors for this or other builds I have a question.

On Binder site, these connectors are noted as  "non-shielded"  http://www.binder-usa.com/psearch#q=product_series%3D691 (http://www.binder-usa.com/psearch#q=product_series%3D691)  What does this mean?  I see no lug to the shell to tie a shield, what am I not understanding here.  With an XLR 3,5 or 7 I'd tie the pin1 or shield to the shell of the connector. 

I'm asking how to tie shields to the connectors?  I plan to use Gotham GAC-7 and Binders on both ends with a Binder female at the PSU. 

*edit  I'm currently digging through the thread and have seen a few others pose this same question.  I'm thinking of adding a solder lug eyelet to the screw for mounting the binder into the PSU chassis and then tie the shield here. 
Title: Re: MK47 PCB tube mic kit - build thread
Post by: micaddict on July 01, 2013, 02:24:37 PM
Tried the 1950's  Miniwatt gold pin "D " getters.
Didn't like them.

Were those TS62s, too, or another type?

And what did you not like about them?
Title: Re: MK47 PCB tube mic kit - build thread
Post by: tfp on July 04, 2013, 07:16:41 PM
Hi guys and Andreas,

I finished this beautifull project one month ago and the mic worked great with the standaard Philips Jan 6028 tubes, Thiersch red line and Ami body . The mike sounded great but with a voice-over recording it needed some serious low cut. I decided to change the tubes with two 1957 WE 408a tubes. I also changed the height (higher) of the capsule with 6mm so it is as high as the original U47.

Now the strange part, I tested the mic today and it sounded almost the same(did analyse signals), but below the 90Hz there is about -10dB less bass so the sound is more mid focused.

My question: Is this possible with changing tubes and/or changing the capsule height? Or do I damaged something in the proces? For example last night the wire of the backplate was broken and I kept microphone on for quite a time!

Thanks for answering!

RJ
Title: Re: MK47 PCB tube mic kit - build thread
Post by: North on July 05, 2013, 02:20:40 AM
Some pics of my build

(http://i1292.photobucket.com/albums/b568/North1962/PSUFront_zpsa0bd34d9.jpg) (http://s1292.photobucket.com/user/North1962/media/PSUFront_zpsa0bd34d9.jpg.html)

(http://i1292.photobucket.com/albums/b568/North1962/DSC_7900_zpsdc0525ff.jpg) (http://s1292.photobucket.com/user/North1962/media/DSC_7900_zpsdc0525ff.jpg.html)

(http://i1292.photobucket.com/albums/b568/North1962/DSC_7859_zpsc2bc90f3.jpg) (http://s1292.photobucket.com/user/North1962/media/DSC_7859_zpsc2bc90f3.jpg.html)
Title: Re: MK47 PCB tube mic kit - build thread
Post by: Winetree on July 05, 2013, 02:40:23 AM
Quote
Were those TS62s, too, or another type?

And what did you not like about them?
Yes, only compared them to new JAN 6028s.
They sounded more lo-fi, smaller, different tone, unlike what a U-47 should sound like.
Just my opinion.

Title: Re: MK47 PCB tube mic kit - build thread
Post by: tfp on July 05, 2013, 08:09:46 PM
Hi Max (sorry for Andreas I mixed something completely up),

I finished your beautiful project one month ago and the mic worked great with the standaard Philips Jan 6028 tubes, Thiersch red line and Ami body . The mike sounded great but with a voice-over recording it needed some serious low cut. I decided to change the tubes with two 1957 WE 408a tubes. I also changed the height (higher) of the capsule with 6mm so it is as high as the original U47.

Now the strange part, I tested the mic today and it sounded almost the same(did analyse signals), but below the 90Hz there is about -10dB less bass so the sound is more mid focused.

My question: Is this possible with changing tubes and/or changing the capsule height? Or do I damaged something in the proces? For example last night the wire of the backplate was broken and I kept microphone on for quite a time!

Thanks for answering!

RJ
Title: Re: MK47 PCB tube mic kit - build thread
Post by: micaddict on July 06, 2013, 05:59:35 AM
Quote
Were those TS62s, too, or another type?

And what did you not like about them?
Yes, only compared them to new JAN 6028s.
They sounded more lo-fi, smaller, different tone, unlike what a U-47 should sound like.
Just my opinion.

Thanks.
And your opinion is much appreciated.
Title: Re: MK47 PCB tube mic kit - build thread
Post by: ioaudio on July 06, 2013, 07:00:30 AM
Hi Max (sorry for Andreas I mixed something completely up),

I finished your beautiful project one month ago and the mic worked great with the standaard Philips Jan 6028 tubes, Thiersch red line and Ami body . The mike sounded great but with a voice-over recording it needed some serious low cut. I decided to change the tubes with two 1957 WE 408a tubes. I also changed the height (higher) of the capsule with 6mm so it is as high as the original U47.

Now the strange part, I tested the mic today and it sounded almost the same(did analyse signals), but below the 90Hz there is about -10dB less bass so the sound is more mid focused.

My question: Is this possible with changing tubes and/or changing the capsule height? Or do I damaged something in the proces? For example last night the wire of the backplate was broken and I kept microphone on for quite a time!

Thanks for answering!

RJ

Hi Rj,

well, first try putting back the old tubes and see if it gets back to normal.
The broken backplate wire should'nt be a problem.

hope that helps
-max
Title: Re: MK47 PCB tube mic kit - build thread
Post by: tfp on July 06, 2013, 07:14:35 PM
Hi Max,

Thanks I was already affraid for that...  The tubes in the mike are difficult to reach because I hung your PCB is in rubberbands. But anyway I am ging to do it because I wanna make sure there is nothing wrong!

All the best!
Title: Re: MK47 PCB tube mic kit - build thread
Post by: JW on July 15, 2013, 03:32:27 PM
Hey folks,

I'm gonna try to mod my MK47 to a MK48 like the schematic adjustments on this page of this thread: http://www.groupdiy.com/index.php?topic=41379.940

Anyway, how high does the voltage rating need to be for those caps? 1000pF, .01uF?

I'm also curious about the voltage requirement for C1 in the original MK47 schematic (which is also a .01uF cap) I'm thinking about putting a little russian PIO in there if the rating is high enough 200V
Title: Re: MK47 PCB tube mic kit - build thread
Post by: adrian on July 22, 2013, 05:58:04 PM
hello!
here are some comparison sample of my first MK47 with a thiersch red line capsule and philips ECG 6028 tubes, (+ Zyance PSU PCB and sommer cable "octave tube" wiring)
all mics are directly plugged into a Fireface800,

the mic doesn't sound bad but I wonder about low end, I was thinking there was more low on a U47 (to sound a bit "darker"..)

on drums (mics were close to each other at approximately 2 meter in front of the drums) (cardioid) :
Original U87 :  https://dl.dropboxusercontent.com/u/20193579/drums%20U87.aif
Original M149 : https://dl.dropboxusercontent.com/u/20193579/drums%20M149.aif
Original CMV563 (with original M7 capsule) : https://dl.dropboxusercontent.com/u/20193579/drums%20CMV563.aif
MK47 : https://dl.dropboxusercontent.com/u/20193579/drums%20MK47.aif

On speach vocal (I had to add some gain digitally because I was far from these mics (approximately 1 or 1,5 meter) (cardioid) :
schoeps M221 : https://dl.dropboxusercontent.com/u/20193579/speach%20M221.aif
Original M149 : https://dl.dropboxusercontent.com/u/20193579/speach%20M149.aif
Original CMV563 (with original M7 capsule) : https://dl.dropboxusercontent.com/u/20193579/speach%20CMV563.aif
MK47 : https://dl.dropboxusercontent.com/u/20193579/speach%20MK47.aif

(here is a ZIP file with audio files if you want download : https://dl.dropboxusercontent.com/u/20193579/MK47%20comparisons.zip )

an other strange thing is polarity,
my MK47 is out of phase but I don't think it's a faulty wiring because when I check with a multimeter  the Audio+ of the mic PCB goes to the PSU XLR out pin 2 ,

so what about the sound? is that the same color as your mics?
Title: Re: MK47 PCB tube mic kit - build thread
Post by: wave on July 23, 2013, 10:31:47 PM
Adrian,
I haven't used our MK47 as a kit mic yet but the vocal test sounds a lot like mine and I'm using a different capsule.
Our DIY FET47 has more low end then our MK47 for sure.

Did you record all the drum tracks at once, i.e. one performance with all the mics live?
If so, how did you position them? Is that you playing the kit?

Dave
Title: Re: MK47 PCB tube mic kit - build thread
Post by: adrian on July 24, 2013, 05:39:36 AM
hello,
yes I put all these mics in front of my drum kit (approximatly 2 meters) and recorded all of them simultaneously,
the mics where 1,5 meter high from the ground,

I have to check my PSU voltage because I adjusted the 105 Volt at home (where I have 242 volts on the electrical network),
but I wonder if the voltage at the studio is more about 230v wich will change the output voltage of the PSU....

(is that possible that the voltage feed to the mic change the low end response?)

and did someone checked the phase of his MK47 between others?

(sorry for my poor english ;)!)
Title: Re: MK47 PCB tube mic kit - build thread
Post by: Melodeath00 on July 24, 2013, 11:09:50 AM
an other strange thing is polarity,
my MK47 is out of phase but I don't think it's a faulty wiring because when I check with a multimeter  the Audio+ of the mic PCB goes to the PSU XLR out pin 2 ,

so what about the sound? is that the same color as your mics?

I recently built a U47 (not the MK47), and my polarity was inverted as well. I just switched the audio wires inside of the PSU to fix it. Any reason you don't want to do that?
Thanks for the files by the way. I will listen soon.

Adrian,
I haven't used our MK47 as a kit mic yet but the vocal test sounds a lot like mine and I'm using a different capsule.
Our DIY FET47 has more low end then our MK47 for sure.

Is that expected? I would think a U47 might have more low end than a FET47.
Title: Re: MK47 PCB tube mic kit - build thread
Post by: tfp on July 27, 2013, 05:20:19 PM
Hi Guys,

I changed the tubes in my mk47 back to the philips jan 6028 (from WE408a 1957) and conducted a couple of tests. The test were very confusing. With normal speech the Philips have more lowend energy below 80 hz and sound better than the WE tubes. But when singing louder the WE sound better  to my ears! :-\

When playing some music through my BM6a's and recording this with the mk47, the difference at close distance is none. But when setting up the mike at about a metre from the speakers the WE tubes sound slightly better!!!

So at this moment I do not know which tube to choose!

Another remark: the height of the capsule is also important for the sound. I am using the Ami body (great body and service) and raised the height of the capsule centre from 3,9 cm to 4,5 (original U47 height). The mike now sound a little bit less airy, I think this is due to the capsule sitting behind the ring of the basket (just like the old pensil trick).

All the best!

RJ
Title: Re: MK47 PCB tube mic kit - build thread
Post by: Pip on July 27, 2013, 08:37:34 PM
an other strange thing is polarity,
my MK47 is out of phase but I don't think it's a faulty wiring because when I check with a multimeter  the Audio+ of the mic PCB goes to the PSU XLR out pin 2 ,

so what about the sound? is that the same color as your mics?

I recently built a U47 (not the MK47), and my polarity was inverted as well. I just switched the audio wires inside of the PSU to fix it. Any reason you don't want to do that?
Thanks for the files by the way. I will listen soon.

Adrian,
I haven't used our MK47 as a kit mic yet but the vocal test sounds a lot like mine and I'm using a different capsule.
Our DIY FET47 has more low end then our MK47 for sure.

Is that expected? I would think a U47 might have more low end than a FET47.

Not my experience at all. FET 47 have great low end thats why they make great distant kick drum mics. In a good room of course.
Title: Re: MK47 PCB tube mic kit - build thread
Post by: adrian on July 28, 2013, 06:23:08 PM
I made some other tests,
my PSU output 105v is OK at the studio,

with a shelf EQ to add between 6 and 9 db below 80Hz it just sound incredible,

(http://sd-2.archive-host.com/membres/up/3233768753986065/Capture_decran_2013-07-29_a_001657.png)
Title: Re: MK47 PCB tube mic kit - build thread
Post by: MicDaddy on July 29, 2013, 06:24:16 PM
ok, so i didn't build an MK47, but rather adopted one from the blackmarket.

I did however build the psu.  Case is from Collective.  I tried to use Chunger's point to point layout, soon found that it wouldn't fit.  With some creative component placement, and removing the dummy load from the circuit, I was able to get it together.

The mic sounds very stellar, I'm extremely happy with it.

I also built a poctop fet47 and it stands up well to the MK47, with a touch more low end and maybe a tad less 'magic'. (whatever that means..)

I thought I'd add my own mic-badge to the Equanox body, but felt bad removing the builder's signature mic-badge, so I leave it as I got it. 

The only mod I performed on the microphone, was to move the B- to pin 7 of the binder, to allow that to make contact before any of the other pins. 

Binder connectors are expensive, but I feel worth the extra money, they are robust and just have a great look and feel, what I expect from a high end microphone.  The cable is GAC-7 Tube from Chunger... (the damn cable was ~$100 to build)
(http://imageshack.com/a/img203/929/08u4.jpg)
(http://imageshack.com/a/img202/430/5s7l.jpg)

Here's how I implemented the dummy load:
(http://imageshack.com/a/img199/1558/dpiz.jpg)
(http://imageshack.com/a/img198/6857/jmy7.jpg)

Title: Re: MK47 PCB tube mic kit - build thread
Post by: JW on July 29, 2013, 09:29:42 PM
I'm wondering if someone can answer my question about wattage of resistors in the "MK48" conversion on page 48 of this thread: http://www.groupdiy.com/index.php?topic=41379.940

For the 150M ohm resistors, is 1/4 watt okay? I see that one of them is in parallel with the 1500 ohm 5 watter, but I think that is for the heater right, which is the most current intensive?

BTW, I built two of these guys and finally settled on the Thiersch blue lines, which are really aweseome. I haven't noticed any lack of low end. In fact, I was contemplating switching the output cap to .47uF to hopefully roll off a little. That said,  I'm recording in small rooms where low end build up is always a problem.

Title: Re: MK47 PCB tube mic kit - build thread
Post by: micaddict on July 30, 2013, 03:43:49 AM
MicDaddy wrote:
Quote
ok, so i didn't build an MK47, but rather adopted one from the blackmarket.

Yeah, I saw the add too and I was surely tempted. But it's got a good home. Hey, it's better off with a daddy than an addict anyway.  ;)
Congrats!


Title: Re: MK47 PCB tube mic kit - build thread
Post by: EvLoutonian on August 01, 2013, 04:23:07 AM
ok, so i didn't build an MK47, but rather adopted one from the blackmarket.
(http://imageshack.com/a/img198/6857/jmy7.jpg)
Dang! Nice work on your mic build, Ben.
& I like the nifty work on the dummy load, too!
Evan
Title: Re: MK47 PCB tube mic kit - build thread
Post by: Melodeath00 on August 01, 2013, 10:17:38 AM
What's the purpose of that dummy load?

Also what was the bit about moving "the B- to pin 7 of the binder, to allow that to make contact before any of the other pins. "? What does that do?
Title: Re: MK47 PCB tube mic kit - build thread
Post by: MicDaddy on August 01, 2013, 10:39:41 AM
What's the purpose of that dummy load?

The psu is not regulated, the dummy load allows adjustments to be made to the psu without having to hook up the microphone.

Quote
Also what was the bit about moving "the B- to pin 7 of the binder, to allow that to make contact before any of the other pins. "? What does that do?

The Binder connector pin 7 (center pin) is physically sticking out a bit further than the remaining pins.  This allows 0V to make contact before all other connections. 
Title: Re: MK47 PCB tube mic kit - build thread
Post by: HellfireStudios on August 01, 2013, 07:58:14 PM
Why would you hook/unhook a tube mic with the power supply still on?

-James-
Title: Re: MK47 PCB tube mic kit - build thread
Post by: MicDaddy on August 01, 2013, 09:15:51 PM
Why would you hook/unhook a tube mic with the power supply still on?

-James-

Did someone suggest for you to do this?  I don't know why anyone would, there is always a possibility that it could happen.

Would you ever put high voltage to a metal chassis?  I wouldn't but that doesn't eliminate the possibility of it happening.  Take a look at an IEC power inlet sometime...  ;)
Title: Re: MK47 PCB tube mic kit - build thread
Post by: HellfireStudios on August 01, 2013, 09:26:53 PM
I was just posing the question to find out if the need for an extended mic cable pin to ground was actually necessary. In use, with locking connectors, an accidental disconnect seems unlikely, and to connect the mic with P/S on would be far from standard operating procedure. I say keep a yardstick around so you can slap any "inexperienced" hands from a distance.

-James-
Title: Re: MK47 PCB tube mic kit - build thread
Post by: maq3396 on August 21, 2013, 11:57:10 AM
Hello all,

Having a bit of a challenge with the PSU...
Keeps blowing fuses.
The IEC measures 120V (Canada)
The black and yellow secondaries of the Triad VPT 230-110 measure 265V when they are "free"
However, as soon as they are connected to the terminal blocks (Zayance pcb) the fuse goes.
No obvious bridging on the solder points.
Currently all connections removed from pattern switch and both cable connectors (only ground at 0V and test load connected).

I am very open to suggestions on how to troubleshoot this.
Is is possible to depopulate the pcb then check as each component is reinstalled?

Thank you in advance
Mac
Title: Re: MK47 PCB tube mic kit - build thread
Post by: zayance on August 21, 2013, 12:48:55 PM
Hello all,

Having a bit of a challenge with the PSU...
Keeps blowing fuses.
The IEC measures 120V (Canada)
The black and yellow secondaries of the Triad VPT 230-110 measure 265V when they are "free"
However, as soon as they are connected to the terminal blocks (Zayance pcb) the fuse goes.
No obvious bridging on the solder points.
Currently all connections removed from pattern switch and both cable connectors (only ground at 0V and test load connected).

I am very open to suggestions on how to troubleshoot this.
Is is possible to depopulate the pcb then check as each component is reinstalled?

Thank you in advance
Mac

Diodes in right direction?
Slow blow? Fast Blow Fuse?
Maybe can post a picture? Or more details?
Title: Re: MK47 PCB tube mic kit - build thread
Post by: maq3396 on August 21, 2013, 01:14:31 PM
Thanks Tony

As I started taking it apart I found 0 ohms across both double terminal blocks.
It is the terminal blocks themselves.
I must have ordered the wrong ones!

Back to the local electronics store for blocks and fuses!

Cheers
Mac
Title: Re: MK47 PCB tube mic kit - build thread
Post by: zayance on August 21, 2013, 01:17:08 PM
Hmmm, please give link to the part.


T.
Title: Re: MK47 PCB tube mic kit - build thread
Post by: poctop on August 21, 2013, 02:08:40 PM
Thanks Tony

As I started taking it apart I found 0 ohms across both double terminal blocks.
It is the terminal blocks themselves.
I must have ordered the wrong ones!

Back to the local electronics store for blocks and fuses!

Cheers
Mac

I have had the same problem during the construction of my very first diy project , the api 312 ,
the terminal block was indeed a ground bus terminal and not a terminal itslef,
hope that is your problem as they say the easiest solution is always the best,
D
Title: Re: MK47 PCB tube mic kit - build thread
Post by: kante1603 on August 21, 2013, 02:12:39 PM
Hmmmmmm......chainsaw? ;D
Title: Re: MK47 PCB tube mic kit - build thread
Post by: maq3396 on August 22, 2013, 12:31:59 AM
Indeed that was the problem!
Two new terminal blocks and the power supply was perfect.
The sales person at the store had never seen one before so they cannot be too common.
For reference the part was Mouser 651-1868733 and is found at:
http://ca.mouser.com/ProductDetail/Phoenix-Contact/1868733/?qs=%2fha2pyFadui1lrDaV3wy6DeCg%252b2JcG%2fM85Z3RH3yEOu1yUJks5TlAw%3d%3d

Thanks....and back to finishing the microphone

Cheers
Mac
Title: Re: MK47 PCB tube mic kit - build thread
Post by: kante1603 on August 22, 2013, 12:50:39 AM
Thanks for pointing that out Mac!

Best,

Udo.
Title: Re: MK47 PCB tube mic kit - build thread
Post by: zayance on August 22, 2013, 04:26:29 AM
Well that was a tricky one.
The pdf datasheet of the part states "Connections internally jumpered" tough but you go with the looks of the
part sometimes so...

Anyway thanks for the link.


T.
Title: Re: MK47 PCB tube mic kit - build thread
Post by: maq3396 on August 27, 2013, 07:27:25 PM
Hello all!

Next newbie question...

About to print a mount to secure the pcb in an Equinox body.

There is quite a bit of extra room inside.

From either an electronic or balance/ergonomics perspective does it matter if the pcb is at the bottom, middle or top of the microphone body?

Thanks for the assistance

Cheers
Mac
Title: Re: MK47 PCB tube mic kit - build thread
Post by: mwacht on August 28, 2013, 05:37:56 AM
Hello,
i have a problem with my mk47 U47. The first lets say 20 hours it works very fine but now i have very much noise on it after 15 minutes running (noise, pops, crackles) and i think the sound distort to fast at a higher SPL. So i measured the actual Voltage from the PSU while Mic was connected and it was dropped down to 85VDC, so something wrong here.

I made the PSU the same as the schematic from Max in this build thread (with choke), i use the t-bone SCT700 housing and cable (105VDC connected over two wires), the heater dropper have a good contact to the housing but it gets really hot but i think thats normal. Also the resistors in the PSU gets very hot.
Maybe someone has a idea?
Thank you and best regards,
Michael
Title: Re: MK47 PCB tube mic kit - build thread
Post by: ioaudio on August 28, 2013, 12:15:15 PM
Hi Michael,

so the voltage is 105Vdc is dropping after 15minutes to 85Vdc?
Do you have a spare set of tubes to try?

-max
Title: Re: MK47 PCB tube mic kit - build thread
Post by: Govinda Doyle on September 14, 2013, 05:19:45 AM
Hi there,
Finally built a pair with dale capsules... amazing fat smooth sound thats clear!
I have a slight issue, my pot fully decreased my mic takes about 111.6 dc, is this a problem with the extra 6.6 volts?
Sounds nice hot haha!
G
Title: Re: MK47 PCB tube mic kit - build thread
Post by: ioaudio on September 15, 2013, 04:37:31 AM
Not really a problem - but you might add some resistance to lower the voltage.
Title: Re: MK47 PCB tube mic kit - build thread
Post by: Govinda Doyle on September 15, 2013, 04:51:55 AM
Another 1k before the pot?
Thanks for quick reply!
Govinda
Title: Re: MK47 PCB tube mic kit - build thread
Post by: ioaudio on September 15, 2013, 05:22:11 AM
A 330Ohm should bring the voltage down, maybe a 500 (two 1k's in parallel) to be able to set the pot approx to the middle position.
Title: Re: MK47 PCB tube mic kit - build thread
Post by: Govinda Doyle on September 15, 2013, 05:32:00 AM
Thanks max!
The mic sounds encredibly good, I have a few really special mics and this is just super!
G
Title: Re: MK47 PCB tube mic kit - build thread
Post by: ioaudio on September 15, 2013, 07:28:08 PM
 :)
Title: Re: MK47 PCB tube mic kit - build thread
Post by: maq3396 on September 19, 2013, 12:15:58 AM
Hello all,

Having a challenging time here...

PSU seems to be fine

Microphone is not!

Not a peep out of it as far as the capsule goes
If you move the tubes a little or change the position of the multimeter probes there is some scratching that comes through the speakers
However, tubes do not get warm (will they start to glow at all?) nor does the resistor mounted in the base of the body
Measure 348VDC across B+/B-
Grounds seem to check out and solder joints have been checked.
Resistance across heater pins is approc 90 ohms

If anyone can recommend a methodical way for troubleshooting this I would be appreciative.

Thanks
Mac
Title: Re: MK47 PCB tube mic kit - build thread
Post by: muffy1975 on September 19, 2013, 06:07:48 PM
Hey,

that sounds like the tubes are not loading the circuit. try a fresh pair of tubes. I highly recommend the ebay dealer that does lots of ten tubes for £30 or so.

does your PSU work with the dummy resistor? does it put out around 105-110V with the dummy resistor?

If the answer to the above question is yes then it will probably be your tubes.

Also, and this is important, check that the traces on the mic PCB are intact. Has one of the traces broken?  This happened to me and it took me ages to realise that the MIC PCB was a little flimsy.

regards

Michael de A


ps yes the tubes will start to glow within 5 seconds of turning on the PSU
Title: Re: MK47 PCB tube mic kit - build thread
Post by: maq3396 on September 20, 2013, 11:40:23 AM
Thanks Michael

Will try new tubes and see

Suspect it is a broken trace...have btpassed two areas already where my butterfingers created issues

Take care
Mac
Title: Re: MK47 PCB tube mic kit - build thread
Post by: maq3396 on September 21, 2013, 12:13:54 AM
It turned out to be traces 2 and 5 where they come off the main pcb to join the smaller semicircular one.
Despite having good solder joints the resistance was off the scale-the trace had lifted right off the pcb and must have been fractured
More point to point wiring and the output dropped to 105V and the tubes began to glow!
Nice sound from the beginning with very low noise (once the microphone body was put on) and no popping at all.
Currently have Equinox capsule but will put in a BeezNeez K6 next time it is taken apart (or perhaps a Beez Neez M7)
Cheers everyone, thank you for all your help. Particularly to iaudio, Zayance and Chunger

Taker care
Mac
Title: Re: MK47 PCB tube mic kit - build thread
Post by: deveng on October 04, 2013, 10:42:46 AM
Just completed my MK47 power supply using a Zayance pcb and Dan's case.  All is working but my output voltage varies.  After setting it to  105.0 volts, it will wander around this reading as much as +/-1 volt.  I checked the input and it doesn't change more than .2 volts.  Anyone else see this?

Regards,
Jeff
Title: Re: MK47 PCB tube mic kit - build thread
Post by: ioaudio on October 05, 2013, 09:50:44 AM
That's just the modulation from the signal (often hum from the open housing) - no problem!
Title: Re: MK47 PCB tube mic kit - build thread
Post by: Aaronrash on October 05, 2013, 10:49:42 AM
Are these kits still availible? I would love to build one of these
Title: Re: MK47 PCB tube mic kit - build thread
Post by: Pip on October 05, 2013, 11:01:49 AM
Are these kits still availible? I would love to build one of these

Check here:

http://www.groupdiy.com/index.php?topic=35667.msg437839#msg437839

http://www.groupdiy.com/index.php?topic=50694.0
Title: Re: MK47 PCB tube mic kit - build thread
Post by: teacat on October 24, 2013, 01:40:52 PM
Getting close to finishing my psu, but i could use a little help with regards to getting the voltages right. I used zayance's pcb and the triad vpt230-110. I'm in the us, 122v out of the wall. checked the voltages this morning with the dummy resistor load- i get a range of 294-280 measuring at the "105v" terminal. at the center of the pattern switch i get 45v and measuring from gnd to either the yellow or black wires coming off the toroidal into the 200v in i get 187v.
nothing caught on fire or exploded at least. 
Title: Re: MK47 PCB tube mic kit - build thread
Post by: SKJGProject on October 25, 2013, 09:55:00 AM
finally finished mine but f**ked up the connection of the pattern switch (switched the terminal connections of the center pin and the 12k resistor ond zayance pcb) on the psu....realized this after 3 hours burn in of the mic

and i was wondering why i could not hear a difference with switching the pattern  ::)

any possible damage due to this error?
mic was passing audio but really noisy and the occasional pops and clicks (used a 6w 1k5 heater dropper resistor and 10w resistors in the psu)
Title: Re: MK47 PCB tube mic kit - build thread
Post by: teacat on October 25, 2013, 10:45:47 AM
Ok, got the test resistor in the right place. Now I get a range of 84v to 70v. Hmm, any ideas what I messed up this time?  I basically built it like chunger's with the zayance pcb, triad toroidal and choke, 1k pot, 3x 1k 10w resistors, etc.
Here's some photos:
(http://farm6.staticflickr.com/5540/10476181225_3df4da59a0_o.jpg)

(http://farm4.staticflickr.com/3675/10476180275_e5549d9103_o.jpg)

It's going to go in this high-tech psu case:
(http://farm4.staticflickr.com/3766/10476192394_e15500598b_o.jpg)

Like this:

(http://farm8.staticflickr.com/7386/10476374763_26f6a63b69_o.jpg)

There should be enough room for the mic, shockmount and cable on the right-hand side. Once I get this voltage issue figured out, just gotta wait for chunger's gt-2b's to come in.
Title: Re: MK47 PCB tube mic kit - build thread
Post by: teacat on October 26, 2013, 09:50:36 AM
Ok. This time when I measured the voltage, it kept going up slowly, starting at 84v and I got it to settle down at 105v. Cool! i need to get those ali clips for my dmm....
Kinda sad that I'm done.  :'(
Title: Re: MK47 PCB tube mic kit - build thread
Post by: SKJGProject on October 27, 2013, 01:30:21 PM
unfortunately the mic is still way too noisy to work with...psu without anything attached is silent, psu with cable only attached silent as well...as soon as i connect the mic
even without turning it on there is noise  :(
Title: Re: MK47 PCB tube mic kit - build thread
Post by: SKJGProject on October 29, 2013, 10:33:15 AM
read the whole thread again and tried a different grounding scheme....still horrible noise

can somebody show me a clearly understandable working way on mic, psu and cable???

atm i have connected pin 7 in the cable to the shield on both sides, in the mic pin 7 to b- (pin 3), pin 3 and pin 7 united in the cable on the mic side.
in the psu my iec ground, pin 7 and pin 3 and the xlr pin 2 are going to the 0v connecor
Title: Re: MK47 PCB tube mic kit - build thread
Post by: poctop on October 29, 2013, 12:35:51 PM
read the whole thread again and tried a different grounding scheme....still horrible noise

can somebody show me a clearly understandable working way on mic, psu and cable???

atm i have connected pin 7 in the cable to the shield on both sides, in the mic pin 7 to b- (pin 3), pin 3 and pin 7 united in the cable on the mic side.
in the psu my iec ground, pin 7 and pin 3 and the xlr pin 2 are going to the 0v connecor

What kind of noise is it , Hum , or hiss or a combination of both or somthing else , maybe if you post a sample that could help a bit.
Best,
dan,
Title: Re: MK47 PCB tube mic kit - build thread
Post by: deveng on October 29, 2013, 02:32:24 PM
Here's an internal pic of my recent MK47 power supply build.  The build is based on Chungers use of a heatsink for the series resistors.  I happen to have a large heatsink laying around in my parts bin so I used it.  Definitely overkill but it works well. 

The MK47 mic is mostly built as well except for installing the capsule.   

Title: Re: MK47 PCB tube mic kit - build thread
Post by: SKJGProject on October 30, 2013, 02:50:05 PM
read the whole thread again and tried a different grounding scheme....still horrible noise

can somebody show me a clearly understandable working way on mic, psu and cable???

atm i have connected pin 7 in the cable to the shield on both sides, in the mic pin 7 to b- (pin 3), pin 3 and pin 7 united in the cable on the mic side.
in the psu my iec ground, pin 7 and pin 3 and the xlr pin 2 are going to the 0v connecor

What kind of noise is it , Hum , or hiss or a combination of both or somthing else , maybe if you post a sample that could help a bit.
Best,
dan,

FML...you should never switch pin 1 and 2 on xlr...noise is gone, only the tube crackles remain...will now leave the mic on for at least 24hours and decide if i need other tubes afterwards...
Title: Re: MK47 PCB tube mic kit - build thread
Post by: poctop on October 30, 2013, 03:12:20 PM
Quote
FML...you should never switch pin 1 and 2 on xlr..

indeed,  ;),
Best,
dAn,
Title: Re: MK47 PCB tube mic kit - build thread
Post by: patterson on November 03, 2013, 07:10:30 PM
and picture #2
Title: Re: MK47 PCB tube mic kit - build thread
Post by: patterson on November 03, 2013, 11:34:34 PM
This is an amazing microphone.  Well worth the time it takes to put it together. Thanks to Max, Ben, Tony, Erik, Chunger and everyone who has posted.  It made the build fun. There was no hum, hiss or crackling - just great sound I'm looking forward to recording.

Picture #1
Title: Re: MK47 PCB tube mic kit - build thread
Post by: SKJGProject on November 05, 2013, 01:17:43 PM
this is how my mic sounds after 72 hours of burn-in.... :(

https://www.dropbox.com/s/e2h89jsvwb5jgga/U47%20crackle.mp3
Title: Re: MK47 PCB tube mic kit - build thread
Post by: zayance on November 06, 2013, 04:58:20 AM
this is how my mic sounds after 72 hours of burn-in.... :(

https://www.dropbox.com/s/e2h89jsvwb5jgga/U47%20crackle.mp3

Try other tubes, it's been posted and said before, crackling, wooshing or whatever afetr burnin is because of the tubes.
Buy some and check them out, btw these seem to be less and less available these days, i wonder why  ::)
Title: Re: MK47 PCB tube mic kit - build thread
Post by: baol on November 17, 2013, 05:53:25 PM
Hi guys, I completed  my mic months ago. After the burning it started to work great using the couple of tubes with the Max's kit. After a few days pop and crackling started againg. I took a new couple of tubes and burned again but after few days I had the same problem... Any idea?
When it worked the sound was great, but now it's not usable.

thank you
Andrea
Title: Re: MK47 PCB tube mic kit - build thread
Post by: Pip on November 17, 2013, 10:59:47 PM
Hi guys, I completed  my mic months ago. After the burning it started to work great using the couple of tubes with the Max's kit. After a few days pop and crackling started againg. I took a new couple of tubes and burned again but after few days I had the same problem... Any idea?
When it worked the sound was great, but now it's not usable.

thank you
Andrea

It's the tubes. If all your voltages check out and the capsule is fine then its the tubes. I myself went through three pairs of tubes before I found happiness. What brand are you using?

check this

http://groupdiy.com/index.php?topic=53676.msg685078#msg685078
Title: Re: MK47 PCB tube mic kit - build thread
Post by: baol on November 18, 2013, 10:43:01 AM
Quote
...If all your voltages check out and the capsule is fine then...
so it could be the capsule too, how to exclude it and check if it's the faulty one?
Here's a sample of the noise (ignore the music and cars background).

https://skydrive.live.com/#cid=75105482BEC2CD23&id=75105482BEC2CD23%21105

As I said the tubes were burned for more than 5 days and they were definitely noiseless.
thank you

Andrea
Title: Re: MK47 PCB tube mic kit - build thread
Post by: adrian on November 19, 2013, 09:51:01 AM
hello,
some news about my 2 MK47,
I'm really happy with them, the mic placement is very important, more than any other mics I have!  it vary a lot between 2 positions, especially the low end,
I love them on sax, trumpet and even on some piano!
here is the frequency response using smaart7,
the 2 mics (mk47 and ref) were 2,5 meter in front of an L-acoustic MTD112,
the trace is the difference between the MK47 and an AUDIX TM1 PLUS test and measurement microphone (with correction curve),
(pink is cardio and green is omni)   this is the first mic (wich have the plexiglass spacer)
(http://sd-2.archive-host.com/membres/up/3233768753986065/Mk47__Audix_TM1_with_spacer.png)

I also found that I prefer when the capsule is not to high in the headbasket (so i removed the plexiglass spacer of the equinox kit body approximatly 5 millimeters thickness )
(red is omni and blue is cardio) it's my second mic (the one without the plexiglass spacer)
(http://sd-2.archive-host.com/membres/up/3233768753986065/Mk47__Audix_TM1_without_spacer.png)


edit : capsule are thiersh red line  and  tube are philips ECG   ,

soon i gonna remove the plexiglass spacer of my first mic.

Title: Re: MK47 PCB tube mic kit - build thread
Post by: baol on November 20, 2013, 04:52:53 AM
Hi boys
Is there anyone who knows where to buy 6028 tubes at a reasonable price? I think I'll need a bucket of them to find the right pair.

thank you all

Andrea
Title: Re: MK47 PCB tube mic kit - build thread
Post by: tfp on November 26, 2013, 07:31:09 PM
Hi Andrea,

I have bought 10 Jan Philips 6028 for my mk47. First 2 tubes I tried where great no noise no popping. I haven't test the others but presume they are also good. If you are interested I can sell you 6 tubes (I keep 2 as spare).

Let me know!

RJ
Title: Re: MK47 PCB tube mic kit - build thread
Post by: baol on November 28, 2013, 03:05:38 PM
One question, which impedance the mic has? I'm using a pre with a variable impedance (from 60 to 3k3 hom), is there a better setting or must I follow my ears?
One more question, is there a nice (I mean EASY) diy amplifier well suited for the mk47?

thank you
Title: Re: MK47 PCB tube mic kit - build thread
Post by: baol on December 22, 2013, 07:59:53 AM
Ok, I'll try again with another question, even if it seems I haven't all that followers :)
Do you think it could be a good thing to clean up with isopropyl alcool the board and then put a protective laquer?
thank you.
Title: Re: MK47 PCB tube mic kit - build thread
Post by: ioaudio on December 22, 2013, 09:21:24 AM
Sorry i missed this question. The nominal impedance of 200 Ohm is the same as the original U47.
Since the High-Z section is build "in the air" with the glass insulators protective laquer is not required.
Title: Re: MK47 PCB tube mic kit - build thread
Post by: baol on December 22, 2013, 09:55:10 AM
I think I haven't understood the reason (due to my immense electronic ignorance), but I take it as an axiom :D
thank you max and merry  christmas
Title: Re: MK47 PCB tube mic kit - build thread
Post by: gary o on December 22, 2013, 11:43:20 AM
this is how my mic sounds after 72 hours of burn-in.... :(

https://www.dropbox.com/s/e2h89jsvwb5jgga/U47%20crackle.mp3

My mic sounded like this went thru mreey hell swapping components tubes ....... turned out to be the the heater dropper resitor......try another one.....
Title: Re: MK47 PCB tube mic kit - build thread
Post by: baol on December 24, 2013, 12:36:29 PM
Hi,
after a 4 days no-stop test I do declare that I fixed every pop issues. I replaced the 1k5 resistor with a chassis mount one, and now everything seems to be ok.
merry christmas everybody!
Andrea
Title: Re: MK47 PCB tube mic kit - build thread
Post by: teacat on January 08, 2014, 11:31:08 AM
Finally got a body(thanks to chunger) to put my mk47 guts into(ok, that sounds.... eww) and she's alive!
What really impressed me was from the first moment turning it on- dead quiet. No hiss, no crackle, no hum. Suddenly I now have in my paws one serious mic and after less than an hour into the burn-in I was off recording a living-room acoustic jam. I used a chassis-mount resistor with some thermal compound and boy does this thing get warm.

Thanks ioaudio!
Thanks chunger!
Thanks zayance!

If I'm ever in Austria, France or the east bay, I'll buy you guys a beer.
I'll post some clips soon.
Title: Re: MK47 PCB tube mic kit - build thread
Post by: ioaudio on January 08, 2014, 04:57:02 PM
Thanks teacat  :)
Title: Re: MK47 PCB tube mic kit - build thread
Post by: Pip on January 13, 2014, 09:32:19 PM
So here is my tail sad but true. I have gone through 3 sets of 408a Western Electric tubes. What happens is the mic will sound fine for weeks at a time and then all of a sudden start making popping or crackling noises. Replacing the tubes with new to me NOS tubes has done the trick twice but here we are again. I don't mean taking them out and reseating them that has not worked. I tried that first of course but had to change tubes. I Know that tubes are a crap shoot. But was just wondering if anyone else has had this reoccuring problem as well?

As a side note I started out with JAN Phillips tubes but they sounded not good at all.
Title: Re: MK47 PCB tube mic kit - build thread
Post by: baol on January 14, 2014, 04:11:47 AM
Hi Pip, I had the same problem: after a few hours every pair of tubes started to pop and crack, last try was to change the 1500 resistor with a wirewound chassis-mount. Now it's completely noiseless.
In the same "repair session" I revised all the solders too, but I'm sure the solution came with the new resistor.
Title: Re: MK47 PCB tube mic kit - build thread
Post by: gary o on January 14, 2014, 05:58:12 AM
I also had the resistor problem others diyer had our same problem I guess its under some strain & as its connected to the cathode.
Title: Re: MK47 PCB tube mic kit - build thread
Post by: teacat on January 26, 2014, 11:54:58 AM
So I finally got to do a real recording with the mk47 as mid in a m/s capturing violin/vox last night. Sounded fantastic but I had one issue where when both the mic and the laptop were plugged into AC there was a horrible static noise. I haven't experienced this problem with this setup until now. I saved my ass by unplugging the laptop while doing takes.  Seems like a grounding issue? It was only when I had the mk47 and matachung c12 plugged in to the AC, with just the other mics it was fine.
Title: Re: MK47 PCB tube mic kit - build thread
Post by: ioaudio on January 26, 2014, 06:18:32 PM
Sounds like a ground loop, happens often with laptops and external psu's and preamps depending on the locations mains.
Title: Re: MK47 PCB tube mic kit - build thread
Post by: etiefenthaler on January 27, 2014, 09:54:05 AM
For all interested:

here's a live recording to watch and listen on YouTube.
http://www.youtube.com/watch?v=xvKaHNFycj4

No cut, no additional reverb or processing or eq. Only rendering to mp3 :(

Recording chain:
Musician - guitar - church - 2 mk47 - mindprint an/di pro - spdif to maudio microtrackII.
Would have got better results with my mytek 8x192 converter. But for YouTube my small mobile-rig converter is more than o.k.

enjoy

Erich

Title: Re: MK47 PCB tube mic kit - build thread
Post by: micaddict on January 27, 2014, 10:50:52 AM
For all interested:

here's a live recording to watch and listen on YouTube.
http://www.youtube.com/watch?v=xvKaHNFycj4

No cut, no additional reverb or processing or eq. Only rendering to mp3 :(

Recording chain:
Musician - guitar - church - 2 mk47 - mindprint an/di pro - spdif to maudio microtrackII.
Would have got better results with my mytek 8x192 converter. But for YouTube my small mobile-rig converter is more than o.k.

enjoy

Erich

Many would pick the usual suspects, i.e. SDCs like Schoeps, DPA et al. But this sounds just great! Warm, smooth and organic, but not lacking too much detail IMO.
Not too noisy, either. LDCs do have an advantage in this regard, but I only mention it because these are tube mics and some have found their MK47 noisy.

I'm not so much into classical guitar, but to this I could listen for hours.

Thanks for posting.
We need more of this.
Title: Re: MK47 PCB tube mic kit - build thread
Post by: sliebers on January 27, 2014, 12:41:55 PM
So here is my tail sad but true. I have gone through 3 sets of 408a Western Electric tubes. What happens is the mic will sound fine for weeks at a time and then all of a sudden start making popping or crackling noises. Replacing the tubes with new to me NOS tubes has done the trick twice but here we are again. I don't mean taking them out and reseating them that has not worked. I tried that first of course but had to change tubes. I Know that tubes are a crap shoot. But was just wondering if anyone else has had this reoccuring problem as well?

As a side note I started out with JAN Phillips tubes but they sounded not good at all.

I'm having the same issue with my build.  I've gone through about 10 sets of JAN Phillips and thought I found 2 pairs that were quiet after about 60 hours of burn-in.  My mic is quiet for about and hour and then starts spitting and crackling.  I'm bummed because it sounds amazing until the noises start.  I really can't use it for anything serious because the noise pops up at critical moments.  I read about changing the 1500 sand bar resistor, but didn't think that was the cause as I heat sank it to the brass base with heat sink compound and a metal strap bolted into the base. 
I'm going to get a wire-wound chassis mount 1K5 and see if that stops the noise.  I hope so, otherwise I'm going to gut the innards and use a different tube.
Title: Re: MK47 PCB tube mic kit - build thread
Post by: ioaudio on January 27, 2014, 12:51:35 PM
The problem with the 1,5kOhm resistor popped (pun...) up a couple of times now - often caused by thermal extension through the mounting - using a aluminium housed resistors solved this.
Title: Re: MK47 PCB tube mic kit - build thread
Post by: dandeurloo on January 27, 2014, 01:24:16 PM
Hey Max and others, I have built 4 of these mics for me and friends.  They all show the same noise as being described.  I have the suggested resistors inside my mics.  It doesn't make a difference, they are still noisy. 

I mounted the resistors to the base of the body (skylar's) and I have thermal paste on them to help the heat transfer.  Has anyone tried a regulated PSU?  Would that make a difference. 

It would be AMAZING to get to the bottom of this, like others have said the mics sound amazing, other then the inconsistent crackle and pops.

Any suggestions would be great.
Title: Re: MK47 PCB tube mic kit - build thread
Post by: gary o on January 27, 2014, 01:39:52 PM
Hey Max and others, I have built 4 of these mics for me and friends.  They all show the same noise as being described.  I have the suggested resistors inside my mics.  It doesn't make a difference, they are still noisy. 

I mounted the resistors to the base of the body (skylar's) and I have thermal paste on them to help the heat transfer.  Has anyone tried a regulated PSU?  Would that make a difference. 

It would be AMAZING to get to the bottom of this, like others have said the mics sound amazing, other then the inconsistent crackle and pops.

Any suggestions would be great.

I had this problem was a right pain changed every part finally I swapped the 1K5 didnt have correct value & wattage one laying around so I made 1K5 out of a few values to test ..... silence it was gorgeous to hear, well not hear..... ordered a metal mount one , tried before mounting worked lovely  cant remember the wattage but Im guessing the higher power rating the less strain the resistor is under .
Title: Re: MK47 PCB tube mic kit - build thread
Post by: ioaudio on January 27, 2014, 01:54:16 PM
Hey Max and others, I have built 4 of these mics for me and friends.  They all show the same noise as being described.  I have the suggested resistors inside my mics.  It doesn't make a difference, they are still noisy. 

I mounted the resistors to the base of the body (skylar's) and I have thermal paste on them to help the heat transfer.  Has anyone tried a regulated PSU?  Would that make a difference. 

It would be AMAZING to get to the bottom of this, like others have said the mics sound amazing, other then the inconsistent crackle and pops.

Any suggestions would be great.

Hi Dan,

probably the thermal paste makes cracking noises? Other than the that the usual suspects (besides tubes) are the 10nF styroflex when soldered too hot/long.

Title: Re: MK47 PCB tube mic kit - build thread
Post by: dandeurloo on January 27, 2014, 02:06:08 PM
Hey Max and others, I have built 4 of these mics for me and friends.  They all show the same noise as being described.  I have the suggested resistors inside my mics.  It doesn't make a difference, they are still noisy. 

I mounted the resistors to the base of the body (skylar's) and I have thermal paste on them to help the heat transfer.  Has anyone tried a regulated PSU?  Would that make a difference. 

It would be AMAZING to get to the bottom of this, like others have said the mics sound amazing, other then the inconsistent crackle and pops.

Any suggestions would be great.

Hi Dan,

probably the thermal paste makes cracking noises? Other than the that the usual suspects (besides tubes) are the 10nF styroflex when soldered too hot/long.

OK, I will try both of these options.  I have been very quick with soldeirng in the Styroflex but still could be that.  I have rewired and cleaned and cleaned the boards.  So hopefully it is one of these two options.  I am surprised that it would be the same on all four mics however.

Could it be the tubes don't love unregulated supplies? 
Title: Re: MK47 PCB tube mic kit - build thread
Post by: ioaudio on January 27, 2014, 02:39:16 PM
Yes, since it occours on all four mics i bet it's the 1,5k / mounting. For a short test you don't have to mount the new resistor.
The passive PSU is fine and used by the large majority - just a couple of posts above Erich presented a lovely guitar recording inside a church.

-max
Title: Re: MK47 PCB tube mic kit - build thread
Post by: scott_humphrey on January 27, 2014, 03:47:34 PM
For all interested:

here's a live recording to watch and listen on YouTube.
http://www.youtube.com/watch?v=xvKaHNFycj4

No cut, no additional reverb or processing or eq. Only rendering to mp3 :(

Recording chain:
Musician - guitar - church - 2 mk47 - mindprint an/di pro - spdif to maudio microtrackII.
Would have got better results with my mytek 8x192 converter. But for YouTube my small mobile-rig converter is more than o.k.

enjoy

Erich

FANTASTIC!
Title: Re: MK47 PCB tube mic kit - build thread
Post by: micaddict on January 27, 2014, 04:32:31 PM
Yup, this is something special.
Great performance.
Great instrument.
Great room.
Great recording.
Made my day.
Title: Re: MK47 PCB tube mic kit - build thread
Post by: Winetree on January 27, 2014, 11:49:00 PM
Should I switch out the 1500-10 watt ceramic resistor I'm using with this?
I've got it zip tied to the side rail. Haven't run the mics long enough for trouble but I'm placing a Mouser order.

http://www.mouser.com/Search/ProductDetail.aspx?R=805F1K5Evirtualkey58810000virtualkey588-805F1K5E
It's only 5 watts but any larger wattage would be too big sizewise.
Title: Re: MK47 PCB tube mic kit - build thread
Post by: gary o on January 28, 2014, 05:46:06 AM
Thats what I have in my mic & works greay for me
Title: Re: MK47 PCB tube mic kit - build thread
Post by: G-Sun on January 28, 2014, 07:04:47 AM
here's a live recording to watch and listen on YouTube.
http://www.youtube.com/watch?v=xvKaHNFycj4
That's just nice sound :thumbsup:
Title: Re: MK47 PCB tube mic kit - build thread
Post by: dandeurloo on January 29, 2014, 10:22:34 AM
I ordered more resistors.  I will try and replace a few and see if the popping and crackling goes away.
Title: Re: MK47 PCB tube mic kit - build thread
Post by: Pip on February 08, 2014, 02:50:38 PM
So here is my tail sad but true. I have gone through 3 sets of 408a Western Electric tubes. What happens is the mic will sound fine for weeks at a time and then all of a sudden start making popping or crackling noises. Replacing the tubes with new to me NOS tubes has done the trick twice but here we are again. I don't mean taking them out and reseating them that has not worked. I tried that first of course but had to change tubes. I Know that tubes are a crap shoot. But was just wondering if anyone else has had this reoccuring problem as well?

As a side note I started out with JAN Phillips tubes but they sounded not good at all.

Following up.

So I replaced the 1K5 resistor with a 10watt wirewound panel mount metal housed version and screwed that bad boy to the aluminum heat sink I had put in the mic body for the ceramic one as opposed to just a clip holding it in place. Well 3 days of burn in with same tubes as before and no popping. I say we have a winner.

http://www.mouser.com/ProductDetail/Arcol/HS10-1K5-1/?qs=%2fha2pyFadujijxGS6LgfEi9lQ2ZQ6DE%2f18e2GSyrwxzudE9N3KjSBg%3d%3d
Title: Re: MK47 PCB tube mic kit - build thread
Post by: Winetree on February 08, 2014, 07:19:32 PM
Pip, Do you happen to have a picture.
Title: Re: MK47 PCB tube mic kit - build thread
Post by: Pip on February 08, 2014, 08:50:47 PM
Pip, Do you happen to have a picture.

IMAGINE NEW RESISTOR SCREWED TO ALUMINUM PLATE THAT IS LOCATED BELOW TRANSFORMER INSTEAD OF CERAMIC ONE SEEN IN SHOT. NOTE THIS IS OF ORIGINAL BUILD THE MIC NOW HAS WESTERN ELECTRIC TUBES NOT JAN PHILLIPS
Title: Re: MK47 PCB tube mic kit - build thread
Post by: sliebers on February 10, 2014, 12:36:00 PM
I wanted to report my findings on the 1K5 resistor swap as well.  I originally had the sandbar 1K5 (included in kit) mounted with heat sink compound to the brass base of the mic.  The popping and crackling noises would appear randomly after about an hour of use.  I then wiped off all the heat sink compound and suspended the resistor in air inside the mic.  The noise seemed to appear less frequently, but was still there.
I ordered an aluminum housed 1K5 10W chassis mount resistor and replaced.  So far, the noise has not shown up.  I have yet to do recording work with the new resistor installed.  That will be the real test as the noises always seem to show up when you are getting the perfect take.
The sound of the mic is fantastic, the tubes are a little noisy on their own, but workable.  My advice to anyone building this mic is to throw out the included 1K5 resistor and start with a chassis mount 10W.
Title: Re: MK47 PCB tube mic kit - build thread
Post by: gary o on February 10, 2014, 01:38:50 PM
I wanted to report my findings on the 1K5 resistor swap as well.  I originally had the sandbar 1K5 (included in kit) mounted with heat sink compound to the brass base of the mic.  The popping and crackling noises would appear randomly after about an hour of use.  I then wiped off all the heat sink compound and suspended the resistor in air inside the mic.  The noise seemed to appear less frequently, but was still there.
I ordered an aluminum housed 1K5 10W chassis mount resistor and replaced.  So far, the noise has not shown up.  I have yet to do recording work with the new resistor installed.  That will be the real test as the noises always seem to show up when you are getting the perfect take.
The sound of the mic is fantastic, the tubes are a little noisy on their own, but workable.  My advice to anyone building this mic is to throw out the included 1K5 resistor and start with a chassis mount 10W.

Maybe at beggining of the build a little note to say if noises appear prime suspect will be dropper resistor could save a lotta hassle for builders  :)
Title: Re: MK47 PCB tube mic kit - build thread
Post by: 0dbfs on February 10, 2014, 01:55:54 PM
It's apparently the "sound of sand". Sorta "grainy"....

Cheers,
jb
Title: Re: MK47 PCB tube mic kit - build thread
Post by: ioaudio on February 11, 2014, 11:19:30 AM
Since this problem popped up i ship the kits with the alu resistor included.
Sorry for the unconvenience.
Max
Title: Re: MK47 PCB tube mic kit - build thread
Post by: 0dbfs on February 11, 2014, 12:00:05 PM
I did two of these (with the sand resistors) and had some discharge noises initially but it settled down after a number of hours. I let them burn in for a couple weeks. My B+ drifts up and down a bit over maybe a 10-15 minute cycle. Plan to rebuild the PSU's at some point since I did them p2p and was going to swap out that heater dropper at the same time. Thought was that as the heat goes up/dn the resistance also varies so just wanted a more robust part in there for that function.

Cheers!
-jb
Title: Re: MK47 PCB tube mic kit - build thread
Post by: ioaudio on February 11, 2014, 02:41:57 PM
Remember that this is a passive psu - not regulated, so fluctuations are normal.
I wouldn't change if you don't have a noise problem with the resistor.
Title: Re: MK47 PCB tube mic kit - build thread
Post by: deveng on February 13, 2014, 05:46:08 PM
Max,

Just got my MK47 up and running.  Fired up first shot with no issues.  I was waiting for an M7 from ChuckD and just got it Tuesday evening.  Installed it today and powered the bad boy up.  Did a high gain check and there's no hum.   A quick voice test and it sounds full.  I'll burn in the tubes for 24 hours before using.   Pictures to come.  Now I can move on to build another from the parts I got from Skylar's sell-off.  That one will have one of the Equinox capsules. 

Thanks for your work on this thing!

regards,
Jeff
Title: Re: MK47 PCB tube mic kit - build thread
Post by: ioaudio on February 13, 2014, 08:30:53 PM
Thanks Jeff!
Title: Re: MK47 PCB tube mic kit - build thread
Post by: teacat on February 22, 2014, 11:54:54 AM
https://soundcloud.com/teacat77/mk47-snip (https://soundcloud.com/teacat77/mk47-snip)

short clip of violin in my bad room...

beesneez 'save phelicity' k47 capsule
we 408a tubes
body similar to the equinox

rec'd through octa-capture, no processing
Title: Re: MK47 PCB tube mic kit - build thread
Post by: micaddict on February 22, 2014, 12:04:39 PM
Nice, too! Somewhat thicker than the C12 in the other thread.



Henk
Title: Re: MK47 PCB tube mic kit - build thread
Post by: G-Sun on February 23, 2014, 05:55:09 AM
https://soundcloud.com/teacat77/mk47-snip (https://soundcloud.com/teacat77/mk47-snip)
Nice. Very helpful for getting an impression of the mics. Thanks!
(Do you take session work?)
Title: Re: MK47 PCB tube mic kit - build thread
Post by: ioaudio on February 28, 2014, 02:20:07 PM
Since i have received a lot of mails and Pms regarding the matter, just a short notice to everyone:

The new U47 Kit & Pcb from users "poctop" and "micandmod" was done without my permission.
Please note that the Mk47 circuit, featuring 2 408a/6028 tubes in parallel/series connection, was my invention.

thanks for your attention,
Max
Title: Re: MK47 PCB tube mic kit - build thread
Post by: Leer on February 28, 2014, 03:49:59 PM
Makes me cringe when I read "our engineers have developed a circuit of two 408 Military NOS in parallel"

Atleast they should give credit where it's due.
Title: Re: MK47 PCB tube mic kit - build thread
Post by: Studio Mollan on March 21, 2014, 08:52:04 PM
Hi guys!
I've been using my pair of Mk47's for about two now and they sound very good indeed!
I'm comparing them to my Flea47 and although they are similar sounding the top end is a lot smoother in the flea. Also the flea sounds overal more polished and more flattering, it saturates more and better than the MK47's do, but i guess thats to be expected from a 5000USD microphone. The mk47 is "faster" more modern sounding i guess and compared to the Flea a bit harsh in the hi end. Its not harsh sounding at all though, just comparing to the Flea.   
Im using the Skylar body with Thiersch red mylar capsule. My Flea has a Thiersch blue PVC and EF12.

Any ideas on how to stretch the MK47 towards the flea? I know its a different cirquit but maybee you can get a bit closer with different types/values of caps?
If anyone experimented on this id be very happy for your thoughts!

Also: Howecome the polystyrene cap is 10nf instead of the original U47 spec 1nf? I tried replacing it with a 1nf SilverMica. Hard to tell the difference, at least on this source.   
/
Emil
Title: Re: MK47 PCB tube mic kit - build thread
Post by: micaddict on March 22, 2014, 05:57:18 AM
Thanks for the comparison.

Quote
Im using the Skylar body with Thiersch red mylar capsule. My Flea has a Thiersch blue PVC and EF12.

The thicker (heavier) and more flexible (for now) PVC alone would make that one less fast and less modern sounding.
Likely smoother/less "harsh", too.

Then there's the tranny, coupling cap etc.

In that order, I guess.



Henk
Title: Re: MK47 PCB tube mic kit - build thread
Post by: Studio Mollan on March 22, 2014, 07:31:37 AM
Thanks for the comparison.

Quote
Im using the Skylar body with Thiersch red mylar capsule. My Flea has a Thiersch blue PVC and EF12.

The thicker (heavier) and more flexible (for now) PVC alone would make that one less fast and less modern sounding.
Likely smoother/less "harsh", too.

Then there's the tranny, coupling cap etc.

In that order, I guess.



Henk
Hi and thanks for your answer. You're right. That's what I've heard from the PVC as well and now also experienced. Any idea of what type of coupling cap for a darker sound?
/
Emil
Title: Re: MK47 PCB tube mic kit - build thread
Post by: micaddict on March 22, 2014, 07:34:49 AM
Purely by coincidence I stumbled upon a Gearslutz thread where someone (buzzjoe) compared a Flea U47 with a Voxorama U47.
The latter is made by Andreas Grosser and is currently the U47 clone that people rave about. I t seems it has surpassed The Wagner in that regard.

Here's the quote:
Quote
Neither the Flea47 nor the Voxorama sounded like I expected. Both sound very good (and virtually noise free) but also very different: the Flea47 sounds VERY smooth, soft and warm while the Voxorama sounds much more forward, open and "modern". The Flea47 sonds very warm and pleasant but I expected a little more "edge" and presence in the upper mids while the Voxorama does have that presence but lacks some "warmth" and low end (compared to the Flea47).
Title: Re: MK47 PCB tube mic kit - build thread
Post by: micaddict on March 22, 2014, 07:37:50 AM
Quote
Any idea of what type of coupling cap for a darker sound?

I'd have to leave that one to others. Max first, probably.

It already has a paper-in-oil, no?



Henk
Title: Re: MK47 PCB tube mic kit - build thread
Post by: ioaudio on March 22, 2014, 08:12:07 AM
Hi Emil,

that's likely the capsule as stated before, hence my suggestion towards the blue line - i had more than a few builders changing from red to blue after the fact.

The 10nF is specified by the original schematics - 0.01µf = 10nF

-Max
Title: Re: MK47 PCB tube mic kit - build thread
Post by: Studio Mollan on March 22, 2014, 08:19:13 AM
Hi Emil,

that's likely the capsule as stated before, hence my suggestion towards the blue line - i had more than a few builders changing from red to blue after the fact.

The 10nF is specified by the original schematics - 0.01µf = 10nF

-Max
Hi Max and thanks for your input!
Ok I will get a couple of blue ones then.
Will keep you posted on my findings.

Am I crazy or does not the original schem say 0,001uf? Maybe different revisions?
Title: Re: MK47 PCB tube mic kit - build thread
Post by: ioaudio on March 22, 2014, 11:44:33 AM
Am I crazy or does not the original schem say 0,001uf? Maybe different revisions?

Never heard about that, do you have a link with the 0,001?

http://www.gyraf.dk/gy_pd/g7/u47.gif
Title: Re: MK47 PCB tube mic kit - build thread
Post by: Studio Mollan on March 22, 2014, 11:52:03 AM
Am I crazy or does not the original schem say 0,001uf? Maybe different revisions?

Never heard about that, do you have a link with the 0,001?

http://www.gyraf.dk/gy_pd/g7/u47.gif

You know what, i probably am crazy. I spent last night (very late) comparing my microphones and I could have sworn it was 1nf. I trust you more than myself in the middle of the night though. I ant check my notes now as I'm in the middle of a session.
Title: Re: MK47 PCB tube mic kit - build thread
Post by: Studio Mollan on March 22, 2014, 12:00:13 PM
Am I crazy or does not the original schem say 0,001uf? Maybe different revisions?

Never heard about that, do you have a link with the 0,001?

http://www.gyraf.dk/gy_pd/g7/u47.gif

Actually I just found my reference. The U47 book by Oliver of AMI.
Title: Re: MK47 PCB tube mic kit - build thread
Post by: ioaudio on March 22, 2014, 12:04:56 PM
Must be a typo.
Title: Re: MK47 PCB tube mic kit - build thread
Post by: Sorr on April 03, 2014, 12:41:24 AM
Have a microphone with a Thierch Blue capsule in for repairs (the person who built it is uncontactable ). It has a noise floor problem.

The top resistor of the capsule divider is 3M instead of 2M, which gives a lower polarizing voltage.
The rear capsule is connected to the relay via a 1nF cap and there is resistor divider from the B+ to it.
With a ~ 10nF cap decoupling cap to ground part way down it.

Just wondering if anybody knows about these mods to the microphone?
Title: Re: MK47 PCB tube mic kit - build thread
Post by: ioaudio on April 04, 2014, 09:54:42 AM
What kind of noise?
The mod might be a U48 conversion? Shouldn't be difficult to revise it to normal.
Title: Re: MK47 PCB tube mic kit - build thread
Post by: Melodeath00 on April 04, 2014, 09:59:43 AM
Actually I just found my reference. The U47 book by Oliver of AMI.
The U47 Book? Why have I never heard of this, and still can't find it when I google it?
Title: Re: MK47 PCB tube mic kit - build thread
Post by: Studio Mollan on April 04, 2014, 12:03:26 PM
Actually I just found my reference. The U47 book by Oliver of AMI.
The U47 Book? Why have I never heard of this, and still can't find it when I google it?

Well its a really small book. A couple of printed pages. I thing Oliver used to sell them cos my tech bought it a few years back. A bit strange now in the digital age. Pay for a couple of printed pages. I wont post it cos i don't know if oliver is stiull charging for it. NOTHING new though. Its well covered here in this forum. A few Schematis and conversions for 5841, Ef12, ef14 etc.

Title: Re: MK47 PCB tube mic kit - build thread
Post by: Sorr on April 04, 2014, 09:33:26 PM
"What kind of noise?
The mod might be a U48 conversion? Shouldn't be difficult to revise it to normal. "

General noise, signal to noise ratio is too high for recording quite vocals.
The new owner had previously changed valves, no difference.

But you are correct, it  was converted to a U48.
Just changed it back, will see about the noise floor.
Title: Re: MK47 PCB tube mic kit - build thread
Post by: Sorr on April 04, 2014, 10:59:35 PM
Can anyone post the link to the connectors and cable BOM?
I cant seem to find it.
Thanks.
Title: Re: MK47 PCB tube mic kit - build thread
Post by: Aleks on May 21, 2014, 02:20:58 PM
Hi everyone,

Finished my MK47 mic today, fired up nicely no pops or crackles. I have left it to burn in with the stock capsule for now and need to buy a quality capsule for future use. Sounds good even with the cheap chinese one supplied.

Thanks to Tony Camp for giving me the inspiration to build the power supply in an ammunition box. I think it looks cool left as is.

Donor mic was a T-Bone SCT-700, these are very cheap from Thomann in Europe and come with shock-mount and carry case.

Need to research my next project now. Thanks to all the people who make this site what it is.

Cheers, Aleks
Title: Re: MK47 PCB tube mic kit - build thread
Post by: micaddict on May 21, 2014, 04:01:39 PM
Congrats!

Cool PSU case BTW.



Henk
Title: Re: MK47 PCB tube mic kit - build thread
Post by: l.e.d on June 11, 2014, 05:06:57 AM
Hi, does anyone know thw wattage of the 100K carbon comp resistor in the mic?
Thanks
Title: Re: MK47 PCB tube mic kit - build thread
Post by: tonycamp on June 12, 2014, 12:20:00 PM
Hi guys!
I've been using my pair of Mk47's for about two now and they sound very good indeed!
I'm comparing them to my Flea47 and although they are similar sounding the top end is a lot smoother in the flea. Also the flea sounds overal more polished and more flattering, it saturates more and better than the MK47's do, but i guess thats to be expected from a 5000USD microphone. The mk47 is "faster" more modern sounding i guess and compared to the Flea a bit harsh in the hi end. Its not harsh sounding at all though, just comparing to the Flea.   
Im using the Skylar body with Thiersch red mylar capsule. My Flea has a Thiersch blue PVC and EF12.

Any ideas on how to stretch the MK47 towards the flea? I know its a different cirquit but maybee you can get a bit closer with different types/values of caps?
If anyone experimented on this id be very happy for your thoughts!

Also: Howecome the polystyrene cap is 10nf instead of the original U47 spec 1nf? I tried replacing it with a 1nf SilverMica. Hard to tell the difference, at least on this source.   
/
Emil

I've tried a bunch of the usual suspect capsules in my mk47, i can tell you, IMO the blueline is the runaway winner in that regard, smoooooth is the top end, and has that chocolatey M7/u47 vibe(as i understand it), not a bright mic at all, just pretty as heck. I'm also on my 6th set of western tubes, i have hit paydirt with this last pair. I will get the aluminum 10k resistor to throw in here, as i've had the crackling on the first sets of tubes, but i attributed that to bad tubes? remember, DIY requires YOU to dial in/polish up your creations, i simply wouldn't trade my MK47 for a single clone out there.
Title: Re: MK47 PCB tube mic kit - build thread
Post by: Studio Mollan on June 20, 2014, 07:19:10 PM
Hi guys!
I've been using my pair of Mk47's for about two now and they sound very good indeed!
I'm comparing them to my Flea47 and although they are similar sounding the top end is a lot smoother in the flea. Also the flea sounds overal more polished and more flattering, it saturates more and better than the MK47's do, but i guess thats to be expected from a 5000USD microphone. The mk47 is "faster" more modern sounding i guess and compared to the Flea a bit harsh in the hi end. Its not harsh sounding at all though, just comparing to the Flea.   
Im using the Skylar body with Thiersch red mylar capsule. My Flea has a Thiersch blue PVC and EF12.

Any ideas on how to stretch the MK47 towards the flea? I know its a different cirquit but maybee you can get a bit closer with different types/values of caps?
If anyone experimented on this id be very happy for your thoughts!

Also: Howecome the polystyrene cap is 10nf instead of the original U47 spec 1nf? I tried replacing it with a 1nf SilverMica. Hard to tell the difference, at least on this source.   
/
Emil

I've tried a bunch of the usual suspect capsules in my mk47, i can tell you, IMO the blueline is the runaway winner in that regard, smoooooth is the top end, and has that chocolatey M7/u47 vibe(as i understand it), not a bright mic at all, just pretty as heck. I'm also on my 6th set of western tubes, i have hit paydirt with this last pair. I will get the aluminum 10k resistor to throw in here, as i've had the crackling on the first sets of tubes, but i attributed that to bad tubes? remember, DIY requires YOU to dial in/polish up your creations, i simply wouldn't trade my MK47 for a single clone out there.

I have orderd a pair of blue lines and expect that to be the final touch to my mk47s. If I can find time for it I'll try the u48 mod later this summer. It looks like a fast and easy mod (well... I've said that before...) but anyone with tips on that would be nice.
Indeed a beautiful sounding circuit/kit and knowing the full potential of this build I probably wouldn't have bought my Flea 47. Super cheap and a fairy easy build. Apart from the possible danger of high voltages I would consider this one of the simplest microphone builds on this forum. If you haven't built one yet, do it!! I've built mk47, u67 and u87. This one worked right away. No bad tubes, no noise. I had pops and crackles once caused by a loose 1k5 resistor. I reattached it to the base, did not change the tubes, and it has probably seen 200 hours of quiet studio time since.
Great job Max and all contributing forum members!
Title: Re: MK47 PCB tube mic kit - build thread
Post by: teacat on June 27, 2014, 01:25:04 PM
Couple things I don't fully understand relating to this mike:
Has anyone built an mk47 in a gt-2b body as well as an equinox? I wonder what effect the headbaskets might have on the sound?

I'm considering upgrading my mk47 with a Thiersch PVC, and I read somewhere that an m7 has less sensitivity than a k47, so would that ultimately mean a higher noise floor?

Thanks, if anyone cares to drop some knowledge.
Title: Re: MK47 PCB tube mic kit - build thread
Post by: Studio Mollan on June 27, 2014, 01:58:39 PM
Couple things I don't fully understand relating to this mike:
Has anyone built an mk47 in a gt-2b body as well as an equinox? I wonder what effect the headbaskets might have on the sound?

I'm considering upgrading my mk47 with a Thiersch PVC, and I read somewhere that an m7 has less sensitivity than a k47, so would that ultimately mean a higher noise floor?

Thanks, if anyone cares to drop some knowledge.

You can go wrong with a thiersch pvc M7. I'm not sure about the sensitivity but it might have something to do with the difference between PVC and MYLAR? The pvc is thicker and less sensitive in the high register.



Title: Re: MK47 PCB tube mic kit - build thread
Post by: Studio Mollan on June 27, 2014, 02:05:05 PM
I've got a question about the polarisation voltage.
My Flea47 is set up for 125v B+ and I've gathered the information that this is fairly common. An old swedish manufacturer, SELA, used M7/K49 in all their microphones and they indreased the voltage from the neumann spec 105v to 120v. Apparently to get more high frequencies, lower noise floor.
Anybody tried this on the MK47? It should be as easy as turning up the voltage to the mike?
/
Emil
Title: Re: MK47 PCB tube mic kit - build thread
Post by: ioaudio on June 27, 2014, 05:22:18 PM
Hey Emil,

thanks for the kind words.
The voltage devider in the u47 is 2:3 megOhm so the capsule already gets the full 60vdc.
Other mic circuits with fig8 require a 120vdc potential to reach the 60v polarisation per side.
Title: Re: MK47 PCB tube mic kit - build thread
Post by: Studio Mollan on June 27, 2014, 05:47:24 PM
Hey Emil,

thanks for the kind words.
The voltage devider in the u47 is 2:3 megOhm so the capsule already gets the full 60vdc.
Other mic circuits with fig8 require a 120vdc potential to reach the 60v polarisation per side.

Thanks for the reply!
Do you know if increasing the capsule polarization to over 60dB would cause a brighter sound? It would increase output right? Can the tubes run on a slightly higher ht voltage for a quick test?

I know I read somewhere that it's possible to do a high impedance measurement with a standard DMM? I think it's possible to measure and the calculate given the impedance reference in the DMM but I don't know how. Help...
Title: Re: MK47 PCB tube mic kit - build thread
Post by: ioaudio on June 27, 2014, 05:53:46 PM
60Vdc is the specified voltage, i wouldn't change anything.
you can measure the voltage between the 2&3meg, before the 100meg.
don't raise B+, the heater would raise too.

Title: Re: MK47 PCB tube mic kit - build thread
Post by: duy_hoang on July 30, 2014, 04:19:30 PM
Hi guys,

my build of mk47 is now completed. However, there is a massive amount of (white) noise.
I already used  a 1,5 K resistor with alu closure, so it might not be the cause for the noise.

Here are the values I have measured:


1-   B+ 105VDC
2-   Heater : left tube pin3: 19.73 VDC; pin4: 37.11 
                   right tube pin3: 1.49VDC; pin4: 19.74VDC
3-   27R  1.493VDC
4-   Backplate 55.6VDC
5-   pin 5: 52.2 VDC


I also tested more than 5 pairs of tubes (all jan type).   :-\

Hoang
Title: Re: MK47 PCB tube mic kit - build thread
Post by: ioaudio on July 31, 2014, 12:56:53 PM
Most of the Jan 6028 need a long time burning in before their noise goes down.
In some cases the 10nF capacitor got burned from soldering, might be the culprit.


-Max
Title: Re: MK47 PCB tube mic kit - build thread
Post by: duy_hoang on July 31, 2014, 02:07:45 PM
Hi Max,

thanks for the reply. The current tubes were burned in for more than 5 days.  I will try to replace the 10 nF capacitor.

Hoang
Title: Re: MK47 PCB tube mic kit - build thread
Post by: ciscan.81 on August 10, 2014, 08:17:34 PM
Hi

I'm hoping someone can give some advice on implementing a permanent voltmeter into a Zayance PCB/Antek Transformer based PSU. Mains voltage drifts around quite a bit where I live.

I've got a 3 wire 0-200V DC meter which requires 7-28V DC to run. I can't find any info on what current it draws.

I am wondering if I should:

A) Power it using one of the 6.3V secondaries on my Antek transformer via an IC bridge rectifier and cap (cap value???) (assuming the 6.3ish volts will be enough)
B) Tap the PSU somewhere near the LED with a series resistor...?

Reading Chunger's "newbie builds..." thread, noise was a problem with his voltmeter...

A filter cap seems to be the solution...I'm not sure what value to use or exactly where to put it, on the meter power supply wire, or 'measure +' wire?...any help appreciated.

Thanks

Title: Re: MK47 PCB tube mic kit - build thread
Post by: Winetree on August 12, 2014, 10:29:07 PM
Here's some of my 47 builds, minus the center one of course.
Title: Re: MK47 PCB tube mic kit - build thread
Post by: chunger on August 13, 2014, 03:14:39 AM
Hi

I'm hoping someone can give some advice on implementing a permanent voltmeter into a Zayance PCB/Antek Transformer based PSU. Mains voltage drifts around quite a bit where I live.

I've got a 3 wire 0-200V DC meter which requires 7-28V DC to run. I can't find any info on what current it draws.

I am wondering if I should:

A) Power it using one of the 6.3V secondaries on my Antek transformer via an IC bridge rectifier and cap (cap value???) (assuming the 6.3ish volts will be enough)
B) Tap the PSU somewhere near the LED with a series resistor...?

Reading Chunger's "newbie builds..." thread, noise was a problem with his voltmeter...

A filter cap seems to be the solution...I'm not sure what value to use or exactly where to put it, on the meter power supply wire, or 'measure +' wire?...any help appreciated.

Thanks

Matador split the 100K LED resistor into 2 values and we are tapping the meter power supply from there.  It induces noise in that configuration but a filter or smoothing capacitor strapped across the supply seems to have alleviated the noise issue.  The safest thing to do would be to use one of the 6.3V secondaries on a separate regulated supply to power the meter.

We are pursuing the "LED tap" solution to keep the topology simple and be friendly to the readily available 230V toroids that are cheaper, smaller, lighter for shipping, and readily available both in the US and in Europe.

The current prototype using the Antek 200V transformer splits the LED resistor. . . 33K--> voltmeter supply -->67.4K--> LED.  I have a .1uf film capacitor strapped across the voltmeter supply as well.  On my particular meter, with the power supply wide open (unloaded) and in "operate" mode, the B+ goes to 232V and the meter supply tops out at 35.4V.  With a microphone in line and the B+ set to the nominal 105V, the meter supply is 7.6V and the LED is a little dim at 1.8V, but I can live with that.

The main dropping resistors are 750K, 1K, and 500K with a 1K trim pot.

I do not think I can hear noise when I connect and disconnect the meter in this configuration but will test further in the next prototype.  in the studio environment.
Title: Re: MK47 PCB tube mic kit - build thread
Post by: ciscan.81 on August 13, 2014, 06:08:25 AM
Great reply  8) , thanks for sharing Chunger.

I'll post again once I've got it sorted (or not :-\)
Title: Re: MK47 PCB tube mic kit - build thread
Post by: ioaudio on August 13, 2014, 10:41:07 AM
Another (prefered) possibility would be a momentary switch for testing the voltage, making sure nothing interferes with the normal operation.
Title: Re: MK47 PCB tube mic kit - build thread
Post by: ciscan.81 on August 13, 2014, 07:09:24 PM
Thanks Max, I did think that might be a good idea...take the meter out completely when not in use!

I did a bit of reading last night on PSUs with bridge rectifiers and smoothing caps.

I found:

V (r) = I/(f *C)

Where V (r) is the ripple voltage after the smoothing cap, I is the current draw of the load in amps, f is the AC supply freqency doubled (for a full wave rectifier) and C is the capacitor value in farads.

So if I choose to use the 6.3v secondary via an inline IC bridge rectifier and cap to power my meter...

V(r) = (0.08/100*0.001)
       = 0.8V

So assuming 6.3V is transformer secondary rms value: 6.3 *1.4 = 8.8V peak voltage...0.8V ripple is a bit less than 10%.

I guessed at my meter's current draw at around 80ma max (I found a few similar ones stating this online).

So, to someone who knows what they're doing, is my basic theory exercise about right?  :-\

Cap value = 1000uf?

Btw, I chose not to use a resistor in my filter as I didn't want to lose any more voltage as my meter requires 7vdc to run.

Anyway,  I'll pick up some parts this morning and do a test...

Thanks again Max and Chunger.
Title: Re: MK47 PCB tube mic kit - build thread
Post by: ciscan.81 on August 14, 2014, 12:14:19 AM
Update on the voltmeter testing for anyone else who is considering it...

I picked up one of these little guys at my local electronics store:
(http://i1240.photobucket.com/albums/gg494/ciscan81/Rectifier.jpeg) (http://s1240.photobucket.com/user/ciscan81/media/Rectifier.jpeg.html)

It's a bridge rectifier IC that's good for 1A @ 400V, cost about $1.

I also got some different value 16V caps, a couple of 1000uf and a 2200uf.

I installed the rectifier circuit like this:
(http://i1240.photobucket.com/albums/gg494/ciscan81/20140814_121238.jpg) (http://s1240.photobucket.com/user/ciscan81/media/20140814_121238.jpg.html)

Cap soldered across the DC + and - output terminals of the rectifier.

I went with the 2200uf as it seems the prevailing wisdom is that larger values = less ripple. I wasn't sure what the meter would tolerate.

Blue/Green wires are 6.3V AC from my Antek transformer and Red/Black are my (hopefully sufficiently smoothed) DC voltage output.

I temporarily hooked it all up to the meter for testing and it all seems to work ok.
(http://i1240.photobucket.com/albums/gg494/ciscan81/20140814_121838.jpg) (http://s1240.photobucket.com/user/ciscan81/media/20140814_121838.jpg.html)

A few observations:


Hopefully noise won't be a problem in this configuration, once I've got my mic done I'll be able to test. I suppose it is quite possible it may be given my less-than-perfect-DC voltage powering the meter.

If it is an issue I guess it's simple enough to install a filter cap somewhere (as Chunger suggests) or put in a switch to remove the meter completely when not in use (as Max has suggested). With the latter solution,  guess I'll just have to bear in mind the 0.3V increase to the PSU DC output when switching the meter out...

I'm sure this is very simple stuff for those who know what they're doing, but it was a nice little learning exercise for me! 8)
Title: Re: MK47 PCB tube mic kit - build thread
Post by: ciscan.81 on August 19, 2014, 03:08:25 AM
...a final update on the voltmeter installation...(with power supplied from 6.3v AC secondary of Antek 05-T200 Transformer)

I decided to design and etch a little PCB (my first) for the voltmeter I installed on my PSU.

(http://i1240.photobucket.com/albums/gg494/ciscan81/MeterPCB.jpg) (http://s1240.photobucket.com/user/ciscan81/media/MeterPCB.jpg.html)

The process was fun and quite satisfying  8). I designed using the popular 'Eagle' software, printed onto some special 'Press n' Peel' paper and then used an iron to transfer the design onto some PC board.  I etched using Sodium Persulphate. I'm sure I broke a few design rules with the layout and tracks, as I got a little impatient, but it seems to work just fine.

For anyone who is interested, the BOM was as follows:

On the 6.3v AC to DC Rectifier side:
1 x Bridge Rectifier DB104 DIL 1A 400V
1 x 16V 2200uf Electrolytic Capacitor (to remove ripple)
1 x 50V 0.1uf Ceramic Capacitor (as a bypass/filter cap)
1 x 50V 0.01uf Ceramic Capacitor (as a bypass/filter cap)

On the 105V supply DC 'measure' side:
1 x 5k (1/2 watt) trimpot (to allow adjustment of the 'measure' voltage the meter sees)
1 x 630V 0.1uf Sprague 'Orange Drop' Capacitor (as a bypass/filter cap)
1 x 400V 0.01uf Sprague 'Orange Drop' Capacitor (as a bypass/filter cap)

In/Out
2 x 2-way terminal blocks (one for 6.3V AC, and the other for earth/105V 'measure')
1 x 3-way terminal blocks (for the 3 meter wires (supply+, earth and 'measure')

I included the 5k trimpot to give me some adjustment on the meter reading. I have tried 3 different meters, and they were all inaccurate by up to 0.5V. I just turned the pot until the meter was reading the same as my DMM.

I put a couple of bypass/filter caps across the 105v section as a 'just-in-case' measure to prevent noise getting to the mic. (Chunger mentioned that he got a little bit of noise when installing a meter, which he fixed with a filter cap.)

Same goes for the smaller value caps on the 6.3v side, I'm sure they're not doing much but "just-in-case"...  ;)

Now to finish my mic and test! :)

Many thanks to Max, Zayance, Chunger and Matador for making this great project available! 8) 8)

If anyone wants a copy of the little PCB PDF file or schematic, send me a PM.
Title: Re: MK47 PCB tube mic kit - build thread
Post by: reginator on August 23, 2014, 02:25:01 AM
Today I finished and powered up my MK47 and it sounds absolutely fantastic! I have it burning in now and so far everything seems to be working great. I built using: BeesNeez M7 Capsule, Western Electric 408A Tubes, GT-2B Body and Chunger's Point-To-Point Power Supply.

This was fun to build and it's a great sounding mic. Thanks ioaudio!  :)

Title: Re: MK47 PCB tube mic kit - build thread
Post by: Category 5 on September 06, 2014, 05:51:34 PM
Did one of these last night.  What a simple seeming, yet challenging build.  A third hand would have made all the difference when bridging all of the Hi-Z components.

A couple of questions.

A - I see Equinox is gone so who has an affordable 47 style body?  Most concerned with head-basket shape and appearance but would like something that looks like a 47.  i see Beesneez has a killer looking kit, but $500 is a bit steep IMO.

B - Had a hard time getting solder to flow onto the Russion PIO cap.  In hindsight I should have used some extra flux but I managed to get it all soldered up.  not my prettiest work though.  At any rate, I did heat the crap out of it while I was working with it, and though it didn't pop or leak I always worry when I hold on heat for too long.  How will I know if I compromised the part?  ...and if I did, I assume this will be a more than adequate replacement

http://www.ebay.com/itm/200837990034?_trksid=p2060778.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT

right?

I may pop it in anyway just because I like the red.  ;)

C - Any standard pin wiring schemes?  I know as long as PSU and mic match it's golden, but if theres a "common" way I'd like to follow it.

Thanks for another really great project Max.  I may have to build another now, just because the second will be 300% easier now that i know what to expect going in.  In fact, on the next i plan to solder the jumpers to the floating tube socket tabs before inserting them, then just bend them down and connect as prescribed.
Title: Re: MK47 PCB tube mic kit - build thread
Post by: Monoklang on September 16, 2014, 03:41:51 AM
I've had some random "crackle" sound in my MK47, I changed tubes, still there. So I spoke with a friend that had change the 1,5 ohm 5w resistor to a 1,5 ohm 10w. So I did, but when I were to connect the right lead to the PCB, that little "solder ring" fell off.

Is there any solution to this, can I jump to another solder point? Or have I f**ked up…??

Best regards
John
Title: Re: MK47 PCB tube mic kit - build thread
Post by: Category 5 on September 16, 2014, 04:43:26 AM
Just solder it to the + voltage rail directly above the delaminated pad.  Double check w Max on that resistor value.  You want to end up w 20V at the heaters and this resistor is what drops B+ to that 20V. 
Title: Re: MK47 PCB tube mic kit - build thread
Post by: Monoklang on September 16, 2014, 05:05:43 AM
Thanks! I thought so myself, but wasn't 100% sure. The crackle is still there, but since it's new tubes I'll wait a couple of days before pushing the panic button.

John
Title: Re: MK47 PCB tube mic kit - build thread
Post by: ioaudio on September 16, 2014, 09:57:14 AM
yes 1,5kOhm is the value-should be allright now.
Title: Re: MK47 PCB tube mic kit - build thread
Post by: Category 5 on September 16, 2014, 11:08:15 AM
Monoklang, are you using 1.5k or 1.5 ohm?  If it's the latter you're over-volting the heaters and probably need a new set of tubes. 
Title: Re: MK47 PCB tube mic kit - build thread
Post by: ciscan.81 on October 16, 2014, 01:03:18 AM
It's done!  8) ...(almost ;))

Here are a few pics of my MK-47 PSU and Mic.


(http://i1240.photobucket.com/albums/gg494/ciscan81/20141016_142230.jpg) (http://s1240.photobucket.com/user/ciscan81/media/20141016_142230.jpg.html)


The PSU is based on a Zayance PCB and Antek 230>200/6.3/6.3 Transformer.


(http://i1240.photobucket.com/albums/gg494/ciscan81/20141014_165722-1.jpg) (http://s1240.photobucket.com/user/ciscan81/media/20141014_165722-1.jpg.html)


My final resistor values were Choke +1k + 1k + 630ohm and a 500ohm pot. This gives me around a 10v B+ adjustment range with 105v usually around centre. I tested with a 2.4k resistor. My mic seems to be a slightly higher load than that.


(http://i1240.photobucket.com/albums/gg494/ciscan81/20141014_165808.jpg) (http://s1240.photobucket.com/user/ciscan81/media/20141014_165808.jpg.html)


(http://i1240.photobucket.com/albums/gg494/ciscan81/20141014_165753.jpg) (http://s1240.photobucket.com/user/ciscan81/media/20141014_165753.jpg.html)


I mounted the pot on the back of the case with a knob so I could adjust the voltage easily. Mains voltage drifts around quite a bit where I live.


(http://i1240.photobucket.com/albums/gg494/ciscan81/20141016_142515.jpg) (http://s1240.photobucket.com/user/ciscan81/media/20141016_142515.jpg.html)


To monitor the B+ voltage I installed a 4 digit voltmeter. I did this by making a small PCB to rectify one of the 6.3V AC secondary outputs of the Antek transformer to a DC power supply for the meter .  I also included a trimpot on on the PCB to adjust the meter for accuracy. (see earlier post for details). I can report back that there are no noise issues with this setup. The PSU is rock solid and quiet.


(http://i1240.photobucket.com/albums/gg494/ciscan81/20141016_130707.jpg) (http://s1240.photobucket.com/user/ciscan81/media/20141016_130707.jpg.html)


In hindsight a 3-digit meter might have been better as I've found the voltage drifts around by about 0.2v constantly. I assume this is due to mains drift. The voltage can also take sudden drops of around 0.5v when a household appliance on the same circuit kicks in eg. fridge or coffee machine in the kitchen where I took the photos.

I don't suppose it matters much in terms of function, but it can be slightly annoying with the digits constantly changing. It would have perhaps been better to be ignorant to the minor changes and be reassured by the display of a solid 105v!

The other 6.3v secondary powers the jewel light - amber colour to match the voltmeter LED's. It's a little too bright so I will swap for a 12v globe to tame it a bit.


(http://i1240.photobucket.com/albums/gg494/ciscan81/20141016_125540.jpg) (http://s1240.photobucket.com/user/ciscan81/media/20141016_125540.jpg.html)


The PSU case is a 4" x 5" x 8" cheap from China one, found on eBay. Everything just fits inside with not much room to spare. I stripped and repainted it to suit my colour scheme. The text and markings were applied using water-slide decals before a final coat of satin clear. Everything is mounted to a piece of 6mm aluminium angle which doubles as a heat-sink for the resistors. The unit runs just warm to the touch.

I also stripped and painted the mic body - a GT-2B from Chunger. The satin-black finish is fantastic but caused grounding issues between the retaining ring, main sleeve and head-basket, resulting in hum problems. I had to scrape some unseen paint away to get a good contact and now it's quiet as can be. There were a few pings from the WE 408a tubes to begin with but after a few hours burn in they are perfect.

I also foolishly attempted to polish the head-basket rings and upright bits and re-plate them with nickel. It turns out there is some aluminium or something that doesn't like electroplating inside the bottom ring of the head-basket. My electroplating guy told me it just wouldn't take the nickel and it showed signs of etching and blackening ???. The top ring and uprights, being brass, plated fine and look great. I ended up painting the bottom ring to match the body - a look I think I actually like.

After testing with a cheap Chinese capsule, I installed a Thiersch Blue Line capsule, which so far sounds fantastic, detailed and smooth. I have a session on tonight with a great male vocalist. I'm looking forward to hearing the results there.

The last finishing touch I want to do is to add a custom mic badge in matching colour scheme to indicate the front side of the mic. I took some of my design cues from the Neumann badge. I etched the design into some 19mm x 0.8mm brass strip using the same method I use to etch PCB's (laser printer 'toner-transfer' method). It took about half an hour to etch in Ammonium Persulphate. Now I just need to have them polished and nickel plated, paint the etched 'lower' section black and bend to shape.


(http://i1240.photobucket.com/albums/gg494/ciscan81/20141016_140115.jpg) (http://s1240.photobucket.com/user/ciscan81/media/20141016_140115.jpg.html)


Apologies for the marathon post, but I am so pleased with this project, I just had to share!

Finally, many thanks to Max, Zayance, Chunger and Matador for providing such a great project. It is now the jewel of my studio!
 
Title: Re: MK47 PCB tube mic kit - build thread
Post by: TNO73 on October 24, 2014, 07:50:12 AM
Hi guys,

my build of mk47 is now completed.  For PSU i used Zayance PCB!
The Problem is that i can´t get to trim the HT pot B+ Voltage to 105 VDC, when PSU is connected to the mic! The maximum i´m able to get is 102VDC.
When i just connect a dummy load of 2.2kOhm instead of the mic to PSU, i´m able to trim to 105VDC.
I tried already different pairs of tubes burned in for at least 48h(all jan6028) - but nothing changed!
The mic is actually passing audio through....
What could be the problem?
THNX
Tom
Title: Re: MK47 PCB tube mic kit - build thread
Post by: Category 5 on October 24, 2014, 11:03:33 AM
What are the specs of your transformer?  You probably just need to drop the resistance a little.  Do you have the parallel 330ohm on top of the 660 in the last slot?  If not, adding it should drop the resistance to around 220 or so and give you some extra adjustment room. 
Title: Re: MK47 PCB tube mic kit - build thread
Post by: ioaudio on October 25, 2014, 09:58:20 AM
102VDC is close enough, but to rise the voltage, drop the resistance.
Title: Re: MK47 PCB tube mic kit - build thread
Post by: TNO73 on October 25, 2014, 10:53:24 AM
What are the specs of your transformer?  You probably just need to drop the resistance a little.  Do you have the parallel 330ohm on top of the 660 in the last slot?  If not, adding it should drop the resistance to around 220 or so and give you some extra adjustment room.

Thank you very much for your help, problem fixed!!
Tom
Title: Re: MK47 PCB tube mic kit - build thread
Post by: reginator on October 25, 2014, 12:06:10 PM
102VDC is close enough...

On my build I can get 105VDC but it drifts over time by +/- ~0.5VDC but never over 1VDC. I keep the mic and PSU in a stable environment and it performs perfectly with the drift. I've been cracking open the case once a week to verify voltage levels but this gets to be a little tedious. I'd like to keep the lid on and maybe check the voltage once a month or so. Is there an acceptable drift range before the mic's performance is affected?

Thanks!
Title: Re: MK47 PCB tube mic kit - build thread
Post by: Category 5 on October 25, 2014, 12:18:26 PM
Remember that in a passive design output voltage is directly related to input voltage.  You are likely only seeing minor fluctuations in your line voltage which are not a big deal and nothing to obsess over.
Title: Re: MK47 PCB tube mic kit - build thread
Post by: reginator on October 25, 2014, 12:46:49 PM
Thanks for clarifying on the voltage fluctuations - I'll keep the lid on and keep recording!
Title: Re: MK47 PCB tube mic kit - build thread
Post by: jordan s on November 14, 2014, 08:39:59 PM
I enjoyed my mic for about a year after the build but it has since displayed intermittent noise. It's a static or white noise sound that pops in only for short, maybe 0.5 second bursts every 10 seconds or so. It's not super loud but loud enough to be audible to me and my clients. I tried cleaning the high impedance area and even replacing the tubes but the noise is still there. Anyone have any suggestions? I love this mic, it sounds amazing but this issue is making it unusable at the moment.
Title: Re: MK47 PCB tube mic kit - build thread
Post by: Category 5 on November 14, 2014, 11:04:20 PM
I enjoyed my mic for about a year after the build but it has since displayed intermittent noise. It's a static or white noise sound that pops in only for short, maybe 0.5 second bursts every 10 seconds or so. It's not super loud but loud enough to be audible to me and my clients. I tried cleaning the high impedance area and even replacing the tubes but the noise is still there. Anyone have any suggestions? I love this mic, it sounds amazing but this issue is making it unusable at the moment.

Sound like you are using western electric tubes.  I have found them to become this way without warning and have yet to uncover the cause.  I recommend trying some rca, Philips, GE or Sylvania 408a tubes and your problem will likely subside.  The hi-z section is floated in both designs so contamination of these parts is unlikely to be the culprit. 

Some members have achieved better results by switching a sand-bar type dropper resistor with the aluminum sinked type but I have found the problem to arise even with this type of dropper resistor.

I hope some of this helps. 
Title: Re: MK47 PCB tube mic kit - build thread
Post by: jordan s on November 15, 2014, 03:01:05 PM
Thanks for the tip, Cat5. The original tubes that I had the problem with were Phillips. I just put some Western Electric tubes in and have not noticed an improvement. I think replacing that cement resistor is the next step.
Title: Re: MK47 PCB tube mic kit - build thread
Post by: muffy1975 on November 16, 2014, 09:05:23 AM
there's so little it could be. Unlikely to be the dropper.

If i were a betting man i would say it were the valves and maybe even their seating.

Michael
Title: Re: MK47 PCB tube mic kit - build thread
Post by: Category 5 on November 16, 2014, 09:31:11 AM
Thanks for the tip, Cat5. The original tubes that I had the problem with were Phillips. I just put some Western Electric tubes in and have not noticed an improvement. I think replacing that cement resistor is the next step.

The WE tubes sound like that when new.  They pop and crackle and have static.  After a 48 hour break in (running signal through mic) they quiet down but in my experience they still can make noise randomly. 

Before anything try another set of Philips and see if things improve.  They are quieter from the get go but even they may require a good burn in to achieve best noise performance. 
Title: Re: MK47 PCB tube mic kit - build thread
Post by: ioaudio on November 16, 2014, 10:57:22 AM
Thanks for the tip, Cat5. The original tubes that I had the problem with were Phillips. I just put some Western Electric tubes in and have not noticed an improvement. I think replacing that cement resistor is the next step.

I would also suspect the cement resistor - there have been a few cases where this resistor has been the culprit. Replace it with a aluminium housed resistor.

-Max
Title: Re: MK47 PCB tube mic kit - build thread
Post by: MicDaddy on November 16, 2014, 12:36:19 PM
Is this do to non-linearities with the rise in temperature?

I'm trying to understand why one would work better than another if both are wire wound, white soap bar vs aluminum sunk resistors?  Maybe the aluminum dissipates  heat better?



Thanks for the tip, Cat5. The original tubes that I had the problem with were Phillips. I just put some Western Electric tubes in and have not noticed an improvement. I think replacing that cement resistor is the next step.

I would also suspect the cement resistor - there have been a few cases where this resistor has been the culprit. Replace it with a aluminium housed resistor.

-Max
Title: Re: MK47 PCB tube mic kit - build thread
Post by: ioaudio on November 16, 2014, 01:03:47 PM
It's the insulation around the resistance wire - it has to be soft avoid crackling noises from temparatur changes.
Title: Re: MK47 PCB tube mic kit - build thread
Post by: jordan s on November 22, 2014, 03:16:37 AM
I replaced the dropper resistor with an aluminum housed 10w and so far the noise is gone! Let's see how it holds up after a few sessions. Thanks for the help.
Title: Re: MK47 PCB tube mic kit - build thread
Post by: MicDaddy on March 03, 2015, 10:42:53 AM
MK burning for several days. 

Intermittent crackling is not what I would attribute to noisy tubes, but it may be a first.

The popping and crackling is violent, clipping the signal.  I'll post some audio clips, both of what I hear as normal tube futzing and this crazy violent popping. 

The microphone will be quiet for even long periods of time, and then it will go on for several minutes of the popping.

jordan s are you still around, is your microphone still behaving well after the resistor swap? 
Title: Re: MK47 PCB tube mic kit - build thread
Post by: MicDaddy on March 03, 2015, 11:30:20 AM
Quick datasheet observation while hunting down an aluminum chassis mount 1.5K (aluminium for you folks across the pond  ;D )

Temperature Coefficient:

Power Resistors Wirewound Aluminum Housed  20 PPM / C

Power Resistors Wirewound Inorganic Potting Compound  300 PPM / C
Title: Re: MK47 PCB tube mic kit - build thread
Post by: Category 5 on March 03, 2015, 01:05:21 PM
MK burning for several days. 

Intermittent crackling is not what I would attribute to noisy tubes, but it may be a first.

The popping and crackling is violent, clipping the signal.  I'll post some audio clips, both of what I hear as normal tube futzing and this crazy violent popping. 

The microphone will be quiet for even long periods of time, and then it will go on for several minutes of the popping.

jordan s are you still around, is your microphone still behaving well after the resistor swap?

Sounds like the trouble I've had with some Western Electric tubes.  What kind are you using?  Are you using the cement style dropper resistor?
Title: Re: MK47 PCB tube mic kit - build thread
Post by: MicDaddy on March 03, 2015, 02:05:03 PM
JAN Philips and what looks like the cement resistor that came with the kit.

The thing will work fine for hours on end and then blasts of popping, it's not like fizzy futzing in the noise-floor, it's like fireworks.
Title: Re: MK47 PCB tube mic kit - build thread
Post by: Category 5 on March 03, 2015, 03:35:04 PM
JAN Philips and what looks like the cement resistor that came with the kit.

The thing will work fine for hours on end and then blasts of popping, it's not like fizzy futzing in the noise-floor, it's like fireworks.

Yeah.  If you are using the cement resistor than that is likely the problem.  A good quality aluminum sinked resistor has solved the issue for more than a few MK47s.

Current kits are already including the newer resistors, that's why I asked.
Title: Re: MK47 PCB tube mic kit - build thread
Post by: MicDaddy on March 03, 2015, 04:03:28 PM
I've got a bunch on the way.  I was curious as I'd seen IOaudio recommend replacing yet the photo for the mk kit at Chunger's place still shows the cement type..

Thanks guys!  I'll follow up with the audio and when the new 1.5K show up.
Title: Re: MK47 PCB tube mic kit - build thread
Post by: ioaudio on March 03, 2015, 08:38:06 PM
Hey,

yes the aluminium resistor should solve that problem - there was a batch of cement resistors showing the fireworks you describe.

-Max
Title: Re: MK47 PCB tube mic kit - build thread
Post by: MicDaddy on March 10, 2015, 12:50:38 AM
Swapped through a few sets of tubes just to exhaust that possibility, popping followed the mic.

Swapped the 1.5k with a 10W aluminum, no more popping...  8)  thanks everyone for your help hunting that down!

Sad news, now my mic is stuck in omni...  did I kill the relay (how to test?), break a trace swapping tubes?   

I'm seeing ~90VDC before the output cap, this seems very high?  Thanks for any tips  :D
Title: Re: MK47 PCB tube mic kit - build thread
Post by: duy_hoang on March 10, 2015, 09:17:25 AM
I had the same problem. The solder pad of the relais was disconnected to the rest. I had to bridged it with an extra cable (the red one).
Title: Re: MK47 PCB tube mic kit - build thread
Post by: MicDaddy on March 10, 2015, 11:38:59 AM
Thank you duy_hoang, so you say you had a trace go open? 

I suspected I had broken one/several of the 90* solder pads where the main and daughter board meet from the stresses of swapping tubes. Would ideally like to secure that daughter board with something supplemental to those 90* solder joints.

From which contact to which did you apply the jumper?  (I suppose I could try to figure it out from the schematic but I don't have the mic in front of me.)

If I'm looking at the diode, would it be cathode to polarity, or anode to ground that was disrupted? 

When switching the pattern, I hear the normal pwop but no polar change...(can you hear the relais inside the mic?) 

I'll chime those two traces with the DMM and see if one is open.  Thanks again!!
Title: Re: MK47 PCB tube mic kit - build thread
Post by: Category 5 on March 10, 2015, 12:08:12 PM
Did you test the mic without the pattern wire connected?  just disconnect it inside the PSU and see if that changes anything.  You would normally be stuck in cardioid in such case.
Title: Re: MK47 PCB tube mic kit - build thread
Post by: duy_hoang on March 10, 2015, 12:23:32 PM
Hi,
 in my case, it was stuck in cardiod mode like Category 5 said. The faulty solder pad was the one of the lower relais pin (see picture)
Title: Re: MK47 PCB tube mic kit - build thread
Post by: duy_hoang on March 10, 2015, 12:25:00 PM
And a picture of the wiring on the back side.
Title: Re: MK47 PCB tube mic kit - build thread
Post by: MicDaddy on March 10, 2015, 12:34:53 PM
Excellent points and tips guys!  So sounds like my relais is stuck on/closed/shorting (term?)...

I'll try to both disconnect the polarity rail at the PSU and inside the mic (should go cardioid?)  If that works to get the mic to cardioid I'll hunt for a short, or replace the relais?  I suppose I could check the relais powered down for open/short?

I'll measure my switch for correct operation, perhaps it failed?

What else might cause the relais to not shut down... if the above fails I'll disconnect the rear diaphragm just for sanity check.  ;D 
Title: Re: MK47 PCB tube mic kit - build thread
Post by: ioaudio on March 10, 2015, 01:22:26 PM
If it's stuck in omni, it means the  relais is active /turned on.
Search around the pattern switch, maybe it's not correctly connected.
90 V is very high, what's your B+?
Title: Re: MK47 PCB tube mic kit - build thread
Post by: MicDaddy on March 10, 2015, 01:38:05 PM
B+ at the PCB under load (mic) ~104+ 
I will double check.
Title: Re: MK47 PCB tube mic kit - build thread
Post by: MicDaddy on March 11, 2015, 07:26:02 PM
 :'( what a stupid problem...  the tubes which I was testing in the mic (northern electric) have some nasty white corrosion underneath. 

Swapped the tubes back for the JANs and my patterns are working, no crazy popping.  Working. 

Thanks again guys! 

(https://fbcdn-sphotos-h-a.akamaihd.net/hphotos-ak-xpf1/v/t1.0-9/10955377_10202560118724286_2273160841102898798_n.jpg?oh=3cc1f55f560dc615492f4d48448b551e&oe=558EE2A0&__gda__=1434619615_c38b3f7f47d5a798abbad216e7ac9baf)
Title: Re: MK47 PCB tube mic kit - build thread
Post by: tonycamp on March 13, 2015, 01:0