micaddict

Re: MK47 PCB tube mic kit - build thread
« Reply #1400 on: April 26, 2016, 04:02:44 AM »
In76d wrote:

Quote
Yes, it's typical for 6028 - i don't know how those tubes can be considered as related to VF14.
Specs are different. Good that many folks like it, but is it anyway close to U47?
You readings are fine for 6028. There 's no option to get real U47 specs here.
For plate is correct, for polarisation - yes your multimeter input impedance is too low, for heaters - it should be a little underheating. 40V was a big underheating for VF14. To get similar result (in theory of course) for 6028 you should get around 13-14V :) I doubt that these tubes can work with that low heater voltage.

AFAIK the 6028 is basically a "hotter" version of the EF95 or 6AK5.

There's an 18AK5, too (Vf 18 Volts).


toneyrn

Re: MK47 PCB tube mic kit - build thread
« Reply #1401 on: July 17, 2016, 06:22:50 AM »
Is it possible to modify this to support a third polar pattern (figure of 8)?

useme2305

Re: MK47 PCB tube mic kit - build thread
« Reply #1402 on: August 02, 2016, 05:31:16 AM »
hey everyone,

i just read about putting the 1,5k resistor in the psu case in the aputis white market thread.

this of course is very easily achieved within this build with a 7 pin connector since we only need 5 pins for this mic.

my initial thought was to  simply make a roundtrip from mic to psu case via two cables and have the 1,5k resistor in the case.

but then i thought why not just put the resistor in the case, connect one end to the 105V source inside the psu and therefore only use one strand of the 7pin cable instead of two. this would be the right way to do it, right?

any cons that come with this solution? why was it not implemented in the original design of the MK47?

EmRR

Re: MK47 PCB tube mic kit - build thread
« Reply #1403 on: July 05, 2017, 09:15:15 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

Did you find a reason?  Several reports in the full thread, seemingly different solutions in all cases.  I have one here doing the same. 
Best,

Doug Williams
Electromagnetic Radiation Recorders

"I think this can be better. Some kind of control that's intuitive, not complicated like a single knob" - Crusty

"Back when everything sounde

gevermil

Re: MK47 PCB tube mic kit - build thread
« Reply #1404 on: July 05, 2017, 09:55:18 PM »
exact same scenario here .

EmRR

Re: MK47 PCB tube mic kit - build thread
« Reply #1405 on: July 06, 2017, 06:40:19 PM »
I notice I have some electrical noise, sounds like ground hum, low but audible when in cardoid mode. Omni is dead quiet.

exact same scenario here .

FIX:  ground pattern control line at PSU for cardioid rather than letting it float.  DPDT switch will let you wire it that way.  At least worked on this one. 
« Last Edit: July 06, 2017, 06:44:16 PM by emrr »
Best,

Doug Williams
Electromagnetic Radiation Recorders

"I think this can be better. Some kind of control that's intuitive, not complicated like a single knob" - Crusty

"Back when everything sounde

Potato Cakes

Re: MK47 PCB tube mic kit - build thread
« Reply #1406 on: July 13, 2017, 10:24:54 AM »
Does anyone still have the schematic and/or BOM for the PSU? It seems the links have been taken down on the original post.

Thanks!

Paul

glimmertwins

Re: MK47 PCB tube mic kit - build thread
« Reply #1407 on: September 04, 2017, 01:05:06 AM »
2nd request for archived versions of the information listed in the first post - photos, BOM, etc.  Looks like ioaudio's mailbox is full so can't message him via the private message feature. Thanks in advance!

Re: MK47 PCB tube mic kit - build thread
« Reply #1408 on: September 10, 2017, 01:48:34 PM »
Does anyone still have the schematic and/or BOM for the PSU? It seems the links have been taken down on the original post.

Thanks!

Paul

This may be a bit late, but I have these...the first one was from Chunger, I'm assuming it's ok to put it up because I got it frome here. I have a couple more files I'll add also

Re: MK47 PCB tube mic kit - build thread
« Reply #1409 on: September 10, 2017, 01:49:40 PM »
Does anyone still have the schematic and/or BOM for the PSU? It seems the links have been taken down on the original post.

Thanks!

Paul



Re: MK47 PCB tube mic kit - build thread
« Reply #1410 on: September 10, 2017, 01:51:37 PM »
Does anyone still have the schematic and/or BOM for the PSU? It seems the links have been taken down on the original post.

Thanks!

Paul

Hope these help



Re: MK47 PCB tube mic kit - build thread
« Reply #1411 on: September 10, 2017, 02:01:36 PM »
Does anyone still have the schematic and/or BOM for the PSU? It seems the links have been taken down on the original post.

Thanks!

Paul

Here's a link to a page here also that was a big help for me when I built the D-47

https://groupdiy.com/index.php?topic=47112.60

Potato Cakes

Re: MK47 PCB tube mic kit - build thread
« Reply #1412 on: September 10, 2017, 02:02:37 PM »
I appreciate the info!

Thanks!

Paul

Re: MK47 PCB tube mic kit - build thread
« Reply #1413 on: September 10, 2017, 02:19:06 PM »
I appreciate the info!

Thanks!

Paul

Cool! Happy to help, I thought I had more, but that's all I can find. I tried to save as much info as I could when I built mine even though I built the other version

Potato Cakes

Re: MK47 PCB tube mic kit - build thread
« Reply #1414 on: September 10, 2017, 03:17:38 PM »
I'm actually using this for a different U47 build, so the only thing I have left to sort out is resistors for a variable polarity pattern, but I may just get lazy and just use 3.

Thanks!

Paul

TDJ

Re: MK47 PCB tube mic kit - build thread
« Reply #1415 on: October 31, 2017, 04:33:43 PM »
Is this kit still being sold?

Phrazemaster

Re: MK47 PCB tube mic kit - build thread
« Reply #1416 on: October 31, 2017, 05:24:28 PM »
Check with Chunger’s white market thread, or his store on the web (store.studio939.com I think)
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** * Kablooie!

Potato Cakes

Re: MK47 PCB tube mic kit - build thread
« Reply #1417 on: December 05, 2017, 06:58:01 PM »
Hello, everyone,

I just finished building the PSU and checked with the test load and after some tweaks to R4 I am able to get the B+ to 105V and everything thing is great. In the past I have used a 180k resistor for the test load that has always seemed fine, but using that here yields very high voltage like there is no load at all. Granted this has been mostly for C12/251 PSUs, but I' almost certain I have used it for a different U47 PSU before, but only almost. Is this just the properties of different PSUs interacting with different mics that need different testing methods? A dumb question, I know, and I'm pretty sure I know the answer. My inquiry mostly relates to learning the different methods for testing my builds and knowing that the readings I get are indeed correct and not marred by faulty procedures on my part.

Thanks!

Paul

Rixsta

Re: MK47 PCB tube mic kit - build thread
« Reply #1418 on: April 10, 2018, 08:51:09 AM »
Can anyone tell me if the SCT700 microphone can only be used for the case/chassis for the MK47 or can parts of the power supply also be used ?

Re: MK47 PCB tube mic kit - build thread
« Reply #1419 on: April 21, 2019, 11:11:09 AM »
Hi all,

I have a couple of questions..
I just completed a second MK47, using a PCB + transformer kit purchased mostly completed from a friend, and using an Equinox body & other parts I had purchased already when I first built one of these mic’s.

The second mic seems to have turned out pretty fine, but I’m noticing it registers 102v at the mic, using the power supply from the first mic, whereas the first mic registers just under 105v at the mic.

I visually inspected all components, and everything looks pretty much essentially identical between the two mic’s.

The only different is that in the first mic I used the Cathedral Pipes ‘Dale M7’ style capsule, whereas in the second mic I installed the Equinox Q-47 (K47 style) capsule.

So one question is, does the capsule itself effect the voltage I’m seeing at the mic, or should I be looking elsewhere?
(and does it matter if the second mic only sees 102v instead of 105v?)

I am yet to build the second power supply, so I can certainly adjust that to suit the second mic, but I’m just curious about whether both supplies should be compatible in the end, with both mic’s.

Also, I noticed the second mic seems to have lower overall  output level than the first one, seems like.

Is this likely to be due to the voltage, and / or different capsule?

Or perhaps another component?

Thanks!
Evan
« Last Edit: April 21, 2019, 11:15:52 AM by EvLoutonian »


 

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