MK47 PCB tube mic kit - build thread

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

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

You did the right thing - nor harm - add resistance if voltage is too high.

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

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

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.

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

I don't see an orientation on the vishay 1813 1uf cap, Does it matter which way? Thanks

North, looking at the schematic it seems they're all NOT polarized caps so the way doesn't matter.

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?

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

maq3396 said:

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

Click to expand...

-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
 

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

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

Thanks for the help!

Cheers
Mac

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.

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.

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:


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:


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?

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.

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