MK47 PCB tube mic kit - build thread

[micaddict]

Thanks!

Any more details, like capsule and body used?

 

[braeden]

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  :

 

[electrisizer]

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 

 

[North]

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

 

[micaddict]

oh i forgot. its the t.bone body and beezneez capsule.

Thanks. 

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.

 

[Joelv]

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


Cheers,
-Joel

 

[ioaudio]

Joel,
it sounds like you tested the mic without the mic body/headbasket assembled.

 

[Joelv]

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

 

[braeden]

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.

 

[HellfireStudios]

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-

 

[maq3396]

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

 

[braeden]

-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

 

[EvLoutonian]

Has anyone tried an MK47 build using an original Neumann PSU?

 

[maq3396]

Thanks Braeden!

Cheers
Mac

 

[useme2305]

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.

 

[EvLoutonian]

..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!

 

[useme2305]

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.

 

[braeden]

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

 

[EvLoutonian]

.. 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.

 

[useme2305]

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 **** 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?