Neumann Vintage U87 Clone : Build Thread.

[Mickey Free]

Yes, now you have me wondering about the orientation on that fet data sheet. And yes, that is the board 2 schematic from the original post on this thread.

So the mic would technically still work if the fet were backwards?

 

[Matador]

Mostly likely yes.  Most JFET's source and drain terminals are interchangeable.  So long as the gate remains in the middle it probably doesn't matter much.

 

[Mickey Free]

Thanks Matador

 

[gary o]

Im currently experimenting with this circuit to learn & make nice mic...wondered if some one could point me in the right direction can anyone tell me the funtiiiions of C1 & C3 ....... Im making a puely cardiod version for now & Im trying to understand what the parts do & which parts to eliminate Im thinking if I lose C1 C2 C3 & R1 R3 R4 R5 plus the switch of coarse ..... doe this sound right or do I still need some parts for cardiod, thanks.

 

[andyfromdenver]

Hi DIY U87 super users!
Couple Qs.  I've had my mic for a while now and seriously loving it (thanks a million!).
One observation the other day.  I was recording a woodblock performance (may be just a wrong mic for the job thing), but it's like the hitting of the woodblock was overloading the mic.
I was a couple feet away, and every time I'd hit, the sound was far away and gross, like the worst dynamic mic.  Does this sound right?
Weirdly, I can do vocals loud and up close and it sounds like what you would expect.

Two things: 1.  Without a scope, I was only able to bias via the recommended voltage reading (can't recall the specifics, but you know what I'm talking bout right?  I have the trimmer in).
2.  When I soldered the Peluso capsule (here's a "only happen once in a smart persons life confession") a tiny blob of rosin, < a millimeter, landed on the capsule.  When it happened it's like time slowed down as the blob arced through the air to my screams of noooooo!  Anyway, that little thing has been haunting me, though I and more experienced friends find it sounds wonderful regardless.

Lastly, I purchased a fellow gdiy guys bom for an 1176 project and included were the styrenes.
Do you think I should swap them in?  Anyone have experience to comment on whether it's worth the effort or not?  I'm ok with marginal/percentages of improvement/vibe.


Anyhoo, I did a nice song with it recently and I think it really compliments my voice.
I love singing soft and up close with the hipass on.  magic!!

Any input appreciated!

And if anyone wants, I can upload said song.

Thanks for reading!
Andy

 

[chunger]

Recent session w/ the U87 clone. . . this is using AMI T13 and the Peluso capsule.

 

[Melodeath00]

That sounds very good, Chung! Is it the U87 just on the vocal, or more? Love that snare too

 

[phonofranz]

Recent session w/ the U87 clone. . . this is using AMI T13 and the Peluso capsule.

Interesting. I'm just back from a session with a totally different genre, nasal indie "depressed" male vocals... Surprisingly (or not) I can hear the same microphone's character, altought I've used different capsule and transformer, particularly in the high-mid range with the same "grainy" air and "forwardness", lacking better terms...

Can I ask what preamplifier did you use, Chunger ?

 

[chunger]

Recent session w/ the U87 clone. . . this is using AMI T13 and the Peluso capsule.

Interesting. I'm just back from a session with a totally different genre, nasal indie "depressed" male vocals... Surprisingly (or not) I can hear the same microphone's character, altought I've used different capsule and transformer, particularly in the high-mid range with the same "grainy" air and "forwardness", lacking better terms...

Can I ask what preamplifier did you use, Chunger ?

Great river preamp into an LA3A.

 

[andyfromdenver]

This is from Dale Ulan:
"If you are in a pinch or in a hurry, and don't mind a compromise, you can use the same trimpot method except measure the voltage at the drain of the mic and get it to about 10 to 11 volts - that'll be in the general ballpark. Then, speak very loudly, very close, but without popping air at the capsule, into the mic while measuring the drain voltage on a DC voltmeter. If the voltage drifts around a lot, then adjust the pot a bit one way or the other to try to keep it from doing that. This is a very crude way of doing what Klaus' method is doing. Obviously his is better and more accurate, but I've done this in a pinch.

If you stop at the first (rough) part of this test (just setting the voltage), you might find that the mic will cut out occasionally on plosives or even loud passages.

If you are using this voltmeter method, make sure you measure the voltage using either a digital or a vacuum-tube voltmeter or an oscilloscope. You can't use a normal 'analog' voltmeter as it will upset the circuit too much."

Quoting a section of this great post, if you saw my post a couple back, I think the issue described here (with the cutting out) is what's going on when I was hitting the woodblock.

I'll repot back when I make some scope-less bias progress.  Also, since I'm opening it up again, gonna go ahead and switch to the Polystyrenes.
Love my DIYU87  

tbc,
Andy

 

[Pip]

This is from Dale Ulan:
"If you are in a pinch or in a hurry, and don't mind a compromise, you can use the same trimpot method except measure the voltage at the drain of the mic and get it to about 10 to 11 volts - that'll be in the general ballpark. Then, speak very loudly, very close, but without popping air at the capsule, into the mic while measuring the drain voltage on a DC voltmeter. If the voltage drifts around a lot, then adjust the pot a bit one way or the other to try to keep it from doing that. This is a very crude way of doing what Klaus' method is doing. Obviously his is better and more accurate, but I've done this in a pinch.

If you stop at the first (rough) part of this test (just setting the voltage), you might find that the mic will cut out occasionally on plosives or even loud passages.

If you are using this voltmeter method, make sure you measure the voltage using either a digital or a vacuum-tube voltmeter or an oscilloscope. You can't use a normal 'analog' voltmeter as it will upset the circuit too much."

Quoting a section of this great post, if you saw my post a couple back, I think the issue described here (with the cutting out) is what's going on when I was hitting the woodblock.

I'll repot back when I make some scope-less bias progress.  Also, since I'm opening it up again, gonna go ahead and switch to the Polystyrenes.
Love my DIYU87  

tbc,
Andy

Yes and do. I have built 2 of these one with Wima caps and the other with Polystyrene caps. After much listening I have decided to take out the Wimas and replace with polystyrenes. IMHO it is the sound we all want from this mic.

 

[Mickey Free]

Hey Udo,

You were helping me trouble shoot about a month ago and I have an update finally. Here's what I've done so far:

-Reversed the FET so it is properly installed in the right orientation. In the process the original FET broke and I had to swap one in and re-bias. This time around the waveform was a little strange, and very slightly saw-toothed. Weird.
-Lifted all Pattern switches to force cardioid mode, as well as the low cut and pad switches.

And so, SAME PROBLEMS. VERY low output and high noise. Could I have installed the capsule wrong? Cant think of what else I am missing here...

Any help is appreciated. Thanks all!

Happy New Year!

Mickey

 

[andyfromdenver]

Yes and do. I have built 2 of these one with Wima caps and the other with Polystyrene caps. After much listening I have decided to take out the Wimas and replace with polystyrenes. IMHO it is the sound we all want from this mic.

Thank you for the vote of confidence.

I got sidetracked working on a guitar  amp (ok, and modded my top loading Nintendo for A/V...) and the day slipped away.  Going to revisit the mic tomorrow

Polystyrene-tastic!

 

[poctop]

Example of using the D-U87 for vocals,  Thanks to Alex G. that shared the link to me ,

https://www.youtube.com/watch?v=okZ3oj9cH-k

Best,
DAn,

 

[andyfromdenver]

I've been listening to lots of the tracks posted.  Great stuff!  Super pros around here

I got serious about the scope-less bias-ing (i'll post a funny pic next).  Sounds better.  I also, cleaned the bits of dust off the capsule, and soooo carefully removed the little rosin blob with a needle (I was envisioning my peluso capsule flushing down the toilet).  That "cut out" sound is gone now when I use a woodblock or maracas.  I think it's about as close to 100% as i'll get without a scope.

Here is a song with the mic for my new album (Marshmallow Coast "Vangelis Rides Again")  the song is called "Hills Are Alive".
I'm singing with my lips pretty much on the mic, no pop filter, just quietly and trying not to plosive.  Hi pass engaged, in cardioid mode.
Also, my diy 1176 and the neve portico pre, with even more hi pass. 
Hope you like it!.

 

[andyfromdenver]

Oh yeah, and the song is unmastered so level may be low.
Here's my bias set up
The looping pedal kept me hands free for adjusting.

 

[Graph]

Hi, i am having some trouble with my finishe(and not working) D U87.

the problem i got, is.. there is not sound, only ground noise(using with a Duet), when i touch the case, it makes some loud noises, and capacitors are a little hot. Maybe a short? Where do i need to start looking for the problem?

Thanks!

 

[andyfromdenver]

Hi Graph. 
You should do quadruple super fine tooth comb checks for miswiring, solder bridges, etc.
Then, what style/size boards did you use, in what body?  Is there a weird fit issue that is grounding the signal.
then, I can't acces certain links at work, but there is a computer drawn schematic with average voltages on it.

But sounds like before you apply power again, Do the first two.  Especially some super throurough continuity checks.

Hope you find it!

If all else fails or you are stumped, some hi res pics of your boards front and back and all wiring would be good, especially incase the xlr connector is miswired too etc.

 

[Graph]

Hi Graph. 
You should do quadruple super fine tooth comb checks for miswiring, solder bridges, etc.
Then, what style/size boards did you use, in what body?  Is there a weird fit issue that is grounding the signal.
then, I can't acces certain links at work, but there is a computer drawn schematic with average voltages on it.

But sounds like before you apply power again, Do the first two.  Especially some super throurough continuity checks.

Hope you find it!

If all else fails or you are stumped, some hi res pics of your boards front and back and all wiring would be good, especially incase the xlr connector is miswired too etc.

Thanks andy, I think its a cold solder or something. Now it "works" at very low lvl and with lot of noises like crackles. Yesterday it worked fine before i went to sleep, and the weird stuff if i change the polar settings, it gets some "explotions"

Capsule is RK 87 from Microphone parts
PCB is the Tapper one
Mic body is MicandMod one.

Update: Well, the drain voltage was pretty high, i got it from 15v to 11v,

The only problem now is this crackle

https://soundcloud.com/grahf-1/ruido-neumann

Hum noise goes away when i close the mic body, so no problem with it, but that crackle, didnt happened yesterday when it "worked" without problems, then i went to sleep and the crackle was the main problem.

All traces are fine.


Edit: All problems went away and now it is working fine.... awesome sound, but need like 10dbs more than other mics.

Update/Edit 2: or testing purpose, i left the mic with phantom power over 2 hour on. When i got back, it was everything noise, and it didnt reproduce any audio. Maybe some capacitor is making any problem?
Thank you again

 

[andyfromdenver]

Poo-ville (that may not translate well, sorry ), maybe your ground connection is bad/intermittent.  Can you clip a jumper or two from a good pcb ground to the rails? 
I'm often in the "it's not the parts" camp, but it could be.  Did you download/print out that scheme with the voltages for comparison?  Sadly, I'm on a phone at home and couldn't find it again! 
Maybe a backwards elytic???  Might be good to break out the camera!

Keep at it . The reward shall be super great.
P.S.  I don't know your electronics background, so if any of my suggestions seem demeaning/elementary, I apologize.