Neumann Vintage U87 Clone : Build Thread.

[useme2305]

1x http://www.banzaimusic.com/Salecom-SKS08LP-Subminiature.html
2x http://www.banzaimusic.com/Salecom-SKS06LP-Subminiature.html

 

[Lakewood]

1x http://www.banzaimusic.com/Salecom-SKS08LP-Subminiature.html
2x http://www.banzaimusic.com/Salecom-SKS06LP-Subminiature.html

Thank you very much!

 

[Lakewood]

Another question: isnt it better to take a pair of metalfilm resistors with 0.1% tolerance for the matching?

 

[Neutrino]

Another question: isnt it better to take a pair of metalfilm resistors with 0.1% tolerance for the matching?

Yes that is possible.

 

[Rixsta]

Hey all
Been looking a little at this thread, Im really interested in building a clone like this, Ive tried to find out if this is a Class-A topology microphone as Im a fan of that kind of sound. 
Also I am currently using an M-Audio Nova microphone and hoping this will be a step up, the Nova is rather thin, its lacking body or much energy in the mid-range and bass department, it does not sound full and its that kind of full and warm/natural sound with transparency and clarity that im looking for in order to get some really good recording done.

I also Own a Prism Sound Orpheus recording device, its a great recorder with high up there sound quality, so am hoping I can match it up with a U87 or U47 clone. Otherwise ill just buy a Rode K2 which is a bit more sensible in the price department.

have built some Nelson Pass amplifiers in the past so pretty into this whole DIY thing!

Have only just joined this forum but looking exited to getting on with making ...stuff!

 

[micaddict]

Welcome! 

 

[Lakewood]

Hey guys,

There is something strange when I'm measuring the IDSS of my JFETS: I connect Pin1&2 to the negative side of a 9V Battery, the positive side of the battery goes into my Multimeter (set to 20mA) and the other wire if the multimeter is connected to Pin3 of the JFET..

I got good values first, ranged from 6mA to about 9mA, but after a while my multimeter only shows 0.1mA if I test the JFET's!
Also the JFET's I've tested before (with good values) are showing 0.1mA now.. How can this be? 

Cheers, Leo!

 

[Carnesd]

Your multimeter fuse is blown.  If the leads on the jfet touch it's enough current to pop the fuse in your meter.

 

[Lakewood]

Your multimeter fuse is blown.  If the leads on the jfet touch it's enough current to pop the fuse in your meter.

Well, thank you very much, that was the Problem x) seems that i accidently touched the other pins  :

 

[TillM]

asymmetrical waveform is abnormal
possible solutions , most to lesser probable :
-bad biasing or bad Jfet , check biasing with a scope and signal injection
-bad source capacitor c8, change it
-bad capsule , try with another or a 80pf capacitor with signal injection, clean it , change it or look foward
-bad polarization resistor(s)  check all voltages with a static voltmeter , clean or change it
-leaking or bad negative feedback capacitors c3 , c5 , c6 or c9  or even c1 , c2 , change it
-bad c7 , check dc after with signal sinus injection , change it
-bad c6, c7 ,L1 , L2 change or remove
-bad output transformer

regards

Big thanks to Frederic and ln76d.
I used the mic for some recording session in the last year, with bad adjustment, but for vocals it work, also with the asymetrical clipping (at vocals there was no asymetrical clipping),
Well, the last couple of months I build a tons of preamps and after finished all projects I look at my u87 clone and think by myself: "You spend a lot of money and it does not work the right way, take your soldering iron and fix it!"
I've to say, I buy some u87 parts again, just for repair.
What i*ve done. I changed the jfet, and soldered the WIMA caps in, cause i see, that I touched two of them with my soldering iron and they was a bit melted.
Then I took the peluso capsule and clean it.
The jfet i now choose with matadors method. So I take one with 9,2 mA.
Then I get a diy oscilloscope from amazon.
I took this one
https://www.amazon.de/kkmoon-15001K-Digital-Oscilloscope-Parts/dp/B01MAWKEUN/ref=sr_1_3?ie=UTF8&qid=1497386451&sr=8-3&keywords=diy+oscilloscope

if you not in europe
https://www.amazon.com/Kuman-Oscilloscope-Source-15001K-pre-soldered/dp/B06Y5DBFXK/ref=sr_1_fkmr0_3?ie=UTF8&qid=1497386465&sr=8-3-fkmr0&keywords=kkmoon+15001K

I highly recommend if you don't need a oscilloscope everyday.
I biased everything and can take my mic for my drums, finally.

 

[babaorum]

I screwed the bottom of the microphone so hard that I can not unscrew it !
And I made some small stripes on the new body ... garglll    :-[ 

Don't you have a tip to do it ?

 

[hugo]

You do not need to unscrew this, solder straight it is clearly doable. To avoid microphonics, use 24 or less awg. I guess, with my poor knowledge

 

[babaorum]

I don't think we are talking about the same thing,
I 'm talking about the part which is screwed around the XLR in the Body SYT-5 from the kit of the D-87M

 

[Seppotron]

Can anybody tell how this compares to microphone-parts T-84 circuit kit?
https://microphone-parts.com/products/t-84-circuit-kit?variant=8667064771

 

[errba]

Hey Mates,

after using my clone for a few months now all of a sudden the mic has become very muffled and has an almost vinyl like sound and pop coming in through the xlr cable that's consistent... any idea of what the issue may be or where i should start?

 

[zaraxisof]

Hi to everyone,
Can i use  680pF caps instead of 470pF,820pF,220pF,560pF for C1/C4,C3,C6,C15 ?

 

[TillM]

ah now I understand your question from the another thread.
Short answer.
No.
This will not work ... or better it could work, but I wouldn't try it.
But here in this forum are better experts to tell you what would happen

 

[zaraxisof]

you got it now  oh so i guess i have to put the same exact values described in BOM  for each one.
Thank u again TillM !

 

[zaraxisof]

and smtng else: the Volts for each one described in BOM must also be followed strictly?

@TillM  you said about original Neumman that it is 160v. Which  could the "max" limit be (if we can say that). 500v? 600v?

 

[TillM]

500v and 600/630v will be fine.

The another question from you, how the styroflex effect the sound, you better wait until the real experts answer your question.