Neumann Vintage U87 Clone : Build Thread.

[kante1603]

an rme babyface von deutschland

Hi,

the babyface itself is balanced exept of the phones and the digital I/Os.
Seems you have attached the wrong breakout cable (BF-BOCMKH) which is unbalanced and is sold as an option.The original interface must have come with a breakout cable that has two male and two female XLRs at least!
Did you buy it used or new?

With the right cable it will work of course.

Or you take any other preamp or console input you have around.

Best regards,

Udo.

 

[wink0195]

gotcha. I got it new so it's balanced but i wasn't sure since it's connected via usb. for power. I went ahead doing calibration as featured in the youtube video.

http://www.youtube.com/watch?v=DtNH46jpwJo

calibration part starts at 9 minutes

Nothing smoked, but I barely got sound out of the dang thing... so I definitely did something wrong. I did't really hear much of a difference between patterns and the noise floor was super high. it wasn't a low frequency whir just more like a high frequency hiss... the behringer switches are really driving me nuts. I think I'll run tests and buy new switches in the meantime. any recommendation for replacement polar patern switches?

My main question now is I see some capacitor in the bom that say to use them instead of the capsule for calibration. How do you do this? I simply wired up the capsule and calibrated. Did I do something wrong???? I will retrace the signal through the circuit point by point in the meantime :/

 

[kante1603]

gotcha. I got it new so it's balanced but i wasn't sure since it's connected via usb. for power. I went ahead doing calibration as featured in the youtube video.

http://www.youtube.com/watch?v=DtNH46jpwJo

calibration part starts at 9 minutes

Nothing smoked, but I barely got sound out of the dang thing... so I definitely did something wrong. I did't really hear much of a difference between patterns and the noise floor was super high. it wasn't a low frequency whir just more like a high frequency hiss... the behringer switches are really driving me nuts. I think I'll run tests and buy new switches in the meantime. any recommendation for replacement polar patern switches?

My main question now is I see some capacitor in the bom that say to use them instead of the capsule for calibration. How do you do this? I simply wired up the capsule and calibrated. Did I do something wrong???? I will retrace the signal through the circuit point by point in the meantime :/

Jesus,that´s not good......

You did things wrong,no doubt-or have a damaged fet,or built something else.....who knows.
Forget about the switches by now.
Did you do the initial voltage tests,did you follow all recommendations here and did you read the whole thread?
We need this as a first basic info from you.
After that we can proceed.....
The mentioned cap (50pF or so) in the bom is not needed for calibration.
Btw.,the scope method is the best by far,but at least we should get this mic up and running even the other way.

Meanwhile let´s get things sorted.

First confirm the phantom is o.k.,measure the voltage coming from the babyface at the female xlr of the breakout cable.Set your dmm to dc and measure between xlr pins 1&2 as well as 1&3.Both readings should be identical,around the 48vdc area.What do you get?

Then lift all seven switch wires from the pcb points and put them aside,we don´t need the switches at this moment.The mic is now-given the capsule is attached-in just cardioid mode (only the front capsule is working now),hpf and pad are disabled.

If phantom is o.k. give it a listen again,did something change significantly?

Also what you can do is measure the xlr pins 2&3 with dmm set to ohms-what do you get?

This is my trial to shoot out several parts being not proper or damaged or hooked up the wrong way.

With the switches desoldered it could be useful to have some pics from the pcb,both sides,if possible from the solder sides too.

Please report back here,

Udo.

 

[LG]

HI Every one,

My build is slowly getting there (then I mean slowly since im kind of learning by dooing...) 
Can someone point out what kind of connectors you use for connecting wires to the Molex headers? I can't realy find it here on the forum, guessing it's some kind of common knowlegd one just knows....

Kind regards from Copenhagen
-L

 

[JessJackson]

First recording i used my u87 on

http://www.youtube.com/watch?v=MzVdDHpSuNc&feature=share&list=UU-Eh1lR_tWVtv9AvxLybMtQ

Had to De ess a lot, top end needs taming, don't expect to hear unprocessed recording from me. lol

J

Hi Jess,

can you post a pure untreated track of the vox please?It's impossible at least for me to comment on the mic sound,it is way to sharp for my ears this way.When you say you even had to de-ess a lot then I would start thinking there's something not so propper as it should be.Can you tell us a bit more on your mic about which capsule you used and if you went for styrenes,transformer choice etc.?
That would be useful.
Personally I can't remember to ever have had a de-esser on a U87 in the past 26 years during vocal tracking.
Just curious,

Udo.

Hi mate i agree...

tx used is ami
capsule used is dans capsule
i used styrenes in the build

Somethings definitely not right.. id be willing to send the mic to someone to take a look at it. it would be interesting to get another perspective on it as I've been all over the circuit and cant trace problem.

chain is u87 > martech mss-10 > tube tech cl1b > avid omni > PT10hd

has more sibilance than my sony c800g and my vintage c12

 

[kante1603]

Hi mate i agree...

tx used is ami
capsule used is dans capsule
i used styrenes in the build

Somethings definitely not right.. id be willing to send the mic to someone to take a look at it. it would be interesting to get another perspective on it as I've been all over the circuit and cant trace problem.

chain is u87 > martech mss-10 > tube tech cl1b > avid omni > PT10hd

has more sibilance than my sony c800g and my vintage c12

Hi,

O.k.,.....
Interesting chain you have there,have never heard of that martech,looks expensive,hahaha.....
Anyway,I have the same caps and transformers in mine,but can you tell me what "Dan's capsule" is?
But for now good luck with troubleshooting,

best,

Udo.

 

[micaddict]

have never heard of that martech

Although I haven't used the Martech MSS-10 myself, I do know it's a well respected, high end pre that is used by top studios.
Expensive, yes. And of course this here community holds some of the happy few who can brew their own high end pres for less. 

 

[kante1603]

Thanksfor the info,

Udo.

 

[wink0195]

After troubleshooting the microphone more last night and trying out Udo's cardioid test with none of the switches attached I was able to get the microphone working somewhat better, however though the noise I described before is less intense, I still have quite a bit of white noise waterfall-like noise that requires an extreme amount of gain (well over 50 dB). I suspect that this is a result of a damaged FET - which I'm actually extremely pleased with because the internal components and the PCB are the cheapest parts of the build.

I'm really hoping that my capsule has not been affected considering I bought a stereo matched pair of capsules in hopes of building a stereo pair of DIY-u87's. Though the FET circuit is likely damaged, the capsules response is still very smooth – it is just hidden behind a great deal of blurry white noise.

I have no problem with yanking out the circuit board and scrapping it if it is necessary, but I really hope that the capsule was not damaged during my clumsy process of wiring up the polar pattern, pad , and low-cut switches. 


To answer Udo's questions regarding whether I've read the entire information on this build bread, I think it's a fair estimate to say that I've intently read about 65% of the total 96 pages. I've also watched Peterson's DIY tutorial video on YouTube at least 100 times by now. Still the first microphone I'm buildingand I know very little about how the microphone actually works. The only thing I really know how to do well is solder and make sure everything is grounded.

Being that I have little to no clue regarding how to troubleshoot an FET circuit, I am actually leaning towards buying new PCBs and completely rebuilding a new FET from fresh undamaged parts. It would be great if I could salvage my matched resistors, my RK-87 (which is 1 of a stereo matched pair), and my AMI T13 transformer.

I hope now to identify my mistakes so that I don't repeat them. I will post photos of my build and the sound sample of the my sickly microphone later tonight once I get done with work. If someone could explain how capsules and FET's commonly get damaged, it might really help me identify where I went wrong and educate me as to not repeat the same mistake(s). Also if you have any tips to testing and troubleshooting both the capsule and the FET I'm all ears.

There are three things that I'm certain when wrong with this build:
1) I clumsily tried to solder all the switches to the b2-pro switch assembly and I'm near sure that I shorted out a few wires that I wasn't supposed to.
2) When I was sealing up the microphone up for a test run, one of the wires to the switches (I think it was the low cut filter) got pinched, cut,and then brushed against the chassis. When I applied phantom power to this I got a nice little zap as my wrist was grounded via a bracelet to an electrical socket ground.
3) When testing the drain on the semiconductor, I'm certain that my big clunky alligator clip touch both hands two and three shorting them out one phantom power was applied.

If anyone can make sense of all this information, it would be much appreciated. That's all I know for now and I will post more info later tonight. Thanks – Andrew

 

[kante1603]

Hi Andrew,

o.k.,the FET (which is the Transistor btw.) is a cheap part,so you can swap it.
After that-as said-do the initial voltage tests.Also test the phantom on your babyface as described before.
Don´t attach the capsule nor the switch wires.
Do the bias next.
If all went well attach the capsule,check it in cardioid mode as described.
Then go on with the switches etc.

Be patient....

What measuring instruments do you have,can you read capacitance with them?
Can you test transistors?
Oh,I forgot to say that you should check the idss too,the procedure is found on page 1.
This will make sure you have a working FET within the specs then.Do that prior to soldering of course.

The capsule might get damaged when touching the membranes,the trial to clean it or fooling around on the tiny screws.

Udo.

 

[Pip]

My suggestion once again is scrap those dang switches. Again think back to how many times once you made your selections with this or any mic with fixed A or B switching options you messed with them during the actual session. Why are so many mics cardioid only!? All the options are available from the PCB with the jumper blocks.

I have my build loaned to a friend right now and have gotten really good feedback about it. He actually liked the idea of the blocks and in no way complained at all about haveing to open the mic to make these changes. By the way his #1 mic of choice is his prized vintage Neumann refurbished U87i. We jave a contender people.

 

[JessJackson]

Hi mate i agree...

tx used is ami
capsule used is dans capsule
i used styrenes in the build

Somethings definitely not right.. id be willing to send the mic to someone to take a look at it. it would be interesting to get another perspective on it as I've been all over the circuit and cant trace problem.

chain is u87 > martech mss-10 > tube tech cl1b > avid omni > PT10hd

has more sibilance than my sony c800g and my vintage c12

Hi,

O.k.,.....
Interesting chain you have there,have never heard of that martech,looks expensive,hahaha.....
Anyway,I have the same caps and transformers in mine,but can you tell me what "Dan's capsule" is?
But for now good luck with troubleshooting,

best,

Udo.

Hi Udo,

Sorry I meant Eric's capsule, I get names mixed up a lot when Ive never met the someone in person.

Yeah martech is just a natural sounding fet pre.. it allows you to insert a compressor after the pre amp stage and before the gain stage, using the martech to make up the gain instead of the compressor.

I have two, one i'm selling if anyone wants it.

thanks for the luck with the troubleshooting, lol

J

 

[kante1603]

Hi Jess,

cool,thought I had missed something with that capsule,hahaha....

Best,

Udo.

 

[Melodeath00]

has more sibilance than my sony c800g and my vintage c12

OT, but are you planning to build the Chunger/Matador C12? I'd love to hear it next to a real vintage C12. Also, I wonder if we will see a GroupDiY C800G project...

 

[wink0195]

Dear Udo,

I have a Mastech MS8268 Digital AC/DC Auto/Manual Range Digital Multimeter which I used during the build for measuring components, checking idss values of transistors, and measuring the matched resistors for R18 and R19. 

I definitely didn't mess with the capsule, clean/touch it or mess with the screws, but I did connect it BEFORE calibrating the idss bias. Does that make a difference?

I'm working sun up to sundown selling roadside produce and I have online classes for college too, so I have more money then time right now. I will post photos and updates when I have an extra hour or so.

Can I measure/test the fet in the pcb? or do I desolder and take it out?

Thanks for all the help
- Andrew

 

[micaddict]

Thanks for all the help

+1

Thanks, Udo, for doing what you're doing in this thread.



Henk

 

[poctop]

Thanks for all the help

+1

Thanks, Udo, for doing what you're doing in this thread.



Henk

+1 For Udo for beeing so generous in here as well.
Best,
Dan,

 

[kante1603]

Dear Udo,

I have a Mastech MS8268 Digital AC/DC Auto/Manual Range Digital Multimeter which I used during the build for measuring components, checking idss values of transistors, and measuring the matched resistors for R18 and R19. 

O.K.

I definitely didn't mess with the capsule, clean/touch it or mess with the screws, but I did connect it BEFORE calibrating the idss bias. Does that make a difference?

You can´t calibrate "...idsss bias...".
The idss measuring is done before soldering in the fet (which again is the transistor,just this single part).
Biasing is then done with the fet in circuit,but the capsule should not be attached.
It does make a difference!

I'm working sun up to sundown selling roadside produce and I have online classes for college too, so I have more money then time right now. I will post photos and updates when I have an extra hour or so.

As said,patience is the key......ommmmmmmm.........

Can I measure/test the fet in the pcb? or do I desolder and take it out?

The answer is already in this post.......

Thanks for all the help
- Andrew

You´re welcome Andrew,

best,

Udo

 

[kante1603]

Thanks for all the help

+1

Thanks, Udo, for doing what you're doing in this thread.



Henk

+1 For Udo for beeing so generous in here as well.
Best,
Dan,

Oh please stop it!
{the man´s face turns red......then a big fart.....} ;D ;D ;D ;D

 

[Cardinen]

Hi All,

I've my U87 clone sitting on the workbench from a long time now, so i hope you can help me.
The main problem is: i'm not able to bias the FET, the voltages seems Ok everywhere but not on the Drain.
I'm using Peluso transformer and RK-87 capsule by M. Parts.

I've swapped 3-4 different FET, now i have the one with the lowest IDSS installed (5mA) and i have just 0.4V on the Drain. Tried to change the trimmer from 10K to 25K/50K don't help.

my voltages (with capsule and transformer, same without):

Phantom:  47.86V

Top of R18: 47.8
Bot of R19: 47.8
Node R18/R19: 46.68V
Zener : 23.83V
node R12/R14: 19.71
FET Drain :  0.42V    (23.3V on the pad without FET and trimmer)
FET Source: 0.32V

I'm using 68M resistors instead of 60M, could be a problem ?

Below you can see two photo, any help will be appreciated.

Thanks