Neumann Vintage U87 Clone : Build Thread.

[doggy6812]

Hey guys. I am having a problem with one of my builds. I have A his that sounds like White Noise.I have clean this board multiple times serious I remove the poly styrene capacitors to clean the board. I am at a loss. I am using a 797 capsule from a 1st gen c1. And Cinemag transformer. This capsule and tranny worked fine and n another Dany pcb. Anyone else have this issue or had it? I have 23.34 v at the zener. 40 v to the capsuleR14 21.2  r12 11.6

 

[Ricardus]

No,  figure 8 is not working.

OK, but why were you talking about Omni mode then, a dozen messages back?

 

[HosaMogami]

OK, but why were you talking about Omni mode then, a dozen messages back?

Every other one of my posts was talking about figure 8, I did mistype one post which is now corrected so my apologies.

 

[Ricardus]

Every other one of my posts was talking about figure 8, I did mistype one post which is now corrected so my apologies.

Oh, OK. No worries. It did throw me off a little but, that's all.

 

[Delta Sigma]

Every other one of my posts was talking about figure 8, I did mistype one post which is now corrected so my apologies.

I'm not familiar with the project - never built a U87 - but I took a quick look at the Schematic. If your voltage is fine (looks like C9/R13 junction to 0V is the place to measure) and there's no shorts between backplates and diaphragms check C2. If Omni and Cardioid are fine, there's not much that can be wrong. Also, remember that in the hi-z sections, all work should be done with gloves (non-powdered nitrile) because oils from your hands may be enough to cause problems in the hi-z sections.

Use the original Neumann schematics along with Dany's for troubleshooting. They paint a pretty clear picture of a not-so-simple hi-z and pattern switching section.

 

[hazer-drum]

I think I may have the same issue, Omni and Cardioid work flawlessly but Figure of 8 has crackling noises on both of my builds...

 

[TLRT]

I think I may have the same issue, Omni and Cardioid work flawlessly but Figure of 8 has crackling noises on both of my builds...

Check shorts between the 2 capsule backplates. Maybe your mount screw shorting the 2 backplates together(those needs to be separated)

 

[DT_Music]

D-U87 Build Thread


To Bias Fet, make sure you install R6 backward in reference to the silk screen like this:

I noticed that the picture you showed was of board V1.1 .  Does the reverse R6 still apply on V1.2?

 

[doggy6812]

Can you guys see this post? I’m not sure that they are being seen.

 

[Ricardus]

Can you guys see this post? I’m not sure that they are being seen.

Yes.

 

[Delta Sigma]

Hey guys. I am having a problem with one of my builds. I have A his that sounds like White Noise.I have clean this board multiple times serious I remove the poly styrene capacitors to clean the board. I am at a loss. I am using a 797 capsule from a 1st gen c1. And Cinemag transformer. This capsule and tranny worked fine and n another Dany pcb. Anyone else have this issue or had it? I have 23.34 v at the zener. 40 v to the capsuleR14 21.2  r12 11.6

Try replacing your capsule with a similar value cap. May help you narrow down the source of your issue. Make sure you wear gloves when working on the hi-z sections of the mic.

 

[doggy6812]

Thank you! I’m gonna give that a shot. I just finished matadors c12 build today. It Went pretty smooth and sounds great but this 87 hiss issue is kicking my butt.

 

[Ricardus]

Any luck finding your issue HosaMogami?

 

[1coin3lives]

Hi all,

87 build newbie here with a suitably newbie question.

I'm having trouble getting started on this build.  I've got the D-87M PCB from Danny and a the full Mouser BOM.

I see that the PCB shows values for each component, but the terminology isn't obvious to me for all of them. The resistors are easy enough, on some of the caps the writing is very small (I'm worried about misreading), and a few I just don't understand.

Is there something along the lines of a master list of parts and values? I'm thinking in terms of something like what Hairball Audio has on this build page (just the table at the top, not the interactive build map). Kind of like a BOM, but specific to the PCB:

http://library.hairballaudio.com/maps/revarack/

I can't seem to find anything like that for the 87, though as a newbie I admit I'm susceptible to overlooking obvious information  .

Any help would be appreciated!

 

[fsalter]

1coin3lives, all the information is there. My experience tells me you can't be lazy, and not read through the thread, especially when what you need is at the begining. He has an excellent excel doc :
"Read This First : Assembly Instruction , Excel BOM and Tips For Assembly and  Important Considerations Here: https://cdn.groupbuilder.com/groupdiy/u/39511/58d1402a02019.xlsx"

 

[1coin3lives]

fsalter, thank you for that link - that's very helpful. I'm not sure how I overlooked that.

Believe me, it's not my intention to be lazy. For what it's worth I've already read a fair bit of this thread - at least the first 30 and last 20 pages. I didn't see that Excel in there somehow.

The issue for me so far as been that there is so much information that I've had difficulty separating what's necessary from what's not.

In any event, I appreciate your help and look forward to moving ahead with the build.

 

[Ricardus]

So the Mouser BOM listed has extra stuff in it. Like 10, 1% 2.2k resistors so you can (hopefully) find an exact matched pair. And also, I think it has 60 megohm and 68 megohm resistors in it, when you only need one of those pairs. I think once upon a time the 60s went out of stock, so someone added the 68s without removing the 60s. The original circuit I think called for the 60s, but the 68s will work fine too. It also has 2 trimmer pots for adjusting your bias voltage for the FET. You only need one, and only one of them has the right pin alignment for the PCB.

Pay attention to how you install the 2N3819!

Also, where did you GET your 2N3819?

This is (all) explained in this thread:

http://www.vintagemicrophonepcbkit.com/Neumann%20U87%20Build.htm

Also, pay attention to capacitor polarity. It matters on electrolytics and tantalums!

This is probably not the best build for a beginner, because it is a little complicated, but good luck!

 

[TillM]

Also 68megaohm was used by Neumann.
There are some alternatives for the 2N3819.
Just look in the thread.
If you don’t solder anything before, the U87 is not a good starting point.

 

[1coin3lives]

Ricardus, I wasn't sure if your post was in reply to me, but I'll respond as if it were 

A GroupDIY member was kind enough to send me a few 2N3819s. For those who still need them I've since discovered one source that still has some:

https://www.ntepartsdirect.com/ENG/PRODUCT/2N3819

Thanks for the other comments. To clarify, I'm probably more intermediate than beginner. But I do suffer from beginner problems sometimes.

Also, where did you GET your 2N3819?

 

[Ricardus]

Also 68megaohm was used by Neumann.

The old schematic I have shows 60, but they'll all work fine.