Neumann Vintage U87 Clone : Build Thread.

[zaraxisof]

thanks TillM once again  8)

 

[Mrosso]

I've got an issue with my completed U87 clone. The volume is so low it is unusable. It's got a Peluso capsule and a T13 transformer. I was pretty meticulous with the build, but I am not being successful at troubleshooting the problem. Any of you guys want to give it a shot? I can ship you the mic and maybe $50? I'm at my wits end, and I really don't want to turn this thing into an expensive brick.

 

[micaddict]

The vintage U87 has lower output than most modern LDC's.

But it should be usable, obviously.

Just in case, may I ask what kind of preamp you use?

 

[Mrosso]

Just in case, may I ask what kind of preamp you use?

Sure, I've tried it through a few different pres, including a Hairball Lola, Capi V28, and a 1073 clone. All sàme result.

 

[micaddict]

Yeah, that was a long shot.

I was just editing my earlier post to add that the vintage U87 is not a "hot" microphone. On the contrary.
But something does seem wrong in your case.

 

[ln76d]

I've got an issue with my completed U87 clone. The volume is so low it is unusable.

Did you set bias corretly?

 

[Mrosso]

Did you set bias corretly?

Yes, I believe I did. It's been a while since I built the mic - it's been stored/unused for over a year. If I remember correctly, I did get the right values on my meter following Chunger's guide. To be honest, I've been building gear for over ten years (back to the old Gyraf days), but I am by no means an electronics engineer. I've been pretty "paint-by-numbers" with everything. The few projects that didn't work properly, I've sold as parts here on the Black Market. I don't want to abandon this one, though.

 

[ln76d]

Don't gave up! 

Measure first voltage in the circuit and report.

 

[micaddict]

Does it even get worse when you use the pad?

 

[rmburrow]

I've got an issue with my completed U87 clone. The volume is so low it is unusable. It's got a Peluso capsule and a T13 transformer. I was pretty meticulous with the build, but I am not being successful at troubleshooting the problem. Any of you guys want to give it a shot? I can ship you the mic and maybe $50? I'm at my wits end, and I really don't want to turn this thing into an expensive brick.

Have a digital DMM by any chance, to make some voltage tests?  No polarizing voltage or improper voltage on the FET, the output level will be low.  Check your wiring first...

 

[Mrosso]

Don't gave up! 

Measure first voltage in the circuit and report.

Thanks. I believe I measured these correctly. Here is what I got with my DMM

 

[ln76d]

Ok, except one looks good.
Disconnect Gate of the FET and measure voltage on the floating Gate node.
If shows nothing - then change voltage range on multimeter.
We will find the "bug"  soon

 

[Mrosso]

I had an idea I wanted to check with you guys. There was some confusion on my side about how to wire the Peluso capsule. Here is a diagram of my wiring. Does this look right? Could this be the problem? Your help is much appreciated. Thanks

 

[Murdock]

It seems that you have two connections coming from the rear backplate (RBK).
But I think you need one from "rear backplate" and one from the "front backplate"... So move the FBK screw to the other backplate.

 

[TillM]

If you wired it up like you show on the picture, this will definitely the mistake.
Your front plate has no ground connection.

 

[Mrosso]

It seems that you have two connections coming from the rear backplate (RBK).
But I think you need one from "rear backplate" and one from the "front backplate"... So move the FBK screw to the other backplate.

Thank you! The capsule connectivity is still a bit confusing. Is this the correct wiring?

 

[TillM]

No,
you have two backplates, one for the front capsules and one for the rear capsule.
You just grounded the rear capsule.
Let the RBK as it is and take the FBK screw in one hole directly behind your front plate.

 

[fsalter]

This is  how you have to do it.

 

[Mrosso]

This is  how you have to do it.

Thank you, guys! I'll try that now

 

[Murdock]

yeah sorry. I should've been more clear.