Neumann Vintage U87 Clone : Build Thread.

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fsalter

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" That doesn't look right. On a 2N3819 L to R when the flat of the transistor is facing you the leads are S G D."
I agree. This is wrong. I'm pretty sure on most jfets you can get away with reversing S and D, but your gate (the middle leg) in the 3819 and NTE312 have to be soldered in the middle.
 

DT_Music

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Mar 16, 2018
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fsalter said:
" That doesn't look right. On a 2N3819 L to R when the flat of the transistor is facing you the leads are S G D."
I agree. This is wrong. I'm pretty sure on most jfets you can get away with reversing S and D, but your gate (the middle leg) in the 3819 and NTE312 have to be soldered in the middle.

You're actually getting to the heart of the question.  I know that the middle is the gate on the 3819, but on the NTE312 the gate is one of the outer legs.  The drawing on the NTE312 data sheet is a little hard to follow so I'm not exactly clear which outer leg is the gate.

So in the picture, I have the leg on the left (which, if you were holding the JFET up to you by the legs with the flat side towards you would be the leg on the right) going to the isolation lug which if I understand correctly should be where the gate goes.

If anyone has a picture of how they connected their NTE312 maybe that would avoid further confusion.
 

Ricardus

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DT_Music said:
You're actually getting to the heart of the question.  I know that the middle is the gate on the 3819, but on the NTE312 the gate is one of the outer legs.  The drawing on the NTE312 data sheet is a little hard to follow so I'm not exactly clear which outer leg is the gate.

So in the picture, I have the leg on the left (which, if you were holding the JFET up to you by the legs with the flat side towards you would be the leg on the right) going to the isolation lug which if I understand correctly should be where the gate goes.

If anyone has a picture of how they connected their NTE312 maybe that would avoid further confusion.

If you have the transistor facing you, with the FLAT side facing you, on the NTE312 the leads are G S D.

That's enough info to solder this in correctly.
 

joakimkarlthomas

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Hi! One of my DIY U87 built with DanyB pcbs have a multipattern capsule (RK87). I skipped the switch pcb but would like to insert a jumper installation to change to figure 8 and omni when needed. I tried to jumper the pads on the board ”CRD” and ”8”. Could not get it to work, is there anything more I need to do? Both sides of the capsule is of course already soldered to the board.
 

Ricardus

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joakimkarlthomas said:
Hi! One of my DIY U87 built with DanyB pcbs have a multipattern capsule (RK87). I skipped the switch pcb but would like to insert a jumper installation to change to figure 8 and omni when needed. I tried to jumper the pads on the board ”CRD” and ”8”. Could not get it to work, is there anything more I need to do? Both sides of the capsule is of course already soldered to the board.

Jumpering CRD and 8 should give you figure eight. At least according to what I'm seeing.
 

bxershrts

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Snow and noise -

Hello everyone - I have built a Dany B U87i. The polar Patterns 'Cardioid and Omni' have low level white noise- like that of snowy hiss yet the figure 8 pattern is very quiet. My first thought was that the pcb has flux that was making a connection between points at the high impedance input or at the switch connections. I have re- cleaned the board with isopropyl and it persists. Perhaps this is a capacitor issue? Has anyone else had this issue? Looking for advice for where to pursue this issue. Everything else works as intended.

Thanks!

 

AV

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Hello everyon.
I am new in GroupDIY and I am trying to build a u87 clon based on a K87 capsule.
I have two questions.
One is the body. I purchased a generic body that do not fit correctly the PCB because I saw no bodies in stock in Studio939.
Have you any alternative body?

Other is how to contact with vintagemicrophonekits.com. Just ordered PCBs and switches and need to kinow how much time will be waiting to receive it.
Regards
 

Ricardus

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AV said:
Hello everyon.
I am new in GroupDIY and I am trying to build a u87 clon based on a K87 capsule.
I have two questions.
One is the body. I purchased a generic body that do not fit correctly the PCB because I saw no bodies in stock in Studio939.
Have you any alternative body?

Other is how to contact with vintagemicrophonekits.com. Just ordered PCBs and switches and need to kinow how much time will be waiting to receive it.
Regards

Bodies are tough. Hopefully someone here can point you in the right direction.

When I ordered my boards I got them in 2 weeks I think. But I am in the US not too far from him.

His contact info is around here somewhere.
 

geekmacdaddy

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Greets. Anyone know the sizes of the screws and spacers for the Switch PCB's on Dany's U87L and the smaller screws that attach the main PCB's to an SYT-5 frame?

Thank you :)
 

egroys

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Apr 18, 2020
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Curious what folks are using as a replacement for the Axial Leaded 63volts 10uF 5x12 20% on the BOM as Mouser is showing 'Obsolete.'

Also, would anyone suggest any changes (like seeking tighter tolerances) or general advice for building a pair?

Thank you!
 
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egroys

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Any opinions on best transformer for this build?
The Cinemag 13113 is half the price of the AMI T13 so I am curious if it's worth the difference.

Thanks!
 
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nielsk

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So, to preface, I have successfully built at least 2 dozen large diaphragm mics, but this one has me stumped.
Green V1.1 PCBs. Mic biases correctly, set to 10.5 VDC at JFET drain.
With no capsule connected I inject tone into the JFET or the FD pad and get good signal out of the mic.
I get nothing out of the capsule. I have tried a Maiku, a Pleuso, and a Chinese (all known to work), no difference. I am seeing about 41 VDC at F BDY pad and about 3 VDC at R BDY.
I have checked all capacitors and resistors (under a gig), no bad solders or solder bridges.
Any ideas?

Update, figured it out. I has installed 2436 FET as I had a noise selected old stock one from Neumann. As it turns out, the footprint on the PCB is for 2n3819, mirror of the original. While it passes tone just fine installed backwards, it does not work with the capsule. I'm sure this info is buried somewhere in the over 3,000 posts in this thread if one were willing to search long enough to find it!
BTW, one the FET is installed backwards they no longer work :-(
 
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nielsk

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Capsule sitting (on edge) on the wood bench wired directly to PCB
Good question, though. I have encountered a bad batch of mounts before, the rubber part had too much carbon in the composition and was acting as a high value resistor connecting the backplate to the chassis!
 

Purplenoise

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Capsule sitting (on edge) on the wood bench wired directly to PCB
Good question, though. I have encountered a bad batch of mounts before, the rubber part had too much carbon in the composition and was acting as a high value resistor connecting the backplate to the chassis!
Long shot but since most of MY mistakes were idiotic….have you checked xlr connection and transformer?
 

nielsk

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Yes, thanks, I have made my share as well!
As I mentioned, I can inject tone directly into the JFET or to the capsule front pad and it comes out of the preamp the mic is connected to nice and clear, this should confirm the mic circuit is functioning correctly from the capsule connection to the XLR pins
 

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