Neumann Vintage U87 Clone : Build Thread.

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Hey guys, does anybody use Moby's Bv.13 in the D-87M blue?
View attachment 112372
Maybe someone can help me with wiring.

View attachment 112371


This is from Moby's Site.

is it correct that i have to solder the 2 white one in the PRI together and in the SEC green and yellow?

Then connect it to the PCB:

black --> P+
red --> P-
white --> S+
blue --> S-

is that correct?
@Moby ? :cool:
Thanks in Advance!

Damian
Yes, correct.
 
Thanks to this fantastic community, I just finished build for my son couple of U87, using SYT bodies (just got them before Jenny's move), Dany's blue PCM, Cinemag 13113, one with a SYT supplied capsule and one with Soliloqueen Capsule. They both work out of the bench, apart the fig.8 of the chineses capsule, probably due to lack of bacplate insulation. I am not trained to appreciate differences, will let this to my son who is completing his training as sound engineer and has planned an A/B/C with a Neumann u87. Again thanks to all !

Now my question. I have assembled the PCB with a low IDSS 2N3819 (8mA), orienting the FET as in the serigraphy, also looking at the build example on Dany's site. By looking at the datasheet IC pinout and the schematics of the board, it seems to me that the 2N3819 is wired with source and drain reversed. Option 1: I read wrongly the schematics Option 2: the circuit works also with the reverse wiring. From my crude knowledge of JFET manufacturing, this can also be the case; the only real impacting change from wiring a 2N3819 in reverse should be the differences in Gate-Source vs Gate-Drain capacitance. I ahve also read somewhere that for the 2N3819 the CGD is higher that GGS, contrary to most JFETs, but I couldn't confirm. Any thougths appreciated.
 
From my crude knowledge of JFET manufacturing, this can also be the case; the only real impacting change from wiring a 2N3819 in reverse should be the differences in Gate-Source vs Gate-Drain capacitance.
That's typically the case with many "simple" FET's (that don't include protection diodes or other additions).
I ahve also read somewhere that for the 2N3819 the CGD is higher that GGS, contrary to most JFETs, but I couldn't confirm. Any thougths appreciated.
All datasheets mentioned 8pF "input" capacitance and 4pF reverse capacitance. Wiring it in reverse would almost always result in lower "gain" (sensitivity) and degraded Signal-to-Noise ratio..
You may be able to make a direct comparison, using a tone generator and a capacitor replacing the capsule and measure the resulting gain.
 
Newbie here and just a little bit confused. I’ve got an Aurycle A460 I’d love to convert to this U87 build. But, in all the pictures I’ve seen so far of the taper builds, I don’t see where the transformer would actually fit. I’ve opened up my A460 and it doesn’t seem like there’s enough room inside for a transformer. What am I missing?
 
Newbie here and just a little bit confused. I’ve got an Aurycle A460 I’d love to convert to this U87 build. But, in all the pictures I’ve seen so far of the taper builds, I don’t see where the transformer would actually fit. I’ve opened up my A460 and it doesn’t seem like there’s enough room inside for a transformer. What am I missing?

I don't know the A460, but doesn't it have a metal bell cover down at the XLR end that the transformer sits inside?
 
If I’m building this project into an Aurycle A460 donor body, do I need to order the switch PCB or can I just connect the existing wires from the pad and cut switch to the taper PCB? Looks like from previous reports I would need to switch the leads of the low cut switch to have it work properly.

For the pattern selector, I’m guessing I could just use some internal jumper posts and unscrew the body to switch when/if needed, right?
 
If I’m building this project into an Aurycle A460 donor body, do I need to order the switch PCB or can I just connect the existing wires from the pad and cut switch to the taper PCB? Looks like from previous reports I would need to switch the leads of the low cut switch to have it work properly.

For the pattern selector, I’m guessing I could just use some internal jumper posts and unscrew the body to switch when/if needed, right?
Yes and yes. No need for switch pcb
 
I'm just curious if anyone knows where the PCBs ship from? I placed an order last Thursday for a PCB and caps I could use to build the U87 into an Aurycle A460 body I've got but haven't heard anything. Just wondering what I should expect there, if anyone knows.
 
"I'm just curious if anyone knows where the PCBs ship from?"
Dany's business is in Montreal, Canada. I know him well and could ask him what's the hold up. But no worries, he may be busy. I know he has a teaching job too.
 
I've almost got all of the parts needed for this build. With the Aurycle A460 donor body, do I need anything in particular to mount the K87 (an Arienne Audio K87) capsule or is the stock A460 mount going to work? Seems like the stock capsule is smaller.
 

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