Neumann Vintage U87 Clone : Build Thread.

[ln76d]

#4. Sorry it's so many posts. I can't get the IMG tag to work.

Ok, for the first look don't see anything wrong, maybe some solder joints could be little bit better (worth to check especially these from cable connections). Hmmm...
What capsule you are using?

 

[Wordsushi]

Ok, for the first look don't see anything wrong, maybe some solder joints could be little bit better (worth to check especially these from cable connections). Hmmm...
What capsule you are using?

Thanks In76d! Good idea. I'll go over the switch connections with a fine-toothed comb. I'm not yet ruling out the possibility that the switch may need to be, er... switched out. I'd suspect the capsule as a possible source of the issue, but it is working in Omni. The capsule is a dual-backplate prototype and I very much apologize I can't say more at this time. I was asked not to give any details about it yet. I built 2 other D87s with the single sided version of this capsule and they sounded great so I wanted to build the full multi-pattern version. Even though I can't get Fig-8 to work yet on this new one, I love it in cardioid on my voice so it's a keeper. I'll never use Fig-8, but it's the principle of the matter in getting it fully functional.

 

[ln76d]

No worry, rather not courious about the capsule  from hobbyst reasons
Exact question should be - is it true separated backplates design?  Take a multimeter and check are the backplates aren't shorted, especially in fig.8 position

 

[Wordsushi]

No worry, rather not courious about the capsule  from hobbyst reasons
Exact question should be - is it true separated backplates design?  Take a multimeter and check are the backplates aren't shorted, especially in fig.8 position

Good question. I just now did as you suggested and it appears the backplates are indeed truly separated. No continuity between the backplates detected in any pattern with phantom power applied.

One other interesting thing I've noticed. As this is the 3rd D87 I've built with this particular prototype 87 capsule (the other two cardioid only, one with a Cinemag 13113 and one other with an AMI T13), this new multi-pattern one (with a Cinemag 13113) sounds  a tad bit more muscular than the other two. All identical BOMs from Mouser, but the first two were built with the taper board inside of GXL 2200 donor bodies, and this one was built with the D87M board in a Chunger SYT-5 large body. Not sure if its the combo of larger headbasket and body size and/or this one having a double-sided capsule, but both D87s in the much smaller GXL bodies sound a tiny bit brighter.  Despite different traffos in the two GXL body D87, they sound identical, but this super-sized one definitely sounds a touch larger to me as well.

 

[ln76d]

Hmmm... Truly don't know what i can advise you more. Definately measure/check all the path which is routing  fig.8.
Ok i can agree that headbasket matters as hell - diameter is also important, amount of meshes etc.
But maybe here the biggest part is the capsule?
Since it is prototype, then maybe these are just differently tuned? To be sure, just swap the other capsule and check
If capsules are exactly the same then just compare headbaskets. CAD should be 3 layer and syt 5 2 layer - here's the clue

 

[R1 Studio]

#2

Hey, looking at your picture, it looks like the brown and red wires should be interchanged. The vintagepcb 87 build thread has s+ to yellow, s- to orange, p- to brown, and p+ to red.  Or do you have it right and the demo has it wrong? I'm using the same pcb, and I'm struggling to get my mic working.

Z

 

[Wordsushi]

Hey, looking at your picture, it looks like the brown and red wires should be interchanged. The vintagepcb 87 build thread has s+ to yellow, s- to orange, p- to brown, and p+ to red.  Or do you have it right and the demo has it wrong? I'm using the same pcb, and I'm struggling to get my mic working.

Z

UPDATE: Apologies. I originally answered this late at night, confusing two of the builds I have done. For some reason I was thinking of the AMI T13 I bought from ZenPro that was wired backwards.

On the above build, the Cinemag CM-13113, is wired the way Dave Guerin at CineMag told me to do it and it's working great. I think the transformer wiring Andrew Schaap has on his demo build may be incorrectly notated.

 

[R1 Studio]

Thank you so much - I'm kind of surprised that I don't see a note or post about it somewhere, since pretty much all of us are dealing with this same issue. I was searching in the thread and could not find anything except my own post.

I'll desolder and resolder later today and see what happens.
you are the man, that is, unless you are a woman.
No seriously, maximas gratias tibi ago.

 

[Wordsushi]

Thank you so much - I'm kind of surprised that I don't see a note or post about it somewhere, since pretty much all of us are dealing with this same issue. I was searching in the thread and could not find anything except my own post.

I'll desolder and resolder later today and see what happens.
you are the man, that is, unless you are a woman.
No seriously, maximas gratias tibi ago.

No worries, dude. Hope you can get yours working.
Semper ubi sub ubi.

 

[R1 Studio]

Help!

I am getting nothing from the capsule, but I am getting 46 from the backplate. After using a more reliable 48v source, I got the following values...

r1 - 0
r2 - 42.6
r3 - 6. 0
r4 - 38.4
r5 - 38.4
r6 - 0
r7 - 3.8
r8 - 38.4
r9 - 0
r10 - 0

r12 - 11.2
r13 - 42.5
r14 - 20.7
r15 - 44.2
r16 - 45
r17 - 22.7
r18 - 46.1
r19 - 45.7

zener - 22.7
L1 and L2 - 46.1

Transformer - p+ (brown) = 0, p- (red) = 0, s- (yellow) = 46.1, s+ (orange) = 46.1

a to aa = 42.6, b to bb = 0, c to cc 38.5, and pin to pin = 3.9

c1 = 0, c2 = 38.5, c3 = .38, c4 = 3.7, c5 = 38.4, c6 = 42.8, c7 = 11.3, c8 = 3.9, c9 = 11.2/42.6, c10 = 20.7, c11 = 44.2, c12 = 22.7, c13 = 45, c14 = 45.7, c15 - 0, c16 = 46.1, c17 = 46.1,

Anybody see anything????!!!

 

[Eitan25]

Hello everyone!
This is my first post and my first mic build ever, so pardon the noob question. I hope one of you wizards can help me out here.

The JFET in the BOM seems to be unavailable and I'm having trouble finding another one with the same specs.
Is there another JFET I could use instead? Any special considerations I need to be making if I use a different one?

Any advice is most appreciated. Thank you!

Eitan

 

[TillM]

Look on ebay.

 

[Eitan25]

Thank you for replying. Nothing on ebay.

 

[kante1603]

Thank you for replying. Nothing on ebay.

Try Amazon.

 

[TillM]

Thank you for replying. Nothing on ebay.

Are you sure ?
https://m.ebay.de/itm/2N3819-10-er-Pack-TO-92-N-channel-J-FET-NATIONAL-SEMICONDUCTOR/382137319542?hash=item58f928c076:g:Of0AAOSwo4pYJJ6y

 

[Eitan25]

Awesome, thank you!!
Because I'm a novice at this, I'm still not confident enough to determine whether a particular FET is acceptable if it doesn't clearly list the exact same specs. But with your help, I noticed that I could use the part number to search.
Thank you for your patience with my beginner question.

 

[kante1603]

You‘re welcome.
As said you can find some on Amazon too.
It would be good if you update your profile with your location.
This helps sourcing parts in your area,and sometimes there are members around who have those parts in their drawer and nearly live next door.


Best regards,


Udo.

 

[Eitan25]

Will do. Cheers!

 

[Eitan25]

I'm ready to wire up my Cinemag CM2480 transformer, but there seems to be some debate on the correct wiring and looking through the forum for a final word has left me confused. Can somebody please confirm whether it's...

A:
p+  red
p-  brown
s+  yellow
s-  orange

or B:
p+  brown
p-  red
s+  yellow
s-  orange

Or is it something else?

Thank you in advance.
-Eitan

 

[Haoxian]

When I adjust R11 to put the FET voltage to 11.5V, but it only has 1.9V less than 10 minutes later. When I adjust to 11.5V again, its voltage will continue to decrease slowly. I wonder why? What went wrong? I use the FET of K170 and the adjustable resistance of 20K. Thank you.