Neumann Vintage U87 Clone : Build Thread.

[a_)_i]

I put together a D87 using poctops PCB and couldn't get it to a point where it is satisfactory to use.

There is too much intermittent noise on the output to make it usable as the mic sends out muffled scratchy noises along with a muffled sounding signal from whatever is in front.

I should point out that on the capsule I used one of the wires was too short to attach to the PCB so I extended it with teflon coated wire, cleaned the joint and covered with heat shrink.

I believe the problem is either i) the above bodged short wire; ii) the bias is incorrect (and I lack the skills and tools needed to do it properly) or iii) there is a wiring error (I don't think this as I've been over it several times).

As it as been sat unused for 3 months and I lack the time to complete the build I was wondering whether anyone can recommend a good mic tech or builder in the UK/Europe who would troubleshoot the build for me?

Thanks in advance

 

[babaorum]

I 'm building a DIY D-U87M , can someone indicate to me on mouser, for example, what kind of toggle switches I must mount on the switches blue pcb ?
(2 switches 2 positions and 1 switch 3 positions)

Thanks in advance.

Baba

 

[dchang0]

I 'm building a DIY D-U87M , can someone indicate to me on mouser, for example, what kind of toggle switches I must mount on the switches blue pcb ?
(2 switches 2 positions and 1 switch 3 positions)

Thanks in advance.

Baba

Easiest way to get those switches is direct from poctop. When you ordered the D-U87M boards, there was an option to buy the switch set. Chunger also has them bundled with the SYT-5 Gen 3 body.

If you do figure out a switch that will work that Mouser carries, please let us know. Someone else mentioned earlier in this thread that they were looking for switches with shorter toggles--I'd like the same since I find that I've often accidentally hit one of the Low Cut or Pad switches on the back.

 

[babaorum]

I found them :
2 positions :
http://www.mouser.fr/ProductDetail/Apem/TL36P000000/?qs=sGAEpiMZZMu3soN126U8Y2IyP06PY1SZ

3 positions SPDT ON-OFF-ON :
http://www.mouser.fr/ProductDetail/Apem/5237WWCD/?qs=sGAEpiMZZMvudeGI7i40XHIXt4K4triMyjjawv%252bW35Y%3d

If someone can confirm it will be ok ... ?

 

[doom3crazy]

Hey guys, im new here. I am an audio engineer/artist but I am looking to expand my knowledge and learn a tid bit about electronics. I am looking to build my first mic and have choose the u87 clone as it seems to have the most information around it and not the most difficult to build.

I would like to build a u87 close to the Stam audio 87 thats coming out with the sowter tranny. Have you guys decided which of the current build of clones is the best? I plan on using a HK capsule by eric heiserman

 

[lkipod]

I found them :
2 positions :
http://www.mouser.fr/ProductDetail/Apem/TL36P000000/?qs=sGAEpiMZZMu3soN126U8Y2IyP06PY1SZ

3 positions SPDT ON-OFF-ON :
http://www.mouser.fr/ProductDetail/Apem/5237WWCD/?qs=sGAEpiMZZMvudeGI7i40XHIXt4K4triMyjjawv%252bW35Y%3d

If someone can confirm it will be ok ... ?

Hey babaorum,

the links seem not to work..

Cheers
Moshe

 

[lkipod]

Hi everyone,

so I'm building the second D87 and I've got a question that I didn't find the answer to. (I admit I didn't read the whole thread, and consider myself a noob )

There is a lot of talk in the forums about floating the high impedance section of microphones, but on the blue pcb (D87M) the turrets only float where one of the 1G resistors (R7) should connect and on the other pcb the gate of the JFet.
Shouldn't R6 and C4 also be floating?

My first D87 sounds pretty amazing, so this is more of a theoretical question.

Thanks for your answers.

Best 
Moshe

 

[dchang0]

@babaorum:

The first switch (2 pos) may work.

The second switch (3 pos) won't work for sure (pin spacing is definitely wrong and the toggle is waaaaaay too long).

 

[micaddict]

Hey guys, im new here. I am an audio engineer/artist but I am looking to expand my knowledge and learn a tid bit about electronics. I am looking to build my first mic and have choose the u87 clone as it seems to have the most information around it and not the most difficult to build.

Welcome to the family!

For a first, this one is (even?) "easier" BTW (and more versatile regarding capsule flavors):
https://groupdiy.com/index.php?topic=61057.0
Not trying to bring you in doubt. If a U87 is what you're after, go for it! You're in good company.

I would like to build a u87 close to the Stam audio 87 thats coming out with the sowter tranny. Have you guys decided which of the current build of clones is the best? I plan on using a HK capsule by eric heiserman

AFAIK the STAM is the only commercial mic sofar that uses this PCB (or the only 87 "clone" that uses the correct circuit for that matter). Not absolutely sure yet about the new Warm Audio.
Also, the guys here build their own (well, most do) and aren't so much into testing commercial versions.
But don't worry; you'll find your answers here. And you'll meet dudes like Dany (U87 PCB) and Eric (Heiserman capsule) et al. 

 

[babaorum]

@babaorum:

The first switch (2 pos) may work.

The second switch (3 pos) won't work for sure (pin spacing is definitely wrong and the toggle is waaaaaay too long).

ho ok ! thanks for your expertise dchang0  I'll search again for the 3 pos.

 

[doom3crazy]

Can someone tell me if the Budget-YT5 body kit from studio939 would work for a u87clone consisting of the pcb kit from danny, the hk87 capsule, and a sowter tranny? (Trying to build something along the lines of the SA-87 by stam audio)

Or would I need the SYT-5 gen 3?

 

[micaddict]

It should work, but to be absolutely sure ask chunger here:
https://groupdiy.com/index.php?topic=50015.0

BTW the very first version had figure eight in the middle position (switch). So gen 2 is in fact gen 3. But the first one was offered by someone else.
Also, earlier on they had dual mesh rather than three layers. The budget one still has this. Three layers is what an original U87 has, but I actually prefer two layers FWIW.

 

[skal1]

Hi lads ,

i am new to the Mic game, i don't really have any knowledge about them but i can solder ;D , what would be the cost of a -U87 Build  and is their a 1 stop place to buy all parts.

Regards

Denis

 

[lkipod]

Hi lads ,

i am new to the Mic game, i don't really have any knowledge about them but i can solder ;D , what would be the cost of a -U87 Build  and is their a 1 stop place to buy all parts.

Regards

Denis

Hey Denis,

welcome aboard!
Be careful, it is totally addictive.
The cost varies with the quality of parts you order.
For example the mic body options start at around 50$ and go up to 148$ for a nice one.
The electronics cost around 60$
The xformer depends... around 100$
Capsule 140$-250$.

Hope that helps

 

[skal1]

Cheers ,lkipod

I am from the UK so i hope i get get these bits from EU


Regards

Denis

 

[micaddict]

Cheers ,lkipod

I am from the UK so i hope i get get these bits from EU


Regards

Denis

Better hurry then. 

The PCB you need has to be ordered from Canada.
But we have a brandnew trade treaty that takes care of that one.   

 

[Neutrino]

I'm currently building one (in Germany). I got the transformer from Sowter which is based in the UK and on top is supposed to be one of the best transformers for this built. Don't have any tests yet, as I'm still waiting for microphone body and capsule from the US to arrive. It will be around 170,- Euros just for shipping and customs + german VAT for the body and the capsule! It's really a bit of a pain 

 

[Neutrino]

Hi there,

I'm not fully certain how to wire the Sowter 1303f transformer to the PCB. I've attached the wiring diagram. My guess when comparing with the original schematic would be

RT  --> BLUE
SW --> GREEN
WS --> BROWN
BL  --> GREY
Mic Body --> BLACK

Can somebody confirm this?

 

[Neutrino]

Nobody?

My understanding is that it is important not to confuse primary and secondary windings (which also can be checked with an Ohmmeter), while a wrong wiring on either primary or secondary would only lead to a polarity flip on the output signal in the worst case.

 

[RuudNL]

For what it is worth: today I did some measurements on the Neumann U87 circuit.
Usually it is advised to adjust the drain voltage of the FET for a certain value. (Around 11 V.)
But I noticed that setting the bias this way, doesn't always result in the lowest distortion.
Also Neumann seems to follow this procedure, they aim for ~ + 10.5 V.
My Neumann U87ai has a voltage of 29.25 V. at the 'top' of the 47K drain resistor, and 10.6 V at the drain. (Rsource = 6.2 K.)
But with a drain voltage a little lower than 10.6 V (~9 V), the distortion drops significantly.
Even at higher output levels, there seems to be a 'dip' in the distortion curve at this drain voltage, so I don't see any disadvantages.
I also tried to bias for 'symmetrical clipping', but this also resulted in a less than optimal result concerning distortion.
So adjusting the source resistor for lowest distortion seems to be the best procedure.
Any thoughts about this?