Neumann Vintage U87 Clone : Build Thread.

[micaddict]

BTW, welcome, Simone. 

Hey, you're not the X-Factor girl by any chance? 



Henk

 

[ln76d]

Thank you  ln76d! Is the theory that the lower the value of the C6, the more high end?

Yes, it's main capacitor in deemphasis circuit.
You can also remove it if you want maximum boost of HF.

 

[storres1]

Okay great! Thank you so much! 

Yes, it's main capacitor in deemphasis circuit.
You can also remove it if you want maximum boost of HF.
[/quote]

 

[storres1]

Bahahahahaha yes I am. That's so funny

BTW, welcome, Simone. 

Hey, you're not the X-Factor girl by any chance? 



Henk

 

[micaddict]

;D



I would personally never remove the whole de-emphasis circuit in a U87.
Better build a different mic in that case.

 

[ln76d]

Schoeps circuit  would be even better for that.
In some microphones am even using higher capacitance for deemphasis.

 

[granger.frederic]

often, with vintage U87 , the lack of top end is due to leakage of C11 and C13,  inducing a drop in the capsule polarization voltage

 

[TillM]

as I said, i've got a phase probleme.
Now I allready changed my JFET and do some solder work.
But the problem is still the same.
I buy a oscilloscope and a new (much better) multimeter.
By checking the voltage with my multimeter i see, that on R12 the voltage is just 11v instead of 19,...v.
How can this happen ?
Shematic shows, that I must use a 47k resistor.
Did I take the wrong resistor ?
Best regards
Till

 

[ln76d]

Measure phantom voltage first.
What did you used for source resistor?
Try to record really loud guitar and check the track is it similar to the previous.
Currently i have one session where most of the drum tracks looks like this. All sounds fine, no problem with mixing or phase correction. All dynamic microphones. No distortion, clipping or any other unwanted symptoms.

 

[TillM]

Phantom Voltage is 46,7v.
I used the resistor from the BOM (47 KOhms).
As I see on the Neumann page, the voltage at the source resistor should be around 10v.
So this seams okay ... well, then the search goes on, why I get the negative phase when I record.

 

[poctop]

Do any of these boards fit a gutted U87AI or TLM67?  Surely at least with some bits left out or modified.

Might This Help,
https://cdn.groupbuilder.com/groupdiy/u/39511/58d02819948ff.zip

D.

 

[emrr]

Thank you sir.  Now to find some Neumann dimensions....

 

[emrr]

I slogged through all 134 pages last night out of curiosity.  Easy to miss some things. 

I see Marc Alan Goodman built some using Neumann capsules and transformers.  I see Matadors capsule bias booster board which doesn't seem to get much attention in this thread.  It all leads me to wonder if anyone with extensive U87 experience has felt the desire to retrofit a U87 with any of these boards to either 1) take advantage of any personal part selection preferences with regards to sonic outcome, or 2) restore a severely damaged original.    Thoughts? 

I'm personally coming at this from the perspective of having a TLM67 and the ioaudio U67 retrofit.  I could consider converting the TLM metalwork to U87, or buy more Neumann metal and make a third preamp for the same body.  I'll venture it's probably a bit obsessive.....

 

[micaddict]

I slogged through all 134 pages last night out of curiosity.

Now that's the spirit. 



Good question BTW.

 

[bnwitt]

Can someone tell me where I can go to buy the PCB boards for this build?  I'm using an MXL 2010 body

 

[bnwitt]

Never mind, I found Dave's site

 

[bnwitt]

I've ordered everything needed to build this microphone except the transformer.  I've been reading that the AMI T13 has had some incorrect wire colors issues and lower output than other brands.  Can anyone tell me if that has been corrected and or which of the three transformers (AMI, Peluso or Cinemag) is the preferred unit for this build and where to buy that particular transformer?  Thank you in advance,
Barry

 

[Pip]

I've ordered everything needed to build this microphone except the transformer.  I've been reading that the AMI T13 has had some incorrect wire colors issues and lower output than other brands.  Can anyone tell me if that has been corrected and or which of the three transformers (AMI, Peluso or Cinemag) is the preferred unit for this build and where to buy that particular transformer?  Thank you in advance,
Barry

IMO I would go with the Cinemag if you don't use the AMI. I have used the AMI in both my builds and I feel that it is fine. It is also easy enough to determine which is the right wires with an OHM Meter. The output being down is news to me.

 

[bnwitt]

I have read a few comments that this build has low output/sensitivity.  Have any of you builder found that to be the case?

 

[ln76d]

I have read a few comments that this build has low output/sensitivity.  Have any of you builder found that to be the case?

Neumann U87 (on which based is your circuit) also have low output - sensitivity is 8mV/Pa - maybe here's the problem that people don't know what they are build?
You know, people read that MXL (one from many chinese examples) is based on u87 circuit, but it have high output due to emitter follower and new U87Ai have 28mV/Pa etc.