Neumann Vintage U87 Clone : Build Thread.

[Matador]

I made a few changes to the BOM:  I subbed in my favorite Nichicon UVZ electrolytic caps where appropriate (they are rater to 105C), and replaced all of the resistors with the Vishay RN55D series of epoxy coated precision 1% resistors.  I went with the Styrene caps and mica's along with Dany's recommended Wima's.

Hi Matador,

Would you happen to have a mouser parts list that details the substitutions you made? I am looking at building a matched pair and would love to be able to compare your choices with the original BOM.

Regards,
Richard

Certainly!

I replaced the Tantalum's with these:
C11, C13 - 2.2uF/63V : 647-UVZ2A2R2MDD
C8 - 22uF/25V: 647-UVZ1E220MDD1TD
C10 - 4.7uF.50V: 647-UVZ1H4R7MDD
C12 - 10uF/63V : 647-TVX1J100MAD

Basically anything in that "VZ" line with the right voltage rating, and a 2mm lead-spacing, 5mm body will fit in place of the tantalums.

For the Styrene's:
C4 - 470pF/50V: Change to 1000pF - 23PS210
C15 - 560pF/50V: 23PS156
C1 - 470pF/50V: change to 560pF - 23PS156
C6 - 220pF/50V: 23PS122

Resistors:
Just replace the values with the Vishay equivalent.  Search for "71-RN55D-F" and you can pick the values from what is available.  These are all 1/8W and will fit right in perfectly.  If you have/want to use 1/4 watt, change the search string to "71-RN60D-F".  They fit but they'll need some creative bending.

I left the drain-to-transformer coupling cap as stock as well as the other film caps.

 

[saxmonster]

Tonight I updated my Capsule mount to a Peluso.  I just didn't like how the other one sat on the cheap plastic mount that came with the aurycle. 

John's mount is actually the same one that is in my Apex 460 tube mic.  I would love to lower that one about 1/4". After working with Johns mount and installing it, I don't think I can change it.  It seems that the black middle section holds the top and bottom metal pieces together.  I think the metal pieces might be glued to the black rubber.  I would love to cut some of it out and lower the capsule in the apex.  Has anyone done any kind of work to this type of mount or know how this new mount is built?

 

[saxmonster]

I did have to drill two holes in the top plate of the microphone body where the switches are.  But a fairly easy upgrade.

-Scott

 

[wave]

Matador,
What does using the higher value caps in C1, and C4 do?

Dave

 

[rjuly]

I made a few changes to the BOM:  I subbed in my favorite Nichicon UVZ electrolytic caps where appropriate (they are rater to 105C), and replaced all of the resistors with the Vishay RN55D series of epoxy coated precision 1% resistors.  I went with the Styrene caps and mica's along with Dany's recommended Wima's.

Hi Matador,

Would you happen to have a mouser parts list that details the substitutions you made? I am looking at building a matched pair and would love to be able to compare your choices with the original BOM.

Regards,
Richard

Certainly!

I replaced the Tantalum's with these:
C11, C13 - 2.2uF/63V : 647-UVZ2A2R2MDD
C8 - 22uF/25V: 647-UVZ1E220MDD1TD
C10 - 4.7uF.50V: 647-UVZ1H4R7MDD
C12 - 10uF/63V : 647-TVX1J100MAD

Basically anything in that "VZ" line with the right voltage rating, and a 2mm lead-spacing, 5mm body will fit in place of the tantalums.

For the Styrene's:
C4 - 470pF/50V: Change to 1000pF - 23PS210
C15 - 560pF/50V: 23PS156
C1 - 470pF/50V: change to 560pF - 23PS156
C6 - 220pF/50V: 23PS122

Resistors:
Just replace the values with the Vishay equivalent.  Search for "71-RN55D-F" and you can pick the values from what is available.  These are all 1/8W and will fit right in perfectly.  If you have/want to use 1/4 watt, change the search string to "71-RN60D-F".  They fit but they'll need some creative bending.

I left the drain-to-transformer coupling cap as stock as well as the other film caps.

Hi Matador,

Thanks for that. That is extremely gracious of you. I am looking forward to getting my head around this matched build. I will be using the Peluso capsules, Cathedral tubes bodies and the tab trannies.

Regards,
Richard

 

[Matador]

Matador,
What does using the higher value caps in C1, and C4 do?

Dave

The gate coupling cap C4 will give more bass response when increased.

C1 was changed to 560pF just so I didn't have to order multiple part numbers.  I haven't noticed that much difference with it to be honest.

 

[bigswole]

Well my mouser order and my peluso PT-87 just arrived time to start putting this together.  I do have one question.  I am gonna determine pattern with an internal jumper,  I am going to use a mxl v69m as a donor mic.  can i use the switch that is -10 db and low-cut in one to select low-cut and pad, or do i need 2 separate switches?

 

[poctop]

Well my mouser order and my peluso PT-87 just arrived time to start putting this together.  I do have one question.  I am gonna determine pattern with an internal jumper,  I am going to use a mxl v69m as a donor mic.  can i use the switch that is -10 db and low-cut in one to select low-cut and pad, or do i need 2 separate switches?

you would need 2 separate switch 
Dan,

 

[bigswole]

thanks, one more question.  Instructions on trimmer says to use pins 1,2 cut pin 3,  but the second trimmer in the BOM  only pins 1 and 3 will reach the pads.  should i cut pin 2?

 

[wave]

thanks, one more question.  Instructions on trimmer says to use pins 1,2 cut pin 3,  but the second trimmer in the BOM  only pins 1 and 3 will reach the pads.  should i cut pin 2?

If you are talking about the murata trimmer it does reach, it's just really close. I had to solder from the top side of the board



I have attached a simple diagram as to how I bent the leads

Dave

 

[bigswole]

Thanks Dave

 

[bigswole]

Here's my problem.  Connect mic up to check voltages and calibrate.  I get a loud hum.  My phantom is good,  but at the mic output i am getting 34.5 volts on pin 3 and 0 volts on pin 2.  At the zener I am getting 34.5 volts no drop,  I stop measuring there because i know my problem is before that point is has to be,  can anyone give me a clue as to why I am getting no voltage on pin 2?

 

[poctop]

Here's my problem.  Connect mic up to check voltages and calibrate.  I get a loud hum.  My phantom is good,  but at the mic output i am getting 34.5 volts on pin 3 and 0 volts on pin 2.  At the zener I am getting 34.5 volts no drop,  I stop measuring there because i know my problem is before that point is has to be,  can anyone give me a clue as to why I am getting no voltage on pin 2?

The Zener Diode is very fragile , have you tried checking is  internal resistance,  you may want to replace it as well , i have been there don that , it seems that the Zener is not doing what it suposed to do take that down to 24V
D
Hope this helps,

 

[bigswole]

what should the internal resistance be?  and would that stop me from getting a voltage at pin 2 of xlr, and i am showing 0 volts at drain.  :-\

 

[poctop]

what should the internal resistance be?  and would that stop me from getting a voltage at pin 2 of xlr, and i am showing 0 volts at drain.  :-\

would you have connected the xlr connector Wrong then have a close look at the silk screen  1= hot 2=cold 3 = gnd, let me know if this helps,  If i remember well the internal resistance of the Zener is about 500K near that ,
dany,

 

[bigswole]

That's it,  hopefully i havent hurt anything

 

[poctop]

That's it,  hopefully i havent hurt anything

about everything in there is a robust as a tank execpt the FET and the Zener 

D

 

[bigswole]

Thanks the Mic is up and running,I am not sure about the calibration procedure.  I don't have a scope,  And I am not getting a dc reading from the drain point to ground.  Trying to search through the forum for what i am looking for.

 

[Splunge]

Hi,

  I finally finished my first build (Aurycle body, RK87 capsule, AMI Xfor), adjusted the bias with a scope and everything seems to work well EXCEPT when I switch in the -10db pad I get no signal and some sputtering noise. Can I assume that the 560pf capacitor is somehow shot... or could it be something else?

  Thanks for any insight...

 

[poctop]

Hi,

  I finally finished my first build (Aurycle body, RK87 capsule, AMI Xfor), adjusted the bias with a scope and everything seems to work well EXCEPT when I switch in the -10db pad I get no signal and some sputtering noise. Can I assume that the 560pf capacitor is somehow shot... or could it be something else?

  Thanks for any insight...

Look in the schemo arorund the pad switch for continuity and or shorts and the switch operation up to the switching point ,
make sure also that youe wire lead is not passed trough the body in the switch section the plastic section it may interfer to a point where it scrunches stuff