Neumann Vintage U87 Clone : Build Thread.

[patxiplg]

@patxiplg:


looks quite nice,I've digged in the old posts and  found my reply #305 on page 16:


http://groupdiy.com/index.php?topic=48030.300


Look at the last pic,the clip symmetry is slightly "odd" too.
Remember this is already the range where the mic is clipping,you won't listen to this in reality.
Since your sine waves look asolutely fine I'd say it is listening time now!


Have fun,


Udo.


Edited for typo.

Thank you all for your help mates! I plugged it in and it sounds amazing!

I think I didn't explain well the question about the amount of gain. If you look at the sine waves from my scope pics, you'll see that the output sine (clipped) is 20x greater than the input one. If I reduce the input to the point where the output does not clip, the gain still is 18 or 19. It's strange since I read that the gain should be 9-12!  Just wanted to ensure that mine is not wrong...

Even the mic is working great I have a problem with the PAD mode... When I engage it, the output signal is correctly reduced but there is a big amount of noise added (like a hiss). What could it caused by?

Thanks in advance!!

 

[errba]

Can i just substitute any polystyrene filter capacitor that matches the same capacitance in the schematic?  I found some that have a lower voltage than the ones justradios offers and there local to the US, being more conventient for me.

It should be fine as long as the operation specs are above 48v for phantom power correct?


Also in regards to biasing the jfets, am i right to assume i can just use a sine wave generator output through my audio interface and then using an xlr cable connceted to the microphone receive the input signal through a software scope or is it necessary to have the mic unplugged? I'm not very familiar with using analogue oscilloscopes if someone can point me in the right direction i'd be greatful..

 

[andyfromdenver]

Can i just substitute any polystyrene filter capacitor that matches the same capacitance in the schematic?  I found some that have a lower voltage than the ones justradios offers and there local to the US, being more conventient for me.

It should be fine as long as the operation specs are above 48v for phantom power correct?


Also in regards to biasing the jfets, am i right to assume i can just use a sine wave generator output through my audio interface and then using an xlr cable connceted to the microphone receive the input signal through a software scope or is it necessary to have the mic unplugged? I'm not very familiar with using analogue oscilloscopes if someone can point me in the right direction i'd be greatful..

Hi errba (in tha' club get tipsy),
re: the polystyrenes, yes if the fit is ok.
re: bias, yes you can use a 1k sine wave test tone from the computer, so long as you have enough juice to drive it into clipping.  One thought though, you will need to send the signal, then separately be receiving it for analysis so i dunno.
For the 1k send, if you can break it out to tip and sleeve, you can easily use a switchcraft 11 or 11a female jack to have easy clip points to inject the signal. 
You will need to power the microphone to check the bias, though the transformer doesn't have to be in circuit.
If you can access a scope, I can help you with the settings.

To detail a super simple set up that I mentioned a few posts back.

synthesizer set to a 1k sine tone-> some boost pedal or pre (to get into clipping territory, start low on the volume)-> 1/4 cable plugged into floating switchcraft 11 female jack-> two clip leads for (+) and (-) -> documented injection points.
If you can set this up, then you can receive via the xlr and perhaps (I don't own or know about software scopes, but assuming you can see the wave form in your computer) visually bias and hear it at the same time.

I realize having typed this that it may read scatterbrained-y  

 

[poctop]

For you Interest ,
I have been Cleaning up the BOM for this project ,
Removed Redondancy and added sub part numbers,
Tantalum Capacitor are the one left for this mic , No More elctrolytics Sub parts

All reference to polystyrene sub parts cap removed ,

PS: this BOM is missing Polystyrene Caps 10pf, 220pf, 470pf X2, 560pf only,
all the other items are in the BOM,  Polystyrene cap Kit can e purchased on the webstore,

Here is the Cleaned up BOM,
http://www.mouser.com/ProjectManager/ProjectDetail.aspx?AccessID=1AD602D54E

only Styroflex cap are not in the BOM for completion of this project,


Thanks All,
Best,
dAN,

 

[errba]

thanks andy, i'll cross that bridge when i come to it... however it seems i have some more issues with sourcing parts, the 47uH inductor from vishay is on backorder for 21 weeks, as far as finding a substitute, would this part work?

http://www.sourcingmap.com/47uh-14w-4color-ring-10-axial-lead-fixed-inductor-100-pcs-p-423352.html

Not sure if the 1/4 wattage power rating has any affect on the circuit and i couldn't find any ratings on the mouser site for the original part.



Thanks for cleaning up the BOM poctop, much appreciated.

Do most of you guys build your test circuit on breadboards? Or are you actually soldering the pieces in one by one and then troubleshooting as you go?

update
found some suitable alternatives on mousers site.
http://www.mouser.com/Search/Refine.aspx?FS=TRUE&N=1525859+4294627068+4294646396+4294626878+4294626926+4294023945+4294413078+4292983193+4294741869+4292214481+1323043

 

[Arkenberg]

Hello Gents,

I am new to this Diy microphone stuff but I am very savy in electronics. I am trying to build a stereo pair of U87s and wondering if you guys might have any recommendations?
I have been studying the schematics and such and have chosen to use a matched pair of 87 capsules from microphone parts.com, the ami t13 transformers from tabfunkenworks and the body of the mics I have two mxl 2010.
Just wondering if it is possible to do this with these parts? I asked the guy from Microphoneparts.com about this and he said it would be nearly impossible and recomended buying his stuff instead.
So if you could please give some insight.
Thanks

 

[Nyquist]

Yep 100% possible. I used the MXL2010 for my build. Just try and match the fets as close as you can and the capsules should be a matched pair as well. the rest of the components should be fairly close in tolerance to each other.

Happy building

 

[Arkenberg]

How might I get FETs that are closely matched?

 

[Nyquist]

Take a look at Chung's build thread here http://studio939.blogspot.com.au/2012/12/vintage-u87-circuit-clone-microphone.html

Lots of good info including JFET IDSS measurement

 

[poctop]

Hello Gents,

I am new to this Diy microphone stuff but I am very savy in electronics. I am trying to build a stereo pair of U87s and wondering if you guys might have any recommendations?
I have been studying the schematics and such and have chosen to use a matched pair of 87 capsules from microphone parts.com, the ami t13 transformers from tabfunkenworks and the body of the mics I have two mxl 2010.
Just wondering if it is possible to do this with these parts? I asked the guy from Microphoneparts.com about this and he said it would be nearly impossible and recomended buying his stuff instead.
So if you could please give some insight.
Thanks

I asked the guy from Microphoneparts.com about this and he said it would be nearly impossible and recomended buying his stuff instead.
So if you could please give some insight.



mmmmmmmmm........  this does not represent the DIY Philsophy for sure and i dont think  it is the right way to get more customer ........

 

[poctop]

IMPORTANT NOTICE

I just noticed Something very Strange about how the mouser BOM works ,
if i go on my website and hit a BOM button from a page , the mouser bom does not contain all the work I have put in to actually find decent alternative part number for the projects ,

http://www.vintagemicrophonepcbkit.com

But.............  if you hit back and then hit the BOM button again all the alternative PN shows up

so if you want to see all the alternative part number i have found during this time this trick will work for you , 
you can try it and let me know,
Best,
Dany ,

 

[Arkenberg]

Thanks guys for the help. I hope I can build these and that they sound good. I want to use them for drum recording.

 

[jasonallenh]

Dany! I'm back to finally finish my build. I've stuffed my boards and mounted them. I believe I'm ready for the scope measurements.

Can I measure with the scope before connecting the transformer? I was able to set my fet voltage to around 11v, but I have been unable to inject my sine wave... I used the r6 leg for sine + and the big sw pad (not the trafo pad) for sine -

With phantom engaged and gain at 60, I got no sign of a signal coming in...

My voltages don't seem wrong.... WHAT HAVE I DONE??

 

[poctop]

Dany! I'm back to finally finish my build. I've stuffed my boards and mounted them. I believe I'm ready for the scope measurements.

Can I measure with the scope before connecting the transformer? I was able to set my fet voltage to around 11v, but I have been unable to inject my sine wave... I used the r6 leg for sine + and the big sw pad (not the trafo pad) for sine -

With phantom engaged and gain at 60, I got no sign of a signal coming in...

My voltages don't seem wrong.... WHAT HAVE I DONE??

Wich version of the pcb do you have,

 

[jasonallenh]

Dany! I'm back to finally finish my build. I've stuffed my boards and mounted them. I believe I'm ready for the scope measurements.

Can I measure with the scope before connecting the transformer? I was able to set my fet voltage to around 11v, but I have been unable to inject my sine wave... I used the r6 leg for sine + and the big sw pad (not the trafo pad) for sine -

With phantom engaged and gain at 60, I got no sign of a signal coming in...

My voltages don't seem wrong.... WHAT HAVE I DONE??

Wich version of the pcb do you have,

I have the v1.2 tapered PCBs

 

[poctop]

Dany! I'm back to finally finish my build. I've stuffed my boards and mounted them. I believe I'm ready for the scope measurements.

Can I measure with the scope before connecting the transformer? I was able to set my fet voltage to around 11v, but I have been unable to inject my sine wave... I used the r6 leg for sine + and the big sw pad (not the trafo pad) for sine -

With phantom engaged and gain at 60, I got no sign of a signal coming in...

My voltages don't seem wrong.... WHAT HAVE I DONE??

Wich version of the pcb do you have,

I have the v1.2 tapered PCBs

did you reversed R6 in respect to the silkscreen as per the instruction for the bias,
Best,
Dan,

 

[jasonallenh]

Dany! I'm back to finally finish my build. I've stuffed my boards and mounted them. I believe I'm ready for the scope measurements.

Can I measure with the scope before connecting the transformer? I was able to set my fet voltage to around 11v, but I have been unable to inject my sine wave... I used the r6 leg for sine + and the big sw pad (not the trafo pad) for sine -

With phantom engaged and gain at 60, I got no sign of a signal coming in...

My voltages don't seem wrong.... WHAT HAVE I DONE??

Wich version of the pcb do you have,

I have the v1.2 tapered PCBs

did you reversed R6 in respect to the silkscreen as per the instruction for the bias,
Best,
Dan,

Yes, It is reversed in relation to the silkscreen and my probe is attached to the longer, exposed lead of R6

 

[poctop]

Dany! I'm back to finally finish my build. I've stuffed my boards and mounted them. I believe I'm ready for the scope measurements.

Can I measure with the scope before connecting the transformer? I was able to set my fet voltage to around 11v, but I have been unable to inject my sine wave... I used the r6 leg for sine + and the big sw pad (not the trafo pad) for sine -

With phantom engaged and gain at 60, I got no sign of a signal coming in...

My voltages don't seem wrong.... WHAT HAVE I DONE??

Wich version of the pcb do you have,

I have the v1.2 tapered PCBs

did you reversed R6 in respect to the silkscreen as per the instruction for the bias,
Best,
Dan,

Yes, It is reversed in relation to the silkscreen and my probe is attached to the longer, exposed lead of R6

Start by first setting the drain voltage to 11.5V and then try the mic ,
to see if it works before attempting to bias ,
it is somehow a logical event to happen ,
Best,
dAN,

 

[jasonallenh]

SO I FINALLY FINISHED!  ;D

I completed my build using the weirder "American" Behringer B-2 that has given a lot of folks fits. I'm adding a link to a PDF guide to show the steps I used to wrangle that particular mic into this project (Dany, maybe you want to post it on the front page??). 

https://www.dropbox.com/s/zm4eexpvpmhwab2/USING%20THE%20AMERICAN%20B2%20FOR%20DANYs%20U87.pdf?dl=0

Kante and Dany were both awesome helping me out, so they deserve all the credit. I'm just the ***** that refused to buy an SYT body

=jh=

 

[Nyquist]

Nice work on the write up mate.