Neumann Vintage U87 Clone : Build Thread.

[Ricardus]

But an actual 2N3819 should have the proper pinout and be mounted as per the silk screening on Dany's PCBs?

 

[Ricardus]

I noticed on the NTE312 spec sheet that it says the Drain and Source are interchangeable.

http://www.nteinc.com/specs/300to399/pdf/nte312.pdf

 

[Duizels]

I am using this one:

http://www.vintagemicrophonepcbkit.com/Neumann%20U87%20Build.htm

I notice now the instructions say the middle leg should be connected to the isolation pin. Not sure where my head was at earlier today. So I think I can proceed now

Update:

I've pretty much finished building and hooked up the mic to my audio interface to measure the drain/bias.
I am not very experienced so I kinda did not expect the mic to work right away. I think I may have made a mistake along the way or have a bad solder somewhere. What I am measuring is:

r6 (drain hole? next to fet) + ground hole = 160 mV (milivolt?)
I tried adjusting my multimeter range (its the first time I ever use a device like this) to Volts, it was in Auto mode now.
Then I think I am getting 0.1 to 0.2 volts... So clearly not in the ballpark I should see?
I have the Mastech  ms8268 multimeter, set to measure Direct current in Volts.

UPDATE 2:

Someone suggested I measure the transformer resistance at the 4 wires and ground.
I keep getting different results, but most times something like 0.0020 nV

Let the troubleshooting commence!

Chris

 

[TillM]

transformer resistance put your DMM in ohm-mode and measure yellow with yellow wire and black with black wire.
Some of the AMI transformers a factory reversed.

 

[Duizels]

Thanks to the tireless help of Till I was able to build my U87 clone. Just plugged it in and it sounds sweet.
Unfortunately, the Peluso capsule I bought from Till got into the hands of my 1yo daughter.... well... it didn't end well...
So my current build is with a cheaper Chinese capsule.

I did not want to flood this thread, so we did all the troubleshooting via personal email exchange.
Starting out I had (and still have) very little experience with electronics, but the time spent reading the forums, watching videos and practicing soldering was worth it. Very cool experience! 

My main problem was after finishing putting everything together was that I lost all phantom power straight at the beginning. After some searching, it turned out that I simply got the XLR wires wrong. Again thanks to the very patient help of Till I could backtrack and sort it out. I replaced more "suspected faults" than I should have, and once the XLR wires were correct, all values checked out immediately within the normal ranges.

Can't wait to use it in the studio, recording some new songs.

Chris

 

[TillM]

Chris you are welcome !

 

[Ricardus]

Looks good. What hardware did you use to fasten the PCBs to the rails on the mic body?

 

[Duizels]

Looks good. What hardware did you use to fasten the PCBs to the rails on the mic body?

Just the regular machine screws I think that came with the mic body. I purchased the mic body set from Pye at http://www.lifelongmusic.co.uk/
The transformer I strapped on with some tie wraps

 

[PG_Sax]

Looking nice Chris! Glad you managed to get it sorted.

Thanks to the tireless help of Till I was able to build my U87 clone. Just plugged it in and it sounds sweet.
Unfortunately, the Peluso capsule I bought from Till got into the hands of my 1yo daughter.... well... it didn't end well...
So my current build is with a cheaper Chinese capsule.

 

[PG_Sax]

But an actual 2N3819 should have the proper pinout and be mounted as per the silk screening on Dany's PCBs?

Yes I think the gate should be in the middle.

 

[Ricardus]

Just the regular machine screws I think that came with the mic body. I purchased the mic body set from Pye at http://www.lifelongmusic.co.uk/
The transformer I strapped on with some tie wraps

OK. I got my mic bodies from Pye today (XMas Eve!) and noticed a bag of hardware, so it's probably in there.

My output xformers from Peluso also arrived! Santa was good!

I think I'll 3D print some straps from the transformers that are a little more elegant than zip ties. We shall see.

 

[Duizels]

I was very satisfied with the mic body parts from Pye. Helpful support as well

Happy xmas!

 

[Ricardus]

Today I'll officially be beginning my build. After Xmas lunch I'll basically have the rest of the day to myself. Yesterday though I went through all of my 2200 ohm resistors to find pairs, and I found 4 at 2206 ohms, and 3 or four other matched pairs as well.

 

[Ricardus]

Does the switch board need to be hooked up to bias the FET?

 

[Duizels]

Now that the Xmas days are over I had some time to do a recording with my u87 clone.
I am running it through a DAV BG-1u mic pre. I am comparing it to my Microphone-parts.com T12 kit https://microphone-parts.com/products/t12-microphone-kit, which I love.

On its own, I like the sound of the U87 clone. It has a definite vintage feel to me, a velvety/silky sound. I liked singing through it, its very mid-sounding to me and "even" and pleasant. Compared to the T12 kit from Microphone-parts things looked much less good all of a sudden. Several things jumped out to me:

• My U87 build is very noisy. Not sure its my build or everyone has this. But the T12 is mega-clean in comparison
• My U87 has very little low end. No warm sounding bottom. This may be my capsule?
• My U87 has a very low output. The T12 was at least 5 times louder
• The T12 has a much tighter and detailed sound with better low end

So a little disclaimer:

This is my first build, so my circuitry/soldering may result in some of the noise? Also, my Peluso capsule broke because my daughter got her hands on it. I put a cheaper Chinese make capsule in this U87 build for now, which may be the reason for the way it sounds. I am no expert so can only guess how much of a difference this makes. 

I can definitely see this U87 be a mic I would use for vocal doubles, a darker silky sound that is not as clear and front-center in the mix as the T12 sound. But certainly, as a vocal mic, this clone is not the winner yet.

Cheers!

Chris

 

[TillM]

The output is not that hot, because it’s styled after the old circuit.
I’ve no noise problems with my mic.
Did you clean the hi-z area with isopropanol ?
It could be the capsule, that’s possible, but I would think it’s because of some soldering points and because the hi-z area is not clean enough.

 

[Gus]

Duizels

Check the transformer, is it wired correctly?

 

[Ricardus]

Has anyone trimmed a little off the isolating pin on both the boards? They don't touch, but they're closer than I'd like. I think I'm going to take a 16th or so off.

 

[TillM]

Definitely trim them a bit

 

[newmod]

Hello everyone,

I am new here and just started building a u87 kit. 

I have a few questions and if you guys could help, that would be awesome! 

1.  The BOM part numbers 538-22-28-4030 qty of 2 connector vertical 3 position // 538-22-28-4020 connector vertical 2 position qty of  4 // 151-8010-E Mini Jumper GF 6mm qty of 3;  According to the information I have been able to find in this thread, I can see diyer's have made use of them on the PAD, OMN CRD and LC sections of the pcb.  That equates to two 2 positions and one 3 position connectors.  Where are the rest being used??  Also, why do we need the mini jumpers (151-8010-E)??  I don't see the use or need for them?  Can someone please enlighten me here? loll

2.  The second question I have is regarding "R11CAL" on pcb version 1.2 green tapered.  There are two parts on the BOM...mouser p/n 72-T93YA-25K trimmer and 81-PV37X253C01B00 trimmer.  I believe 81-PV37X253C01B00 trimmer is just meant as an option cause it's smaller?  I intend to use  the 72-T93YA-25K trimmer.  Can you guys confirm this?  So the next question regarding the trimmer is on the R11 pad section where am I inserting this part?  As I understand it, on this particular board, I should insert the trimmer's three pins right in the middle so that I can see the two holes on either end of the trimmer?  Also, from what I can see, the pcb is only using two pins on the pcb trace, correct?  Can someone just verify which of the holes from the trace lines in R11 are actually doing something with the trimmer.

3.  By now, its clear that the Fairchild 2N3819 is obsolete...loll.  So it seems like the NTE-312 is the replacement.  Has anyone experienced any problems when using this transistor?

4.  Also, can anyone recommend a particular style or brand of hookup wire?  I am trying to use the highest quality components on this mic and want to minimize the noise where ever possible. 

5.  When receiving my capsule, how would one go about checking the capsule for tuning?

6.  I noticed guys testing their mic's and generating these really cool graphs!  Where do I get my hands on that software so I can perform these tests as well?

Happy New Year everyone!