Neumann Vintage U87 Clone : Build Thread.

[DIZ]

Hey guys,

I was referred to this thread to ask you guys one simple question and I want you guys to be brutally honest.

How does your DIY U87's compare to (I know this is after the vintage model) the U87ai? S/n ratio, headroom, and sonically?

I was about to purchase a U87ai with a Jim William mod on it (just a few component replacements, not a big mod) but was then referred to Klaus Heyne but his mod is just out of my budget at the given time. But then was also referred to the DIY route. I'm all open to options, and am curious to see how these do stackup against an actual Neumann. Thanks in avance guys.

 

[Dvaughn]

Hey guys,

So I took a few pics of my capsule hook up just to give myself some piece of mind. 

This one is the front of the mic, I connected the diaphragm terminal to FD on the board, and the screw/wire you see in the mount is connected to the body of the front diaphragm and wired to FBK on the board.

http://imageshack.us/a/img196/6594/ehid.jpg

This one is the back of the mic, I again connected the diaphragm terminal to RD on the board, and the screw/wire you see is connected to the body of the rear diaphragm and wired to RBK on the board.

http://imageshack.us/a/img5/4013/nzjo.jpg

I tested the connections with the DMM and got 0 ohms for all the capsule connections, and I also checked to see if the 2 backplates were isolated and got a reading of around 460 ohms, is this normal?

I went ahead anyway and biased the fet using the drain leg and the pot I have installed to get 11.5V, everything seemed cool.  I then checked signal and everything seemed cool in terms of no noise and clear non distorted signal, the capsule sounded great.  The low cut worked and the pad seemed to work (sounded a little darker). 

The polar patterns seemed a little strange to me though, cardioid was the strongest signal wise and sounded really nice in front, as I went to the side it seemed to get a bit thin, and then actually became a little stronger in the rear (than the sides)

Omni seemed Omni in terms of level around the mic but there were pretty big frequency changes (thinning out of low end) as I went to the sides of the capsule.

Fig 8 was much lower in signal ( significantly lower ) I had to crank my pres and the pattern didn't seem that clear, it didn't reject the sides as much as I would think.

I really need to get something to compare this too.

So because I wanted to be sure everything was normal I started checking voltages against the schematic.  The zener was fine, I'm not sure I was measuring the phantom in the right spot but wherever I did measure it seemed in the ballpark.  But the big discrepancy was the capsule connections.  On the schem it said 40V for the FBK connection and in Cardioid I had 18.6V on FBK and the same on RFK and 0V on both diaphragms.  I couldn't find the 40V anywhere.  Could this be the reason the patterns seem a little off? 

Thanks for taking the time to reply if you do,

Dylan

Some other shots of the build

http://imageshack.us/a/img845/7003/rrg7.jpg
http://imageshack.us/a/img6/1552/7imt.jpg
http://imageshack.us/a/img541/9369/kz8x.jpg

 

[burglar]

I used an iPad, an Alesis I/O Dock, and a special cable (1/4" to gator clips unbalanced) I made to get the sine wave. The app wasn't cheap (Faberacoustical Signal Scope Pro), but because this works, the computer idea should work, as well. I would think that special cable would still be needed.

-James-

Hey, thanks James.  I'll look into it.  In the mean time, I fired up the mic having just biased with the DMM.  I have to say, it's a bit brighter than I thought it would be.  Have a listen to these clips.  The room I did them in is terrible and I only had access to a mackie onyx pre.  Would be interested to hear some other opinions?

https://soundcloud.com/sdosuk/87-test-4-0001-audio-snare-2/s-wzm0N?in=sdosuk/sets/87-sound-tests/s-wzm0N  4" from grill

https://soundcloud.com/sdosuk/87-test-8-0001-audio-snare-2/s-wzm0N?in=sdosuk/sets/87-sound-tests/s-wzm0N  8" from grill

B

 

[burglar]

Unfortunately when I opened the mic and attached the wires for the rear diaphragm, on putting it back together I have a much lower output and so loads more noise floor.  Am I likely to have done something to the capsule?  Is the outer rim of the capsule sensitive to dirt or grease from hands? 

I have tried removing the wires for the rear diaphragm so I just have the front connected as before but the problem is still there.  Very heartening as I felt I was so close! 

Perhaps I got some dirt on the boards whilst taking apart / putting back together.  What are the sensitive areas?

B

 

[poctop]

Unfortunately when I opened the mic and attached the wires for the rear diaphragm, on putting it back together I have a much lower output and so loads more noise floor.  Am I likely to have done something to the capsule?  Is the outer rim of the capsule sensitive to dirt or grease from hands? 

I have tried removing the wires for the rear diaphragm so I just have the front connected as before but the problem is still there.  Very heartening as I felt I was so close! 

Perhaps I got some dirt on the boards whilst taking apart / putting back together.  What are the sensitive areas?

B

Look like you might have a wire that is not connected or the solder is cracked , Visually inspect to make sure ,
if they were no noise in initial test that that is probably not the problem,

hope this helps,
D

 

[poctop]

Hey guys,

So I took a few pics of my capsule hook up just to give myself some piece of mind. 

This one is the front of the mic, I connected the diaphragm terminal to FD on the board, and the screw/wire you see in the mount is connected to the body of the front diaphragm and wired to FBK on the board.

http://imageshack.us/a/img196/6594/ehid.jpg

This one is the back of the mic, I again connected the diaphragm terminal to RD on the board, and the screw/wire you see is connected to the body of the rear diaphragm and wired to RBK on the board.

http://imageshack.us/a/img5/4013/nzjo.jpg

I tested the connections with the DMM and got 0 ohms for all the capsule connections, and I also checked to see if the 2 backplates were isolated and got a reading of around 460 ohms, is this normal?

Do you mean if you remove the capsule from the mic you have 460ohm between the 2 backplate if yes then it will not work

Take a simple step first , connect only one side capsule that is the front : backplate (FBK) and capsule center to FD same for RD and RBK on the rear side

you should be able to get 40V on the leg of C15


I went ahead anyway and biased the fet using the drain leg and the pot I have installed to get 11.5V, everything seemed cool.  I then checked signal and everything seemed cool in terms of no noise and clear non distorted signal, the capsule sounded great.  The low cut worked and the pad seemed to work (sounded a little darker). 

The polar patterns seemed a little strange to me though, cardioid was the strongest signal wise and sounded really nice in front, as I went to the side it seemed to get a bit thin, and then actually became a little stronger in the rear (than the sides)

Omni seemed Omni in terms of level around the mic but there were pretty big frequency changes (thinning out of low end) as I went to the sides of the capsule.

Fig 8 was much lower in signal ( significantly lower ) I had to crank my pres and the pattern didn't seem that clear, it didn't reject the sides as much as I would think.

I really need to get something to compare this too.

So because I wanted to be sure everything was normal I started checking voltages against the schematic.  The zener was fine, I'm not sure I was measuring the phantom in the right spot but wherever I did measure it seemed in the ballpark.  But the big discrepancy was the capsule connections.  On the schem it said 40V for the FBK connection and in Cardioid I had 18.6V on FBK and the same on RFK and 0V on both diaphragms.  I couldn't find the 40V anywhere.  Could this be the reason the patterns seem a little off? 

Thanks for taking the time to reply if you do,

Dylan

Some other shots of the build

http://imageshack.us/a/img845/7003/rrg7.jpg
http://imageshack.us/a/img6/1552/7imt.jpg
http://imageshack.us/a/img541/9369/kz8x.jpg

 

[burglar]

Unfortunately when I opened the mic and attached the wires for the rear diaphragm, on putting it back together I have a much lower output and so loads more noise floor.  Am I likely to have done something to the capsule?  Is the outer rim of the capsule sensitive to dirt or grease from hands? 

I have tried removing the wires for the rear diaphragm so I just have the front connected as before but the problem is still there.  Very heartening as I felt I was so close! 

Perhaps I got some dirt on the boards whilst taking apart / putting back together.  What are the sensitive areas?

B

Look like you might have a wire that is not connected or the solder is cracked , Visually inspect to make sure ,
if they were no noise in initial test that that is probably not the problem,

hope this helps,
D

Thanks Dan,

I took the mic to a session today and simply having it plugged in with 48v for 10 minutes, it quietened right down.  It's doing the typical U87 low mid thing beautifully now.  This clip is mic with slight waves PIE comp, 6" from grill.  Also, through Neve 1073 in a well treated booth:

https://soundcloud.com/sdosuk/oli-vocal-u87/s-CpdVY

Very happy with the response and roundness of the bottom end and the fantastic handling of sibilance.  This vocalist is a tricky one to record as well.  He has a tendency to get resonant / harsh. 

Happy chappy.  Thanks to all who helped. 

   

 

[atticmike]

Finally got screws to connect the other capsule and it's not working. On the working capsule, there is a connection between the front and backside, on the none-working, there isn't. Everything is perfectly put together. Got any idea where that might come from?

Mike

 

[tskguy]

Mike,

The 87 capsule out of the circuit should have the 2 sides of the backplate be isolated electrically. Is that the case?

 

[atticmike]

Mike,

The 87 capsule out of the circuit should have the 2 sides of the backplate be isolated electrically. Is that the case?

And when connected to the circuit?

Because the none-working one is def. isolated inside the circuit, the working one has a connection inside the circuit.

 

[atticmike]

forget about the hum.

the issue must be where both sides connect.

any ideas guys?

what's dan's take on this issue? where might it come from?

 

[poctop]

forget about the hum.

the issue must be where both sides connect.

any ideas guys?

what's dan's take on this issue? where might it come from?

not sure here where we are standing on this but is the capsule out of the circuit have continuity on the 2 backplate ?

 

[atticmike]

forget about the hum.

the issue must be where both sides connect.

any ideas guys?

what's dan's take on this issue? where might it come from?

not sure here where we are standing on this but is the capsule out of the circuit have continuity on the 2 backplate ?

Ruled out the capsule, it's the mic. You got any idea where the issue might be that it's not connecting both sides, which is what it does with the working mic?
That'd save me from tearing the mic apart again.

 

[Dvaughn]

Hey guys,

So I took a few pics of my capsule hook up just to give myself some piece of mind. 

This one is the front of the mic, I connected the diaphragm terminal to FD on the board, and the screw/wire you see in the mount is connected to the body of the front diaphragm and wired to FBK on the board.

http://imageshack.us/a/img196/6594/ehid.jpg

This one is the back of the mic, I again connected the diaphragm terminal to RD on the board, and the screw/wire you see is connected to the body of the rear diaphragm and wired to RBK on the board.

http://imageshack.us/a/img5/4013/nzjo.jpg

I tested the connections with the DMM and got 0 ohms for all the capsule connections, and I also checked to see if the 2 backplates were isolated and got a reading of around 460 ohms, is this normal?

Do you mean if you remove the capsule from the mic you have 460ohm between the 2 backplate if yes then it will not work

Take a simple step first , connect only one side capsule that is the front : backplate (FBK) and capsule center to FD same for RD and RBK on the rear side

you should be able to get 40V on the leg of C15


I went ahead anyway and biased the fet using the drain leg and the pot I have installed to get 11.5V, everything seemed cool.  I then checked signal and everything seemed cool in terms of no noise and clear non distorted signal, the capsule sounded great.  The low cut worked and the pad seemed to work (sounded a little darker). 

The polar patterns seemed a little strange to me though, cardioid was the strongest signal wise and sounded really nice in front, as I went to the side it seemed to get a bit thin, and then actually became a little stronger in the rear (than the sides)

Omni seemed Omni in terms of level around the mic but there were pretty big frequency changes (thinning out of low end) as I went to the sides of the capsule.

Fig 8 was much lower in signal ( significantly lower ) I had to crank my pres and the pattern didn't seem that clear, it didn't reject the sides as much as I would think.

I really need to get something to compare this too.

So because I wanted to be sure everything was normal I started checking voltages against the schematic.  The zener was fine, I'm not sure I was measuring the phantom in the right spot but wherever I did measure it seemed in the ballpark.  But the big discrepancy was the capsule connections.  On the schem it said 40V for the FBK connection and in Cardioid I had 18.6V on FBK and the same on RFK and 0V on both diaphragms.  I couldn't find the 40V anywhere.  Could this be the reason the patterns seem a little off? 

Thanks for taking the time to reply if you do,

Dylan

Some other shots of the build

http://imageshack.us/a/img845/7003/rrg7.jpg
http://imageshack.us/a/img6/1552/7imt.jpg
http://imageshack.us/a/img541/9369/kz8x.jpg

Thanks for the reply Dan,

When I tested the capsule connections it was connected in the circuit ( the reading of 460 ohms between the back plates) I tested with the dmm actually touching the capsule, when I measure from FBK to RBK on the board i'm getting like 660ohms, once again in circuit.

I powered up the mic again and tested at c15 because I thought maybe I was measuring wrong at the capsule connections but again I got the same voltage right at 17.9v, instead of 40v.  I'm getting this reading at FBK, RBK, and leg of c15, all of the other voltages on the schem seem to be fine.  Does it look like the capsule is hooked up ok based on the pics?  I haven't tried connecting only the front side of the capsule (FD and FBK) vs only the backside (RD and RBK) is that what you meant?

Thanks

Dylan

 

[atticmike]

Also, between the marked two points, I can measure resistance on the working mic, the not-working has none:

Also the fact that the working mic's capsule when connected to the circuit has connection between both sides and the other one doesn't.

No idea where I might start looking for the culprit?

 

[poctop]

Hey guys,

So I took a few pics of my capsule hook up just to give myself some piece of mind. 

This one is the front of the mic, I connected the diaphragm terminal to FD on the board, and the screw/wire you see in the mount is connected to the body of the front diaphragm and wired to FBK on the board.

http://imageshack.us/a/img196/6594/ehid.jpg

This one is the back of the mic, I again connected the diaphragm terminal to RD on the board, and the screw/wire you see is connected to the body of the rear diaphragm and wired to RBK on the board.

http://imageshack.us/a/img5/4013/nzjo.jpg

I tested the connections with the DMM and got 0 ohms for all the capsule connections, and I also checked to see if the 2 backplates were isolated and got a reading of around 460 ohms, is this normal?

Do you mean if you remove the capsule from the mic you have 460ohm between the 2 backplate if yes then it will not work

Take a simple step first , connect only one side capsule that is the front : backplate (FBK) and capsule center to FD same for RD and RBK on the rear side

you should be able to get 40V on the leg of C15


I went ahead anyway and biased the fet using the drain leg and the pot I have installed to get 11.5V, everything seemed cool.  I then checked signal and everything seemed cool in terms of no noise and clear non distorted signal, the capsule sounded great.  The low cut worked and the pad seemed to work (sounded a little darker). 

The polar patterns seemed a little strange to me though, cardioid was the strongest signal wise and sounded really nice in front, as I went to the side it seemed to get a bit thin, and then actually became a little stronger in the rear (than the sides)

Omni seemed Omni in terms of level around the mic but there were pretty big frequency changes (thinning out of low end) as I went to the sides of the capsule.

Fig 8 was much lower in signal ( significantly lower ) I had to crank my pres and the pattern didn't seem that clear, it didn't reject the sides as much as I would think.

I really need to get something to compare this too.

So because I wanted to be sure everything was normal I started checking voltages against the schematic.  The zener was fine, I'm not sure I was measuring the phantom in the right spot but wherever I did measure it seemed in the ballpark.  But the big discrepancy was the capsule connections.  On the schem it said 40V for the FBK connection and in Cardioid I had 18.6V on FBK and the same on RFK and 0V on both diaphragms.  I couldn't find the 40V anywhere.  Could this be the reason the patterns seem a little off? 

Thanks for taking the time to reply if you do,

Dylan

Some other shots of the build

http://imageshack.us/a/img845/7003/rrg7.jpg
http://imageshack.us/a/img6/1552/7imt.jpg
http://imageshack.us/a/img541/9369/kz8x.jpg

Thanks for the reply Dan,

When I tested the capsule connections it was connected in the circuit ( the reading of 460 ohms between the back plates) I tested with the dmm actually touching the capsule, when I measure from FBK to RBK on the board i'm getting like 660ohms, once again in circuit.

I powered up the mic again and tested at c15 because I thought maybe I was measuring wrong at the capsule connections but again I got the same voltage right at 17.9v, instead of 40v.  I'm getting this reading at FBK, RBK, and leg of c15, all of the other voltages on the schem seem to be fine.  Does it look like the capsule is hooked up ok based on the pics?  I haven't tried connecting only the front side of the capsule (FD and FBK) vs only the backside (RD and RBK) is that what you meant?

Thanks

Dylan

remove the capsule from circuit and measure the 2 backplate they should be isolated meaning infinite resistance ,
and with no capsule measure the pad FD to see if you get the 40V and then you will be able to split the problem

 

[poctop]

Also, between the marked two points, I can measure resistance on the working mic, the not-working has none:

Also the fact that the working mic's capsule when connected to the circuit has connection between both sides and the other one doesn't.

No idea where I might start looking for the culprit?

Remove the capsule from circuit and then check the 2 backplate for isolation and then with no capsule measure all the reference voltage from schematic and you will be able to go forward also comparing the 2 mics without capsule you will be able to identify if the difference is in the mic or the capsule ,
you could also swap the capsule and split it that way as well
hope this helps,
Dan,

 

[atticmike]

Also, between the marked two points, I can measure resistance on the working mic, the not-working has none:

Also the fact that the working mic's capsule when connected to the circuit has connection between both sides and the other one doesn't.

No idea where I might start looking for the culprit?

Remove the capsule from circuit and then check the 2 backplate for isolation and then with no capsule measure all the reference voltage from schematic and you will be able to go forward also comparing the 2 mics without capsule you will be able to identify if the difference is in the mic or the capsule ,
you could also swap the capsule and split it that way as well
hope this helps,
Dan,

Dan, I already told you I was able to rule out the not working capsule since I put the other in the working mic and it works too. That means I got a flaw in my build of that particular not working mic. All I ca tell is what I showed on the picture, at the working mic a connection between the two marks and at the not-working one none. Also, the working mic creates a connection between the front and backplate, the not working one doesn't. Any idea where that might come from?

 

[poctop]

Also, between the marked two points, I can measure resistance on the working mic, the not-working has none:

Also the fact that the working mic's capsule when connected to the circuit has connection between both sides and the other one doesn't.

No idea where I might start looking for the culprit?

what I would do is to remove the capsule and focus on the amplifier section wich in this case is the problem,  start by measuring all the reference voltage of the amplifier and then from there check any discrepancy you ma find at this point identify the suspect node and verify for solder bridge or cold solder, and resistor value and caps for shorts or open condition , most of the time it is a simple thing.
hope this helps,
Dan,


Remove the capsule from circuit and then check the 2 backplate for isolation and then with no capsule measure all the reference voltage from schematic and you will be able to go forward also comparing the 2 mics without capsule you will be able to identify if the difference is in the mic or the capsule ,
you could also swap the capsule and split it that way as well
hope this helps,
Dan,

Dan, I already told you I was able to rule out the not working capsule since I put the other in the working mic and it works too. That means I got a flaw in my build of that particular not working mic. All I ca tell is what I showed on the picture, at the working mic a connection between the two marks and at the not-working one none. Also, the working mic creates a connection between the front and backplate, the not working one doesn't. Any idea where that might come from?

 

[jasonallenh]

Ok,

so as part of my plan to get the Bhrngr B-2 working as a u87, I intend to bypass the switch PCB and wire each individual switch directly to the PCB. The PCB will only serve a structural purpose to hold the switches in place. I am unsure how the switching relates to the PCB, so if I could get a little direction in terms of what switch lead goes to what point on the PCB, that would be a HUGE help!