Neumann Vintage U87 Clone : Build Thread.

[poctop]

Dan are saying I can use with stock "C1" capsule?, 

with stock capsule cardiod only is possible ,
D

 

[Mr.GrinchSD]

AHAHAHA so how do I measure the calibration drain voltage what do I set the multimeter to. ALSO the mic is working but It fluctuates in and out! WHAT could be causing this???

 

[JessJackson]

MIC COMPLETE!

one problem though..

on SYT-5 body when pattern switch is all way to the right (cardioid on body) i get continuous pops and noise louder than the capsule... in middle its behaving itself but acts like cardioid and to left it behaves and is like omni / maybe figure 8 with the rear capsule louder than the front.

anyone? I have checked my cables but i still may have the capsule wired wrongly,, maybe even switch. It could be anything else?

cheers

J

 

[tskguy]

Jess,

If you have a chuck d body the pattern switch is mislabeled. The middle position is cardioid the other two I correct if memory serves. As for the pop during changing patterns is normal. I usually make the polar decision prior to setting the gain. How does the capsule sound???

Eric

 

[Mr.GrinchSD]

HAHAH its. . . . ..  WORKING ;D

 

[JessJackson]

Jess,

If you have a chuck d body the pattern switch is mislabeled. The middle position is cardioid the other two I correct if memory serves. As for the pop during changing patterns is normal. I usually make the polar decision prior to setting the gain. How does the capsule sound???

Eric

Thanks Eric,

I haven't checked it on an artist yet. I'm cutting Tyga on a Rick Ross record this week and although 87 isn't what i've used on Tyga for the last 7 years, (normally c12 / u67) I was going to cut it using this mic.

I do have a chuck D body. but why is there continuous loud pops and squeals in the right position. center (cardioid) is fine but quite high noise floor.

Somethings not right.

 

[Pip]

Jess,

If you have a chuck d body the pattern switch is mislabeled. The middle position is cardioid the other two I correct if memory serves. As for the pop during changing patterns is normal. I usually make the polar decision prior to setting the gain. How does the capsule sound???

Eric

Thanks Eric,

I haven't checked it on an artist yet. I'm cutting Tyga on a Rick Ross record this week and although 87 isn't what i've used on Tyga for the last 7 years, (normally c12 / u67) I was going to cut it using this mic.

I do have a chuck D body. but why is there continuous loud pops and squeals in the right position. center (cardioid) is fine but quite high noise floor.

Somethings not right.

My suggestion is to check the FET bias. Keep in mind this is a clone of a U87I not a U87AI. The gain is about, if I remember correctly, 10db less in the U87I due to it not having the voltage multiplier circuit. If your FET is set to high the circuit has a tendency to pick-up more EMI and modulate. That would explain the squeal. My experience has been that most people who are used to the U87AI are surprised at the output difference.

The pop when you switch patterns is correct thats what all U87's do. In my opinion its a drag. Be careful you can hurt things. Sorry if I state the obvious. The other pops when not switching might be a bad capsule. Check that the capsule is not damaged. You can try swapping leads (make the front the back and the back the front) if the problem moves that could be it. If it doesn't it points to circuit problems.

Hope this is helpful.

It's making noise which is a good sign. you are almost there. Good luck.

 

[JessJackson]

Thanks pip,

ok so in the center it works as cardioid and sounds great, to the left sounds great and sounds omni.

To the right, its not as noisy as it was yesterday... the front capsule is on but it sounds duller on the front (less tops) and full on the back. with some now low level intermittent whooshing.

 

[Pip]

Thanks pip,

ok so in the center it works as cardioid and sounds great, to the left sounds great and sounds omni.

To the right, its not as noisy as it was yesterday... the front capsule is on but it sounds duller on the front (less tops) and full on the back. with some now low level intermittent whooshing.

Check C2 make sure its OK. Also is your Capsule single or double backplate?  Lastly is the switch OK?

Forgive me but I don't understand "sounds omni"? When in Omni as you turn (along its vertical axis) the mic and talk into it it should have equal loudness all the way around. So when in cardioid as you turn mic the sound should drop of as the rear capsule comes to bear on the sound source with the maximum drop off being directly at the rear capsule and then as you continue  to turn the mic the sound should come back as you get back to the front. In figure of 8 the sound drop offs should only happen as the side of the mic faces the sound source. So two sides two null points. Sorry if I am being Master of the Obvious here.

The reason I say this is if the mic is working in Omni then this points to the switch.

 

[kante1603]

The reason I say this is if the mic is working in Omni then this points to the switch.

I have the same feeling here.Easy enough to check.

Good luck,

Udo.

 

[rjuly]

I have three sets of Polystyrene Filter Cap kits for the U87 build for resale in the UK and Europe at cost. See my thread in the Black Market.
http://www.groupdiy.com/black-market/a-few-polystyrene-filter-cap-kits-for-u87-build-uk-and-europe-only/

 

[JessJackson]

Thanks pip,

ok so in the center it works as cardioid and sounds great, to the left sounds great and sounds omni.

To the right, its not as noisy as it was yesterday... the front capsule is on but it sounds duller on the front (less tops) and full on the back. with some now low level intermittent whooshing.

Check C2 make sure its OK. Also is your Capsule single or double backplate?  Lastly is the switch OK?

Forgive me but I don't understand "sounds omni"? When in Omni as you turn (along its vertical axis) the mic and talk into it it should have equal loudness all the way around. So when in cardioid as you turn mic the sound should drop of as the rear capsule comes to bear on the sound source with the maximum drop off being directly at the rear capsule and then as you continue  to turn the mic the sound should come back as you get back to the front. In figure of 8 the sound drop offs should only happen as the side of the mic faces the sound source. So two sides two null points. Sorry if I am being Master of the Obvious here.

The reason I say this is if the mic is working in Omni then this points to the switch.

cheers pip,

Capsule is erics capsule... its double backplate (as far as i'm aware)

I tried to use the mic in cardioid last night in a session and realised the noise floor is way too high. I know that they are supposed to be 10db quieter than AI versions but this is like 15-20db. for cutting intimate softer vocals which is what i was trying to do there was not enough gain. Seems like something wrong with my build other than just figure 8.

pip, cardioid behaves as cardioid and omni behaves like omni. cheers.

Anyone in LA who'd be kind enough to help me with this build? Im getting close.

cheers

J

 

[JessJackson]

I checked capsule for shorts, no shorts. backplates are independent from one another / capsule seems good.

I checked switch for shorts and continuity at circuit board

in center position no continuity
in left position continuity between OMNI & CRD
in right position continuity between CRD & 8

it seems switch is good, output on cardioid still v low

having done more testing it seems that when in fig 8 only the rear diaphragm picking up audio. front of capsule not on.

Cheers

 

[Pip]

I checked capsule for shorts, no shorts. backplates are independent from one another / capsule seems good.

I checked switch for shorts and continuity at circuit board

in center position no continuity
in left position continuity between OMNI & CRD
in right position continuity between CRD & 8

it seems switch is good, output on cardioid still v low

having done more testing it seems that when in fig 8 only the rear diaphragm picking up audio. front of capsule not on.

Cheers

Start tracing back from Front cap connection.

best

 

[HellfireStudios]

I checked capsule for shorts, no shorts. backplates are independent from one another / capsule seems good.

I checked switch for shorts and continuity at circuit board

in center position no continuity
in left position continuity between OMNI & CRD
in right position continuity between CRD & 8

it seems switch is good, output on cardioid still v low

having done more testing it seems that when in fig 8 only the rear diaphragm picking up audio. front of capsule not on.

Cheers

Try reversing the front and back capsule connections on the PCB. If cardioid is okay and the front capsule works in figure-of-eight, then the capsule is the culprit. Technically, no matter the polar pattern selected, the head amp in the mic handles only one signal (i.e., there isn't a seperate head amp for each side of the capsule). So, if you're getting sound from any side of the capsule, the electronics are probably ok (excluding polarization electronics). Good luck.

-James-

 

[JessJackson]

I checked capsule for shorts, no shorts. backplates are independent from one another / capsule seems good.

I checked switch for shorts and continuity at circuit board

in center position no continuity
in left position continuity between OMNI & CRD
in right position continuity between CRD & 8

it seems switch is good, output on cardioid still v low

having done more testing it seems that when in fig 8 only the rear diaphragm picking up audio. front of capsule not on.

Cheers

Try reversing the front and back capsule connections on the PCB. If cardioid is okay and the front capsule works in figure-of-eight, then the capsule is the culprit. Technically, no matter the polar pattern selected, the head amp in the mic handles only one signal (i.e., there isn't a seperate head amp for each side of the capsule). So, if you're getting sound from any side of the capsule, the electronics are probably ok (excluding polarization electronics). Good luck.

-James-

Hi James, thanks

Ok so... my capsule is wired as such. FD to FD, BD to BD, front backplate (closest to front of mic) mounted through insulated screw on back side of capsule to FBK, rear capsule (furthest from front of mic) attached on mount screw of saddle to RBK


I tried 2 things just now... (when i refer to "front" i am talking polar pattern switch at front to determine front of mic)

1st Test (I swapped the diaphragm wires FD and RD on the circuit board only and left the backplates in place)

CRD = Has reversed.. back of mic sounds good, front is now off
OMNI = both side are on but sounds out of phase
8 = Same problem as before (has NOT reversed) front is on back is off.

2nd Test (I swapped the back plate connections also.

CRD = Has reversed.. back of mic sounds good, front is now off
OMNI =  both side are on
8 = Same problem as before (has NOW reversed) front os off back is on.

Additionally I noticed that when inserting the PAD there is roll off on the top end and sounds dull.

Very Strange Stuff, P.S I'm using all styro caps for this build. very clean build just like changers.

J

 

[HellfireStudios]

Sounds like the capsule might be ok, since the problem seems to be in figure-of-eight mode, I would check C2 and R4 for faulty parts or cold solder joints.

-James-

 

[JessJackson]

thanks mate, working on it now!..

also chunger showed measuring drain from here

but data sheet shows pin 3 as source and pin 1 as drain.

IF data sheet is correct then circuit board silk screen is wrong and we all need to install FET in opposite direction with flat side toward bottom of mic.

Could this be why everyone is getting low output?

Direct link to data sheet: http://www.mouser.com/ds/2/68/2n3819-31474.pdf

 

[kante1603]

Hello J,

your measuring pin connection looks correct (drain).
In the link you posted the drawing seems to show the bottom(!!!) view.That's done pretty often,sometimes stated somewhere close to the drawing or pic.All good here I think.
About lowish level "all" might have:The issue was solved a while ago and refered especially to the AMI T13 transformer meaning the colour coding was reversed on a batch a lot of us bought them from.
I have done four mics meanwhile,and they are working fantastic.Again:A u87 compared to a u87Ai does have a lower level around -10 to -11dB,not more.

Best regards,

Udo.

Edit:Here's a proof for that jfet-thing (taken from the fairchild description):
http://www.mouser.com/ds/2/149/2N3819-106215.pdf

Edit #2:It still seems you have your capsule miswired.Do you have a capacitance meter or a dmm capable measuring capacitors?
If so measure say the front diaphragm connection to one of the backplate wires,you'll get a reading on your meter.Write it down or remember it.Now while leaving the front dia. wire connected swap to the other backplate wire.You'll get a reading from here too!But it will be different from the first!
The pair with the higher value is the correct pair to hook up to the front connections on the pcb.
We are looking for roughly 50 pF.
Same on the other side.

Edit:About out-of-phase signals:In figure eight the back is always reversed compared to the front!
Search for "Blumlein" or "MS" stereo techniques on the web,it's very well explained there.

 

[ramshackles]

Hi
I've built 2 of these lovely mics, using the 'set-and-forget' method of setting 11.5V at the drain.

I'd like to go back and bias the fet using the listening method, but can't find much in these pages related to it.

Can anyone give any tips on how to do it, what I should be listening for?