Neumann Vintage U87 Clone : Build Thread.

[fazeka]

Not sure if I understand correctly as I built my mic a while back and haven't been following this thread, but FWIW for my build (which I thought was based on Dany's switch PCBs, I used (1) T103MH9ABE and (2) T101MH9ABE (T Series, subminiature toggles)...

 

[dreadheaded]

Fazekas suggested component is definately more correct then the 7103, it could be made to work at a push but is actually slightly too large

 

[kmozart]

THANKS DAN For all your help!

The Mics Sounds GREAT!!!  I used AMI Transformer and a $100 Capsule.

Comparing it to my Original Vintage U87, Even Un-biased, sounds so damn close!! 

I can hear the distortion a little, but expecting that to go away after biasing the microphones.

Build was very easy! 

I still negotiate with myself which capsule to get, but even the one I got for testing,is not bad at all!! 

Love building gear that I will use!!

I will recommend do everybody!


THANKS!!! 

 

[poctop]

THANKS DAN For all your help!

The Mics Sounds GREAT!!!  I used AMI Transformer and a $100 Capsule.

Comparing it to my Original Vintage U87, Even Un-biased, sounds so damn close!! 

I can hear the distortion a little, but expecting that to go away after biasing the microphones.

Build was very easy! 

I still negotiate with myself which capsule to get, but even the one I got for testing,is not bad at all!! 

Love building gear that I will use!!

I will recommend do everybody!


THANKS!!!

Thanks to you ,
8)

 

[OrganizedKonfusion]

Ok, here is a noob question for anyone who might know. Is a Fluke 177 good enough to match R18,19? Or should I try the wheatstone method? Sorry if this has already been answered in here.

 

[Matt_Oliver]

Thanks to poctop, chunger, and everyone who has put in the work on this.

I used Matt's capsules and Cinemag iron. Next pair I'm planning to use tskguy's capsules.

I had a pair of SP-1s lying around at the studio and decided to just use those as my donor bodies, but if you're starting a build I wouldn't recommend SP-1s;  you will find yourself doing a lot of Dremel-ing and hacking. Miraculously managed to get it all securely fit.

 

[Matt_Oliver]

One more pic with pcb exposed.

I biased the other mic and put in "permanent" resistors but I think I'm going to leave the variable resistor in this one.

Anyway I'm super happy with the way they sound. They went straight to work and they're getting the job done for sure!

 

[Krumlee]

Ok, here is a noob question for anyone who might know. Is a Fluke 177 good enough to match R18,19? Or should I try the wheatstone method? Sorry if this has already been answered in here.

The original Neumann spec is that they should match to 1% or better ie within 22ohms. I think the 177 measures to the nearest ohm in that range, so you should be fine.
Good luck with your build.

 

[OrganizedKonfusion]

Ok, here is a noob question for anyone who might know. Is a Fluke 177 good enough to match R18,19? Or should I try the wheatstone method? Sorry if this has already been answered in here.

The original Neumann spec is that they should match to 1% or better ie within 22ohms. I think the 177 measures to the nearest ohm in that range, so you should be fine.
Good luck with your build.

Thanks! I'll post pics when I finish! Still waiting on the mic body.

 

[jakobz]

I finally got  to populate the old D U87  pcbs i had lying around. I have browsed through this great thread but still have a couple of questions

1. My donor mic do not support lowcut, pad or pattern switch. do i just leave these solder pads alone or is there anything i should do, if i just want it to work in cardiod.

2. I have a Sowter 1303f transformer. It has 5 wires: 2 primary 2 secondary and one electro static shield. as far as i can tell solder pad 1-2 (rt-sw) is the secondary and 3-4 (bl - ws) is the primary, but where do i connect the electro static shield wire?

3. I cant figure out what the  rt pad and sw pads are for, what am i missing here ?

 

[poctop]

I finally got  to populate the old D U87  pcbs i had lying around. I have browsed through this great thread but still have a couple of questions

1. My donor mic do not support lowcut, pad or pattern switch. do i just leave these solder pads alone or is there anything i should do, if i just want it to work in cardiod.
nothing to do

2. I have a Sowter 1303f transformer. It has 5 wires: 2 primary 2 secondary and one electro static shield. as far as i can tell solder pad 1-2 (rt-sw) is the secondary and 3-4 (bl - ws) is the primary, but where do i connect the electro static shield wire?
primary = highest resistance pair = rt  ---sw
Secondary lowest resistance pair = ws ---- bl
electrostatic Shield will go to gndlink pad it just needs to be grounded to mic chassis

3. I cant figure out what the  rt pad and sw pads are for, what am i missing here ?
Those are to inject a sine tone in it to test the preampflier
for biasing with a scope those pad are not used as the signal is injected directly to R6 before the fet couping cap

 

[jakobz]

Thank you for helping out poctop

 

[silky smoove]

here's my build.

finished it with pretty much no problems at all.
biased it with my scope.
output is on the lower side though.
while selecting the FET it read 7,5mA when testing it.

just to re-assure that i have a perfectly working mic...i need 45db of gain from any of my preamps to get a decent signal with about the usual 10db of headroom in my UFX when speaking into the mic in cardioid 15cm away from the headbasket.

i have the lead reversed version of the T13..so yes, i know about this issue. i installed it both possible ways anyways before settling for the correct way with a near healthy amount of output level.

the capsule is from microphone-parts dot com

Sorry to dig up such an old post, but this addresses an issue I'm having. I used the same parts list (T13 with reversed leads, RK-87 capsule, and a FET in the 7.8mA range).

The build went fine, but the output is quite a bit lower than expected. I have a U87ai on hand that is WAY WAY WAY hotter. I realize these are different circuits, but I didn't expect the difference to be quite so great. I'm getting levels more akin to a dynamic mic. In comparison to my SM58, there isn't much of a level difference.

Does this sound normal to everyone?

 

[poctop]

here's my build.

finished it with pretty much no problems at all.
biased it with my scope.
output is on the lower side though.
while selecting the FET it read 7,5mA when testing it.

just to re-assure that i have a perfectly working mic...i need 45db of gain from any of my preamps to get a decent signal with about the usual 10db of headroom in my UFX when speaking into the mic in cardioid 15cm away from the headbasket.

i have the lead reversed version of the T13..so yes, i know about this issue. i installed it both possible ways anyways before settling for the correct way with a near healthy amount of output level.

the capsule is from microphone-parts dot com

Sorry to dig up such an old post, but this addresses an issue I'm having. I used the same parts list (T13 with reversed leads, RK-87 capsule, and a FET in the 7.8mA range).

The build went fine, but the output is quite a bit lower than expected. I have a U87ai on hand that is WAY WAY WAY hotter. I realize these are different circuits, but I didn't expect the difference to be quite so great. I'm getting levels more akin to a dynamic mic. In comparison to my SM58, there isn't much of a level difference.

Does this sound normal to everyone?

10db should be about the difference in output between Ai and I ,
vintage circuit will be something like 10b less intense and this is normal , but you have to assess that if not then you might have a bias problem ,
Best,
Dan,

 

[silky smoove]

I did some more comparisons and you're right, it is just about 10db quieter on the meter bridge of the board. I think having the levels of the AI model be a known quantity set an expectation that wasn't in line with reality. Now that I know what to expect I'm quite happy with the build.

After gain matching on the preamps (tried both a UA 610, and an Avalon 737), the differences are very apparent. The AI is a lot brighter, especially in the upper mids. This build is noticeably smoother and less harsh by comparison, but ultimately does lack that sheen up top. The lows on this build are a little thinner than the AI which can honestly get boomy on certain sources. I wouldn't qualify either mic as better, just different. All told I'm very happy with this build. Good thing I built two of them!

 

[ironman187]

Hey all, I just finished this build using an Auricle A460 as a donor mic, a Lundahl LL1636 transformer, and a Vintage Microphones V-K87 capsule from micandmod.com. The issue I am having is the microphone has low output and sounds very "*****" for lack of a better word. I suspect impedance matching is the issue here, but am not sure. I have the Lundahl transformer wired up to the "D" configuration on the spec sheet which is 1:10  2.5Ohm/200Ohm.  Here is a link to the spec sheet. http://www.lundahl.se/wp-content/uploads/2013/05/1636.pdf Please advise.

 

[Krumlee]

Hi ironman,
I'd be very interested in how the LL1636 sounds when you've got this working right - I've got a spare one in the junk box. I used Cinemag 2480s in my D87 builds, but I was wondering about the 1636.

I'm not sure why the datasheet says that configuration D isn't recommended - anyone know?

Let's deal with the obvious stuff - in that config, pins 10 & 16 form the '10' side of the transformer, so these need to be connected to rt and sw. Pins 3 & 7 are the '1' so they go to ws and bl. Is that how you've got it?

Also, did you clean the boards really well (especially round the fet)?

The D87 does have low output compared to most modern mics, but it depends on what you mean my 'low'.

Hopefully someone else will have some better ideas for you..

 

[jakobz]

Hi again
I just finished this build and been doing some tests. I dont have any audible noise and i get a signal through which sound fine but very low. I have read in several posts that it is supposed to be a quite low signal from this circuit, but compared to an sm57 it is a very low signal and i am pretty certain it is lower than it is supposed to. I am using the Sowter 1303f transformer which is 9:1. As far as i could tell it is a replica of the original transformer, so i just assumed it would be fine, but I dont  see anyone else in this thread using this specifik transformer, and i am wondering if it may not be suited for this project after all? Any thoughts on this?

 

 

[ironman187]

Hi ironman,
I'd be very interested in how the LL1636 sounds when you've got this working right - I've got a spare one in the junk box. I used Cinemag 2480s in my D87 builds, but I was wondering about the 1636.

I'm not sure why the datasheet says that configuration D isn't recommended - anyone know?

Let's deal with the obvious stuff - in that config, pins 10 & 16 form the '10' side of the transformer, so these need to be connected to rt and sw. Pins 3 & 7 are the '1' so they go to ws and bl. Is that how you've got it?

Also, did you clean the boards really well (especially round the fet)?

The D87 does have low output compared to most modern mics, but it depends on what you mean my 'low'.

Hopefully someone else will have some better ideas for you..

Buahahaa! I feel like such an *****. I have them swapped! From what I understand given this information as well as previous information  it should be wired as follows.

WS- Pin 3
BL- Pin 7
SW- Pin 16
RT- Pin 10
CGND- Ground

I'm just guessing based on what I was able to glean from the schematics and various sources on the web. I used no-clean solder flux so I didn't think I would need to clean the board, but I'll give that a shot as well. Furthermore, I don't have the resources right now to properly balance R18 & R19, but I can't imagine that would cause the sound I was getting. At any rate, the difference between this mic and almost every other mic I've had hooked up to my firepod was about 25 db. Please let me know if I have my positives and negatives for the transformer swapped. I'll throw up some sound files once this is where I want it sound wise. 

 

[Krumlee]

WS- Pin 3
BL- Pin 7
SW- Pin 16
RT- Pin 10
CGND- Ground

I've just double checked, and that looks good to me. If you have the transformer backwards (in terms of turns ratio) then that would give you a nice impedance mismatch which would probably explain a lot of what you're hearing. The vintage U87 is roughly 10dB lower compared to modern mics.

Also triple-check that you've got all the other transformer pins wired together correctly [it's always stupid stuff like that!]

You should be OK with R18 and R19 especially if you bought 1% resistors to start with.

Did you bias the fet? If you don't have a scope then an initial setting of about 10.5v at the drain should be OK to start with.

Let us know how you get on - it sounds like you're really close.