Neumann Vintage U87 Clone : Build Thread.

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FarisElek

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Just built a second one just now. Only Figure 8 working perfectly. Cardioid and Omni sounds like there is a strong wind hitting them. Also, when biasing to 11.5, it capped out at around 11.42 and wouldn't go any higher. What the heck did I do wrong now?

Ryan
 

FarisElek

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Correct me if this sound totally wrong. But I switched out the switches in my last build just in case. In this build I reused to the switches because I thought there was no way that was whats wrong with it. I'm stuck in only figure 8 working again. The other two create loud wind noise. Could it be that it's a bad switch?

Ryan
 

FarisElek

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I tried my best to clean the switch PCB with the littel clearance I have and it got so much better. Still a little bit of wind static sound but it's almost gone. I think I need to really wash the switchboard. I already did. But I guess not well enough.

Ryan
 

FarisElek

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Okay, scrubbed it and it changed and the slowly went back to working perfectly in figure 8 and poorly in the other two positions. I think I can safely assume this is a switch problem? If i toggle the switch back and forth and turn it on, it will be weird in all three positions and then slowly go back to the way it's been. Where can I buy just a single 3 way switch?

Ryan
 

Ricardus

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FarisElek said:
Okay, scrubbed it and it changed and the slowly went back to working perfectly in figure 8 and poorly in the other two positions. I think I can safely assume this is a switch problem? If i toggle the switch back and forth and turn it on, it will be weird in all three positions and then slowly go back to the way it's been. Where can I buy just a single 3 way switch?

Ryan


Email him for a part number and then just look around.
 

FarisElek

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Do you think a switch could do that? I just went to town on this PCB and it's still doing the same thing.
 

DT_Music

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Has anyone used the LA-8 Capsule from Luke Audio?  I had been planning on using the Heiserman Capsule but prices seem to have gone up recently so I'm checking alternatives.  Luke Audio mics have gotten good reviews and I just saw that he sells capsules for DIY builds.  Here's what he had told me about the LA-8 (K87 Style)
"Yes, we make a K87. 34mm , electrically isolated, 1 micron Mylar, platinum sputtered, and are $250.  All around a fantastic capsule, slightly brighter than what you may consider a vintage 87 but that depends on the circuit and how true it is as well"

I'm intrigued but I'm also going for as legit of a vintage 87 clone build that I can.  Has anyone used these or compared them with the Heiserman capsules?
 

FarisElek

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OH MY GOD. I'm so happy I could cry. I figured out what I did wrong. I took the capsule off to bias the fet with a scope and saw that I had the rear-side of the capsule reversed. It's working sooo good. I am so done building mics for a long time. Thank you all even if you didn't answer me. Getting my thoughts into the forum helped me through.
 

FarisElek

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DT_Music said:
Has anyone used the LA-8 Capsule from Luke Audio?  I had been planning on using the Heiserman Capsule but prices seem to have gone up recently so I'm checking alternatives.  Luke Audio mics have gotten good reviews and I just saw that he sells capsules for DIY builds.  Here's what he had told me about the LA-8 (K87 Style)
"Yes, we make a K87. 34mm , electrically isolated, 1 micron Mylar, platinum sputtered, and are $250.  All around a fantastic capsule, slightly brighter than what you may consider a vintage 87 but that depends on the circuit and how true it is as well"

I'm intrigued but I'm also going for as legit of a vintage 87 clone build that I can.  Has anyone used these or compared them with the Heiserman capsules?

That's really thin mylar. It'll probably be snappy and bright, which might be a cool of desired thing for you.  I didn't want a bright microphone. I went with the BeesNeez capsule and I've been having a field day since finishing my build.  Creamy, neutral, clear, and gorgeous are all words I would use to describe my build. I made another build with a cheap no-name Chinese 87-style capsule I had lying around  and I've had several blind tests with friends that are audio engineers. Everyone's favorite is the Beesneez. The cheap capsule has a high-end hairiness that is hard not to hear on vocals. It kind of accentuates sibilence and mouth sounds just a hair. On other sources they're almost matched.

Ryan
 

FarisElek

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Had a blind shoot out with a Neumann TLM 103 and a modded Warm WA-47 yesterday. In both cases my engineer friend and I could tell which mic was which, and in both cases we preferred the sound of the 87. Very crazy! Really wish I had access to a  real U-87i to shoot out with.
 

FarisElek

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Hey! I wanted to post a quick sample of my 87 build. I've been worrying lately that is sounds darker than it should. I did my best not to get alcohol on the polystyrene's but I definitely got some on them. What do ya'll think. This was recorded 4 inches from the 12th fret, pointed straight on. No EQ or anything. Just Capi VP28. Appreciate any feedback.

https://soundcloud.com/user-368056288/d-u87-guitar-test



 

Delta Sigma

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Sounds good to me. It's been 20 years since I've tried a U87 on an acoustic but I did have a similar experience with my D67 on acoustic. Compared to my other builds (Elam 251, M49, U47) and my Beesneez Lulus, my 67 sounded too dark on my acoustic, epecially poointed at the 12th/14th fret area.

Using the 67 in the bridge area though, had a richness that the other mics did not.
 

FarisElek

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Thank you for the feedback. I actually really like it with 80hz cut on the VP28 + a smidge of EQ on the highs. Very vintage sounding compared to the cheap condensers I have been using. I'd much rather low cut and adda little high than have to spend time cutting several weird ugly frequencies, so I'm happy. I just got in my head that it may be unusual.
 

jessemproctor

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poctop said:
If you are working on the Blue Version of the pcb you should adress your question in the other thread for this one ,
I have posted in the opther thread for this one.


Dan,

Hi Dan, I wasn't able to find the other thread you mentioned in this reply.  I'm having a similar issue with figure-8 being low volume.  Everything else in working order and sounding great.  This is my 7th build and I haven't run into this problem before.
Thanks!
Jesse
 

dachmanaudio

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Oct 4, 2019
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Hey Matadaor! I hope this isn't a silly question, but how does one go about calculating Vgs at 1% Idss

I can do the Idss measurement no problem, but am not sure I understand the Vgs at 1%. 

Any help is much appreciated, thank you!

Best
J


Matador said:
Thanks for all the kind words!

I created a simple PHP script to do all the calculations for everyone.  It's located here:

http://www.musicalsparks.com/images/curve_tracer/jfet_bias.php

You plug in the two values that you measure for your JFET, and it will do all of the math and tell you the values of all the resistors, the gain, and calculate the maximum input signal before clipping.  If you have a handful of JFET's (even different types), you can plug in the data and see what it gives.

For example, if I use my nominal JFET that I have (IDSS = 10.79mA, VGS at 1% IDSS = -3.4V), this is what is spit out:

VP = -3.77777777778 V
gmo = 5712.35294118 µmho
β = 0.756046712803m
VDD = 21 V
VD = 10.5 V
IDQ = 225 µA
RD = 46.6666666667 kΩ
VGSQ = -3.23224990585 V
RS = 14.3655551371 kΩ
gm = 824.889108622 µmho
AV (gain) = 38.494825069
Headroom Analysis

Output swing headroom (positive) = 10.5 V
IDO (ohmic) ≤ 282.182455648 µA
Output swing headroom (negative) = 6.72222222222 V
Maximum input signal before clipping = 174.626646833 mV

For those of you without a scope and only a simple DVM, this calculation for the source resistance should be VERY close to the optimal value for that JFET.

I went through most of my stash of 2N3819's and have a few near the extremes of the ranges.  I'll breadboard up the circuit and inject a test signal and we'll see how close the math is to reality.
 

doqmemory

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May 9, 2020
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Another D87 joins the world! Mic-Parts RK-87, Cinemag CM 13113 and body from chunger. It is quiet and rich sounding, complementing my other microphones nicely.

Mike
 

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doqmemory

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Note the custom AT-ST there for the bias. I need to order some more resistors so I don't have to solder 4 of them (the closest I had.

Thanks to Dan and everyone who has posted here in the past decade. This was a fun distraction for social distancing blues.  Now I just have to finish my D47FET before I start something else, like a FET847.

Mike
 

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Ricardus

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Dec 2, 2018
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doqmemory said:
Another D87 joins the world! Mic-Parts RK-87, Cinemag CM 13113 and body from chunger. It is quiet and rich sounding, complementing my other microphones nicely.

Mike

Does he have the bodies back in stock with the graphics for the switch patterns and such?
 

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