Neumann Vintage U87 Clone : Build Thread.

[signalflow]

Would the Mxl V6 body accommodate the build?

The V6 looks like it would be better suited for a G7 build rather than the U87.  The mounting brackets are set for a rectangular PCB where the U87 has angled boards. And it does not come with any switches for pattern, pad or hpf.  If your looking for a body try the white market there is a reasonably priced one there.

-Casey

 

[HellfireStudios]

Check out http://recordinghacks.com/microphones/MXL/V6 for information that may make you rethink gutting that mic. Mainly it is designed and built in California, and gets decent reviews. The mic this project was originally built into was a bottom-dollar Aurycle. Just something to think about.

-James-

 

[HellfireStudios]

I just bought a Tektronix 150MHz Dual Channel Scope, but it has no probes (which doesn't suprise me). When I saw how simple they seemed, the idea came to me to make my own probes. After some searching, there is still debate on whether a DIY probe is viable, but I came across this site: http://emcesd.com/1ghzprob.htm He seems to know more techno-jargon than I care to wrap my head around at the moment, but says it can be done. Any thoughts? Thanks.

-James-

 

[kevinkace]

Would Mouser part 270-330K-RC be a reasonable replacement for RN55D3303FB14 (which is out of stock)?

 

[wave]

Would Mouser part 270-330K-RC be a reasonable replacement for RN55D3303FB14 (which is out of stock)?

Yes

Dave

 

[Matador]

While I wait for my styrene caps to show up, I was thinking about breadboarding up the front end of the circuit to show how the JFET parameters (like IDSS and VP), the source and drain resistors, and Zener voltages all played together in this simple voltage amplifier stage.  Is there any interest in me doing this and providing the scope shots?  I could test both the 2N3819 as well as the 2SK170BL.

 

[wave]

Matador,
I would like to see your results, especially the difference between the 2 FETs. I'm doing a build for a client and I'm trying to decide if I should go with the 2SK170. Since you have way more tech expertise in this, your tests could be very helpful to me.
By the way, is it better to have a low idss? I'm still confused as to what is better in the way of gain and noise. I picked the lowest in my bacth of 2N3819 fets but didn't some people use higher number idss fets with better gain results? As you can probably tell, I really don't understand how the idss and Vp relate to what I should be looking for to achieve good results in the amplifier.

Thanks,
Dave

 

[0dbfs]

+1 Matador!

That would be very interesting and useful for many in selecting and understanding what the FET is doing here and how the various parameters affect the operation in the circuit and ultimately the sound and capability of the microphone.

the FET does appear to be a slightly important component since it's the only active component in the ckt, all the signal goes through it, and the part also appears to vary significantly from piece-to-piece regarding the critical parameter ranges.

Thx,
jonathan

 

[geekmacdaddy]

Wanted to thank Eric (tskguy). I sent him a capsule from an old U87 who's diaphram was stretched and sounded like it. Eric reskinned it, and all I can say is, I have a guy who thought his Neumann was dead, and he is now screaming over the phone, "It's alive!!!". Apparently, he is a happy recording engineer. He said that he'd give me mp3's of voice and acoustic guitar. I'll post them when I get them. Still haven't biased mine.

 

[tskguy]

Sweet!! I am glad he is happy so far. Can’t wait to hear the clips.
Eric

 

[geekmacdaddy]

Ok. Clips (Done by my friend, who's U87 it was) of the U87 I pulled the K87 out of, and sent to tskguy for a re-skin.

1st clip is voc and acoustic guitar. both were recorded separately, no eq, through vintek pre's into an mBox3

https://dl.dropbox.com/u/87086401/Acoustic%20and%20Vocal%20no%20eq.aif

2nd is the same w/eq

https://dl.dropbox.com/u/87086401/Acoustic%20with%20vocal%20eq.aif

Vocal, no eq

https://dl.dropbox.com/u/87086401/Vocal%20no%20eq.aif

 

[tskguy]

Sounds pretty darn good if i do say so myself  ;D ;D ;D

Geek, how does your 87 sound?? wink wink nod nod..

E

 

[geekmacdaddy]

It doesn't. I'm not smart.

 

[tskguy]

Geek, I know thats not true, your very smart!!

 

[geekmacdaddy]

It's alive. Definitely darker than the U87 I a/b'd it with, and a heavy 1k bump, bit honky, but could be good in a mix. Here's photo's and 3 clips.

The first clip is of the real U87 (re-skin by tskguy). 2nd clip is my clone, no eq. 3rd with eq. Thanks for the help Eric.

https://dl.dropbox.com/u/87086401/U87.aif

https://dl.dropbox.com/u/87086401/CloneNoEq.aif

https://dl.dropbox.com/u/87086401/Clone%20EQ.aif

 

[kevinkace]

Looks nice!

I have a Pacific Pro Audio LD-One and actually like it stock! Didn't find it usable?

 

[geekmacdaddy]

Looks nice!

I have a Pacific Pro Audio LD-One and actually like it stock! Didn't find it usable?

Usable? Yes. Brittle? Yes. I took the chance that having it as a donor for a U87 clone would make it eminently more usable. 

 

[wave]

Yo Geek,
I listened to your samples and  I'm hearing (at least I think) that your fet isn't biased correctly and there's some distortion in the signal. Did you just set it at 11.5V and roll with it?

Dave

 

[geekmacdaddy]

Dave,
Good ear. I had 2 XLR wires backwards so I didn't get too far trying to bias, at which point I just popped on the capsule. Eric diagnosed the problem quickly, so I didn't bias, just  set it for 12  volts.  I'll go back in and try again.

Jeff

 

[poctop]

+1 For Geekmacdaddy,  i specially like the place when we hear " Its Hotter Now"  8)

Good Job ,  thanks For you nice Picture,

Dany,
Best,