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Author Topic: U-87 mic mod question  (Read 592 times)

Donn

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U-87 mic mod question
« on: February 15, 2022, 01:35:10 PM »

Hello,

I have a version 04, and have made the following modifications:

1. Remove HP and LP filters
2. Removed the sub-board, and replaced with a 2N3819 (I located a small stash of Texas Instruments 2N3819s). Biased and good to go.
3. Lowered the capsule polarization voltage to 47VDC.

Is there anything else circuit-wise that can be done that will bring it closer to the pre 04 circuit/pre "A" specs, or make further sonic refinements?

Donn
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RuudNL

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Re: U-87 mic mod question
« Reply #1 on: February 20, 2022, 09:52:25 AM »

1 - Do I get the impression that you removed the frequency dependent network altogether? Does it sound 'better' now? (I doubt it...)
2 - As long as you can find a 'good' 2N3819 (there are many fakes nowadays), it might be an improvement. Although some people think the sub-board is better...
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Donn

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Re: U-87 mic mod question
« Reply #2 on: February 26, 2022, 03:04:42 PM »

1 - Do I get the impression that you removed the frequency dependent network altogether? Does it sound 'better' now? (I doubt it...)
2 - As long as you can find a 'good' 2N3819 (there are many fakes nowadays), it might be an improvement. Although some people think the sub-board is better...

1. As I'm sure you know, all new Neumann's have their infamous high and low pass filters to conform to German broadcasting regulations. They should be the first thing to go with U87Ai used in a music application IMO. I can't imagine any sonic benefit from this additional circuitry outside of voiceovers and broadcast (and I think it's questionable there too).  Fortunately, it's easily removed.

2. The TI 2N3819 is genuine. As for the sub-board being better, I've seen debates over headroom and S/N Ratio, but I wonder how common it is for producers and artists to hear a more musical sound from revisions 04 and 05 with the sub-board. And if Neumann also believed they sounded better, why did they return to the 2N3819 FETS and ditch the sub-boards?

Donn
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klaus

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Re: U-87 mic mod question
« Reply #3 on: February 27, 2022, 12:51:39 PM »

Agree with your second point.
Your first point is factually incorrect: Neumann's version of the Braunmühl-Weber double-backplate capsule design requires[/] attentuation of the high frequencies in the mic processor. That attenuation tames an extreme high frequency rise (±[email protected]).

Without it, the mic will be offensively bright and unmusical.
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Klaus Heyne
German Masterworks®
www.GermanMasterworks.com
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