Bob Katz Ultimate Passive Processor

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mediatechnology
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Bob Katz Ultimate Passive Processor

Post by mediatechnology »

Bob Katz posted here back in July with questions about using the Insert Switcher to switch a transformer "color" box. Bob had some WE 111's he was interested in trying along with some vintage UTC and shared the results with me. Here are some of the pics and measurements...

The box allows introduction of a variable series resistance and DC current injection which was suggested to him by Bill Whitlock.

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The schematic:

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Some of the measurements:

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Additional pdf measurements:

WE 111 +10 dBu 60 Hz Spectrum Direct vs DC inject
https://proaudiodesignforum.com/images/ ... inject.pdf

WE 111 +10 dBu 60 Hz Spectrum Direct vs Series R
https://proaudiodesignforum.com/images/ ... ries R.pdf

UTC A20 +10 dBu 60 Hz Spectrum Direct vs Series R
https://proaudiodesignforum.com/images/ ... ries R.pdf

WE 111 IM Direct vs Series R
https://proaudiodesignforum.com/images/ ... ries R.pdf

Transformers freq resp with & without series R
https://proaudiodesignforum.com/images/ ... ries R.pdf

MEA-2 Freq resp BS & Treb Boost
https://proaudiodesignforum.com/images/ ... Boost.pdf

MEA-2 Phase BS & Treb Boost
https://proaudiodesignforum.com/images/ ... Boost.pdf

WE111 Phase direct
https://proaudiodesignforum.com/images/ ... direct.pdf

WE111 Phase 400R rotation
https://proaudiodesignforum.com/images/ ... tation.pdf

WE111 Phase DC inject thru 14kR
https://proaudiodesignforum.com/images/ ... u 14kR.pdf

After living with it for awhile Bob writes:
After doing some attempts at mastering with the WE111, it's a wonderful, sweet, warm transformer with "just enough color" for my purposes. A little bit of series R gives it versatility. Adding series R lowers the level so to be fair, try to listen at matched levels by using some kind of gain makeup in the mastering chain.

I also have found that the DC injection is a bit too fuzzy sounding for my tastes. So for anyone trying this sort of circuit, I suggest increasing the value of R that's in series with the DC until a more subtle amount of distortion can be achieved.
emrr
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Re: Bob's Ultimate Passive Processor

Post by emrr »

Thanks
Best,

Doug Williams
Electromagnetic Radiation Recorders
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