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