In Reply to: RE: PSE 2a3 operating points? 320V @45mA 5K Fine posted by andy evans on May 26, 2012 at 13:09:13:
Andy, the advantage of separate Cathode Rs is that you can use these to balance the idle currents. Also, if you choose to trade off the slightly better technical performance afforded by bypassing (all or part of each) then you will gain better AC signal matching.
Personally, I'm not a fan of 100% Cathode Biasing. In my 845PSE monos I use (mainly) fixed biasing through Pos and Neg PSUs and just enough Cathode Biasing via adjustable Rs to balance idle current of each tube. I use DC coupling and my main (coarse) control for idle current is via adjustment of the DC grid voltage, set in the driver stage.
Happy to share if can be bothered with the additional complexity. Advantages are A2 drive on peaks, DC coupling and great balance.
Cheers,
Naz
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Follow Ups
- Separate Cathode Rs for PSE - Naz 22:11:18 05/28/12 (2)
- RE: Separate Cathode Rs for PSE - andy evans 00:36:14 05/29/12 (1)
- Fixed Bias can be done in so many ways - Naz 01:09:39 05/29/12 (0)