In Reply to: RE: Fixed, cathode, and back bias posted by Thermionic27609 on December 29, 2014 at 14:59:21:
"Shared bias, whether fixed or not, calls for matched tubes and low DC resistance in the grid circuit. A great example is transformer coupling between the driver and power tubes. "
Amen. I have power amps that run four KT120s PPP with shared bias provided by a single CCS (no bypass cap, Class A differential). The output stage is coupled to the driver with an IT. I tried using two cathode current sources and a cap as described in above post. While this arrangement has the advantage of maintaining DC balance, I didn't care for the coloration the capacitor added.
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Follow Ups
- RE: Fixed, cathode, and back bias - JKT 12/29/1422:01:59 12/29/14 (10)
- RE: Fixed, cathode, and back bias - Naz 23:25:55 12/29/14 (9)
- RE: Fixed, cathode, and back bias - JKT 15:09:52 12/30/14 (0)
- RE: Fixed, cathode, and back bias - DAK 11:52:25 12/30/14 (7)
- RE: Fixed, cathode, and back bias - Naz 17:14:49 12/30/14 (6)
- RE: Fixed, cathode, and back bias - DAK 18:32:49 12/30/14 (5)
- RE: Fixed, cathode, and back bias - Naz 04:27:20 12/31/14 (4)
- RE: Fixed, cathode, and back bias - DAK 11:46:13 12/31/14 (3)
- RE: Fixed, cathode, and back bias - JKT 14:54:04 12/31/14 (2)
- RE: how do you implement the TL431? nt - DAK 17:06:13 12/31/14 (1)
- RE: how do you implement the TL431? nt - JKT 15:31:42 01/4/15 (0)