RE: 6BG6G mono amp sounds great but

Posted by PeterI (A) on June 13, 2017 at 20:47:08

In Reply to: RE: 6BG6G mono amp sounds great but posted by Blackdog on June 13, 2017 at 18:54:07:

Thanks, I was wondering if that was the calculation. The spec is supposed to be 1.2V at cathode, which would be 1.2 divided by 25ohm = .048, about right.

If I turn my bias adjust all the way to the other extreme, I had -26.6v on the grid, the cathode read .660v and the plate voltage plummets down to 294V. But cathode reading was moving in the right direction

Solved it mostly, by bypassing a dropping R in the pi filter which bumped up the B+ and now I can adjust for 1.2V at the OP tube cathode. I can raise B+ further if I go from 5R4 to 5V4 rectifier.
Thanks to responders.

Edit: The Sams Photofact schematic said -45V on grid which must be wrong, but it was what I had to go by. -33V is dialed in nicely.

Pete

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Follow Ups Full Thread

Topic - 6BG6G mono amp sounds great but - PeterI 16:14:31 06/13/17 (21)

This is what they look like... (pic) - PeterI 14:33:52 06/14/17 (4)

RE: This is what they look like... (pic) - Triode_Kingdom 23:19:29 06/14/17 (0)

RE:Nice work! (nt) - vinnie2 18:47:19 06/14/17 (0)

They look great! (nt) - Tre' 18:03:52 06/14/17 (1)

Thanks (pic) - PeterI 18:41:01 06/14/17 (0)

Schematic shows - FenderLover 06:20:36 06/14/17 (12)

RE: Schematic shows - PeterI 07:28:48 06/14/17 (11)

RE: Schematic shows - Audio Pete 14:47:27 06/15/17 (0)

That's not correct - Triode_Kingdom 10:16:19 06/14/17 (4)

RE: That's not correct - Audio Pete 14:44:08 06/15/17 (2)

RE: That's not correct - Tre' 20:32:20 06/15/17 (0)

RE: That's not correct - Triode_Kingdom 19:47:42 06/15/17 (0)

Thanks for info NT - PeterI 16:10:34 06/14/17 (0)

RE: Schematic shows - FenderLover 07:37:25 06/14/17 (4)

RE: Schematic shows - PeterI 07:54:45 06/14/17 (3)

RE: Schematic shows - FenderLover 09:24:00 06/14/17 (2)

RE: Schematic shows 5U4 5V4 - PeterI 10:24:22 06/14/17 (1)

RE: Schematic shows 5U4 5V4 - FenderLover 16:50:10 06/14/17 (0)

RE: 6BG6G mono amp sounds great but - Triode_Kingdom 19:24:13 06/13/17 (0)

RE: 6BG6G mono amp sounds great but - Blackdog 18:54:07 06/13/17 (1)

RE: 6BG6G mono amp sounds great but - PeterI 20:47:08 06/13/17 (0)

Follow Ups

RE: 6BG6G mono amp sounds great but - PeterI 20:47:08 06/13/17 (0)

RE: 6BG6G mono amp sounds great but

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