Without detailing the process, it basically boils down to you cannot "tweak" this amplifier. It is marginally stable when configured exactly as original, and only then. But the mate to this amplifier, the one that runs the other channel, seems to have tolerated a few extra parts and tweaks with fewer or no problems. That amp has always been stable. I cannot find a single physical difference between the two, but there it is. I should say that this applies to the +/-3200V tube output stage. The input stage is low voltage solid state and seems to be happy in both amplifiers, with some tweaks allowed. It seems like I have been working on the faulty amplifier for a year, but based on my original post below, it was "only" five months or so. Could have been faster but I don't like to work on the amplifier for at least a day after having had it powered up, for fear of getting a deadly jolt from charged up capacitors. So, I changed something, fired up the amp, made some measurements, and shut it down, and then waited 24 hours or more before attacking it again. It took some time in between failures to plan a new strategy, as well.
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Topic - I think I fixed the problem with my Beveridge OTL DD amplifier - Lew 11:50:29 10/13/20 (11)
- Question about capacitor ratings for the cognoscenti - Lew 11:31:50 10/20/20 (2)
- When that thing was built - Ralph 13:27:27 10/20/20 (1)
- RE: When that thing was built - Lew 14:32:02 10/20/20 (0)
- RE: I think I fixed the problem with my Beveridge OTL DD amplifier - airheadair 22:21:05 10/13/20 (2)
- RE: I think I fixed the problem with my Beveridge OTL DD amplifier - Lew 16:22:01 10/14/20 (1)
- RE: I think I fixed the problem with my Beveridge OTL DD amplifier - 6bq5 23:09:32 10/14/20 (0)
- RE: I think I fixed the problem with my Beveridge OTL DD amplifier - 6bq5 14:20:04 10/13/20 (4)
- carbon composition shunt resistors - Lew 09:07:58 10/18/20 (0)
- We should talk.... - Lew 16:16:04 10/14/20 (2)
- 470K resistors - Ralph 08:50:25 10/15/20 (1)
- RE: 470K resistors - Lew 09:18:55 10/15/20 (0)