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previous: Derrick Re: Not your typical bias problem! -- 5/7/1998 9:55 AM

Back to Derrick's Problem

5/8/1998 8:08 AM
liam	Back to Derrick's Problem What output tubes are you using? I've found 28mA seems to work very well in my Marshalls, BUT I once had a pair of tubes, marked GE, made in China and giving exactly the symptoms you describe, but the HT fuse would blow occasionally on warm up. New tubes of better manufacture solved the problem. Have you tried changing tubes? Also, the biasing method I mentioned before is really good and accurate, and I've found that at 460-475 Volts, most of my amps don't really need more than about 27-28mA, and I DEFINITELY can't run the 36mA that people have suggested to me without excess heat. The reduction in crossover distortion between 28mA and 35mA in the two amps I have tested is minimal.

5/8/1998 8:08 AM

liam

Back to Derrick's Problem

What output tubes are you using? I've found 28mA seems to work very well in my Marshalls, BUT I once had a pair of tubes, marked GE, made in China and giving exactly the symptoms you describe, but the HT fuse would blow occasionally on warm up. New tubes of better manufacture solved the problem. Have you tried changing tubes?

Also, the biasing method I mentioned before is really good and accurate, and I've found that at 460-475 Volts, most of my amps don't really need more than about 27-28mA, and I DEFINITELY can't run the 36mA that people have suggested to me without excess heat. The reduction in crossover distortion between 28mA and 35mA in the two amps I have tested is minimal.

Replies:

Derrick Yes I have also been biasing for ar... -- 5/8/1998 10:29 AM