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Original Message

Got the DC-offset blues

Posted by ChasLieb on September 24, 2015 at 20:47:23:
One of my amps is dead flat pegged at zero when the DC offset switch is tripped, but the other is staunchly at 2 volts. I had a 6as7 blow some time ago and replaced it but no change. Tried measuring all tubes and replacing the lower performing ones and balancing measurements from one bank to another in the two rows. Tried moving the 6sn7s about. Tried removing the bottom plate and measuring the large and small resistors on the 6as7 tube sockets but no dice, they all measure about the same. The trimmer pot does not make it move more than about 1/4 of a volt if that much no matter if turned to extremes. Sound wise it seems as if the other amp is doing all the work so the sound seems localized to its speaker, but if you approach the speaker for the bad amp you hear sound, just not in the same intensity as its brother. Not sure if that could be an effect of bad DC offset or if I have a different issue. Yes I tried switching the cables to see if it were the preamp or the interconnect.

Not sure where to look next. Help.