Over the years I've repaired more amplifers than I could count. I seemed to hook up with the Phase Linears and have specialized in them. Hey, it provides steady work!
I often thought that I could cure the output turnoff thump of the Series II amps by modifying the power supply for the opamp to keep it powered up until the main power supply caps discharged.
I recently set out to accomplish this task. After some experimentation, I put an outboard power supply on the opamp supply so that the opamp would never lose power. One channel was dead quiet while the other still had a thump. I compared the voltage stages in both channels and found the last voltage stage in one channel shutdown and that appeared to cause the thump. I swapped semiconductors between channels and that made no difference.
Anybody care to offer a guess? I can provide a pdf of the schematc if necessary. Yeah, I could put a relay in, but I'd rather address the real problem.
I often thought that I could cure the output turnoff thump of the Series II amps by modifying the power supply for the opamp to keep it powered up until the main power supply caps discharged.
I recently set out to accomplish this task. After some experimentation, I put an outboard power supply on the opamp supply so that the opamp would never lose power. One channel was dead quiet while the other still had a thump. I compared the voltage stages in both channels and found the last voltage stage in one channel shutdown and that appeared to cause the thump. I swapped semiconductors between channels and that made no difference.
Anybody care to offer a guess? I can provide a pdf of the schematc if necessary. Yeah, I could put a relay in, but I'd rather address the real problem.
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