This noise lasted a couple of minutes when it first occurred--I was out of the room and thought they were digging up the street outside, or maybe it was World War III starting. Electronic chaos, hard to describe, neither very high nor very low, mid-range. I rushed to turn the system off. I left the S.E.X.amp in the sytem. When the noise occurred next, I saw that it was right channel only. It was brief that time, and brushing the phono stylus soon after turn-on told me that the amp was normal for a few seconds after it was warmed up enough to play, but that the noise, now identified as right channel only, started up less than a minute after turn-on, lasting only 5 or 10 seconds. That's been the pattern since that second time, and a tube swap doesn't change it away from the right channel. Both tubes look normal. I did resistance checks, and the two channels were very close to identical across the board, though both different a few places, I thought due to the Magnequest transformer/choke upgrade. Voltage checks with a dummy speaker load seemed useless since I wouldn't know if the malfunction was happening. I did run the amp briefly with such a load, to see if anything got warm, and only the CL-90 inrush limiter did: it got very slightly warm. Has anyone had a similar experience with this or another amp? It's usable, since the noise doesn't seem to pose a threat to my speakers (though for later testing I've hooked it up to less valuable speakers than my Oris 150 horns), but I'd still like to get rid of it, as you call all well imagine. Thanks for any suggestions to help.
