Quote:
Originally Posted by oldominion
I've been having some pretty severe microphony issues with my 3.1a preamp of late. My assumption was, of course, the tubes. At Dennis's suggestion, I tried some 6dn7 instead of 6sn7; they sounded great in fact, and were cheap. So when I started to get the very fine, pinging and ringing sounds I assumed the cheap 6d's were at fault, so plugged in my trusty old Sylvania 6sn7...only to find that, after a period of warm up, the high pitched pinging and ringing returned.
I also have 6922/6dj8 in my phono stage, another tube that is prone to microphony, but I'm pretty sure I can trace it to the 3.1a preamp.
Has anyone ever experimented with rolling the 6bx7?
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Don’t have an 8 pin Inspire LP so cannot reply about tube recs but you may try cleaning the tube sockets and pins. I was once having microphonic issues with multiple sets of tubes and this solved it. Some deoxit, and Qtips on the sockets and an abrasive pad on the pins. Vintage tubes can have a fair amount of oxidation on the pins which can gom (Madison County, NC term)up the connections.
Good luck.