Something curious is happening with/to my beloved Mk. III's: after six months of great enjoyment one of the Svetlana Winged C 6550's decided to go nukuler. Or, at least I think it did: I flipped on the amps and with the preamp volume at 0, I heard white noise emanating from one of the speakers which kept getting louder by the second. I flipped off the amps and decided that one tube was bad.
As I was taking said tube out via a rocking motion, I could hear static coming through the corresponding speaker as I jiggled the tube. I chalked it up to a cap that hadn't discharged or something equally benign. Again, the preamp was off, the source component was off and (yea, before anyone asks) the damn amps were off! But (hint...) they were plugged in.
I inserted the original, tired KT88's that came with the amp and everything was fine: re-biased the amps, even turned them down to 1.3V and rocked out to the groovy sounds of Slim Whitman.
Not wanting to leave good enough alone, I decided to have the amps converted to triode. So I started removing the tubes and (come on, you know the rest), when I got to the socket that had held the "bad" tube, I got the same staticky sound as I jiggled the KT88 to dislodge it. Again, being quite adept at ignoring reality, I just blanked it out.
So the amps get converted to triode, we fire them up, get glorious sound out of them and I left for home. Having received a replacement set for the suspect 6550's I proceeded to remove the KT88's. Yup, same staticky sound on that one tube socket.
So ... what gives? The preamp has not been on for weeks now. The amps have not been turned on for weeks since the triode mod. Yet every time I jiggle a tube in that one particular socket in order to remove it, I get crinkly, static (apologies for the high-fuluting, hyper-technical nomenclature) noise. Never when I insert a tube, just removing it and always the same socket.
Any help/suggestions will be greatly appreciated.