My unit has more hiss than before. I'm going to eventually do a socket retention and cleaning to see if that helps, but most other users don't seem to have the issue (at least after searching here). Oh well. Jay
So you mean hiss as in the noise floor is being raised - not hum correct? I played the piss out of my 200 last night and while I was getting some unwanted hum (from a pooping ground in the rehearsal studio) I did not experience any audible hissing or wooshing or anything else I attribute to a raised noise floor. I got Kt88's in mine as well as a 12AX7 in V1.
Treble up to high? That's about the only way mine with get a lil hissy. Usually though it's really quiet. try the ground lift maybe?
My treble is at 3.5...almost completely down. With the stock 6550s the hiss (yes it's a noise floor issue) is much less audible after taking the amp out of standby than with the EH KT-88s. As I understand the design - the ground lift only affects the DI feed...I tried it anyway with no change. Jay
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