HELP NEEDED: Mark IV noise problem

[generalgrievous]

This is going to seem strange, but it's been driving me crazy and I'm definitely not imagining it.

When playing through the Mark IV (either straight in or through the power-amp only with the Axe-FX) I get this irritating rattling/static-y feedback as notes fade out, but only on certain notes. It only seems to happen around the A-A#-B notes higher up the neck, like in the guitars second octave.

I know this probably sounds crazy, and it's driving me crazy. I've tried multiple guitars, playing the offending note in different ways (bends etc., same result) the local Mesa tech recently gave the amp a clean bill of health, and it's packing a quartet of newish =C= power tubes.

ANY suggestion at all, no matter how crazy, is much appreciated.

PLEASE HELP!

 

[dodger916]

Could be a preamp tube. Does this happen in a certain channel(s)? Does it happen with or without reverb? Is it a combo or head?

 

[ryjan]

I had a similar problem and it turned out to be the speakers. I couldnt tell you why but they made a wierd, tinny sound in the higher frequencies. Replaced them and the problem went away. Try a different cab. So how does that axe fx sound through the simul-class?

 

[generalgrievous]

It's a combo, and it happens on all channels. I never use the reverb.

The Axe-FX sounds amazing, apart from the aforementioned problem. I honestly can't tell the difference between it and the real thing. Hugely versatile and all the effects are top quality. If it's wrong, then I don't want to be right.

 

[ryjan]

Right on man. I'm SERIOUSLY considering trading the Mark IV for an axe fx and a stereo power amp. Still could be a speaker problem. Voice coils do wierd things sometimes. Try running in class A. If it still does it then swap the inner power tubes with the outer ones. My vote is on the speaker though.