Mark IV with HORRIBLE BARK on 100 watt setting

[recycledsound]

Seems to be fine at half power setting but switch it over and hit a chord and there is a really bad "distorted BARK" in front of it???

Power Tubes seems to check out OK?

Any clues?

Anyone??

Appreciate it.....

 

[MusicManJP6]

I thought the Mark IV was 85 watts?

Anyway, check your power tubes in a dark room for excess glow (or no glow). Tap each preamp tube with a pencil eraser and listen for noises (or lack there of)...

Try another power outlet...

Check your cables too

 

[recycledsound]

I tested the tubes (although I don't have a cunductance tester) no shorts or gas and they register WAY up there on the GOOD/BAD scale.....

I have heard this nasty noise before (didn't document it - dummy)
and power tubes didn't seem to be the answer.

I have also switched them around to see if I could make it go to the half power setting without success.

 

[JERMO]

Is this a combo amp? Or do you have it plugged into a cab?

 

[trem]

Not sure what you mean with "bark". Did you mean flabby, crackly low end? It might be your speaker. It could also be your power tubes. Tube testers aren't really reliable.
http://forum.grailtone.com/viewtopic.php?t=28826

Try it with different tubes and cabs to isolate the problem.