#1
My friend's amp has been giving him trouble (squealing whenever he's not playing) and we've tried everything to make it stop but we can't get the volume over 2 before it starts to squeal and the guitar isn't even above bedroom volume at that point.
we think it may be dirty power.
There is a transformer right in his backyard.
could that be overpowering the amp or something causing the problems?
#2
-what amp is it?
-how many watts is it?
-how many gain are you using?
-how close are you to the amp?

that might help...

EDIT: It could also be microphonic pickups in the guitar...
Gear:
Fender Jazzmaster
Boss DS-2
Digitech RP150 (with Line6 EX-1 Exp pedal)
Orange Crush 30R


My Youtube Page
Read this!You know you really want to...

#3
bugera 1990
120 watts
gain has been everywhere from all the way, to backed off a lot.
and we've been real close, and as far away from the amp as the cable will let us go.
still the same issue with everything we've tried.
#5
Also, have you tried different guitars?
If so, sguit is right with the microphonic preamp tube
Gear:
Fender Jazzmaster
Boss DS-2
Digitech RP150 (with Line6 EX-1 Exp pedal)
Orange Crush 30R


My Youtube Page
Read this!You know you really want to...