I've got an Ampeg VL503 (please don't be a wanker and say the amp itself is the problem). Whenever I turn on the Loop, the tone becomes much 'weaker'. If I press the 'bypass loop' button, the tone is a motherfucker.
This amp has one of those loops that has a +4/-10 switch but it makes no difference because ultimately the tone is strongest when the loop is off.
When I use the loop, I tend to use the MXR 10-band EQ. Is this known for tonesuck?
I guess I shouldn't overlook the fact that the cables I use for my loop were purchased when Bush was in office.
The v8 in the preamp is for the loop. I've tried a Sino 12at7, chinese 12ax7. It doesn't seem to make much difference.
Weaker how? That's a pretty broad term you've used there. Does the gain drop? Is the bass response affected? Can you post clips?