Amp buzz

[the budget]

Hello everyone,
I'm not sure exactly where to post this but i have been searching and haven't been able to find too much so here goes.

I play an Ampeg SVT3 PRO that is a few years old. The Amp itself seems to have developed a buzz or hiss. Coming out of the speaker itself it isn't too bad but when running out of the preamp out or direct out in the back the buzz is sometimes as loud as the bass itself coming through. It seems to be worse at some venues vs. others but I use a power conditioner and the ground lift doesn't have any affect on it. I have tried all the controls individually and none seem to effect it too much. The one thing that did is going from pre to post eq but this only affected it slightly and not enough to make it playable.

Do I just have faulty wiring somewhere, tubes going bad, or maybe something else. I even tried unplugging other lights on the same line as my amp to no avail although i am not completely ruling it out because in bars who knows what in on which circuit.

Any help would be greatly appreciated Thanks

The Budget

 

[matthiu23]

i opened my ampeg 610 cab and found that the white plug was wired wrong. the red and black wires were switched around so the horn wasnt grounding. they pull up out of it and can be pressed back in with a guitar pick. replace the plug with the white wire facing the horn control.