Well...thank you so much for the "Tip of the Return Circuit" hum test! This is a used amp that I've had for some time now. It seems that the return circuit was reversed! The outside of the RCA cord, just touching it, gave a hugh hum! The tip...nothing. Well I knew that was wrong! So I soldered it correctly AND I think it's working like it's supposed to....meaning, what I thought was normal reverb effect was waaaaay outta whack! Never able to turn the POT up more than 3 or 4. After realizing the original tank "Accutronics Reverb Tank 9AB1C1B" has a decay time of 1.2 to 2.0 secs (short), it seems to be working like it should. I just hope it didn't damage any components of the reverb circuit. The new tank I got has a decay time of 1.75 to 3.00 secs (medium). So buying I new tank without isolating the problem wasn't a total lose :loco Thanks again......