Slight hum from left speaker -- Help appreciated


Two weeks ago I installed a new amp and preamp (Pass Aleph 30/FT Audio LW-1) in my system and since then I've had a very slight hum from my left speaker. It's not distracting, but it's something I'd like to get rid of. I've switched out interconnects and speaker cables and nothing changed. I did a search for ground loop hums and I could not find any useful information other than cable TV may be a problem and we don't have cable. Any hints on what could be causing the hum would be greatly appreciated. Thanks!
budrew

Showing 2 responses by budrew

Uh, excuse my ignorance, but how does one "float the ground"? (Thanks for the useful tips!)
I tried it all. I floated the ground, exchanged the right and left speaker wires (the hum moved to the right speaker), changed right and left amp-preamp interconnects (no change), and moved wires and interconnects around. Nothing solved the problem. My preamp is passive so I'm only turning the amp on for this testing. The only thing that was proven was that the left speaker wire seems to tbe the trouble. Whichever speaker it was connected to was humming. Is this an amp problem? I am using the RCA inputs. The amp also contains balanced inputs and there are "short jumpers" between pin 1 and 3 on each channel. I checked them, but they seem firmly placed. The hum is very slight. Thanks!