Speaker buzz with SS amplifier, input disconnected

Like Arh is asking above, is this a really bad hum/noise or is this just the tiny hum you might get from a floating input?

When 60 Hz hum becomes really bad, it can create a buzzing hum. The 60 Hz wave is so strong that it clips off at the peaks and creates many new frequencies that are higher order harmonics of 60 (120, 240, 480, 960 Hz, etc.).

If this is a pretty loud hum, then it sounds like you have either had a big electrolytic cap in the power supply going bad, or there is a short in the amp that is so bad it is bleeding the power supply down. If it is an internal short, then it will smell bad and be overheating. If it is just an electrolytic filter cap, it might slightly smell acidic, but won't be overheating that bad.

Anyway, sounds like she needs an overhaul.

Did these amps have this problem from day one, or is this recent?

Do you have any other equipment near the amps that is on?

Do you have florescent lighting or light dimmers?

If you swap the physical position of the left and right amps, does the greater hum stay with the amp?

If you move one of the amps and speaker to another room, is the problem still there?

I'm trying to figure out if you might have electromagnetic pickup (radiated pickup). You can tell if it is radiated because when you move the amp around, the pickup will be greater or less.

Dimmers and florescent lights transmit higher frequencies that sound like buzz.

Power conditioning doesn't get rid of radiated pickup.

Possibly both amps are having electrolytic cap breakdown, but that normally happens one at a time on older amps.

What I meant about moving it to another room was to see if a different AC branch of power or if a different electromagnetic environment caused a change. You should check everything before going through the hassle and cost of sending it back. Also the repair dude is going to be pretty puzzled if he gets them on the bench and can't find a hum.

But is sure does sound like a power supply hum to me.