Bad Hum Coming Through Amp, What Happened?

DITTO what Almarg said about a possible ground problem. Maybe a loose star ground, or a cold solder joint at a ground point. Definitely not output stage, because it varys with volume control.

Ehaller, I took your advice first figuring that even if it wasn't the problem, it would at least be something to do as good maintenance (similar to tightening the screws on a chassis every so often). The toroidal transformer was tight, but after I took a wrench to it, I got about 2 whole revolutions to get that sucker in as tight as possible. After I turned on the unit, I found out that the buzz had gone down about 20%. Kudos to you for this suggestion!

I still had 80% of the noise to deal with, so up next...

Almarg, I stopped at Target on the way home and picked up a 2-pack of cheat plugs for $1.79, so now I tried adding these to the system. After I plugged the equipment back in and turned on the amp, I heard... SILENCE! Incredibly excited, I turned on the cd player and phono pre-amp, started the volume at zero, and turned it from 0-max on all of the inputs and heard, once again, SILENCE!

All of my woes have been solved, thanks to everyone here for their opinions and help identifying the ground as the problem, and especially to Ehaller and Almarg for their ultimate solutions to the problem!

Now to think that I spent money on a new AC receptacle, power cable, and power conditioner all in an effort to fix this problem, when it took $1.79 to eventually solve it. Oh well, they were upgrades I needed a push to do anyways...

Thanks again, everyone!

I have used those ground cheater plugs before & they work great. Does anyone know the downside of using them if any?

I use a piece of electrical or teflon tape to cover the grounding plug on the IEC of the equipment. That way, you are not introducing a cheap cheater plug into the electrical path.

I have used those ground cheater plugs before & they work great. Does anyone know the downside of using them if any?

Aside from the additional contacts which are introduced into the ac path (which could be eliminated by following Rtn1's suggestion), I think that the one downside would be the fact that the safety benefit of having a safety ground on each piece of equipment is lost.

However, assuming that at least one piece of equipment in the system does not have its safety ground defeated, and that should generally be the preamp or integrated amp, the chances of a problem resulting would seem to be extremely remote. The only scenarios I can envision where a problem would result are:

1)A piece of equipment that is being connected into the system is plugged into the wall through a cheater plug, before the interconnects to the rest of the system are connected. That component has an internal short which causes its chassis to be electrically "hot" (i.e., at 120vac potential). The user connects an interconnect cable to it, and then simultaneously holds the shell of the rca connector at the other end of the cable in one hand while touching the chassis of a grounded component with the other hand. He will receive a shock. Or, similarly, the user plugs a component with a hot chassis into the wall before connecting it into the system, and simultaneously touches its chassis and some grounded object.

2)A component with its safety ground defeated develops an internal short causing its chassis to become electrically hot. All of the interconnects (probably two, for left and right) between that component and the rest of the system are defective in such a way that their shields have an abnormally high resistance (say 10 ohms), but the shields are not completely open. High levels of ac current would be conducted through them, that would cause them to overheat but would not be sufficient to cause the circuit breaker to trip.

As I say, the scenarios in which a problem would result are pretty far-fetched.

Regards,
-- Al