speaker ground hum

10) Connect the pre amplifier (without any source connected to it) to the amplifiers.

11) Switch ON the pre amplifier.

12) Switch ON the Left amplifier ONLY, and listen for any hum / noise.

13) Switch OFF the Left amplifier.

14) Switch ON the Right amplifier ONLY, and listen for any hum / noise.

15) Switch OFF the Right amplifier.

16) Switch OFF the pre amplifier.
06-14-10: Tvad

Tvad,

Problem with the check list associated equipment is not 100% isolated from the input of the amp/s.

It doesn't matter if the other associated equipment is turned off. If a ground loop current is present it will travel through the equipment safety ground through the signal ground of the equipment then through the ic/s ground until it exits the safety equipment of another piece of equipment. From one ic connected amp to the preamp output to the other amp input.

As you can see it would not matter if the equipment was on or off.

I will state though with some preamps turned off the design circuitry of the preamp could and will break the the ground loop current flow path of a problem source/s connected to the inputs of the preamp. Damn, I hope Herman doesn't read this post.....

Jea48, I'm not a technician nor an electrician. As a result, I'm not in a position to discuss the validity of the steps provided.

I simply posted a checklist provided to me by a technician from an audio manufacturer. It has been very helpful to me in my troubleshooting a buzz in my system.

There are further steps from the tech, which were also helpful, but I think I'll not post them since I'm not qualified to discuss why they may or may not work.

Good luck to you, OP! Buzz/hum is a PITA to diagnose and eliminate, IMO.

There are further steps from the tech, which were also helpful, but I think I'll not post them since I'm not qualified to discuss why they may or may not work.
06-14-10: Tvad

Sorry Tvad,
my post was not meant as a criticism of your post. I am far from an expert when it comes to audio....
I hope my comments on this thread or any other thread does not sway someone from posting.

Again please accept my deepest apology....
Jim

No apology necessary, Jea48. I'm just not equipped to defend the checklist's validity without further study of your criticism, which I admit I am too lazy to do.

I will say the source of the buzz was finally traced once the tech instructed me to systematically plug all the components into an extension power strip that was alternately plugged into several different outlets in the room.

The problem turned out to be lack of common ground between certain outlets.

Raybo76, Many times the culprit is the Cable TV cable or an outside antenna cable. Make sure you unplug all cables of these to test.