speaker ground hum

try plugging in to different outlets
especially if there is a subwoofer

Raybo76,

Assuming the hum you are hearing from the speakers is due to a ground loop you need to start from each amp and build out to the source/s.

Start with only one amp connected to the preamp. (Unplug all other ics from the preamp's inputs as well as outputs.
Unplug all other associated equipment from the AC power outlets.) Isolate everything else from these two pieces of AC powered equipment.

If no hum...

Connect the second amp to the preamp. Check for hum.

If no hum...

Connect one front end source to the preamp. Check for hum.

I recently was dealing with a hum issue. A technician gave me the following troubleshooting checklist to follow, which worked very well. It is intended for monoblocks, but it can be revised for a stereo amp.

1) With all components DISCONNECTED from the AC mains electrical supply, make sure that the amplifiers are connected to the loudspeakers correctly.

2) Remove all 'cheater' / 'shorting' plugs.

3) Disconnect the preamplifier from the amplifiers, so that there is no input signal to the power amplifiers.

4) Use standard, supplied AC power cables.

5) Connect all components to the same AC circuit; source, preamplifier and BOTH power amplifiers.

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

7) Switch OFF the Left amplifier.

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

9) Switch OFF the Right amplifier.

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.

17) Connect a source to the preamplifier, preferable a CD player.

18) Switch ON the source.

19) Switch ON the preamplifier.

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

21) Switch OFF the Left amplifier.

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

22) Switch OFF the Right amplifier.

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.

All excellent suggestions. If all else fails have
your Cable TV ground checked where it enters your house.
This eliminated a terrible hum in my family room
surround system. Good luck.

want to thank everyone who responed to my problem ,the audiogon community are great people....thanks again ..raybo76....