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Hum From Speaker

1. I hear a low Hum from my speakers.
2. When I increased the volume the Hum does not increase.
3. I disconnected everything from Amp except the speakers and I still hear the Hum. Not even the interconnects were connected to the Amp. Just the Amp plugged into the wall with a cheater plug as a test.
4. All other components were disconnected from the wall.
5. I can't hear any Hum from the Amp unless I put ear right on the Amp.
6. My Amp is a Sunfire 5x200

Does not seem to be ground loop.

Any Ideas? Any Solutions?

Thanks ahead of time.
srlaser
ghstudio
141 posts
 
Some possible causes people forget about include light dimmers (especially halogen), lamps that you turn on by just touching them, lights that turn on automatically at dusk, small transformers plugged into the wall, florescent light fixtures or even "energy saver" light bulbs, pool pump, water heater.

Turn off every circuit breaker in your home except for the one that you have the amp plugged into...then make sure there is nothing plugged into any other outlet on that circuit...nothing.
srlaser OP
17 posts
 
Once my Powervar ABC-1200-11 gets here I going see if that helps. If not I am going to try my dedicated 20 work space outlet with nothing else hooked to the outlet. Can't turn off the every circuit breaker because I share that with the apartment next door.

If I still have a problem I am going assume the Amp is the problem and call Sunfire for service. If Sunfire finds something wrong with the Amp, I think I should ask the Ebay guy to pay for the repair. What do you think?

Thanks for the help and I will keep you posted
srlaser OP
17 posts
 
I got the powervar and still the Hum is there. Try a different outlet still Hum is there.

So I am convinced that the Ebay guy sold me an amp with a low hum. I searched the internet and found that in old amps the power supply caps can dry out and cause the hum I am getting.

My amp is ten years old.

So does it make sense if I ruled everything out except the Amp that the old Power Supply Caps of the Amp can cause the Amp to hum?
ghstudio
141 posts
 
simple answer: yes
srlaser OP
17 posts
 
I dropped my Amp off to a local repair guy today and hummed at his place too. Wasn't easy to find one. He is charging me $50 per Cap (2) and $75 FOR labor.

He believes the two caps are causing the problem but if it isn't the caps, it could be the two bridge rectifiers. If the caps do not solve the problem, then we will try the rectifiers.

I will post the results of the repair job. I guess my point is not all humming is caused by ground loops or noisy electrical feed from the mains.
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