Buzzing Cambridge Audio A500...

It's buzzing/humming and I don't know why. I checked the manual for guidance but none of the suggestions helped. I've unplugged everything from it and powered on but the hum persists. I've also tried it away from the rest of my electro stuff but to no avail. The hum isn't really loud but it's noticeable if the music is turned low or during quiet passages. I got it used but it didn't hum initially. Has anybody else had a similar problem? It's equipped with the optional MM phone stage. Could that have something to do with it? I thought about opening it up but I don't know what I would be looking for. Any thoughts would be appreciated.

Disconnect everything except the speakers. Turn off any lights on dimmers. Make sure the amplifer isn't near any other electrical appliance. Turn off any appliances with motors such as vacuum cleaners, washers, diswashers. If you still hear a hum, there is every possibility that the power supply filter capacitor is leaking and will have to be replaced. This can only be done by a service technician.

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Originally Posted by SpartanFan

It's buzzing/humming and I don't know why. I checked the manual for guidance but none of the suggestions helped. I've unplugged everything from it and powered on but the hum persists. I've also tried it away from the rest of my electro stuff but to no avail. The hum isn't really loud but it's noticeable if the music is turned low or during quiet passages. I got it used but it didn't hum initially. Has anybody else had a similar problem? It's equipped with the optional MM phone stage. Could that have something to do with it? I thought about opening it up but I don't know what I would be looking for. Any thoughts would be appreciated.

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If it's a 60hz hum, then it's either a filter cap like Skeptic posted, or you might have some ground fault problem. Try plugging it into a different circuit in your house, not just a different outlet. Try calling Cambridge Audio for advise if it doesn't help. Good luck

Be certain that your amplifier is not sitting on a steel or aluminum table or rack. I once found an amplifier picking up hum just by sitting on an aluminum folding table. The table acted as an antenna and coupled the emf directly into the preamp. When we lifted it off the table, the hum disappeared. Set it down again and it came back.

I don't know if this is your problem but I have the same product and I get some static sound occasially and it's because sometimes when I walk acroos the room and touch my DVD player I get a static shock which apparently charges some if not all the components in the chain. I have a Sheffield Labs CD that has a number of uses like a break-in track and a static discharge track. All I know is that when I play that track the scratchy noise goes away.

Thank you all for the advice. As it turns out, the buzzing is caused by the outlet it was plugged into. I took it to another dorm room and the buzzing was gone. On the plus side, I don't have to have it serviced. The downer is I can't really do anything about the school's crappy wiring (to the best of my knowledge...). Would a power conditioner help?

It depends on what kind of power conditioner. A cheapie with only an MOV won't do anything. A slightly better one with a small capacitor and and/or an inductor might help some. Only a high quality UPS which supplies a clean reliable distortion free signal is a sure fire fix. IF THAT IS REALLY YOUR PROBLEM. But it is easy to jump to the wrong conclusion. It is also possible that other emf in your dorm room radiating directly into your receiver is the cause. If that is the case, no power conditioner will help. It is cheap and easy to experiment with extension cords to see if moving the receiver around the room helps. Also try other outlet in the same room. It may be on a different circuit. If you have a long enough extension, say a 50 or 100 footer, see what happens if you keep the receiver where it is but run power from a corridor outlet or another room. The kind of problem you describe is usually not traceable to a particular circuit or outlet. If it is, try talking to the maintenance department. BTW, a defective flourescent lamp either on your desk, in the ceiling, or in the next room could also be the cause. More investigtion may be necessary to really pin it down so don't be too fast to spend your money on something that may not work.