Added a power amp, now HUM and BUZZ- HELP! (1 Viewer)

[joe goswami]

I had the same problem back when I had my Denon AVR-1400/Adcom GFA-545II setup. I too ran a ground wire from the amp chassis to my grounded AC Outlet. This minimized the hum but didn't eliminate it at low volume with my ears close to the centre channel speaker.

My new setup Denon's AVR-1802/GFA-555II doesn't exhibit this and I've removed a couple components in my system permanently (CD Player, & AC-3 Box). This may have removed a possible ground loop that was inherant in my old system.

I really can't explain what happened here but my hum is totally a thing of the past.

Regards,

Joe

 

[Mike_P]

Get an outlet tester ($2) at the hardware store and check that your outlets are wired correctly. You could have your hot line switched with the neutral, or the neutral switched with the ground, or the ground may not be connected at all. The lights on the tester tell you what the problem is when you plug it in to the outlet. Neutral is the line that should carry the current back to your circuit breaker. The ground line should not carry current under normal operation. This line is normally tied to the chassis inside your equipment, and in the breaker box it should be tied to the one common ground point of your house. The hot line carries the current to your equipment. If your outlets aren't wired correctly, your lamps may work fine, but more sensitive electronic components won't.

As mentioned in other posts, be sure all components are plugged in to the same circuit. With the outlet tester, it is easy to turn one breaker off and check which outlets are dead, meaning they are on the same circuit.

Check for light dimmers, florescent lights, motors (refrigerators, air conditioners, etc.) on the same circuit. Dimmers in particular put a lot of noise on the line. Any of these problems may require assistance from an electrician to correct.

I think you said your DVD player has a 2 prong plug on it, and when you connect the DVD player, you have the hum. Try a different DVD player. It may be that your upgrade to the Rotel amp has "forced" you to upgrade your DVD player. Don't you hate it when that happens?

Anyway, good luck with your problem,

Mike P

 

[Matt Stryker]

HAHAHAHAHA! I unplugged my CATV cable and my hum is completely gone! YESSSSSS!

For those who are interested, the Radio Shack part number for the FM Trap is 15-579.

 

[NicholasF]

Mike_Ch, when you said you tried any connection, did this include optical? Is this an option for you?

I used to have a slight hum with a Hafler pre/power combo, but replaced the pre with a Yamaha and switched to all optical connections for audio and plug all video straight to TV. Obviously I still have to use an RCA cable between the receiver and the Hafler power amp, but luckily they play well together. No more hum, and no need to use Radio Shack ground loop isolators between the preamp and the other audio components!

From what I understand, optical has a slight advantage over coax, in that it doesn't carry ground and this eliminates one more variable when trying to isolate misbehaving components and ground loop hums. Perhaps this might save you from having to use the electrical cheater plug.

-Nicholas