Hum from my home theater's speakers


Hi,

I finally hooked up all my gears and tested my system last night. This is the first time I hooked up everything.

There is big hum noise from FL, FR, center speakers and subwoofer. I didn't check sorround speakers beause the hum is just too loud from the speakers I mentioned above.

This is my setup:
* Blu-ray player pre-amp Theta Dreadnaught Digital I power-amp 5.1 speakers.
* Pre-amp is also connected to projector through HDMI.
* Connection between pre-amp and power-amp are all balanced cables.
* Connection between pre-amp and sub is balanced cable.

I bought the system several months ago, almost all used (except blu-ray player, pre-amp and projector), and didn't have time to hook them all up until today. But I did tried partially hook them up as following:
laptop playing songs/video pre-amp Theta Dreadnaught Digital I power-amp FL, FR, C and sub speakers
Initially there was hum when I used RCA cables between pre-amp and power-amp, but later I changed to balanced cable and the hum was gone.

Now with the full setup, the hum is back. The full setup is in a different room from the test setup (not sure if this matters because this means things are plugged into different outlets).

Below are a few things I have tried:
* When pre-amp is turned off, there is no hum.
* When I unplugged the power-amp, the hum stops, including subwoofer's hum.
* When I plug power-amp in, the hum starts immediately. There is a power switch at the back of the power-apm (like this one: http://www.wpclipart.com/computer/hardware/.cache/power_switch_OFF.png). Even if the switch is turned off, there will be hum immediately from sub if I plug power amps in.
* I searched and some articles said: if there is only one audio equipment is grounded, there will be no ground loop hum. So I tried to unplug all others with ground connection and leave only power-amp plugged, along with others that doens't have gound connection, the hum remains the same.
* I also tried make the active and neutral on the power-amp's plug contact outlet's active and neutral, and leave ground untouched, the hum is till there.

How could I solve my problem?

Thanks.
deeperblue
Try to isolate the amp onto a different power circuit and see if that solves your problem...

-RW-
Deeperblue,

Do you have your H/T system connected to a CATV provider or a SAT provider?

If CATV for a test disconnect the provider incoming CATV RG6 coax cable from the cable box and then check for hum. If hum is gone buy a Jensen coax ground isolator.

If you have SAT satellite dish disconnect the SAT RG6 coax cable from the SAT receiver and check for hum.
If hum is gone.... Post back.... The fix is a little more complicated.....
Most subwoofers come with a cheater plug. Place a cheater plug on the sub. A cheater plug can be bought at Home Depot, it turns a three prong plug into a two prong plug thus lifting the ground.