2ch amp and HT receiver connected to same speakers

Summitav, are you saying that the CATV coax would cause a hum even if it is not connected to my HT receiver?

Sometimes yes. Chances are it has a connection somehwere, if even to the same electircal wiring in your house.

It is simple enough to listen for the hum, and just unscrew the coax (AT THE WALL)

If the HUM stops, then you know the cause.

Then to find out what to do about it.

Install banana plugs on your cables for a quick disconnect when you switch between systems. Never run with both connected at the same time.

If the co-ax is hooked up to anything that is hooked up to the speakers where you hear the hum, it could be the co-ax. Of course, it COULD also be a bad cable somewhere in the system as well.

Process of elimination. But this is what makes our hobby so much fun right? Absolutely start with cable or satellite. If it is not cable or satellite kill all other breakers in the house except the one feeding your system. See if the ground loop is gone, if it is start turning each breaker on one by one to see if it comes back. If it comes back when you turn on a certain braker you've found your problem. If all breakers are off and you still have the ground loop I would start unhooking cables one at a time, until it goes away. It could be a faulty cable, certain component, who knows? A lot of possible causes. With time and patience you should be able to figure out. Good luck and let us know what you discover. Have fun!

Summitav, are you saying that the CATV coax would cause a hum even if it is not connected to my HT receiver?

Thanks everyone for the helpful comments. Regarding the ground loop, I have all my equipment powered by the same dedicated circuit. I have also tried the Granite State Ground Control and a cheater plug with minimal effect. The only input to the HT receiver is my DVD player via HDMI. The HT receiver outputs to my Projector, also via HMDI, and to my 2ch preamp via RCA. Thanks for any other ideas!

Try this simple test. When you can hear the HUM, simply walk to the wall (no place else. It HAS to be at the wall) and unscrew the coax CABLE at its very entrance to the room. If the HUM stops, then it is your incoming cable not being grounded.

If it does not then you have your work cut out for U.

Thanks everyone for the helpful comments. Regarding the ground loop, I have all my equipment powered by the same dedicated circuit. I have also tried the Granite State Ground Control and a cheater plug with minimal effect. The only input to the HT receiver is my DVD player via HDMI. The HT receiver outputs to my Projector, also via HMDI, and to my 2ch preamp via RCA. Thanks for any other ideas!

Good answer Swampwalker, this is the problem many times. Of course, the simple test is to have everything hooked up using the HT bypass, but with the incoming CATV from the wall disconnected from the system. If the hum is gone, an isolation transformer will solve the problem. A simple, inexpensive cure to the problem.

regarding ground loop, have you tried an isolation xfrmr on your CATV (assuming that w HT bypass, you have a display that may be tied to the cable or sat co-ax)?

I'm still thinking to solve the ground loop. I've helped lots of buddies hook up using HT bypass, or just taking front preouts to an input on the preamp, then always setting it's volume control to the same position. It's hard for me to believe the ground loop cannot be solved.

I use banana plugs to change amps with the same speakers.

02-03-11: Jamesg
Install banana plugs on your cables for a quick disconnect when you switch between systems. Never run with both connected at the same time.

This appear to be the best option of not destroying anything albeit a little inconvenient especially if one often switches between music and HT frequently. I am doing the same thing in my system.

I am not too convinced on the Niles switch box as I believe it may degrade sound quality with an extra box inserted into the chain. Bill is on the right track in contacting both Niles and Adcom as some amp manufacturers may not recommend doing this out of technical reasons(not associated with sound quality).

http://www.nilesaudio.com/images/PDF/SPK-1_Cutsheet.pdf

This is an excerpt from audioreview.com forums.

Niles SPK-1 Amplifier selector

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Well I finally found the solution to my dilema of wanting to run 2 amplifiers on one set of spealkers. I wanted to run a HT receiver form multichannel and a 2ch amp for stereo music using the same speakers, To do this you usually have to have a preamp with a HT bypass or set up a tape loop. However, I found this product by niles audio, its an amplifier switcher and its good up to 600wpc and is 12v triggered, for only $95.

Niles SPK-1 www.nilesaudio.com/images/PDF/SPK-1_Cutsheet.pdf

Now the question is, can I hook up my zone 2 of my AV receiver'2 preamp and use this as the 2ch side with a dedicated 2ch power amp. I'll be calling Niles and Adcom on this one.

Bill

Install banana plugs on your cables for a quick disconnect when you switch between systems. Never run with both connected at the same time.

What have you done to eliminate the ground loop?

DON'T DO IT!!!!!!!

The amps will shunt each other and possibly damage each other.

Either get a good switch or figure out a cure to the ground loop.

Kal