Pre-amp hum?

[ocdSCHACK]

I bought a Yamaha 7.1 receiver about a year ago...I bought the cheapest one with pre amp outputs because that's what I needed with an active setup. I didn't consider it cheap at $550.00, but pre amp outputs are a rarity these days. To my point:
I have a hummmmmm............
I've grounded the various components to each other and minimized every possible cause. I noticed that when there is no signal from an input source (i.e. XBOX or Cable Box,) there is no hum. Once the signal or sound comes on, a hum presents itself. In other words, if -80 dB is the min, -79dB has a hum much greater than -80 or mute. Is this a problem with the cheaply made and overpriced receiver I bought or another typical ground problem? If it's a receiver problem, what can I do to help stop the problem? Put sleeving on the wires? Change capacitors? Tie bricks to it and throw it in bottom of the Mississippi?

The hum isn't bad, but with decent speakers, I notice the hell out of it. I'm depressed thinking a $550 receiver(w/ a reliable reputation) can't transfer a signal without a hum. Any one have a similar experience or suggestions on how I can solve or lesson this problem?

[diru]

X-box connected to the internet ?

Cable modem ...... ?

Cable television ?

I would disconnect anything , that has anything to do with incoming cable line .


One other thing , disconnect subwoofer .


This is way out there but it does happen , sometimes when using more then one outlet in some rooms , this can place your gear across L-1 / L-2 . This can cause a voltage differential across neutral / ground between gear . Fix for this is to attempt running everything on its own separate 20 amp circuit .

I got my money on the cable line bringing in the noise .

[djg]

I have a Yamaha RX-V663, which fits your description. No hum, connected to a PS3 with wireless internet, cable HD DVR, and a couple of outboard amps. I doubt it's your receiver unless it's defective.

I watched the cable tech install the cable, and it is properly grounded.

[Sydney]

Have you tried an isolation transformer?

[williamrschneider]

Have you tried an isolation transformer?

+1

I had a BAD hum when I connected both a TV cable and other electronic items together. The problem went away with the TV cable disconnected.

Check out isolation transformers from Jensen if disconnecting the TV cable eliminates hum. Cable is notorious for doing this.

http://www.jensen-transformers.com/iso_vid.html

[Sydney]

Useful related info from the Jensen site:
http://www.jensen-transformers.com/apps_wp.html
( Whitlock is da man -IMHO of course! )