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Discussion Starter #1
Just received my AVR-X4000 last week and I absolutely love it except for the fact that it seems to produce lots of noise in the rear channels with Dolby Digital/Comcast cable as a source. The noise comes through the tweeters and is easily audible from 6-8 ft away.

My front channels are powered by separate amps at 360 watts per channel and the rears are powered by the receiver amp so Audyssey has attempted to balance the difference by attenuating the fronts by -8db and the rears are up +8db. Could this gain difference explain the noise? Or is this inherent to DD? I did not seem to have the same issue with my prior receiver, a Rotel RSX-1056. Any insight would be helpful, thanks!
 

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I would suggest turning the gain in the rears down to 0 or +2 then see if the noise is still present...that much gain sounds too high to me...especially if your going to be listening at higher volume levels....
 

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If the problem really only occurs with the DolbyDigital/ComCast source, I'd guess that it stems from that source. Which way have you connected the receiver to the AVR? HDMI? TosLink?, analog stereo? Just to double check this, try to change the input port. If the noise vanishes then, the respective input might be defective (or the cable was just poorly protected). If the noise remains, it's either the output of your ComCast receiver or a problem with the broadcast dolbDigital signal.
Good luck and have fun with your AVR!
 

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I had some overall static noise in my system. I added one of the cheap-o inline cable line filters from Parts-Express and problem solved.
 

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Discussion Starter #6
If the problem really only occurs with the DolbyDigital/ComCast source, I'd guess that it stems from that source. Which way have you connected the receiver to the AVR? HDMI? TosLink?, analog stereo? Just to double check this, try to change the input port. If the noise vanishes then, the respective input might be defective (or the cable was just poorly protected). If the noise remains, it's either the output of your ComCast receiver or a problem with the broadcast dolbDigital signal.
Good luck and have fun with your AVR!
I think this is the right explanation. It might even be only certain TV channels. Zero issues with DTS sources too and no issues with Bluray or my WD Live TV, even with DD content. Whew, glad it's not the Denon!
 

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Discussion Starter #7
So, it IS the Denon. I decided to connect my old Rotel RSX-1056 today and play some Dolby Digital sources that exhibited high noise floor from the rear speakers with the Denon. After matching levels (which needed a lot of gain for the rears since the Rotel has half the preamp voltage that the Denon has), there was still no noise floor. Even with gains turned way up on the Rotel! But this X4000 has been problematic with other issues even after a microprocessor reset so it is going back to the retailer.
 

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I registered to answer this, for those who may be searching around for a solution to this problem. :) The issue is with Dynamic EQ, under Audyssey in the Audio setup. Turn it off and the hissing with Dolby Digital, and to a lesser degree DTS, goes away. Frankly, it's an awful, unnatural sounding effect, so you're better off with it disabled anyway.

Cheers,
Jeremiah
 
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