I have Comcast cable. I take audio from the cable/DVR box via HDMI (only about 3 feet) to aging Harman Kardon AVR. In the last few weeks, the audio cuts in and out, but only on certain channels (like Turner Classic Movies, my favorite channel). Comcast has reset my box twice remotely, their default means of offering help, to no avail.
It very well could be a low signal, but there could also be a loose fitting some place that could be causing your issues as well. A bad fitting any where from the tap to the tv could also be causing the problem.
If you would like more info, email me....and if not, I would set up a trouble call and have a tech come out and check the house for the things mentioned above and for noise.
If it is only on certain channels, then I would suspect that those channels don't support the 5.1 audio selection set on your AVR. Have you tried setting the AVR to dolby digital 2.0 and see if the droputs occur. I know on my DirecTv receiver some channels don't offer a very good 5.1 digital feed and the sound is more dolby pro logic than dolby digital.
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