Originally Posted by greyflag
I'd like to deal with an audio issue which will affect whether or when I replace my AVM-50. I watch a good amount of cable, and I recently picked up a used Oppo BDP-103D to see what the Darbee might do for both cable and BluRay. I will upgrade my Kuro later this year and probably upgrade the processor as well. At this point the AVM-60 is my preferred choice. However.....
With the Oppo in the chain (Arris Comcast box to Oppo HDMI In to the Anthem) nasty things can happen. The local cable company sometimes inserts their own commercials in stereo into a channel broadcasting in Dolby 5.1. When this happens, nasty audible pops occur as the three devices deal with the change in audio formats. Pops occur when changing channels as well. Changing the Oppo's output to LPCM does not help. I contacted Anthem and asked if this behavior will also occur with the AVM-60, as i would like to use the Oppo's video processing for cable sources. I got a qualified "maybe".
With Bob and others here well versed in all things Anthem and Oppo, I'd love to hear some opinions and suggestions.
You really should not be getting transients when the digital audio input format changes, but of course you can't really know what the Comcast box is receiving at those transitions, and what it is sending out.
That said, if what you are hearing is a single Pop, what may be happening is that you have a DC voltage bias in your setup -- a type of ground loop problem. With a DC voltage bias, volume "0" is not voltage 0, and when the signal returns you get a pop as the muting lifts (during the transition of digital formats) and the voltage on the outputs jumps back to that DV voltage bias level.
A DC voltage bias can exist because something in your video setup is putting voltage on the cable shields of the cables connecting your equipment. This type of garbage is more commonly heard as 60 cycle power line "hum", particularly in the subwoofer. The voltage travels between you equipment on the shields of the cables connecting them -- and can pass through devices even when they are "off".
Ground loop garbage current can happen if you are using multiple outlets to power your equipment and they don't happen to all be at the same ground level. It can also happen if the feed line for your Comcast box is not properly grounded where it enters your house -- garbage outside your house comes into your house that way on the cable shield of that feed line. It can also happen if you have a faulty device (power amps are the usual culprit) that is leaking voltage to its chassis shield.
Figuring out the source of the problem can be a neat trick. But here's a good place to start: f your cable box happens to be a DVR, try this: Disconnect the Comcast feed wire where it comes out of the wall, and play some recorded content on the DVR. Do the Pops go away?