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Audio drop-out from cable box unless I use L-PCM

post #1 of 11
Thread Starter 
I am using a Yamaha RX-v371 receiver, connected to a motorola RNG 150N cable box (comcast). Using HDMI for the connections.

If I connect the cable box straight to the TV, there's no problem. If I connect it through the receiver, the audio cuts in and out sporadically on many channels.

After some time searching, I tried setting the cable box audio output to L-PCM (default is AUTO) stopped this happening, but if I understand correctly this means I'm now limited to 2 channel (or 2.1), and won't be able to take advantage of anything broadcast in 5.1 surround.

I have two identical cable boxes, and tried switching them, with no improvement. I connected a blu-ray player to the reciever (using hdmi) and was able to watch in 5.1 with no audio dropout. I switched the cable box and blu-ray hdmi ports on the reciver, and the problem followed the cable box. I tried changing the cable too with no luck.

If anyone has any suggestions or can clarify whether I'm correct about PCM being sub-standard to 5.1, I'd really appreciate it.
post #2 of 11
HDMI handshake issues with cable/sat boxes are quite common. Although setting the BDP to PCM would get you 5.1, setting the cable/sat box will only get you 2.0. The most often recommended solution is to connect HDMI from the box to the TV directly and optical from the box to the AVR for DD 5.1 audio. If this doesn't resolve the issue, then you're stuck with PCM 2.0 unless you want to change out the cable box for another model/brand.
post #3 of 11
You can find the manual for your cable box here: https://www.pace.com/universal/support/pace-rng150n/ Go to the Making HDMI settings. I'd try the Pass Through setting. P 18.

If this doesn't work I'd give up on HDMI audio. You're not the only one. Check P 16 of the manual and go to "Receiving audio from other input sources". You can assign an optical or coaxial from AV1 - AV4 to that HDMI input. I guess Yamaha (like many others) correctly has a work around for HDMI audio problems. Yes, it's a PITA!
post #4 of 11
Thread Starter 
Thanks a ton for the advice & manual link guys,

I'll try out the pass-through and see how it goes.

With that said, the idea of connecting the cable box right to the tv then only feeding the audio to the receiver may actually be better for me - seems like that way I'd have a choice of tv speakers vs. surround sound speakers when watching tv.
post #5 of 11
Thread Starter 
I've tried a few more things but unfortunately the problem is still there.

Setting the box to passthrough while having it all connected to the receiver through hdmi resulted in no audio.

I've got an optical cable and connected the cable box to an optical port on the receiver. In 'auto' mode it says dolby digital, but the sound still drops out. Same with pass through.

Even more annoyingly the cable box reverts back to 'auto' after a few hours (I'm not the only one having this problem) so even if I use the PCM workaround, it doesn't stick.

Anything else I might be able to try, or if I have to call comcast is there anything in particular I should be asking them to check/adjust? Every time I call they 'send a signal' to the cable box which seems to reset it but doesn't actually solve the problem.

When it's connected through the tv, and using the tv speakers the sound is ok.

thanks very much for any other suggestions.
post #6 of 11
Before jacking around with cables and alternate connections...
Make sure the Motorola box has the latest/greatest firmware.

Just my $0.02...
post #7 of 11
Thread Starter 
Thanks, any idea if that's something I need to specifically ask comcast to update if it doesn't, or should they be doing this automatically?
post #8 of 11
Quote:
Originally Posted by wolfestone View Post

Thanks, any idea if that's something I need to specifically ask comcast to update if it doesn't, or should they be doing this automatically?


Cable companies do little for upgrading unless they sell more premium services.. You should contact your local Comcast office, try to talk to someone who knows something and ask about firmware.
  • What is the latest version?
  • How to check what version is in your box?
STBs (set top boxes) are among the worst for HDMI compatiability when used with an AVR..

Box may work fine into a video display but not through an AVR..

Just my $0.02..
post #9 of 11
Thread Starter 
Excellent, thank you. I specifically requested new (not refurb/used) boxes when I upgraded to HD, but the tech only brought used ones.

There's a comcast center near me, I'll see if I can get them switched out for new ones.

Thanks very much for the suggestion, that wouldn't ever have occurred to me.
post #10 of 11
Hi, wondering if you ever resolved this? Rng150n to ysp-3000, same audio drops with HDMI or optical unless I switch to PCM, which doesn't get saves nor offer the best audio experience.

What did you end up doing? Thanks.

Jesse
post #11 of 11
Quote:
Originally Posted by JKing3 View Post

Hi, wondering if you ever resolved this? Rng150n to ysp-3000, same audio drops with HDMI or optical unless I switch to PCM, which doesn't get saves nor offer the best audio experience.
What did you end up doing? Thanks.
Jesse
It's probably a chip problem in your receiver/processor. If it's good with a DVD then it's the signal from the cable/sat box that is incompatible. Here's a problem stated from a well known manufacture. Happens on my Arcam processor also. I think there are a lot of incompatible chipsets out there.

I am experiencing audio (Sound) dropouts when watching a Dolby Digital broadcast from my Satellite or Cable Box that is connected to my receiver with the digital optical or the coax connection.

We have been working with Dolby Laboratories on a repair for the Dolby Digital broadcast issue that occurs with digital cable systems as well as digital satellite broadcast. We are aware of the issues that have affected our receivers with the newer version of broadcast encoding that Dolby Laboratories has been using. We have since had success with a new version of chipset that we have installed in each of the receiver models that have been affected. If you own one of these units while using any form of Dolby Laboratories Digital broadcast and are experiencing the audio dropouts and would like to have the issue resolved, please check our website for your nearest authorized service location. Take the unit to them with your bill of sale, at that point please call us at XXX-XXX-XXXX and select option 2 for our product support team. We will assist having the unit repaired for you.

At least this company will fix for free
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