Comcast cable box Optical out to Direct Stream

Why cant I send the digital signal from my Comcast cable DVR out to the Direct Stream?

I have my Comcast cable box set to 1080p output. I have an HDMI cable running to my TV with the analog outs going to my Receiver.

But, I also want to use an optical cable to my Direct stream. When connected to the Cable box the optical cable red light glows at the end but when connected to the direct stream I get no sound?

Any suggestion?

Most probably because you try to send 5.1 surround sound to a renderer that does not have decoder for this buit-in.

You need to send LPCM 2ch. from the source.

While not of specific use to you, as a point of reference I use a TOSLINK connection from my U-Verse DVR and it works fine. I would think if the issue is a 5.1 mix being sent there would be an option to change to 2.0 mix. Did you check the menu options on the DVR?

Thanks for the replies. I think you guys are right on about the output signal. At this point I’m not sure how to change the output or how to access the internal menu.

And believe me I don’t want to call Comcast for advice…

I had the same problem with my Fios box (and a different DAC in my second system) and was not able so solve it. It appeared that even when set to 2-channel mode it was sending 2-channel Dolby (AC3 or whatever). PCM was not an option. In my main system I connect my cable box to the TV via HDMI and I am able to set the TV to put out 2-channel PCM, which works fine with my DS.

So, If I am understanding this right unless the cable box outputs PCM , it will not work with the Direct Steam?

The DS needs PCM - it doesn’t have a dolby digital decoder for example. Many cable/satellite boxes have a PCM/DD or 2 channel/multichannel option buried somewhere. With DirecTV it’s under the audio options.