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Digital Signal from Digital Cable??

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9 replies to this topic

#1 of 10 OFFLINE   RonJon



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Posted November 15 2003 - 02:55 PM

I just upgraded to the newest digital cable converter box that Comcast carries in the Philly area. It's a Motorola DCT 2000. I any event, it has a coaxial digital audio out,optical audio out and composite audio out. It also has S-VHS video out. I connected the S-VHS out to my TV and I noticed an improvement especially in the premium channels.
However, I cannot get a digital audio signal via the coaxial audio out into my Onkyo receivers coax digital input using a standard RCA cable. I also have the composite cables running out of the L/R composite audio outs on the DCT 2000 cable box into the Onkyo for the analog signal.
I found 1 or 2 channels(Starz) that were indicating 5.1 digital broadcast but the Onkyo would not sense and switch to digital nor could I manually change to digital...so the receiver was not getting the digital signal.

What do I need to to do to receive digital audio from the cable box? thanks!

#2 of 10 OFFLINE   Michael Reuben

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Posted November 15 2003 - 03:33 PM

To get Dolby Digital sound from a TV broadcast, you need a number of things:
[list=1][*]A provider (cable or satellite) that actually supplies a DD signal (not all do);[*]A program that is broadcast with a DD signal (not all are);[*]A cable or satellite box that can process a DD signal (not all can);[*]A digital output from the cable or satellite box (not all have them); and[*]An HT setup that can process Dolby Digital.[/list=1]
It sounds like you may need to confirm that your local Comcast provider is actually sending the DD signal (item 1). If they say they are, then you may have a problem with your configuration (e.g., the assignment of the coax input on the Onkyo).

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#3 of 10 OFFLINE   RonJon



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Posted November 15 2003 - 09:47 PM

Thanks Michael. Would I do better to utilize the Toslink optical digital output over the coax? Does using regular shielded RCA cable instead of actual coax cable have any effect on the situation? Thanks!

#4 of 10 OFFLINE   Jim Lenneman

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Posted November 16 2003 - 04:23 AM

I don't believe that the Motorola 2000 series will process or output a 5.1 signal. It will (with the SPDIF coax output) put out a digital signal, but it's PCM stereo. At least that was my experience with that box. The Motorola 5100 box (which I now have) will output 5.1 if it's broadcast as such.

Jim L

#5 of 10 OFFLINE   Ronnie Schildha

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Posted November 17 2003 - 01:41 AM

I had the same box. The type of audio output by the box has to be configured (stereo, pro logic, dolby digital are the choices I believe). These are set by using the onscreen setup menu. Use the coax output with a digital coax audio cable and it shouls work if your cable company is sending out dolby digital audio. Some don't

#6 of 10 OFFLINE   Andy Goldstein

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Posted November 17 2003 - 01:46 PM

hey gang! thanx for this thread. i was wondering why my reciever was switching to one of the surround modes instead of dolby digital when i selected the digital cable box. it seems to have forgotten that i selected DD. it was set to stereo. switched it back this morning WOW! much better!

andy g.
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#7 of 10 OFFLINE   Jose T

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Posted November 17 2003 - 03:08 PM

RONJON, I just got Comcast newest HDTV box in the S Jersey area. The box supplied was the Scientific Atlanta 3100 model and its only as coxial out for DD.

#8 of 10 OFFLINE   RonJon



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Posted November 17 2003 - 10:02 PM

This box has both coax and optical as well as SVHS for video.
I connected the SVHS and it makes a difference in overall picture quality as was stated elsewhere in the forum. However, the digital sound connection is questionable as I have hooked up an RCA cable from the coax out. I have only seen 1-2 broadcasts that indicate what I believe was the DD 5.1 signal in use but my Onkyo receiver showed Pro Logic II
and never switched. I do not think the receiver will allow me to assign digital if it is not receiving a digital signal.

#9 of 10 OFFLINE   Yohan Pamudji

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Posted November 19 2003 - 06:40 AM

Do you have your surround receiver configured to associate that particular digital input with the cable video input? If not, it'll just take the stereo audio inputs that are adjacent to the cable video input on the back of your receiver. Does that make sense? Basically you have to tell your surround receiver that you want it to get its audio from the digital input whenever your cable input is selected. A while back I had cable with Time Warner and they used a Scientific Atlanta (?) box. The only channels with Dolby Digital were the premium movie channels, and even then only a few of their broadcasts were in DD. When I switched back to the non-digital non-premium channels I had to switch my audio on the surround receiver back to the stereo inputs. It was a pain in the rear.
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#10 of 10 OFFLINE   Jay Foster

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Posted November 19 2003 - 12:38 PM


I have to do the same thing you were doing now. The digital channels only "light up" the left and right speaker on my receiver. I have to switch the audio from digital once I go back to a "regular" channel. I have the Motorola Cable Box 5100.
Jay Foster