Digital Audio Problem

[Maxie]

I am trying to connect my cable box (Scientific Atlanta Explorer 3240HD) to my A/V Receiver (Sony STR-D2020) using the Digital Optical and/or Digital Coaxial Audio connections and get a pulsed noise. Connecting my DVR player to the A/V receiver works ok and I get proper surround sound.

Yesterday I had two Cable techs out trying to get surround sound from the cable box via the Digital Optical/Coaxial connections to the A/V receiver and they thought it must be the cable box so they replaced the box and still get the pulsed noise.....any idea what the problem is? The cable company is sending another tech out this morining with another cable box.

Thanks for any help.
Maxie

[Sonnie]

Hi Maxie... that sounds really strange, but it is obviously in the cable box since your DVD player works fine. I wonder if the techs know of anyone else that is using the digital output on their cable box to know that it indeed works.

[Maxie]

Thanks Sonnie; I'll ask the cable guy when he comes this AM. The two techs that were here yesterday didn't even know what Dolby was so I don't give much hope on help from them. The pulsed noise looks like Pulse Code Modulation (PCM) on the A/V display. I have never heard PCM so I can't be sure that is the noise. Scientific Atlanta's web site doesn't give any info either. I don't think its the A/V receiver and hate to buy another one right now just to find out.

[Otto]

Maxie wrote:

The pulsed noise looks like Pulse Code Modulation (PCM) on the A/V display.

Hi Maxie,

What do you mean by that?

Does the cable box have any settings for the type of output it will produce on the digital outputs? PCM, bitstream, etc.? Try them all, of course.

I don't think it's your receiver, either, and I would not want to trade that piece out to prove that it's the cable box. You've tried all the digital inputs, right? Especially the one that's working with your other piece of hardware...

Also doubtful, but it could be a cable. I'd just show them the DVR or DVD player working, and then simply unplug it and plug in the cable box. All else is equal that way.

Good luck. I think it's a problem with the cable box.

[bobgpsr]

Hi Maxie,
The Sony STR-D2020 is such an old (circa 1999) receiver are you sure it has Dolby Digital (DD also known as AC-3)? If not the cable guys need to set the cable box to just output/convert to 2 channel linear PCM which I am sure will work. Practically all current receivers now will do either 5.1 DD bitstream or 5.1 dts bitstream along with the original 2 channel linear PCM on their S/PDIF inputs (coax or optical Toslink).

[Maxie]

The Sony STR-2020 is an oldie, but it does have Dolby Digital Surround, as well as the Digital Sound Effects. It has front, surround and center speaker outputs and I have added a powered sub-woofer. It really sounds nice playing DVD's using the Digital Optical or Coaxial input to the A/V receiver.

The cable box is set for Digital Dolby but there is a pulsed noise on the center channel speaker when using the Digital Optical or Coaxial input on the A/V receiver (same input as used with the DVD player). When using the analog audio output from the cable box into the Tape, CD or DAT input of the A/V there is some surround sound but not as dynamic as the DVD player. I think it is a bad cable box and have convinced the cable guys of that....they just don't many HD cable boxes but promised to bring another one today.....we'll see!
Maxie

[salvasol]

Maxie wrote:

The Sony STR-2020 is an oldie, but it does have Dolby Digital Surround, as well as the Digital Sound Effects. It has front, surround and center speaker outputs and I have added a powered sub-woofer. It really sounds nice playing DVD's using the Digital Optical or Coaxial input to the A/V receiver.

The cable box is set for Digital Dolby but there is a pulsed noise on the center channel speaker when using the Digital Optical or Coaxial input on the A/V receiver (same input as used with the DVD player). When using the analog audio output from the cable box into the Tape, CD or DAT input of the A/V there is some surround sound but not as dynamic as the DVD player. I think it is a bad cable box and have convinced the cable guys of that....they just don't many HD cable boxes but promised to bring another one today.....we'll see!
Maxie

Did you try a different cable??? ... Have you talked to Sony or checked the troubleshooting online???
Good luck finding a solution .....

[Maxie]

Well the fourth cable tech showed up yesterday and verified that all the cables were CORRECT. He went into the cable box programming; set the Audio to "OTHER" instead of "Digital Dolby" and the pulsed noise disappeared. He finally found a channel transmitting Surround Sound and there came the audio!! His explanation was that some channels carry different Digital Dolby programming and then the cable box must be set to "Digital Dolby" for that to work. Non Dolby channels you set the cable box to "Other".

I told the cable guy that my understanding of Surround Sound is that Digital Dolby technology transmits digital audio formats of Mono, Stereo, 5.1, 6.1 and 7.1 Surround Sound formats. He said that he has wired only two cable boxes to A/V receivers with Digital Coaxial and that was the way he set the cable box for Surround Sound. He suggested that I find a cable movie that displays the Digital Dolby logo and then reset the cable box from "other" to "Dolby Digital". Hopefully I can find a movie soon and check this out.

One positive thing about the situation is that I got a newer cable box, the Scientific Atlanta 3250HD which came with operating instructions and is listed on the SA web site. The older cable box was a 3240HD that came with an 8300HD instructions.

Anyone know any engineers at Scientific Atlanta I could call and get some correct info?

[bobgpsr]

Maxie wrote:

...my understanding of Surround Sound is that Digital Dolby technology transmits digital audio formats of Mono, Stereo, 5.1, 6.1 and 7.1 Surround Sound formats.

My understanding is that legacy DD does not support discrete 7.1 or 6.1 surround. Dolby Digital:EX does support matrixed back surrounds IIRC.