Set top box question

PhilNYC · « **on:** 8 Nov 2005, 09:24 pm »

Wasn't sure where to post this...it's an audio question about a HD cable set top box...

I have a Scientific Atlanta Explorer 4200HD set top box, and I would like to connect the coax digital output to a 2-channel DAC (Bel Canto DAC2). The DAC2 does not take Dolby Digital input...it must be fed a PCM signal.

On the 4200HD's settings for Digital Audio Output, it gives me two options..."Dolby Digital" and "Other". Does anyone know if "Other" is a PCM output? If not, is there a way to set the 4200HD to output a PCM signal?

ctviggen · « **Reply #1 on:** 8 Nov 2005, 10:01 pm »

I'm guessing that it would be PCM (what else is there?). But I don't know. I have a 4200HD, which I find actually has picture breakup a lot. I also hated the interface so much I bought a Replay so that I could use the Replay's interface. Would you not use surround sound? That's one of the benefit of HD -- surround sound is nice for football, music, etc.

PhilNYC · « **Reply #2 on:** 8 Nov 2005, 10:09 pm »

I'm not sure what else there is either, but I'm having some trouble getting a signal lock, so I wanted to see if anyone knew if it might be something else.

I'd love to use surround sound, but unfortunately the setup of the room is not friendly for that. That plus the fact that most of the time my TV is tuned to Barney and Sesame Street doesn't make me feel its worth it...hearing "I Love You, You Love Me" in Dolby 5.1 is just too much for me to take...

JoshK · « **Reply #3 on:** 8 Nov 2005, 10:21 pm »

I don't have the SA, but I use the digital out from both my Panasonic EVR-e80H and my newly acquired LG 3410 HD tuner/DVR. The LG has in its menu DD or PCM, the Panasonic had a choice like DD or, iirc, dolby stereo, which is just PCM too. You aren't going to hurt anything trying it, and I bet "other" is PCM. Then again I've heard that not all boxes that output DD output PCM since you need a chip to convert the signal to PCM or even in some cases an ADC.

PhilNYC · « **Reply #4 on:** 8 Nov 2005, 10:29 pm »

Quote from: fabaudio

But you want to hear "I love you, you love me" through a Bel Canto Dac!?

Eh...better than the harsh built-in DAC of the SA4200HD...

OBF · « **Reply #5 on:** 9 Nov 2005, 07:48 pm »

Hmm....this is an interesting discussion for me because I tried a brief experiment the other night but didn't have time to follow up. I'm trying to decide if I need an ADC card for a TacT preamp if I was to buy one, and tv is the only analog source that I can think of. I tried connecting the coax out to my DAC and just got hash, but didn't get to check the menu to see if it was set for 5.1 output. I think my HD STB is a Motorola of some sort.

But the part I'm confused about is I thought most cable channels are still analog, so I assume the audio is analog. Would a STB take an analog signal and digitize it to PCM before outputting via the coax jack?

ctviggen · « **Reply #6 on:** 9 Nov 2005, 08:35 pm »

In my community, the channels under 100 are analog. The STB does not digitize these (my Replay, however, does). Channels above 100 are digital. This is another reason the Replay is useful -- it's more seemless.

PhilNYC · « **Reply #7 on:** 9 Nov 2005, 08:47 pm »

Quote from: ctviggen

In my community, the channels under 100 are analog. The STB does not digitize these (my Replay, however, does). Channels above 100 are digital. This is another reason the Replay is useful -- it's more seemless.

Before trying to use my Bel Canto DAC, I was using a Denon 3801 AV receiver. Had the digital out from the set top box plugged into the 3801 and it worked for every channel (I didn't even try hooking up the analog outs). So apparently either CablevisionNJ sends digital audio out from the source, or the set top box is converting to digital on the fly.

ctviggen · « **Reply #8 on:** 9 Nov 2005, 08:49 pm »

That's better -- when I was using the cable box, I had to switch inputs for my HT system when going from less than 100 to over 100. That's no fun! Now, I just use my Replay if I'm on non High Def and the cable box on high def.

PhilNYC · « **Reply #9 on:** 10 Nov 2005, 05:43 pm »

Well, it appears that "Other" is something other than PCM, because I can't get a signal lock on it with my Bel Canto DAC2 at all. The DAC2 is fine with the PCM output on both my DVD player (Denon 2900) and my Playstation 2, but it refuses to lock onto the signal put out by the SA4200HD regardless of whether I set it to "Other" or "Dolby Digital" (I don't expect it to work with a DD signal, as Bel Canto has told me it wouldn't).

Any thoughts/ideas? What format could "other" possibly be? Does a Dolby-Digital-to-PCM converter box exist?

ctviggen · « **Reply #10 on:** 10 Nov 2005, 08:07 pm »

Phil,

If you go here:

http://www.scientificatlanta.com/explorerclub/UserProfile.asp

You can sign up and get the manual for the 4200HD. This may tell you what "other" means (could it be MPEG?).

PhilNYC · « **Reply #11 on:** 10 Nov 2005, 08:11 pm »

ctviggen...already did that, and no good information about it (all they say is "use the digital out with your surround system").

I spent about 30 minutes on the phone with SA's tech support (most of it on hold)...they didn't know the answer, but suggested that I flash the firmware to see if there were upgrades to the firmware that would correct the signal lock, so I had my cable company do that. I'm not home, so I can't test it out til tonight...

ctviggen · « **Reply #12 on:** 10 Nov 2005, 08:22 pm »

I've never liked Scientific Atlanta stuff, and this is one of the reasons why.

OBF · « **Reply #13 on:** 10 Nov 2005, 11:54 pm »

My STP is a Motorola DCT5100 and the lousy user menu only has picture/tv setting and closed captioning. There was nothing I could find relating to the SPDIF output or converting to PCM or audio settings of any sort.

So I still don't know, even with a different STB, whether I'd be able to use a TacT preamp without an ADC card. Sounds like it would depend on the box and the cable provider (Comcast) but it's kind of disconcerting to not know before you buy something.