Question for the audiophiles on a 2 channel setup for TV and movies..

Ok guys, I have a question that I can't seem to figure out on my own. I know you guys will be able to set me straight.

In a nutshell, I have a 2 channel setup. (Axiom M60's). I had the 5.1 setup but we did some remodeling and have a modern look going now. The 5.1 system made things look a little cluttered. The wife didnt approve and thus I now have a 2 channel setup.

What I have been doing is having my cable STB output Dolby Digital and getting the Dolby Digital signal through 2 channels.

Being more of a videophile and now just getting into the audio side of things, it was always my belief that anything Dolby Digital was just better. lol.

Last night I decided to set the cable STB to output 2 channel only (PCM) and all of the sudden my speakers came to life. Sound is much more clear and real sounding and the surround effects were much better.

One thing I noticed was a little loss in bass when setting the cable box to output 2 channel only as opposed to Dolby Digital. Why is this?

Last part of confusion for me is, I have my cable box and DVD player connected to my reciever via Toslink Optical Audio Cable. Is this the right connection for a 2 channel setup or should I use the analog connection?

Sorry for the long post. Hopefully this all makes sense. Thanks for any help.

Hi New2,

Something here is confusing:

"Last night I decided to set the cable STB to output 2 channel only (PCM) and all of the sudden my speakers came to life. Sound is much more clear and real sounding and the surround effects were much better."

You said you were now running 2-channel stereo. Do you mean that the surround effects heard through the two stereo speakers "came to life"?

As to the other questions, perhaps your set-top box is not doing the Dolby 2-channel mixdown from DD 5.1. Did you check the STB menu?

Dolby Digital is a compression algorithm, so a lot of data is thrown away compared with PCM. However, it's normally quite transparent; you might hear a few subtle differences from PCM and a 2-channel Dolby Digital feed, but it should never be dramatic or something is wrong.

Usually a PCM should have the same amount of bass as a DD feed, but a PCM mix and DD 5.1 mix are done separately, so there may be differences.

There is another variable as well. Most cable systems insert their own compression algorithms to increase available bandwidth for other services (phone, internet, etc.) and the ever-increasing number of video channels. I doubt very much if your STB is delivering uncompressed 2-channel PCM. It would require too much bandwidth, and cable systems wouldn't accommodate it.

A better comparison would be to play a DVD of a concert and set your DVD player to do the mixdown to two channels. Then compare that with the CD version of the same concert in two channels. Assuming the mixes were similar, the two should sound very similar in terms of sound quality, detail and frequency response.

A Toslink optical digital connection should normally deliver either a Dolby Digital 5.1 datastream or a PCM 2-channel feed form your DVD player.

Regards,