2. digital
  3. 1110057331

How to get multichannel sound from a CD?

I was at a friend's place recently and heard him play CDs through his new Linar multichannel amp, which has the ability to direct part of the stereo signal to the back speakers. The effect was surprisingly good: spatiality and power increased, without any apparent damage to sound quality (as long as the rears were not too loud!).

This got me thinking: Rather than wait forever for the major labels to start releasing good quality multichannel recordings in SACD or DVD-A, why not explore ways to get extra spatiality out of my existing large CD collection?

So I'm looking to find out what options exist for doing this. I'm just gathering info at this point, so any tips you have are of interest--a bonus would be your comments on how good it sounds, but just hearing about an option is good too.

Note that I do care very much about sound quality issues such as timbre, tonality, musicality. The best options for converting CD to multichannel will do minimal/no damage to essential sound quality, but will add spatiality.

So far I know about the following:
-The Linar amps, and maybe other multichannel amps, that just direct the sound to the back
-the Meridian 861 processor has a mode for this. Super expensive, supposed to be good.
-the McCormack universal player has a mode also. Stereophile seemed to like it a bit less than the Meridian for this purpose, but it costs a lot less.
-I think DTS has a processing mode in some receivers which can do this (I'm not much of a home theater guy, no receiver in my system, so I'm sure many of you will know more than I about this).

Any others you guys know about?
calanctus
kkurtis
43 posts
 
An old technology that still works surprisingly well is the Yamaha DSP system in several different options. Rather than try to extract out of phase information, it uses a vast array of measured locations to recreate the enviornment of the listening experience. Generally this uses two front (extras) and two rears. The original concept was to run the front speakers throught the unit but is best used with an extra two channel output into the DSP to keep the front two as pure as possible. This approach offers unlimited processing options but I just use a Jazz and a Chamber setting depending on the music. Since this is infinitly adjustable as both effect and volumn, you can create the effect that best suits your room and expectations. You can put a pipe organ in a cathedral with extreme reverberation and feel you are in a hugh space. These units are often available at Audiogon. I use in-walls and have excellent results. You can also turn it off. I am using Watt-Puppy 7's with high end stuff in an excellent room and the Yamaha adds a little "feel" when I want the ambience of a concert hall or jazz club. The trade offs are more than acceptable. Good luck.
gregmacknass2
17 posts
 
As I and Kkurtis both stated Yamaha reciever is going to be your best bet for 5 channel stereo. He summed it up quite nicely. happy listening.
Greg
eldartford
4,262 posts
 
Calanctus...All the matrix multichannel schemes involved out-of-phase signal being emphasized in the rear channels, and deemphasized in the fronts, with the exact ratios varying somewhat between systems. The SQ LP system also involved some plus and minus 90 degree phase shifting which allowed a SQ decoder to provide better separation. All systems work best when the recorded material was encoded for the particular kind of decoder used for playback, but there is enough commonality between schemes that decent results may be achieved with differing schemes.

DSP (Digital Signal Processing) uses delay and recirculating signal to create an artificial echo that simulates hall acoustics. Usually the playback system includes a way to select different amounts of this echo effect, so as to simulate large and small halls. Outboard equipment for DSP were the first consumer applications of digital technology to audio, and replaced metal spring devices that were previously used. Many present-day surround sound processors include DSP...why not, because it is easy to implement since the signal is already in digital format. My Rotel SS processor has DSP, but I rarely use it. If I want to do multichannel playback of two channel material I usually use Dolby Prologic II. PLII has a useful three channel mode that gets me a signal for the center front speaker without any rears. DTS sends less to the rears.
calanctus OP
151 posts
 
Thanks Kk, Greg, Eld. Intereesting to know about the Yamaha, but I suppose that newer technologies such as Logic7 and Trifield could have an edge for sound quality.
cinematic_systems
282 posts
 
They are all different;

In order of intrusiveness (changing timbre and adding its own sound)

Yamaha DSP (these are great on anechoic recordings otherwise there is delay on delay)
Logic 7 (not as good as maybe it should be thickens and blotches the sound)
Dolby Prologic II (a little splashy in the rears but good timbre tracking)
Trifield (as transparent as it gets at the moment)

Trifield is designed to work with regular CD's and like Dolby prologic 2 is a little more advanced than Eldartford indicates as they can consider arrival times and a variety of phase angles. etc.
More to discover