Stereo to 4 or 5.1 Expansion

With the arrival of DVD the interest in Dolby Digital 5.1 and later DTS has increased significantly and with that so has the interest for multi-channel speaker systems. Games using 3D sound is another major reason several people know owns a multi-channel syste, However, far from all games, music and DVD movies features a multi-channel format (or in case of games use 3D sound).

Many owners of multichannel system felt that they really would like to take advantage of the surround speakers even when listening to stereo content. The first simplest solution to appear in the PC market was to just duplicate the front channels to the rear channels. In this article we will cover several technologies that goes a step beyond this.

In some cases users have found them so impressive they consider it to be an alternative even for movies using true Dolby Digital or DTS soundtracks. You may find that very surprising or even odd there could be anything better than true DD 5.1/DTS or downmixed to 4-speaker (in cases where you don’t have a 5.1 system). In many cases we also agree there is no better option but there are reasons why you sometimes or perhaps always might find other options to be better.

The first most obvious reasons is of course if you happen to lack the options of getting true 5.1 because the DVD player you own only offers stereo output. Another less obvious reason is that the rear channels on many DVD movies are still optimized for a movie theater where you must be more careful how you use the rear channels so as to not ruin the experience for people sitting in the back of the theater.

In a home theater environment this is not an issue, which is why many find DD 5.1 movies don’t take full advantage of the rear channels. This is why some listeners prefer to instead set the DVD player to stereo or Pro Logic and use a stereo to multi-channel expansion algorithm being used, a bit of reverse process from 5.1 to stereo downmixing. Can be interesting to note that according to Philips internal (non scientific) studies most prefer QSound’s QMSS mode over the correctly positioned DD 5.1. Other similar technologies include Dolby Pro Logic II, SRS Circle Surround II, Labtec M3D and Creative Labs CMSS. Some of these are also true alternatives to DD 5.1 and DTS in that they are not just 2 to 5.1 expansion algorithms but also an audio format.