Why QS (and not Peter Scheiber Matrix)?

[kfbkfb]

I don't understand the usefulness of the 90 degree phase shifts in the QS Matrix system, the Scheiber Matrix provides the same "3dB all around" channel separation as QS.

It would be much easier to make an encoder (and decoder) that only uses phase reversals and a Variomatrix type decoder could be developed to dynamically enhance Scheiber Matrix channel separation.


Kirk Bayne

 

[Sonik Wiz]

I don't understand the usefulness of the 90 degree phase shifts in the QS Matrix system, the Scheiber Matrix provides the same "3dB all around" channel separation as QS.

It would be much easier to make an encoder (and decoder) that only uses phase reversals and a Variomatrix type decoder could be developed to dynamically enhance Scheiber Matrix channel separation.


Kirk Bayne

Whoosh! 2:32 AM for this post. You're either up late or very early pondering the great questions of surround sound.

Trusting my memory, such as it is, the weak spot on the Scheiber encode/decode system is center back. If you do the maths any signal pair wise mixed into Lb/Rb to make center back actually decodes as an attenuated center front. Of course center back is frequently avoided in practice but it also meant a sound panning between the rear speakers would not decode correctly. Sansui wanted a system that using conventional mixing practices could position a sound anywhere around a 360 deg horizontal circle.

Although there are several Regular Matrix encode/decode schemes I am most in favor of the official Japanese approved RM system. This used a decoder just like the Scheiber model but did not use pair wise mixing at the encode side. It simply said using a decoder as such any sound position can be represented by a corresponding amplitude/phase relationship. It used a "position encoder" to do this and center back was defined by equal level opposite phase signals that decoded properly.

If the Scheiber approach was compromised a bit for encode/decode the decode portion is great for stereo to surround. The Fosgate Space Matrix group of decoders designed in collaboration with Peter Scheiber did exactly this. Because Jim Fosgate is so closely identified with SQ decoding it was assumed by many that the Space Matrix decoders were SQ. Elsewhere on the forum I posted a thorough analysis/ test/ upgrade on a DSM 360 decoder & it clearly shows it is set up for Scheiber type RM decoding.

 

[par4ken]

Sansui wanted a system that using conventional mixing practices could position a sound anywhere around a 360 deg horizontal circle.

As well as positions inside the circle. Carole King "Music" has an insert showing the placement of the instruments in the original mix. That LP features IMHO the best QS mix ever done.