The problem of matrix system.
I tried experiments as to whether or not the Principle of superposition is established as a system. (Principle of superposition: whether correct results can be obtained even if simultaneous input to multiple channels is performed)
→ Specifically, when the same signal is put in two different channels, it is a question of whether to localize at the center.
With Sansui QS system, regardless of the presence or absence of steering logic,
○ Same signal is applied to the front left and right channels, the rear left and right channels → Plays correctly, localizes in center of front and back.
○ Same signal is applied to the front and rear channels on the left side and the front and rear channels on the right side → Plays correctly, localizes to true left, true right.
○ All channels same signal → Plays correctly, localizes directly above.
△ Same signal is sent to diagonal channels on right front and left rear, diagonal channels on left front and right rear → undefined signal. However, although not properly reproduced on the diagonal channel as the original sound, fortunately it will be erroneous so that it becomes the same signal of all channels, and as a result it localizes just above.
Since the result depending on the models in the CBS Sony SQ system is changed, Assuming that the logic of the W/M logic decoder or self made logic decoder is logic,
○ Same signal is applied to the front left and right channels, the rear left and right channels → Plays correctly, localizes in center of front and back.
Same signal is applied to the front and rear channels on the left side and the front and rear channels on the right side → Undefined signal. It changes with the presence or absence of logic as follows.
○ When there is no logic → Plays correctly, localizes to true left, true right.
× When there is a logic → Not correctly restored, True right is moved to right front and left is moved to rear left. (Undefined signal cause, direction can not be determined and logic malfunction)
× All channels Same signal → Undefined signal. Not be restored correctly, Play back from diagonal channels on left front and back right.
△ Same signal is sent to diagonal channels on right front and left back → undefined signal. Fortunately, Not played correctly, but fortunately the same as the input, play from the diagonal channels on the left front and the back right.
× Same signal is sent to diagonal channels on left front and back right → undefined signal. Not restored correctly. Play from the diagonal channels on left front and right back, which are not correctly played, opposite the input.
Conclusionis
In Sansui QS system, reason of overlapping is almost established and there are few problems. However,
In CBS Sony SQ system, all but front left and right channels and rear left and right channels are undefined and problem of overlapping is almost not established and there are many problems.
→ Reverberation and like and front and back feeling can not be reproduced correctly.
→ Can not place instruments between channels by volume balance.
→ Can not be encoded correctly with 4 channel discrete surround source.
Though it is, In QS / SQ encoder formerly prepared for
adjustment, true right and true
left are (Simply do not generate same level signals in front and rear channels
on right side and front and rear channels on left side) In QS system, signal of
right, the left signal, SQ system is the phase difference 90 degree relation
and signal of level ratio 0.414, individually encoded and QS and SQ properly
localize right and true left.
CBS Sony SQ system is theoretically known to be inferior in separation performance compared to Sansui QS system.
As mentioned above, since it is not possible to handle correlated signals before and after, we found that it was a specification of 2 channels in the front + 2 channels in the back, which was not a 4 channel system.
In any case,
the system with a lot of restrictions on software creation is certain, and
furthermore, it leads to the expansion of the damage of the destruction of
cultural heritage, so this is also due to the many reasons why the CBS Sony SQ
system withdrew in a few years It was probably one of them.
As an
aside, when listening to the sound source recorded by the matrix system in
stereo,
In QS
system, sounds of right rear and left rear are localized outside the right
speaker and outside left speaker, respectively. However,
In SQ
system, sounds of right rear and left rear are stereotyped in the "reverse
direction", front center slightly to left, front center slightly to right.
→Although the compatibility of the forward channel was good
in the SQ system, it seems that there was a mistake in the specification of
encoding (phase shift) of the back
channel.
After all, the point that the SQ system is highly compatible with the current stereo system was a propaganda complaint, but for the above reasons, the reality seems to be lower compatibility than the QS system.