Is there a matrix cross-reference chart somewhere that says what will happen (what you'll hear) if you play, say, an SQ record through a QS decoder? Or an RM record through an EV-4 decoder? Or vice versa or whatever? Would be handy.
Matrix cross-reference
- Thread starter boojidad
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Len Feldman wrote a magazine article about this (amplitudes in LF,RF,LB,RB and phase angles also).
I've been searching worldradiohistory.com for it, IIRC, I posted the link in QQ (somewhere) before.
Kirk Bayne
I've been searching worldradiohistory.com for it, IIRC, I posted the link in QQ (somewhere) before.
Kirk Bayne
Not what I was looking for (see chart on pdf page 31), however...
https://www.worldradiohistory.com/A...0s/1972/Radio-Electronics-1972-10.pdf#page=29
Kirk Bayne
https://www.worldradiohistory.com/A...0s/1972/Radio-Electronics-1972-10.pdf#page=29
Kirk Bayne
I think that there were other articles with similar diagrams also penned by Len Feldman. The diagrams shown in that article are for the EVX-44 decoder and don't even show even QS encoding/decoding.
Those type of comparisons are valid for decoders without any logic enhancement. The results through more advanced decoders would be much harder to predict and would continuously change!
Those type of comparisons are valid for decoders without any logic enhancement. The results through more advanced decoders would be much harder to predict and would continuously change!
https://www.worldradiohistory.com/A...0s/1973/Radio-Electronics-1973-07.pdf#page=16
This letter and answer mention some of the problems using amplitude info only when evaluating matrix systems.
Kirk Bayne
This letter and answer mention some of the problems using amplitude info only when evaluating matrix systems.
Kirk Bayne
MidiMagic
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I have investigated this thoroughly.
I use the Poincare sphere (also called Scheiber sphere) to compare the systems.
I represent the sound image locus with a circle around the listener.
Most of the regular matrix systems (SS, HF, DQ, EV4, QM, QX, QS, DS, PL, PLII) can be played on each other's decoders with only minor shifts of side images forward or backward. The circle shown is for Dolby Surround. I mix using the same circle.
The next matrix to appear was SQ.
Playing an SQ record through an RM decoder places the F and B signals in the same places. LF to straight L, and RF to straight R. LB and RB seem to be in the center of the room (all speakers equal amplitude).
Playing an RM record through an SQ decoder actually places most of the RM directions in nearly the correct direction. The F, LF, RF, and B signals always work the correct way, making these images. Since RM records do not produce SQ LB or RB signals, both back signals are the same
UMX/BMX is very different from the previous systems. The left and right is set by L and R channel amplitude in both RM and UMX. But RM uses inphase vs antiphase to control front to back image location. UMX uses 90 degrees L lead R for front and 90 degrees L lag R for back. Thus there is no front-back compatibility between RM and UMX.
However, you can use an SQ decoder to play UMX. Place the LF speaker to L, the RF speaker to R, The LB speaker to F, and the RB speaker to B. Also reverse the phase of the LB speaker.
Matrix H is halfway between RM and UMX, with 45 degree phase instead of 90 degree..
H plays on RM with reduced F-B separation.
H plays on UMX with reduced F-B separation.
RM plays on H with reduced F-B separation.
UMX plays on H with reduced F-B separation.
Ambisonics is close to RM and each can play on the other with slightly reduced F-B separation.
I use the Poincare sphere (also called Scheiber sphere) to compare the systems.
I represent the sound image locus with a circle around the listener.
Most of the regular matrix systems (SS, HF, DQ, EV4, QM, QX, QS, DS, PL, PLII) can be played on each other's decoders with only minor shifts of side images forward or backward. The circle shown is for Dolby Surround. I mix using the same circle.
The next matrix to appear was SQ.
Playing an SQ record through an RM decoder places the F and B signals in the same places. LF to straight L, and RF to straight R. LB and RB seem to be in the center of the room (all speakers equal amplitude).
Playing an RM record through an SQ decoder actually places most of the RM directions in nearly the correct direction. The F, LF, RF, and B signals always work the correct way, making these images. Since RM records do not produce SQ LB or RB signals, both back signals are the same
UMX/BMX is very different from the previous systems. The left and right is set by L and R channel amplitude in both RM and UMX. But RM uses inphase vs antiphase to control front to back image location. UMX uses 90 degrees L lead R for front and 90 degrees L lag R for back. Thus there is no front-back compatibility between RM and UMX.
However, you can use an SQ decoder to play UMX. Place the LF speaker to L, the RF speaker to R, The LB speaker to F, and the RB speaker to B. Also reverse the phase of the LB speaker.
Matrix H is halfway between RM and UMX, with 45 degree phase instead of 90 degree..
H plays on RM with reduced F-B separation.
H plays on UMX with reduced F-B separation.
RM plays on H with reduced F-B separation.
UMX plays on H with reduced F-B separation.
Ambisonics is close to RM and each can play on the other with slightly reduced F-B separation.
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