Google "Quadraphonic sound logos" to see some of the ways to get the information.
Note the following:
- If the encoding method is not mentioned, it is usually the original Electro-Voice matrix. It was the only matrix on the market at the time.
- QM and QX are variants of QS.
- HD, DQ, EV, QS, RM, QM QX, and DS are so close to each other on the record that you probably won't notice any difference in playback.
- There are three different groups of matrix systems:
- - The RM group (regular matrix) listed above.
- - The PM group (phase matrix) includes SQ and EV-U.
- - The UM group (uniform matrix) includes UMX, BMX, UD4, H, and Ambisonic.
- Matrix is the only way to put quad on many kinds of media.
- There are more Dolby Surround (DS) recordings than any other kind of matrix.
Discrete systems are usually incompatible with matrix systems.