| Product Name | Manufacturer | Type | What it is |
|---|---|---|---|
| 2-4 Enhance | Sony/Columbia | Derived | Deriver |
| 2+2 | Koss | All | 4-channel headphone |
| 2+2 | Fisher | Matrix | RM matrix decoder |
| Audio Pulse Enhancer | Audio Pulse | Derived | Enhanced stereo |
| AutoVary | UniQuad | Matrix | Separation enhancement |
| BMX | Denon | Matrix | Basic version of UMX (BBC Matrix F) |
| CD-4 | JVC / RCA | Discrete | Discrete carrier phonograph record |
| Circlesurround | SRS | Matrix | Cinema matrix |
| Composer | Lafayette | Matrix | RM matrix decoder |
| CSG Process | Haeco | Compatible Stereo | Compatible stereo generator |
| Decoder-4 | Sanyo | Matrix | Adjustable matrix decoder |
| Dolby Stereo | Dolby Labs | Encoder | Film matrix encoder |
| Dolby Surround | Dolby Labs | Matrix | Matrix decoder |
| DQ | Dynaco | Matrix / Derived | Abbreviation for Dynaquad |
| Dual Triphonic | Denon | Matrix | Matrix decoder |
| Dynaquad | Dynaco | Matrix / Derived | Matrix / derived decoder |
| EV | Electro-Voice | Matrix | Old Electro Voice EVX-4 matrix |
| Fosgate MP | Fosgate | Matrix | Separation enhanced Dolby Surround |
| Ghent | Columbia | Encoder | SQ Matrix encoder |
| Haeco CSG | Haeco | Compatible Stereo | Compatible stereo generator |
| Hexaphonic Tridee | Dolby? | 3D Matrix | 3D Dolby Stereo |
| Matrix E | BBC | Matrix | BBC Matrix E - Equal Separation Matrix |
| Matrix G | BBC | Matrix | BBC Matrix G - Modification of Matrix F (BMX) |
| Matrix H | BBC | Matrix | BBC Matrix H - Modification of Matrix G |
| Phase-4 | London Records | Record Label | A trademark † |
| Phase Matrix | EIAJ | Matrix | EIAJ definition of SQ (PM) |
| Phase Matrix | Sansui | Matrix | SQ matrix decoder |
| Phase Q4 | Sylvania | Matrix / Derived | Matrix / derived decoder |
| Phase Shift Network | Harmon Kardon | Derived | Deriver |
| Phlazex | UniQuad | Encoder | Wide stereo / RM encoder |
| PM | EIAJ | Matrix | EIAJ definition of SQ (Phase Matrix) |
| Pro-Logic | Dolby Labs | Matrix | Separation enhancement |
| Product Name | Manufacturer | Type | What it is |
| Qaudio | Toyo | All | 4-channel equipment line, decoder |
| QM | EIAJ | Matrix | EIAJ definition of front-oriented matrix |
| QM | Pilot | Matrix | Regular matrix decoder |
| QM Acoustic Effect Simulator | Toshiba | Derived | Deriver |
| QMX | Denon | Matrix | Discrete version of UMX matrix |
| QS | Sansui | Matrix / Derived | QS matrix decoder (BBC Matrix A) |
| QUAD | QUAD IAG Ltd. | Trademark acronym | A trademark "Quality Unit Amplifier Domestic" † |
| Quadaptor | Dynaco | Matrix / Derived | Dynaquad matrix / derived decoder |
| Quadradial | Marantz | Matrix / Derived | Matrix / derived decoder |
| Quadralizer | Pioneer | Matrix | Matrix decoder |
| Quadrant | H H Scott | Matrix / Derived | Matrix / derived decoder |
| Quadraplex | Magnavox | Matrix | RM matrix decoder |
| Quadrasizer | SSI | Matrix / Derived | Matrix / derived decoder |
| Quadrasonic | Panasonic | Discrete | Tape machines |
| QuadraSync | Akai | Discrete | Tape overdub sync device |
| Quadrix | Kenwood | Matrix / Derived | Matrix / derived decoder |
| Quadruplex | Panasonic | Matrix Decoder | RM matrix decoder |
| QuasiQuad | BSR | Derived | Deriver |
| Quatrasonic | Eico | Matrix / Derived | Matrix / derived decoder |
| Quatravox | Realistic | Matrix / Derived | Matrix / derived decoder |
| Quintaphonic | The Who / Sansui | Matrix | 3-track film, QS, discrete center front |
| QX | Denon | Matrix | EV-type matrix record |
| Product Name | Manufacturer | Type | What it is |
| Regular Matrix | EIAJ | Matrix | EIAJ definition of QS (RM) |
| RM | EIAJ | Matrix | EIAJ definition of QS (Regular Matrix) |
| Sel-Sync | Ampex | Discrete | Tape overdub sync device |
| Simul-Sync | TEAC | Discrete | Tape overdub sync device |
| Spheround | UniQuad | Matrix | 3-D surround-field matrix |
| SQ | Columbia | Matrix | SQ Matrix (BBC Matrix B) |
| SRS | SRS Labs | Derived | Enhanced stereo |
| Stereo-4 | Electro-Voice | Matrix | EV matrix decoder |
| Stereo-44 | Electro-Voice | Matrix | EV Universal matrix decoder |
| Stereo-180 | Audionics | Encoder | Matrix encoder mic layout |
| StereoQuad | Columbia | Matrix | Matrix (meaning of SQ) |
| Studio-4 | Utah | Derived | Deriver |
| Surrfield | UniQuad | Matrix | Surround field matrix |
| Tate SQ | Fosgate | Matrix | Separation enhanced SQ decoder |
| Tetraphonic 3D | (unknown) | 3D Matrix | Tetrahedral speaker decode for Hexaphonic Tridee |
| Tetrix | BBC | Matrix | BBC Matrix E - Equal Separation Matrix |
| UD-4 | Denon | Matrix | Discrete / Matrix QMX phonograph record |
| UM | EIAJ | Matrix | EIAJ standard for UMX matrix |
| UMX | Denon | Matrix | Discrete / Matrix systems BMX and QMX |
| Universal | Electro-Voice | Matrix | EV Universal matrix decoder |
| Universal | Metrotec | Matrix / Derived | SQ, EV, derived decoder |
| Variblend | Columbia | Matrix | SQ Separation enhancement (BBC Matrix D) |
| Vari-Matrix | Marantz | Matrix | Adjustable RM decoder |
| Vario-Matrix | Sansui | Matrix | QS Separation enhancement (BBC Matrix C) |
| XM | Denon | Matrix | Denon Triphonic and Dual Triphonic QM systems |
| ( • ) | SRS Labs | Derived | SRS stereo enhancer |
| ( • ) | SRS Labs | Encoder | SRS enhanced stereo recording |
† NOT quadraphonic or surround
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