QUADRAPHONICS

ABOUT THE VARIOUS SYSTEMS OF THE 1970S,
AND WHAT YOU NEED TO PLAY THEM TODAY

When surround sound first appeared in the late 1960s, various systems were developed by different companies and individuals for the purpose of using the existing phonograph record, recording tape, and stereo radio technologies for surround sound. Of course, the worst thing possible happened. Each company created a different system and patented it, hoping to be the winner in the marketplace. The result was chaos.

All of the surround sound systems are based on either a multiple-track recording method, or some kind of encoding and decoding system. Those using an encoding and decoding system have a decoder inserted into the sound system at some point. Most systems insert the decoder after the pre-amp. Others insert it after the phonograph pickup cartridge, or between the power amplifier and the speakers. Read the instructions to find out where the decoder belongs. Of course, all of the components after the decoder must be duplicated, so there are four channels.

Note that some of the systems are now totally unavailable. For example, none of the experimental FM quadraphonic systems would be in use today, because the Federal Communications Commission (FCC) never approved any of them. So decoders for these systems are totally useless today.

On the other hand, quadraphonics is not dead. It is transformed. In 1976, a system appeared that outperformed all of the old quadraphonic systems. It is Dolby Stereo, originally created for the movie Star Wars. It solved two of the problems the old systems could not solve: Placing a sound image to the side of the listener, and keeping the front center vocalist out of the back speakers.

The old systems were withdrawn from the market, as Dolby Surround took over the home market in 1982. At that time, "quadraphonics" was renamed as "surround sound." Many more recordings have been issued in surround sound than were ever issued in all of the old quadraphonic formats combined.

THE SIMPLE APPROACH TO QUADRAPHONICS


Quadraphonic recordings can be divided into these groups. Each needs its own player or decoder:


  1. Discrete tape - 4 discrete tracks on tape.
    • Tapes - Includes Reel-to-reel tapes and Q8 cartridges
    • Players have 4-channel tape heads.
  2. Regular Matrix (RM) and (QM) - Simple sum and difference based matrices
    • All media - Includes Dynaco, Stereo-4, QS, and Dolby Surround
    • Two forms exist: symmetrical RM and front-oriented QM
    • Can use Dolby Surround Pro Logic decoder
    • Can use a passive surround decoder (e.g. UniQuad UQ-1A)
  3. Phase Matrix (PM) - Based on CBS SQ matrix circular back encoding.
    • All media - Includes SQ and Stereo-44
    • Basic 10-40 decoder can play Regular Matrix. Logic decoder can not.
  4. Uniform Matrix (UX) - Matrix with phase shifts on all channels.
    • All media - Includes BMX, UD-4, H, and Ambisonic
    • Rare type - don't buy decoder unless you have records.
  5. CD-4 - A fragile radio frequency carrier on each groove wall for discrete
    • Only records - Includes CD-4 discrete 4-channel
    • Requires special pickup, now rare.
    • Don't expect this to work unless records are pristine and very clean.
  6. Discrete digital encoding - 4 or more digital tracks.
    • CDs & DVDs - Includes Dolby Digital, AC-3, DTS, and SACD
    • Players have the decoders built in, and multiple outputs.

Get only the decoders and players you need, and use multiple input selector switches to select the correct devices.

Quadraphonics can be added to an existing surround sound system with a 6-channel discrete input.

More on Quadraphonic Compatibility

Build the UniQuad UQ-1A Quadraphonic Decoder

The Quadraphonic Systems page is a table containing all known encoding systems, with information on how they work and how you can play them today. The stylus modulations in the record groove are shown, so you can visualize the phase relationships. Tape and stereo radio used the same matrix encoding means, but the phase relationships were not so obvious. The Poincaré Energy Sphere is used as a tool to show the distance (and separation) of any two of the modulations.

 

THE SYSTEMS

The following table contains a list of all known systems, with brief information about them. A minus sign denotes lower compatibility.

SURR denotes how accurately the system places musical parts.
HALL denotes how well concert hall ambience can be reproduced.
SYNTH denotes how well a surround effect is produced from stereo recordings.
MONO denotes how compatible the recording is in mono playback.
USE denotes the relative abundance of recordings of each type.

QUADRAPHONIC SYSTEMSPERFORMANCE
SYSTEMABBRTYPEEIAJORIENTEDCOMPATIBILITY SURRHALLSYNTH MONOUSE

SCHEIBER AND SANSUI QSQS, RMRegular matrix RMSquare DD EV DQ DS RM HT TP0.50.50.70.0#2
THE DYNACO DIAMONDDDRegular matrix RMSquare QS, EV DQ DS RM HT TP0.50.60.90.0(#9)
ELECTRO-VOICE STEREO 4EVRegular matrix QMFront QS DD DQ DS RM EU HT TP0.61.01.00.0#5
DYNAQUADDQRegular matrix QMFront QS DD EV DS RM EU HT TP0.50.70.90.0#9
CBS SQSQPhase matrix PMWide EU UQ0.60.200.1#3

CBS SQ 10-40 BLENDSBPhase matrix PMFront EV- DQ- SQ UQ0.80.40.20.1(#3)
DENON UMX, BMX, and UD-4UMUniform matrix UXSquare HM-0.30.500.8#8
 JVC RCA CD-4 C4 DiscreteCDSquare -0.40.400.8#4
ELECTRO VOICE UNIVERSALEUPhase matrix PMFront EV- DQ- SQ UQ0.70.50.30.1play
BBC MATRIX HHMUniform matrix UXSquare UM-0.50.50.40.9#10

BBC MATRIX H REVERSEDHRUniform matrix UXSquare -0.50.50.40.9#11
UNIQUAD EQUAL SEPARATIONUQPhase matrix PMSquare EV- DQ- SQ EU0.80.50.30.1none
DOLBY SURROUNDDSRegular matrix QMFront QS DD EV DQ RM EU HT TP1.00.50.40.0#1
CIRCLESURROUNDCSPhase matrix PMFront DS0.30.100.2#7
DENON BHJ AND UHJUJAmbisonic UXSquare UM HM QS- DD- EV- DQ- DS- RM-0.40.40.30.9#6

HEXAPHONIC TRIDEEHTRegular 3D matrix QMOctahedron QS DD EV DQ DS RM TP0.50.40.50.0#12
TETRAPHONIC 3DTPRegular 3D matrix RMTetrahedron QS DD EV DQ DS RM HT0.50.40.50.0play
COMPATIQUADCQPhase matrix PMFront QS DD EV DQ DS RM SQ EU UQ HT TP0.60.60.7n.a. play
PHASE LOCATIONPLPanless matrix n.a.Square SQ EU- UQ-0.80.40.00.0none
SPHEROUND SOUND FIELDSFRegular Matrix + QMTetrahedron QS DS DD EV DQ RM EU HT TP1.00.70.81.0new

RESOURCES

What you need to play these recordings depends on what you want to achieve. Several levels of complexity are possible:

  1. A Dolby Surround system. This can play the Regular Matrix systems, as well as H, HR, CS, and Ambisonic.*
  2. Adding an SQ decoder (or the Metrotec E-V/SQ decoder) adds the ability to decode most of the phase matrix systems.*
  3. Other decoders can be added, with selector switches to select the correct decoders.
  4. A Dolby Surround system, an SQ decoder, an RM decoder, and a system to switch the speakers to different outputs.*
  5. An infinitely adjustable system that handles any matrix system.
  6. An infinitely adjustable system that handles any matrix system, with switchable presets for the various matrix systems.*

* The page author has used these systems at various times.



The Page Author's Current Setup: Decoders & Switching System

The use of the Dolby Surround, RM, and SQ decoders, with phase inverters, summing networks, and speaker amp source switching is probably the easiest way to handle the greatest number of matrices with only a small investment. It is not perfect, but gives results near the intended ones. The following system uses 10 speakers (8, if you aren't interested in 3-D), and handles all of the above systems except CD-4:

Equipment used:

  • A. Dolby Surround receiver with discrete in and preamp output
  • B. Modified Metrotec decoder, unused switch position gives unblended SQ
  • C. Tandy Surround decoder in Archer Video Sound Processor, wide stereo option
  • D. Switchbox with phase inverters and variable and fixed blend circuits
  • E. Phase switches for the various speakers
  • F. Variable Delay Control
  • G. Level Control
  • H. Amplifiers

Speakers:

  • speaker locs F - Center Front speaker
  • M - Main speakers LM (left) and RM (right)
  • W - Wing (side) speakers LW (left) and RW (right)
  • P - Posterior speakers LP (left) and RP (right)
  • B - Center Back speaker
  • V - Vertical speakers Z (zenith) and N (nadir)

Signal classifications:

  • RM - All RM & QM (QS, EV, DQ, etc) blend variations
  • USQ - All PM (SQ, EU, UQ, etc) blend variations
  • UH - All UX (UM, HM, HR, and UJ) variations
  • Theater - DS and CS
quad shelves

 
 
   C

 
F

G D

       B

 
H    H

 
 
  

 
  

 
 
E    A

 
 

 
 
  H  H

The following tables describe the operation of the author's system.

Matrix
Switch
FM M
Blend
WP P
Blend
BVUSQ Accuracy

QS, RM (TSF RM RVB)TWS RM RVB.41(TWS RM RVB)TWB H RM RVB .41 (TSB RM RVB)OFFNORM 1.0
DD TSF RM RVB(TWS RM RVB).41TWS RM RVB(TWB H RM RVB) .41 TSB RM RVBOFFNORM 1.0
EV (TSF RM RVB)TWS RM RVB.2(CQ TWB RMB)TWB H RM RVB .8 (TSB RM RVB)OFFNORM 1.0
DQ (TSF RM RVB)TWS RM RVB0(CQ TWB RMB)TWB H RM RVB .58 (TSB RM RVB)OFFNORM 1.0
SQ (UH CQ USQ)UMXW H CQ USQ.05(USQ)XHB CQ USQ .05 (CQ USQ)OFFNORM 1.0

SB (UH CQ USQ)UMXW H CQ USQ.1(USQ)XHB CQ USQ .40 (CQ USQ)OFFNORM 1.0
UM HF UMX(HL UMXL)0UMX SQF H(HD UMX) 0 H UMXOFFNORM 0.95
C4  Not possible 0
EU (UH CQ USQ)UMXW H CQ USQ.2(USQ)XHB CQ USQ .41 (CQ USQ)OFFNORM 1.0
HM HF UMXUMXW H CQ USQ0UMX SQF HTWB H RM RVB 0 H UMXOFFNORM 0.8

HR HRFUMXW H CQ USQ0UMX SQF HTWB H RM RVB 0 HROFFNORM 0.8
UQ (UH CQ USQ)UMXW H CQ USQ.32(USQ)XHB CQ USQ .32 (CQ USQ)OFFNORM 1.0
DS DS †DS0OFFDS 0 OFFOFFNORM 1.0
CS (& S-180) (UH CQ USQ)UMXW H CQ USQ.05(USQ)XHB CQ USQ .05 (CQ USQ)OFFREV CS 1.0
UJ UH CQ USQUMXW H CQ USQ0TWS RM RVBTWB H RM RVB 0 H UMXOFFNORM 0.7

HT DS †DS0(TSS)DS 0 (TSS)DSVNORM 1.0
TP ‡ (UH CQ USQ)UMXW H CQ USQ.32(TSS)(TSS) 0 TSSDSV ‡NORM 0.9
CQ (UH CQ USQ)UMXW H CQ USQ.2CQ TWB RMBXHB CQ USQ .41 (CQ UQ)OFFNORM 1.0
CQ with DS DS †DS0USQDS 0 OFFOFFNORM 0.8
PL UH CQ USQUMXW H CQ USQ.9USQXHB CQ USQ .3 CQ USQOFFNORM 1.0

SF (TSF RM RVB)TWS RM RVB.2(CQ TWB RMB)TWB H RM RVB .6 (TSB RM RVB)DSVNORM 1.0


- Channels with positions in parentheses can be switched OFF, or set to TSS if available.
- Channels set to OFF can also be switched to TSS if the position is available.
- For matrix H or HR, the HF and HRF positions are better than H on the F switch. Use H on the F switch for UJ.
† OFF on the author's DS system, which won't drive the author's front (center) speaker properly.
‡ Use the SQ positions on the Metrotec decoder instead of the I/Q positions.
SWITCHSWITCH POSITIONS

Front Speaker
 F
F OFF LR

L+R

TSF RM RVB

Tandy LF+RF

UH CQ USQ

SQ LF+RF

HF UMX

SQ -LB

HRF

SQ RB

DS**‡

Dolby C

Main Speakers
 LM & RM
M OFF LR

L R

TWS RM RVB

Tandy LF RF

UMXW H CQ USQ

SQ LF RF

HL UMXL

SQ -LB

HRL

SQ RB

DS**

Dolby L R

Wing Speakers
 LW & RW
W OFF CQ TWB RMB

Tandy LB RB ††

TWS RM RVB

Tandy LF RF

USQ

SQ LB RB

UMX SQF H

SQ LF RF

TSS

Tandy S S

-

Posterior Speakers
 LP & RP
P OFF TSS

Tandy S S

TWB H RM RVB

Tandy LB RB †

XHB CQ USQ

SQ LB RB

HD UMX

SQ RB

HRD

SQ -LB

DS**

Dolby S S

Back Speaker
 B
B OFF TSS

Tandy S

TSB RM RVB

Tandy LB+RB ††

CQ USQ

SQ LB+RB

H UMX

SQ RB

HR

SQ -LB

-
Vertical Speakers
 Z & N
V OFF TSS

Tandy S S

TSB RMB RVB

   Tandy LB+RB LB+RB ††

SQB

 SQ LB+RB LB+RB

DSV

SQ RB LB

DSI

SQ LB RB

-

USQ
 LW, RW, LP, & RP
W & P NORM

SQ LB RB

REV CS

SQ RB LB

         
MEANINGS OF SWITCH POSITIONS
OFFChannel muted
HMatrix H
RVBReverb (On Archer Unit)
CQCompatiquad HDMatrix H Deep mode TSBTandy Stereo Back †
DSDolby Surround ** ‡ HFMatrix H Front Mode (preferred) TSFTandy Stereo Front
DSIHexaphonic Tridee, swap zenith and nadir HLMatrix H Long Mode TSSTandy Stereo Surround
DSVHexaphonic Tridee HRMatrix HD (H Reversed) TWBTandy Wide Stereo Back †
LROriginal Left and Right HRDMatrix HR Deep mode TWSTandy Wide Stereo
RMRegular Matrix (QS, EV, DQ) HRFMatrix HR Front Mode (preferred) XHBExtreme Hall Background *
RMBRegular Matrix Back (QS, EV, DQ) HRLMatrix HR Long Mode UHUHJ Front, H Front
SQBSQ Back channels* UMXUMX CSCircleSurround, Ghent
SQFSQ Front channels* UMXLUMX Long Mode NORMAll except CS
USQPhase Matrix (SQ, EV-U, UQ, CS) UMXWUMX Wide Mode REVReversed channels
*  Experimental position.
** This position is on the receiver, and affects all ** channels simultaneously.
† This position is derived from the Tandy Surround front outputs inside the switch box.
†† This position is derived from the Tandy Surround front outputs inside the switch box, with a fixed blend setting.
‡ Dolby Stereo front (dialog) output not used on the author's DS system: The author's front (center) speaker needs an equalization curve different from that of the main speakers. Since the surround receiver can't provide separate equalizations, the front speaker is always fed from the switchbox.

Author's setup

Properties of the Page Author's Surround System

LINKS

QUADRAPHONIC AND SURROUND INDEX PAGE

Quadraphonic Systems

Quadraphonic Compatibility

UniQuad UQ-1A Quadraphonic Decoder

Encode surround sound with your mixer

UniQuad Phlazex Quadraphonic Encoder

Stereo and Surround Sound

Mixing your own music