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 until long after interest was gone. So decoders for these systems are totally useless today (but there also were none sold).

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The old systems were withdrawn from the market, as Dolby Surround (the home version of Dolby Stereo) took over the home market in 1982.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:

Discrete tape - 4 discrete tracks on tape.
- Tapes - Includes Reel-to-reel tapes and Q8 cartridges
- Players have 4-channel tape heads.
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)
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.
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.
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.
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.

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 SYSTEMS						PERFORMANCE
SYSTEM	ABBR	TYPE	EIAJ	ORIENTED	COMPATIBILITY	SURR	HALL	SYNTH	MONO	USE

SCHEIBER AND SANSUI QS	QS, RM	Regular matrix	RM	Square	DD EV DQ DS RM HT TP	0.5	0.5	0.7	0.0	#2
THE DYNACO DIAMOND	DD	Regular matrix	RM	Square	QS, EV DQ DS RM HT TP	0.5	0.6	0.9	0.0	(#9)
ELECTRO-VOICE STEREO 4	EV	Regular matrix	QM	Front	QS DD DQ DS RM EU HT TP	0.6	1.0	1.0	0.0	#5
DYNAQUAD	DQ	Regular matrix	QM	Front	QS DD EV DS RM EU HT TP	0.5	0.7	0.9	0.0	#9
CBS SQ	SQ	Phase matrix	PM	Wide	EU UQ	0.6	0.2	0	0.1	#3

CBS SQ 10-40 BLEND	SB	Phase matrix	PM	Front	EV- DQ- SQ UQ	0.8	0.4	0.2	0.1	(#3)
DENON UMX, BMX, and UD-4	UM	Uniform matrix	UX	Square	HM-	0.3	0.5	0	0.8	#8
JVC RCA CD-4	C4	Discrete	CD	Square	-	0.4	0.4	0	0.8	#4
ELECTRO VOICE UNIVERSAL	EU	Phase matrix	PM	Front	EV- DQ- SQ UQ	0.7	0.5	0.3	0.1	play
BBC MATRIX H	HM	Uniform matrix	UX	Square	UM-	0.5	0.5	0.4	0.9	#10

BBC MATRIX H REVERSED	HR	Uniform matrix	UX	Square	-	0.5	0.5	0.4	0.9	#11
UNIQUAD EQUAL SEPARATION	UQ	Phase matrix	PM	Square	EV- DQ- SQ EU	0.8	0.5	0.3	0.1	none
DOLBY SURROUND	DS	Regular matrix	QM	Front	QS DD EV DQ RM EU HT TP	1.0	0.5	0.4	0.0	#1
CIRCLESURROUND	CS	Phase matrix	PM	Front	DS	0.3	0.1	0	0.2	#7
DENON BHJ AND UHJ	UJ	Ambisonic	UX	Square	UM HM QS- DD- EV- DQ- DS- RM-	0.4	0.4	0.3	0.9	#6

HEXAPHONIC TRIDEE	HT	Regular 3D matrix	QM	Octahedron	QS DD EV DQ DS RM TP	0.5	0.4	0.5	0.0	#12
TETRAPHONIC 3D	TP	Regular 3D matrix	RM	Tetrahedron	QS DD EV DQ DS RM HT	0.5	0.4	0.5	0.0	play
COMPATIQUAD	CQ	Phase matrix	PM	Front	QS DD EV DQ DS RM SQ EU UQ HT TP	0.6	0.6	0.7	n.a.	play
PHASE LOCATION	PL	Panless matrix	n.a.	Square	SQ EU- UQ-	0.8	0.4	0.0	0.0	none
SPHEROUND SOUND FIELD	SF	Regular Matrix +	QM	Tetrahedron	QS DS DD EV DQ RM EU HT TP	1.0	0.7	0.8	1.0	new

RESOURCES

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

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

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

G D

H H

E A

H H

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

Matrix Switch	F	M	M Blend	W	P	P Blend	B	V	USQ	Accuracy

QS, RM	(TSF RM RVB)	TWS RM RVB	.41	(TWS RM RVB)	TWB H RM RVB	.41	(TSB RM RVB)	OFF	NORM	1.0
DD	TSF RM RVB	(TWS RM RVB)	.41	TWS RM RVB	(TWB H RM RVB)	.41	TSB RM RVB	OFF	NORM	1.0
EV	(TSF RM RVB)	TWS RM RVB	.2	(CQ TWB RMB)	TWB H RM RVB	.8	(TSB RM RVB)	OFF	NORM	1.0
DQ	(TSF RM RVB)	TWS RM RVB	0	(CQ TWB RMB)	TWB H RM RVB	.58	(TSB RM RVB)	OFF	NORM	1.0
SQ	(UH CQ USQ)	UMXW H CQ USQ	.05	(USQ)	XHB CQ USQ	.05	(CQ USQ)	OFF	NORM	1.0

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

HR	HRF	UMXW H CQ USQ	0	UMX SQF H	TWB H RM RVB	0	HR	OFF	NORM	0.8
UQ	(UH CQ USQ)	UMXW H CQ USQ	.32	(USQ)	XHB CQ USQ	.32	(CQ USQ)	OFF	NORM	1.0
DS	DS †	DS	0	OFF	DS	0	OFF	OFF	NORM	1.0
CS (& S-180)	(UH CQ USQ)	UMXW H CQ USQ	.05	(USQ)	XHB CQ USQ	.05	(CQ USQ)	OFF	REV CS	1.0
UJ	UH CQ USQ	UMXW H CQ USQ	0	TWS RM RVB	TWB H RM RVB	0	H UMX	OFF	NORM	0.7

HT	DS †	DS	0	(TSS)	DS	0	(TSS)	DSV	NORM	1.0
TP ‡	(UH CQ USQ)	UMXW H CQ USQ	.32	(TSS)	(TSS)	0	TSS	DSV ‡	NORM	0.9
CQ	(UH CQ USQ)	UMXW H CQ USQ	.2	CQ TWB RMB	XHB CQ USQ	.41	(CQ UQ)	OFF	NORM	1.0
CQ with DS	DS †	DS	0	USQ	DS	0	OFF	OFF	NORM	0.8
PL	UH CQ USQ	UMXW H CQ USQ	.9	USQ	XHB CQ USQ	.3	CQ USQ	OFF	NORM	1.0

SF	(TSF RM RVB)	TWS RM RVB	.2	(CQ TWB RMB)	TWB H RM RVB	.6	(TSB RM RVB)	DSV	NORM	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.

SWITCH		SWITCH 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
OFF	Channel muted	H	Matrix H	RVB	Reverb (On Archer Unit)
CQ	Compatiquad	HD	Matrix H Deep mode	TSB	Tandy Stereo Back †
DS	Dolby Surround ** ‡	HF	Matrix H Front Mode (preferred)	TSF	Tandy Stereo Front
DSI	Hexaphonic Tridee, swap zenith and nadir	HL	Matrix H Long Mode	TSS	Tandy Stereo Surround
DSV	Hexaphonic Tridee	HR	Matrix HD (H Reversed)	TWB	Tandy Wide Stereo Back †
LR	Original Left and Right	HRD	Matrix HR Deep mode	TWS	Tandy Wide Stereo
RM	Regular Matrix (QS, EV, DQ)	HRF	Matrix HR Front Mode (preferred)	XHB	Extreme Hall Background *
RMB	Regular Matrix Back (QS, EV, DQ)	HRL	Matrix HR Long Mode	UH	UHJ Front, H Front
SQB	SQ Back channels*	UMX	UMX	CS	CircleSurround, Ghent
SQF	SQ Front channels*	UMXL	UMX Long Mode	NORM	All except CS
USQ	Phase Matrix (SQ, EV-U, UQ, CS)	UMXW	UMX Wide Mode	REV	Reversed 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

Phase reverse switches on the F, LW, RW, LP, B, Z and N speaker lines, for experimentation.
The SQ decoder was modified to provide the unblended basic SQ modulations, using the unused switch combination on the panel.
Blend controls on the switch box control the matrix parameters.
The switchbox derives the RM and Tandy Surround back signals from the Archer Tandy Surround decoder front outputs.
The surround signal from the Tandy Surround decoder is used for location enhancement.
The Tandy surround delay control has been moved to a separate front panel control, since different matrices require different delays.
The front outputs of the Tandy Surround decoder can be set for a wide stereo effect that helps separation in some cases.
The thumper (T) is a subwoofer. A separate amplifier drives it.
The thumper always uses the L+R signal, since deep bass must be recorded laterally on stereo phonograph records.

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