A look at surround sound

Quadraphonics first appeared in 1969, shortly after the first multitrack studio recorders appeared on the market. Here is a list of several thoughts and ideas I had and things I did when I was experimenting with quadraphonics:

  1. My first idea for more than two stereo channels - 1963:

    I had an idea for putting three channels in a record groove. But the speaker location I envisioned was centered high over the center of the regular stereo pair. I intended a phono cartridge sensitive to different vertical angles for the high channel and the others. I now know that this would have produced distortion.

  2. A stereo with a center channel

    In 1968, I came across a stereo system with a center channel amplifier and speaker. The center channel was the sum of the left and the right channel, corresponding to the modulation of a mono record.

    This is an example of three channels being decoded from two - a matrix system.

  3. "Now It's Quadrasonics"

    This 1969 article was the first one I ever saw on 4-channel stereo. 0  It described a method of using 4 tracks on tape to record a concert, including the ambient sounds of the concert hall. I later found out from an email I received that Pink Floyd had made 4-channel live concerts that same year.

    At that time, I had thought that 4 channels would be the end of my favorite recording medium, the phonograph record (and my associated favorite, the record changer). But near the end of 1969, I heard of a system called the Scheiber system (invented by Peter Scheiber) that could put 4 channels in a single record groove. 0  This was worth investigating.

  4. Incompatible 4-Channel Tape Formats

    Record companies started making discrete quadrasonic reel-to-reel tapes in 1969 and eight-track quadrasonic tapes (Q8) the following year. But the tapes were not compatible. They would not play on standard players without losing half of the sound.

    I thought at the time that a totally incompatible system would not sell. I didn't find out until years later that I was right, because reel-to-reel quadrasonic recorder sales exceeded projected expectations. See below to find out why this happened.

  5. July 1970: My Revelation of future 4-Channel Systems

    By July of 1970, I had much more information than what I knew in 1969. More articles had been published on the various systems, and I had taken some mathematics and electronics courses necessary to understanding the various systems:

    After reading the article on the Hafler system, I sat down at a desk and quickly sketched out what I thought were the three most likely possibilities for the Scheiber system:

    1. CBS SQ stylus motions My first sketch was a system where the front channels were encoded on the record in the normal way, and the back channels were encoded using 90 degree phase shifts that produced circular stylus motions (second diagram here, at right). I rejected it as having too much front-to-back crosstalk for use with recordings of concert-hall ambiance. But it would work with records, tape, and stereo FM.
    2. My second sketch was a variation of Jerry Minter's FM system for a stereo record combined with the Westrex 45/45 stereo groove. But since it would not work with tape or FM stereo, it was definitely not the Scheiber system. I also rejected it because the groove would be very fragile, and it would require a special playback stylus.
    3. My third sketch was a system which had modulations spaced 45° apart in the stereo groove, instead of the usual 90° spacing (third diagram here, at right). The front modulations were 22.5 ° from the horizontal (mono) modulation, and the back modulations were 22.5 ° from vertical. It was essentially the Hafler system rotated by 45° in the room and 22.5° in the record groove. It was a system that could be used for records, tape, and FM stereo.

      I decided that this was probably the correct guess.

    I still have those sketches, all on one piece of notebook paper. It is amazing how prophetic those three little sketches were:

    1. Scheiber stylus motions My first sketch turned out to be the CBS SQ system, written down by me before CBS had even thought of it. But at the time, I thought it had no practical use for recording concert-hall ambiance, because of the low front-back separation and nonexistent separation between center front and center back.
    2. My second sketch turned out to be CD-4. Unknown to me, It was being developed by JVC in secret at the time I drew the sketch.

      Again, I thought at the time that it would be too difficult to use. I was right about that too, as seemingly insignificant events showed me the fragility of the system. Radio DJs had discovered they could not slip-cue the Minter records back in the '50s without making a swooping squeak when the record started turning. The blank groove is not blank.

    3. My third sketch turned out to really be the Scheiber system. I found out in September of that same year that I was right (see below). The encoding and decoding equations were published then.

      It was also the QS system, being developed by Sansui at the time I made the sketches. I found out about it the following year. It is also related to the Electro-Voice and Dynaquad systems (see below).

    I had just sketched out the three main competing quadraphonic systems of the future within a half-hour period in July 1970.
    But I wouldn't know that until late 1971.


  6. What do we call it?

    In 1970, marketing people and writers were trying to decide what to call four-channel sound. Here is a list of some of the suggestions and comments about them:

    Quadraphonic was chosen by record stores by 1972.

  7. The Scheiber system is revealed

    In September 1970, the details of the Scheiber system were revealed. 3 It was the matrix I outlined above, with a gain-riding system to turn down the speakers that had only crosstalk. This gain riding system was easily fooled, and often drowned out hall ambience.

    In my opinion, the Scheiber system was never put into production because each record company was hoping to develop its own system to avoid paying patent royalties. But Scheiber collected anyway, because his patent covered ALL matrix encoding/decoding systems (Note that all of the quadraphonic patents have expired by 2012).

    But even though his system was never used by any recording company, Scheiber still deserves the credit for inventing the concept of matrix quadraphonic recording and playback.

  8. I also thought up two other possible discrete quadraphonic phonograph record systems.

    In the summer of 1970, I sketched out two other possibilities for discrete quadraphonic records:

    1. My first sketch was an expansion of the Cook dual groove system, but with the grooves next to each other, rather than in separate bands on the record. But the shortened playing time and the difficulty of starting the record playing in the middle of a selection were sufficient disadvantages to this system.
    2. The second sketch was a two-level groove with two styli of different sizes, one above the other in the same groove. This could not have worked, because one level moving in one direction while the other level moved in the other direction would cause problems in the groove. The playing level would also be a lot lower.

    Neither of these would have been viable. They were just some wild ideas I had jotted down. But RCA did have a patent on a dual-groove system.

  9. Geluk Pseudo-Quad system, Utah Studio-4, and Denon QX

    In 1970, the Geluk system for phonograph records was announced. It was a stereo record with an ultrasonic control tone added that controls pan pots to change the direction the sound comes from. This idea worked for Cinerama, but is not a good idea for music. And it would cause the same trouble with DJ slip-cueing.

    Utah made a speaker matrix device that made fake 4-channel from the sum and difference signals. The front left and front right speakers get the left and right channels from the stereo signal. The left back gets the sum of the two stereo channels, while the right back gets the difference of the two stereo channels. This was useless in its intended form, but could be used to implement the Hafler diamond by putting the left back speaker in the center front.

    The Denon QX system was a commercially sold version of their Dual Triphonic system that used 5 speakers. It was essentially equivalent to the Dynaco 5 speaker version of Dynaquad.

  10. My first experiments with the Hafler diamond system.

    DD-1 In August 1970, I built an adaptor from a block of 6 RCA jacks, a resistor, and a rheostat (right) to connect to a friend's stereo set that had speakers connected by RCA cables. He had used Y adaptors to connect two more speakers to the stereo, with one speaker on each wall of a square room. I replaced that arrangement with the Hafler diamond.

    The rheostat is adjusted to minimize left channel sound in the right speaker and right channel sound in the left speaker. It compensates the front speaker load.

    We spent some time listening to stereo records with this setup, and for the first time heard the stereo enhancement effect of matrix quadraphonics and the recovery of hidden ambience in live recordings. Right then, I knew I never again would be content with ordinary stereo.

    I discovered one stereo recording where the stereo channels were recorded out of phase with each other. The instruments intended to be between the stereo speakers were in the back speaker instead of the front. Unfortunately, the record belonged to someone else, and I have forgotten what record it was. It was classical.

    HP-1 Later I built an adaptor with a block of 8 RCA jacks (right) that would hook up six speakers: four using the Hafler connection, plus two more speakers hooked up as normal stereo speakers - a hexaphonic system. We got to play with it for only an hour, because I had borrowed speakers to set it up and the owner wanted them back. But the sound images of the musical parts were more stable than the images with the 4-channel setups were. This system needed no adjustment.

    I later discovered that this hexaphonic system was identical to the Denon Dual Triphonic system.

    I also sketched out an octophonic system, but never got to try the idea until 2010.

    Both of these circuits can be built with screw terminals instead of RCA jacks. Be sure to observe polarity.

  11. 1971: I used the Hafler diamond system for a live theatrical production.

    This started with a friend coming to me with this question: "Is there any way to easily synchronize 5 tape recorders?" They wanted to place sound effects around the audience of a live theater production. The play was "Ondine", and they wanted to make the voices of ghosts, beings, and other sound effects come from different directions in the auditorium.

    I told him that it would be easier to use one stereo tape recorder with multiple speakers and the Hafler 4-channel system. We wired the system to speakers placed on a catwalk that circled the rim of the auditorium above the audience. I used a small stereo mixer and a preamplifier that had two sets of outputs reversed in phase to each other to encode the recordings. My concept of using a mixer to encode was born.

    We had the ghostly voices coming from various directions, thunder rolling across the auditorium, and other sound effects placed over the stage to match events on the stage. The cues were separated with leader tape, so the tape was started for each cue and stopped between cues.

    The play took place in early 1971. The sound effects were quite effective. I believe it was the very first use of matrix quadraphonics in a live theater presentation.

    Unfortunately, since the sound tapes belonged to the school, I have no recordings of this event. I don't even have the auditorium to show where it happened anymore - it was torn down to build a computer building.

    See a detailed account of this at Quadraphonic Mixing a 1971 Stage Play

  12. Stereo-4, Dynaquad, and QS.

    Later in 1971, I acquired the following materials and information:

    I experimented with the Dynaquad circuit, using it with the Stereo-4 and Dynaquad records:

  13. 1971: I hooked up a quadraphonic system for a jukebox for a local business.

    I used a variation of the Dynaquad system connected to the speaker outputs of a stereo jukebox. It used essentially the Stereo-4 decoding parameters.

  14. Adjustable separation passive (speaker matrix) decoder.

    uq-1 I built a variable separation decoder that works in a manner similar to the Dynaquad. I called it the UniQuad UQ-1, and used it to investigate the effects of changes in matrix parameters, as well as for listening to music on a daily basis from late 1971 to 1974. I still have two UQ-1 and two UQ-1A units (including the original). Two of these are still in service.

    The UQ-1 (right) has the basic circuit in the UQ-1A. Follow the link to see the UQ-1A plans. The UQ-1 differs from the UQ-1A in the following ways:

    Using the width and depth controls, I was able to vary the matrix playback parameters to emulate any of what would eventually be called the Regular Matrix (RM and QM) systems (Scheiber, Stereo-4, Dynaquad, and QS). In doing so, I discovered the properties of the various matrix systems and found which was optimum for each kind of music.

    This was even more effective with the Berlioz "Requiem". The two choirs were more definitely located using either the Stereo-4 settings or the QS settings.

    I also discovered the inability of human hearing to correctly locate sounds panned directly to the sides of the room when the speakers are placed in the corners of the room and the listener is facing forward (see below).

  15. Ears are not designed for quadraphonic speakers.

    I independently discovered the inability of human hearing to correctly locate sounds positioned directly to the sides when the speakers are located in the corners of the room and the listener is in the proper place facing forward. I had to turn my head to hear them.

    Here are the angles of the speakers from the listener at three different listener locations (note that the original encoding angles are the angles in the left diagram):

    315.0°   0.0°  45.0°       326.3°   0.0°  33.7°       333.4°    0.0°  26.6°      

    Recording made using angles in left diagram.

    Key to table below:

    • Centered = Centered on Listener
    • ## = ambiguous locations
    • † = speakers play in opposite phase
    270.0° listener head  90.0° 296.6° listener head  63.4° 315.0°
    225.0° 180.0° 135.0° 243.4° 116.6° 270.0° listener head  90.0°

    The human hearing system behaves as follows when listening to a single pan-potted discrete quadraphonic musical part. Note that the angles are shown on the right side of the listener in the following table. The same angles also happen in opposite directions on the left side.

    Perceived locations
    Listener is in Center of Room Listener Halfway Back in Room Listener Between Back Speakers
    DirectionResult DirectionResult DirectionResult
    0.0° 0.0°Good 0.0°Good 0.0°Good
    22.5° 22.5°Good 18.4°Good 14.0°Good
    45.0° 45.0°Good 33.7°Good 26.6°Good
    67.5° 45.0°Poor 41.5°Fair 33.7°Good
    90.0° 45.0 ## 135.0°Bad 116.0°Poor 45.0°Good
    112.5° 135.0°Poor 116.0°Poor 63.4°Good
    135.0° 135.0°Good 116.0°Good 90.0°Good
    157.5° 165.0°Good 145.0°Good 90.0°Good
    157.5° † 157.5° †Good 135.0° †Good 135.0° †Good
    180.0° 180.0°Poor 180.0°Poor CenteredPoor
    180.0° † 180.0° †Good 180.0° †Good 180.0° †Good
    Centered 0.0° ## 180.0°Bad 0.0°Fair 0.0°Fair

    This is what the listener really hears.

    315.0°   0.0°  45.0°       326.3°   0.0°  33.7°       333.4°    0.0°  26.6°      


    • † = speakers play in opposite phase
    • ## = ambiguous locations
    ## listener head ## ## listener head ## 315.0°
    225.0° ## 135.0° 243.4° 116.6° 270.0° listener head  90.0°
    225.0°† 180.0°† 135.0°† 243.4°† 180.0°† 116.6°† 270.0°† 180.0°†  90.0°†

    A better way of locating sound images is needed.

  16. That hole in the back.

    Early in the development of matrix quadraphonics, one problem was the "out of phase hole in the back" predicted by the encoding and decoding equations. It was mentioned by several authors in various audio articles. 0  This was usually between the back speakers, but with the Hafler diamond system, it was between the right speaker and the back speaker.

    It was not the problem the math predicted it to be:

  17. Investigating separations between signals and speakers (part 1)

    In the summer of 1971, I did the calculations for the matrices I then knew about, and created a table showing how well each system would work with various kinds of music. This is a condensation of that table:

    System Quadraphonic Separation Stereo Synth Separation Center
    Back −
    Mono ¤
    Music Performance Original
    FrontBackSides FrontBackMono-
    play ¤
    Scheiber 3.0 dB3.0 dB3.0 dB 8.3 dB8.3 dB8.3 dB40 dB FairGoodGoodGoodBad BlurCenter Back
    Hafler (3 speaker) 25 dB0.0 dB3.0 dB 25 dB0.0 dB25 dB40 dB GoodGoodGoodGoodBad BlurRight Back
    Hafler (4 speaker) 25 dB0.0 dB3.0 dB 25 dB0.0 dB25 dB40 dB GoodGoodGoodGoodBad GoodRight Back
    E-V Stereo-4 8.3 dB0.2 dB4.9 dB 14 dB4.1 dB19 dB40 dB BetterGoodGoodBetterBad BlurCenter Back
    Dynaquad 25 dB1.2 dB1.2 dB 25 dB4.8 dB12 dB40 dB FairFairFairGoodBad BlurCenter Back
    Sansui QS 3.0 dB3.0 dB3.0 dB 8.3 dB8.3 dB8.3 dB40 dB FairGoodGoodGoodBad ◊ BlurBoth Sides
    Hall Ambience 3.0 dB0.0 dB8.3 dB 8.3 dB3.0 dB25 dB40 dB BestPoorGoodGoodBad BlurCenter Back

    ¤ This is how each system plays on a normal mono player.

    ◊ This system provides best mono play by equally mixing decoder outputs.

    Blur indicates that turning the head is needed to hear side images.

    The Hall Ambience system was my own idea of finding a way to maximize concert-hall ambience. I set the UQ-1 Width control for QS, and the Depth control for maximum depth (no back separation). It does work better than playback using any of the standard matrix parameters. Encoding would be done with a QS encoder with nothing but hall ambience fed to the back channels. Several Vox classical albums are recorded in QS in this way.

  18. Comparing Systems for Concert Hall Ambience (Part 1)

    The following separations are critical to the quality of concert hall ambience:

    System Separations to LB Separations to CB .. Ambience Worst Case
    Pan LF 22.5° LPan CF22.5° R Pan RF Pan LF 22.5° LPan CF22.5° R Pan RF Wd LBWd CB Nr LBNr CB
    Scheiber 3.0 dB5.1 dB8.3 dB14.2 dB40.0 dB 8.3 dB14.2 dB40.0 dB14.2 dB8.3 dB 3.0 dB8.3 dB5.1 dB14.2 dB
    Hafler (3 spkr)       8.3 dB14.2 dB40.0 dB14.2 dB8.3 dB  8.3 dB 14.2 dB
    Hafler (4 spkr)       8.3 dB14.2 dB40.0 dB14.2 dB8.3 dB  8.3 dB 14.2 dB
    E-V Stereo-4 4.9 dB10.1 dB19.0 dB11.2 dB5.3 dB 5.1 dB10.7 dB40.0 dB10.7 dB5.1 dB 4.9 dB5.1 dB10.1 dB10.7 dB
    Dynaquad 1.2 dB4.3 dB11.7 dB17.7 dB6.0 dB 3.0 dB8.3 dB40.0 dB8.3 dB3.0 dB 1.2 dB3.0 dB4.3 dB8.3 dB
    Sansui QS 3.0 dB5.1 dB8.3 dB14.2 dB40.0 dB 8.3 dB14.2 dB40.0 dB14.2 dB8.3 dB 3.0 dB8.3 dB5.1 dB14.2 dB
    Discrete Tape ‡ 30.0 dB30.0 dB30.0 dB30.0 dB30.0 dB 30.0 dB30.0 dB30.0 dB30.0 dB30.0 dB 30.0 dB30.0 dB30.0 dB30.0 dB
    Hall Ambience 8.3 dB14.2 dB40.0 dB14.2 dB8.3 dB 8.3 dB14.2 dB40.0 dB14.2 dB8.3 dB 8.3 dB8.3 dB14.2 dB14.2 dB


  19. Regular Matrix: RM and QM

    RM stylus motions The Japan Phonograph Record Association (JPRA) issued an industry standard defined as "Regular Matrix" (RM) in 1971. It includes the equal separation matrix systems I mentioned so far (the Scheiber, Hafler diamond, and QS systems).

    The Japan Phonograph Record Association (JPRA) also issued an industry standard defined as "Quadraphonic Matrix" (QM) in 1971. It includes the front-oriented matrix systems I mentioned so far (Stereo-4, Dynaquad, and QX).

    The RM and QM standards state that leftness and rightness are determined by the relative strengths of the left and right channels in the encoded recording, and that frontness and backness are determined by the relative phase between the channels. Front sounds are recorded in both stereo channels with the signals in phase with each other, and back sounds are recorded in both stereo channels with the signals in opposite (180°) phase.

    The difference between RM and QM is in the separations between the channels. RM has equal separations all around (between front channels, between back channels and between adjacent front and back channels) and infinite diagonal separation. QM has greater separations between front channels and often between adjacent front and back channels, but lower separation between back channels and diagonally. RM places a sound recorded in just the left channel of a stereo record to the middle of the left side. QM moves it close to the left front. Sounds on the right are similarly placed.

    QM stylus motions The upper diagram at the right shows the basic modulations of the RM system as stylus motions. Notice the even spacing. Right-click on it and select "View Image" to see a larger version.

    The lower diagram at the right shows the basic modulations of a QM system as stylus motions. Notice the wider spacing of front signals and the narrower spacing of back signals.

    The circular motions indicated in brown or black are not part of the RM standard. Of the early RM matrix systems, none used the circular motion except QS. The QS encoder produces the black clockwise circular motion when the same signal is panned equally to all 4 channels (placed at the center of the room). It does not produce the brown motion. The QS decoder properly locates the black circular motion in the center of the room.

    The Electronic Industry Association of Japan (EIAJ) also issued an RM standard and a QM standard.

    The encoding parameters of all of the RM and QM systems are so close together that the records are nearly indistinguishable from each other. The main differences between these RM and QM systems are in the decoders and speaker placements.

  20. Enter SQ

    Up to this point, all matrix systems already proposed (Scheiber, Hafler, Stereo-4, Dynaquad and QS - collectively RM) were almost identical. Recordings made in these systems were interchangeable, with only slight shifting in sound images. It looked like the matrix race was over before it had begun. But that was soon to change.

    In July 1971, Columbia and CBS announced a matrix system with totally different properties - the Stereo-Quadraphonic (SQ) matrix. 5, 7  It works on a somewhat different principle than the regular matrix. But it is identical to that first sketch I made in July of 1970. The diagram at right shows the ideal SQ modulations.

    The SQ system was designed as a result of a directive from Columbia corporate headquarters. It said that any quadraphonic system used by Columbia must have full separation between the left-front and right-front channels in stereo and in quadraphonic play. This removed from consideration the RM systems and the "New Orleans" systems they had been trying out before (see below).

    It also prevented SQ from being seriously used for recording concert-hall ambience. The ambience must be recorded at a higher level to be heard with SQ, and at even a higher level to get it past the early gain-riding separation-enhancement systems used.

    Before the directive, the CBS labs were investigating systems similar to QS and BMX (but before either of those systems were revealed) in New Orleans LA. They referred to these systems as the "New Orleans" matrix systems in an article published about the development of SQ. 10 

    SQ stylus motions SQ has the following signals (see upper diagram at right):

    * Rotations are as seen from front of the pickup cartridge. Both circles are concentric, and are easier to see if you right-click on it and select "View Image" to see a larger version.

    The JPRA issued an industry standard defined as "Phase Matrix" (PM, also known as SQ) in 1971. It includes the SQ and Electro-Voice Universal systems (below). The EIAJ also issued such a standard.

    SQ blended stylus motions The SQ system was designed to be used with separation-enhancement circuitry. If separation enhancement is not used with a cheaper decoder, CBS advises that a 10% blend between the front decoder outputs and a 40% blend between the back decoder outputs be used to provide more separation between center front and center back.

    This is called the 10-40 SQ decoder (suggests paying taxes). See the stylus-motion diagram of 10-40 SQ playback at right. Note the horizontal orientation of front material and the vertical orientation of back material.

    This somewhat improves the ability to handle ambience, but it is not as good as any of the RM or QM systems except Dynaquad. It also lets the 10-40 SQ decoder play RM and QM recordings.

    The separation-enhancement circuitry originally used gain-riding techniques to emphasize either the front channels or the back channels. It detects cases where program material is either predominately front or predominately back, and adjusts the gains appropriately. Their original gain-riding system was easily fooled by program material, and often turned down concert-hall ambience while increasing separation.

    Without either the 10-40 blends or the separation enhancement, sounds panned to center front and sounds panned to center back would come from all 4 speakers at equal levels.

  21. My Opposition to SQ

    My analysis of SQ showed that there was only a 3 dB separation between any sound placed in any part of the front stage area and either of the back speakers. This means that the crosstalk from any of these sounds would drown out any concert hall ambience in the recording. The gain-riding circuits would further turn down the ambience.

    Since one of the reasons I was interested in quadraphonic sound was the recording of concert hall ambience, I was concerned that the SQ system was the system least compatible with classical music ambience reproduction. SQ emphasizes left-to-right separation, but for ambience recording, front-to-back separation must be maximized, not left-to-right. I later found out that the SQ records with ambience had the ambience exaggerated so it would get past the inadequate separation and the gain riding.

    I was quite upset at the time that the market clout of Columbia Records could force a system that is inadequate for classical music ambience onto the market as a standard. I had already seen other cases where market clout had caused an inadequate system to be adopted instead of a better system that had no financial backing.

  22. Mono Compatibility Problems (Part 1)

    All of the systems described so far have the same problem when the record is played through a monophonic radio or record player. When correctly encoded (as opposed to an error in encoding caused by an encoding hole) any sound panned to center back disappears from mono playback.

    The creators of most matrix systems told record producers to avoid panning any vital program material to center back, because it disappears in mono playback. But there are certain sounds that belong at or near center back, because they would be out of place in mono playback. They are reverb and concert-hall ambience.

    Record producers were also told to place the bass and the kick drum between the front speakers, because the bass is reinforced by having the two speakers in phase. Also, the record groove can take more deep bass with a lateral modulation than with any other.

    Examine the stylus vector diagrams of all of the systems discussed so far, looking for the violet vector for center back. Note that in every diagram, the center back vector is vertical. That means that it will disappear (except some crosstalk or distortion) from mono play.

    Note that in some of the diagrams, the blue vector and the magenta vector follow the same path (but with opposite rotation), and they seem to combine to produce a violet trace on a low-resolution monitor. Right-click on an image and click "view image" and display a larger version to see the two colors. Ignore such color combinations here.

    In the separation table above, the "Center Back − Mono" entry shows how much of the center back signal gets to mono playback. 40 dB is considered to be inaudible.

    QS has the special feature that a QS record can be played through the QS decoder and then be mixed to a perfect mono signal for play or broadcast purposes. The other systems can't do this. 18 

    CD-4 (see below) has no mono compatibility problem. All signals play at normal levels in mono.

    Some of the matrix systems outlined below are attempts to prevent the center back sound from totally disappearing in mono play. Their mono compatibilities will be covered further down in this page.

    In most of the matrix systems outlined above, concert hall ambience disappears almost entirely in mono playback.

  23. Separation Enhancement 1: Gain Riding

    The first form of separation enhancement was gain riding. The system divided the decoder outputs into pairs of channels and adjusted the gains of those pairs oppositely to enhance separation.

    The Scheiber system divided the channels into diagonally opposite pairs. The SQ front-back logic divided the channels into the front pair and the back pair.

    One disadvantage of the gain-riding system is audible pumping of the sounds as the gain-riding device adjusted the gains. This pumping was audible as sudden changes in the loudness of a part (particularly a low-level part).

    The gain-riding systems sacrificed the fainter sounds for the dominant sounds. In particular, gain riding removed almost all of the concert-hall ambience in the recording, especially in SQ. The pumping effect also changed the level of the ambience, making it seem to appear and disappear.

  24. JVC Discrete Record

    In July 1971, JVC announced that it had developed a system that could record 4 discrete channels on a phonograph record. 6  They revealed that multiplexing using a 30 KHz carrier recorded in the record groove was involved. They named it CD-4. A special pickup cartridge, stylus, cables, and demodulator are needed to play it.

    This was what my second sketch in July 1970 outlined. But it was not a major contender at the time.

    Specifications: 30 KHz carrier, 16 KHz to 44 KHz carrier band, 30 Hz to 14 KHz baseband)

    The JPRA and EIAJ issued industry standards for this, defined as "CD-4", in 1972.

  25. Electro-Voice Universal decoder

    EV 44 stylus motions In October 1971, Electro-voice announced the EV-44 universal decoder. It plays Stereo-4, QS, and SQ records without having to be switched between systems (it also decodes Dynaquad). This was quite useful, because quadraphonic records could be stacked on a record changer without the user having to pay attention to which kind of matrix was used on each particular disc.

    This was the first matrix decoder to actually appear on the market with an active separation-enhancement device included. If a predominating center front signal is present, it blends the back channels, reducing the separation to near that of the old EV matrix. It was the first separation-enhancement system that did not remove the concert-hall ambience in the process of increasing the separation.

    At the time it was released, it could play all of the matrix systems that existed. Once UMX and Matrix H appeared, this was no longer true.

    Notice how similar this is to the SQ 10-40 blend matrix.

  26. UQ equal separation matrix

    Basic Poincare Sphere The Poincaré Sphere (also called the Stokes Sphere, the Foucault Sphere, and the Fresnel Sphere) was originally conceived by Henri Poincaré in 1892 to describe polarized light, and by Foucault to describe free-swinging pendulum motion. It was adapted by Peter Scheiber in 1971 to describe the phase relationships between the stereo channels of a recording, and I independently discovered it for the same purpose in September 1971.

    The Poincaré Sphere, representing phono stylus modulations, is shown in the diagram at right as follows:

    Equal Separation matrix sphere in September 1971, using the Poincaré Sphere, I calculated out a matrix with a 4.77 dB separation between the desired channel and each of the 3 other channels. Note that all I had to work with at the time was a slide rule (scientific pocket calculators cost hundreds of dollars in 1971), so the figure I got was 4.8 dB.

    I placed a tetrahedron (regular triangular pyramid) in the sphere, with the left front and right front near the left and right front points of Stereo-4. The resulting modulations appear at right on the Poincaré and in a stylus vector diagram below it:

    UQ ES stylus motions Unknown to me until 1982, Peter Scheiber had already made the same calculations in 1971. 8  He also created another equal separation matrix that was tested as BBC Matrix E (see below).

    I built two decoders that specifically decode the UQ Equal Separation matrix, as well as most other matrix systems. See info on these devices below.

    An interesting aside here: Peter Scheiber and I had independently made most of the same discoveries and calculations on the same matrix systems. I wonder how many other people also did exactly the same thing. As we shall see below, many developments occurred in parallel to each other at nearly the same times, but in different locations.

    Notice how similar this is to the SQ 10-40 blend matrix and the Electro-Voice universal decoder. All three have properties that are very close to each other.

  27. Denon Uniform Matrix

    In mid 1972, Denon came out with a system under the name Uniform Matrix (UMX). 9  It is similar to Regular Matrix, but has a 90° phase shift between the encoded channels.

    UMX has the following signals (see diagram at right):

    UMX stylus motions * Rotations are as seen from front of the pickup cartridge. Both circles are concentric, and are easier to see if you right-click on it and select "View Image" to see a larger version.

    This was the only matrix system totally compatible with mono playback. But the stereo playback left a lot to be desired to the human ear, with front material tending to the left, and back material tending to the right,

    UMX was later separated into BMX (a 2-channel encoded matrix) and QMX (a 4-channel encoded matrix for multiplex broadcast). The first two encoded channels of QMX are the same as BMX, and can be played through a BMX decoder.

    UD-4 was the semi-discrete phonograph record using QMX for frequencies 3 KHz and below, and BMX for frequencies above 3 KHz. This uses a lot less bandwidth than CD-4 does. It can be played through a BMX decoder or a UD-4 demodulator. No special pickup cartridge is required. UD4 also caused the swooping noise if a DJ slip-cued it.

    Specifications: 22 KHz carrier, 18 KHz to 26 KHz carrier band, 15 Hz to 15 KHz baseband)

    In 1974, the JPRA and EIAJ issued industry standards for UMX, defined as "UX".

    This was never really used anywhere but in Japan, because it messed up stereo listening. But it led to the development of the later BBC Matrix H and the UHJ Ambisonics systems.

  28. Independent Parallel Discoveries

    In 1970, I independently sketched out SQ, CD-4, and the Scheiber system and, in 1971, UMX and my equal separation matrix. It is quite interesting how many other parallel discoveries were made throughout the quadraphonic industry:

    It's amazing how many minds independently created the same solutions.

    Or is it the fact that the Poincaré Sphere provides only a limited set of solutions to choose from?

  29. Comparing Systems for Concert Hall Ambience (Part 2)

    Adding the new systems to the table of separations critical to the quality of concert hall ambience:

    System Separations to LB Separations to CB .. Ambience Worst Case
    Pan LF 22.5° LPan CF22.5° R Pan RF Pan LF 22.5° LPan CF22.5° R Pan RF Wd LBWd CB Nr LBNr CB
    Scheiber 3.0 dB5.1 dB8.3 dB14.2 dB40.0 dB 8.3 dB14.2 dB40.0 dB14.2 dB8.3 dB 3.0 dB8.3 dB5.1 dB14.2 dB
    E-V Stereo-4 4.9 dB10.1 dB19.0 dB11.2 dB5.3 dB 5.1 dB10.7 dB40.0 dB10.7 dB5.1 dB 4.9 dB5.1 dB10.1 dB10.7 dB
    Dynaquad 1.2 dB4.3 dB11.7 dB17.7 dB6.0 dB 3.0 dB8.3 dB40.0 dB8.3 dB3.0 dB 1.2 dB3.0 dB4.3 dB8.3 dB
    Sansui QS 3.0 dB5.1 dB8.3 dB14.2 dB40.0 dB 8.3 dB14.2 dB40.0 dB14.2 dB8.3 dB 3.0 dB8.3 dB5.1 dB14.2 dB
    SQ 3.0 dB3.0 dB3.0 dB3.0 dB3.0 dB 3.0 dB8.3 dB40.0 dB8.3 dB3.0 dB 3.0 dB3.0 dB3.0 dB8.3 dB
    SQ 10-40 3.7 dB6.4 dB8.3 dB6.4 dB3.7 dB 4.0 dB9.4 dB40.0 dB9.4 dB4.0 dB 3.7 dB4.0 dB6.4 dB9.4 dB
    EV-U Enh On 5.0 dB10.3 dB19.4 dB10.3 dB5.0` dB 5.1 dB10.7 dB40.0 dB10.7 dB5.1 dB 5.0 dB5.1 dB10.3 dB10.7 dB
    EV-U Enh Off 4.4 dB6.9 dB8.3 dB6.9 dB4.4 dB 5.1 dB10.7 dB40.0 dB10.7 dB5.1 dB 4.4 dB5.1 dB6.9 dB10.7 dB
    BMX 3.0 dB5.1 dB8.3 dB14.2 dB40.0 dB 8.3 dB14.2 dB40.0 dB14.2 dB8.3 dB 3.0 dB8.3 dB5.1 dB14.2 dB
    CD-4 *‡ 30.0 dB30.0 dB30.0 dB30.0 dB30.0 dB 30.0 dB30.0 dB30.0 dB30.0 dB30.0 dB 30.0 dB30.0 dB30.0 dB30.0 dB
    Hall Ambience 8.3 dB14.2 dB40.0 dB14.2 dB8.3 dB 8.3 dB14.2 dB40.0 dB14.2 dB8.3 dB 8.3 dB8.3 dB14.2 dB14.2 dB


  30. Every matrix has at least one encoding hole.

    Michael Gerzon's article 12  covers the problem of panning a sound all the way around the listener. No matter which matrix system is used, a phase reversal must occur somewhere in the path the sound takes around the listener:

  31. Great-Circle Matrix Systems

    Basic Poincare Sphere When a sound is recorded as circling around the listener, any matrix that encodes this motion as a great circle (as plotted on the Poincaré Sphere) is called a Great-Circle Matrix. One example is an encoding matrix that goes around the "equator" of the Poincaré Sphere (RM and QM).

    A great circle is any of the possible circles formed by a plane intersecting a sphere that passes through the center of the sphere. It divides the sphere into equal hemispheres. The equator is an example of a great circle on the earth. So is a combination of the 0° and 180° meridians.

    All Great-Circle Matrix systems with 4 channels and equal separations have 3 dB separations between adjacent channels.

    This Great-Circle Matrix designation assumes that the encoding holes in the various systems have been removed through hole-removing techniques (see above). The multiple-mixing-bus recording techniques mentioned above can be used to do this.

    Great-circle matrices can be converted to other great-circle matrices through simple sum and difference and phase change matrix transformations. Any great-circle matrix can be converted to any other great-circle matrix.

    The following matrix systems are Great-Circle Matrix systems. The order of the listed colors in the table shows the movement on the Poincaré sphere (shown at right) of a sound panned clockwise around the listener starting at the front:

    QS and Scheiber Equator oliveredvioletcyanolive
    Dynaquad and Hafler Equator oliveredvioletcyanolive
    Stereo-4 Equator oliveredvioletcyanolive
    UMX and BMX Opposite Meridians blackredbrowncyanblack
    BBC Matrix H (see below) 45° diagonal orangeredbluecyanorange
    Matrix HR (see below) 45° opposite diagonal pinkredyellowcyanpink
    Phase Location (Denon experiment) Opposite Meridians olivebrownvioletblackolive
    Dolby Surround (see below) Equator oliveredvioletcyanolive

    The following are not great-circle matrix systems:

    All of these matrices that are not great-circle matrices have sharp angles or curves in the path on the Poincaré of a sound panned clockwise around the listener. Except for some of them that are very similar to each other, they cannot be converted to other matrix systems.

  32. 1971, RCA chooses CD-4

    In October 1971, RCA announced that it was going to produce records using the CD-4 discrete phonograph record. They also announced that no stereo versions of the same albums (without the CD-4 modulations) would be sold. 0 

    This was the last of my 1970 sketches to become one of the three major contenders in the quadraphonic market. My unintentional prophecy was fulfilled.

    They lost me as a customer that day, because the CD-4 system seemed to be too fragile to withstand normal use by all but purists. Buying used records would be a gamble, because the buyer could not visually inspect the disc and know whether or not the CD-4 carrier is damaged.

    Warner/Elektra/Atlantic decided to use CD-4 the following year. But they did issue stereo versions of their records. 0 

    I had the fear that CD-4 would cause the end of the phonograph record. This did not happen, but look below for what "CD-4" had to do with the end of the phonograph record.

  33. The Day the CD-4 Died (Bye-Bye CD-4 Pie in the Sky*)

    I was in a stereo store in 1973, listening to a demonstration of the CD-4 system. The following events happened:

    1. I noticed that the walls of the room were covered with mirrors, possibly to make the listening area look as big as they said the quadraphonic system would make it sound like. The sound reflection properties of mirrors might have also been the reason why they were there.
    2. The record actually sounded good, with no ticks or pops and none of the hiss I expected from a worn carrier. I was sitting in one of the chairs they put in the middle of the room for that purpose.
    3. The CD-4 system did nothing to remove the inability to locate sounds panned directly to the sides. I had to turn my head to hear them.
    4. A woman walked up to one of the mirrors near the turntable and put makeup on her face with a powder puff.
    5. As the woman walked away from the area, the speakers suddenly started emitting sounds that I can only describe as Rice Krispies on steroids. It sounded like many people were breaking pencils in half.
    6. The store manager ran over when he heard the sounds. "What happened?" he screamed. He then asked, "What did you do?", as though I was responsible for the loud snapping noises.
    7. I replied that I had just been sitting in the chair listening to the music.
    8. He then asked, "Did you see anyone do anything or anything happen that could have caused this?"
    9. I said, "A woman put powder on her face at that mirror by the turntable." He then promptly emitted a strange sound halfway between a growl and a gurgle.
    10. Turning the Demodulator switch to Stereo caused the music to continue without the snapping noises. When the switch was turned back to CD-4, the noises resumed.
    11. The next thing the manager tried to do was clean the record. He used a special cleaner made for CD-4 on the record several times. There were fewer snapping sounds where the record had not yet been played, but in the area that had already been played with powder on the grooves, the sounds were as loud and frequent they had been the first time.
    12. He then took the record into the back room and stayed there for a while. He came back and put the record back on the turntable. It played without making the noises. I wondered if he had a way to clean it, until I overheard him tell another employee that yet another CD-4 record was ruined. He had opened another copy of the record.

    Others reported a phenomenon they called "sandpaper quad." The record produces a hiss similar to sandpaper continuously being rubbed on wood when played through the CD-4 demodulator. This is due to the carriers on the record being worn down.

    I then knew what I had suspected about the fragility of CD-4 was true. I wanted nothing to do with it. It would be useless for ambience when the records became worn. A laboratory clean room was needed to use it.

    Seedy-4? Birdseedy fore.

    * Note that Don ("American Pie") McLean's record company had selected CD-4.

  34. Causes of CD-4 malfunctions:

    Operation of the CD-4 system is so fragile that many seemingly very minor problems can cause it to malfunction. Here are the troubles to look for:

    1. If the record has very tiny dust motes ground into the grooves, they sound like many people breaking pencils in half.
    2. If the carrier on the record is worn, it sounds like someone continuously using sandpaper.
    3. If the pickup cartridge vertical angle is wrong, it causes mistracking (breaking up).
    4. If the pickup cartridge overhang or offset angle is wrong, it mistracks on only certain parts of the record.
    5. If the antiskate is misadjusted, it causes mistracking. Shibata styli need more antiskate than elliptical styli.
    6. If the tonearm wires are pulling on the arm, it causes mistracking.
    7. If the tonearm has too much pivot friction, it causes mistracking.
    8. If the tracking force is too low, it causes mistracking.
    9. If the cables have too much capacitance, it causes carrier dropouts.
    10. If there is a ground loop, it causes a variety of troubles.
    11. Cell phones, WiFi, or other radio equipment can cause interference.
  35. 1972, Many preamps and receivers were made with missing functions

    I noticed that many of the quadraphonic receivers and preamps were missing the ability to perform certain functions that users would want. Some of the more common deficiencies were:

    1. Tape monitor - This was missing more often in the early units.
    2. Often only one matrix system was provided. This was especially true if the manufacturer had signed contracts with one particular matrix system developer.
    3. Most of the units with more than one matrix position provided only two positions - RM and PM (SQ).
    4. Often when RM and SQ were provided, only SQ had separation enhancement.
    5. Almost all units provided no way to record a discrete 4-channel source to 2-channel tape. A few recorded only the front channels.
    6. Many units provided no way to record decoded 2-channel matrix material to a discrete 4-channel tape.
    7. Several units did not allow using the tone controls when playing a tape.
    8. Several units had only two balance controls, with no way to correct a diagonal imbalance.
    9. Most units had only one discrete 4-channel input (owner couldn't connect Q-8 and CD-4 simultaneously).
    10. Most units did not provide for the case where an owner had separate 2-channel and 4-channel components of the same kind or source, and provided only one set of jacks for that kind of component.
  36. My First attempt at solving the Side Image Location Problem.

    I read an article on a stereo width enhancement system that mixes a phase-reversed, filtered, delayed, and attenuated version of each stereo channel into the other channel. 0  The effect is to make the stereo image seem wider than the speakers. It was later sold as a stereo-enhancing device, including the one in the Archer TV Sound Processor.

    I used a different approach. I connected an extra speaker to each speaker and placed it under the diagonally opposite speaker, moved back from the front of that speaker by a distance equal to the delay mentioned in the article. I made a small control panel to provide filtering, phase selection, and level control.

    This did portray the sound images encoded to the side in the correct locations. But it made that tension feeling in people's heads that usually results from out-of-phase speakers. It was also tricky to adjust, and the adjustments depended on listener location. While it worked, it was not very practical, and it also made the concert-hall ambience harder to hear. I soon stopped using it.

  37. Separation Enhancement 2: Diagonal Delays

    The second form of separation enhancement was diagonal delays. Several audio engineers tried the same kinds of experiments I tried. The effect was too dependent on listener location to be useful, and it also caused that out-of-phase feeling in the ears.

  38. The QS Variomatrix

    In 1972, Sansui announced the QS Variomatrix 14 , a method of increasing the separation of a regular matrix by varying the matrix parameters of each output according to the direction of the biggest sound source in the recording. The decoding angles are adjusted to move away from the major sound source.

    For example, with a strong sound source at left front, the decoding angles of the right front and the left back channels move toward the right back, and their levels increase so their outputs are the same level they were at before the change. Thus the sound the listener hears remains unchanged.

    If the strong sound at center front, the decoding angles of all four channels move toward center back and are increased in level to compensate for the change in decoding angle. Again, the listener does not notice any change in levels.

    Pumping is almost nonexistent with the Variomatrix.

    Some QS Variomatrix decoders divide the audio into three frequency bands, running each band through a different Variomatrix unit. This keeps a strong note in one band from affecting notes in the other two bands.

    This is the first separation-enhancement system that does NOT damage concert-hall ambience while increasing channel separation.

  39. SQ Variblend

    At about the same time, CBS announced their SQ Variblend decoder. 10  It works in a way similar to the Variomatrix, except that it moves the decoding parameters in only one direction.

    Unlike the QS Variomatrix, this was announced well before it appeared on the market. And it is designed to work with the front-back gain riding, not by itself.

    This separation-enhancement system also does NOT damage concert-hall ambience while increasing channel separation when used alone. But when used in combination with the SQ front-back logic, it does degrade the concert-hall ambience. They did not make a Variblend unit without the front-back logic.

  40. My Autovary Device

    When I read about the QS Variomatrix, I wondered if a passive speaker matrix could have separation enhancement. Then I got a copy of an electronics projects book with a tubeless squelch circuit. 15  The circuit uses the fact that a light bulb increases its resistance tenfold when it is lit and hot. This proved useful.

    I connected a light bulb into the Depth circuit of one of my UQ-1 decoders. A 50 ohm rheostat and a switch to short both out were connected in parallel with the light bulb. This adds what I call the Autovary blend to the back channels when a strong center front signal is present.

    My UQ-1A contains my back Autovary circuit. Follow the link to see it. By this time I designed UQ-1A, I discovered that the switch was unnecessary, since I was always setting the Autovary control to the same place whenever I turned it on.

    The Autovary system seems ideal. I have never heard any pumping from it. Apparently the light bulb has just the right timing to make the change in matrix decoding angle inaudible. And it does not disrupt concert-hall ambience located at center back.

    I also designed another Autovary circuit to automatically adjust front decoding angle. It did not work as well as the back one.

  41. Separation Enhancement 3: Automatic Matrix Varying

    The third form of separation enhancement was automatic matrix varying. It works by quickly changing the matrix coefficients to maximize separation between the signals that are actually there.

    This separation-enhancement system preserves the fainter sounds, including concert-hall ambience.

  42. BBC Matrix Trials and Matrix H

    H stylus motions In 1974, the British Broadcasting System ran a series of trials 20  between eight different matrix systems:

    The result of these trials was a choice for Matrix H, which was used for only a few experimental recordings, although after it was published, some other record companies tried it. Its stylus motion diagram is shown at right.

    In addition, one set of published specifications accidentally showed playback parameters instead of recording parameters. A few recordings were made with the reversed parameters, reversing the directions of the stylus rotations. I call this version HR.

    In 1977, separation enhancement similar to the QS Variomatrix was added to Matrix H for experimentation. 21 

    The goal of Matrix H seems to be mono compatibility for sounds at center back. Only BMX/UMX, Matrix G, and Matrix H encode sounds panned to center back in a way that they play through a mono player. No other matrix (except the then future UHJ Ambisonics and my surround-field system) could do this.

    Matrix HJ was later renamed as the UHJ Ambisonic matrix.

    All of the systems tested by the BBC have symmetrical separations between adjacent channels. But what they failed to do in these matrix trials was to test the front-oriented (QM) matrices Stereo-4 and Dynaquad. For concert-hall ambience recovery, these perform much better than any of the systems the BBC tested.

    I didn't have access to the article above until 2006, because I did not know what to search for. I found it by accident while searching for something else.

  43. A Movie in QS

    In 1975, the rock band "The Who" made a movie version of their rock opera "Tommy". The title of the movie was "Tommy - the Movie". It was the first movie made in matrix surround sound. 0 

    Their system, called Quintaphonic Sound, used a then-standard three-track film soundtrack. But they encoded the left and right track in the Sansui QS matrix. The center track was a third discrete track used for the movie dialog. The Sansui QS logo and the words "Quintaphonic Sound" are included in the opening title and end credits.

    The problem was that most of the theaters showing the movie did not have a QS decoder, and just played the three-track soundtrack through the three speakers behind the screen. But even then, the out-of-phase nature of the back information caused people sitting near the front of the theater (facing forward) to hear the surround effects anyway.

    When stereo VHS copies of this movie were made, the Quintaphonic sound was retained, with the dialog track mixed equally into the left and the right track, to produce a normal QS recording.

    The soundtrack album is an enigma. There appear to be two versions of it.

    1. The first version has the QS encoding from the movie.
    2. Polydor was the record company that sold the album. When Polydor signed contracts for the CD-4 system (instead of QS), they apparently created a new mixdown of the album that removed the QS encoding.
  44. Dolby Stereo and Dolby Surround

    Dolby Laboratories originally created Dolby Stereo for the movie "Star Wars". The basic matrix used is a combination of the Hafler diamond and QS. 0  But they made some changes to the basic matrix that made Dolby Stereo much more successful than any previous quadraphonic system:

    Dolby Surround stylus motions Later, Pro Logic was added to Dolby Stereo to increase the separation. It works very much like the QS Variomatrix works.

    In the early 1980s, the surround sound of Dolby Stereo was made available to the general public with the production of Dolby Surround VHS tapes and home components. They are designed to work in the home (with fewer surround speakers and fewer adjustments). A decorrelator is added to the surround outputs to keep the listener from locating the surround speakers.

    From 1977 to 1980, I kept buying movie soundtrack albums and finding that they decoded perfectly in QS. For those 4 years, I thought they were encoding the movies in QS. The only movie surround system I knew about was the QS system used for "Tommy".

    I had no information on Dolby Stereo, because the audio magazines I subscribed to did not cover movie theater sound. So I thought (from the name) that Dolby Stereo was just a noise-reduction system (I saw it in the movie credits). In 1980, Peter Scheiber told me about Dolby Stereo being a surround sound system. I then found some articles about Dolby Stereo and the home version called Dolby Surround. 0 

    Dolby Surround works with records, tapes, FM radio, and VHS as well as with film soundtracks. It works quite well for concert hall ambience too. Some CDs were made in Dolby Surround for just this purpose. For quadraphonic purposes, Dolby Surround blew everything else out of the water (including CD-4).

    Dolby Surround fixes the side imaging problem. When the listener is facing forward, all of the sounds come from the correct direction. And it works quite well no matter where the listener is sitting in the theater.

    Dolby Surround fixes the panning problem. When the listener is facing forward, all of the sounds come from the correct direction and move in the expected directions when standard panning techniques are used. This also works quite well no matter where the listener is sitting in the theater.

    A Dolby Surround decoder can be used to play any RM or QM matrix, including QS, Stereo-4, Dynaquad, and others. Even though the speakers are not located where these matrix systems expect them to be, the sound images are very close to where these systems intend them to be. And the side images work.

    The converse is true too: An RM or QM decoder can correctly play a Dolby Surround recording. This is why I thought those soundtrack records were in QS. The side imaging is only partially fixed in this case.

  45. 3-D Dolby Surround

    A few experimental movies were made IN 1978 with a 3-D version of Dolby Stereo that had high and low speakers in the theater. The height was encoded with the clockwise and anticlockwise motions common to SQ. The encoding of these movies also made it to the soundtrack albums.

    In the Dolby Surround diagram above, the black circle (clockwise) is the down direction. The brown circle (anticlockwise) is the up direction.

    I seem to have two of these records - at least, they seem to have the encoding. And they were made too early for them to be encoded in Circlesurround:

    I decoded this with my passive decoder (above), set to the UQ matrix. I also set the Left Back speaker on the floor at center back, put a milk crate on top of it, and put the Right Back speaker on top of that. All of the speakers were originally sitting on milk crates to raise them off the floor (so the image speakers mentioned above could be put under the milk crates). This gave me the 3-D effect when I sat in the center.

  46. Separation Enhancement 4: Delayed Back Channels

    The fourth form of separation enhancement was delayed back channels. Delaying the back channels provides the delayed sound cues that provide the correct image location for sounds panned in any direction from the listener.

    This is the first system that provides panning the sound in any direction and having the listener hear it in the proper direction. But it has one problem: The listener must be facing forward.

  47. Matrix Math, for Real

    In 1978, I took an applied linear algebra course. I learned how to use the mathematical entity called a matrix. The matrix quadraphonic systems are based on this mathematical kind of matrix. Here are the rules of matrix.

    The following equations are the matrix equations used in quadraphonics:

    The process used for quadraphonic matrix is called matrix multiplication.

    The Electro-Voice Stereo-4 System is shown. But it works for any matrix system.

    input matrix
      C = E F  RB  
      ×       product

      1.0   0.3   1.0 −0.5
    LF + 0.3 RF + LB − 0.5 RB  
      0.3   1.0 -0.5   1.0   0.3 LF + RF − 0.5 LB + RB  
    encoder matrix       encoded output
    encoded input
      S = D C  R  
      ×       product

      1.0   0.2
    L + 0.2 R  
      0.2   1.0   0.2 L + R    
      1.0 −0.8   L − 0.8 R    
    −0.8   1.0   − 0.8 L + R    
    decoder matrix       decoded output
     1.0   0.3   1.0  −0.5 
    LF + 0.3 RF + LB − 0.5 RB
    encoded input
      S = D E   0.3   1.0  −0.5   1.0    S = D (E F)  0.3 LF + RF − 0.5 LB + RB    
      ×               ×       product

     1.0   0.2 
     1.06   0.5   0.9  −0.3 

     1.0   0.2 
    1.06 LF + 0.5 RF + 0.9 LB − 0.3 RB
     0.2   1.0     0.5   1.06  −0.3   0.9   0.2   1.0    0.5 LF + 1.06 RF − 0.3 LB + 0.9 RB  
     1.0  −0.8     0.76  −0.5   1.4  − 1.3   1.0  −0.8    0.76 LF − 0.5 RF + 1.4 LB − 1.3 RB  
    −0.8   1.0    −0.5   0.76  −1.3   1.4  −0.8   1.0    − 0.5 LF + 0.76 RF − 1.3 LB + 1.4 RB  
            decoder matrix     combined matrix output

    The ironic thing is that matrix mathematics is often taught in a course which is often called "Discrete Mathematics".

  48. A Standard at Last!

    Dolby Surround quickly became the de-facto standard for surround sound recording from around 1978 to the late 1990s, when Dolby Digital started to appear in DVDs. Most VHS tapes are in Dolby Surround, as is the analog track of most DVDs.

    Even phonograph records, cassette tapes, and CDs were recorded in Dolby Surround, and most CDs of film soundtracks still are (as of 2015). Discrete systems need up to 7 channels to equal it in sound location.

    Dolby Surround is a versatile and useful surround sound system that should have remained the standard. It is still quite useful. I have encoded live recordings in it. Unfortunately, the upgraders always want to change things.

  49. My Compatiquad (CQ) Matrix Decoder that Decodes RM, QM and PM Matrix Systems

    CQ stylus motions Before the details of the EV universal decoder were published, I devised a decoder that could play QS, Stereo-4, Dynaquad, Hafler diamond, and SQ records when they are stacked together on a record changer. It does not require adjustment during the stack.

    The decoding coefficients were chosen for the following purposes:

  50. My Passive Matrix Decoder that Decodes All Matrix Systems

    In 1976, I had an idea for making a passive matrix decoder that goes after the power amplifiers and can decode all matrix systems. I then built a small version that could do just RM, QM, and CQ, and the CQ part worked correctly at only the midrange frequencies (the CQ decoder above). I called it UQ-4.

    In 1981, I built the entire device. This works at all audible frequencies and handles more matrix systems. I called the finished unit UQ-44.

    How I Afforded this Project

    I was an independent contractor repairing record changers at the time most of the quadraphonic developments happened. This did not pay enough for the experiments I wanted to do. I also did some tutoring for university students. But I had some very good luck.

    Once a year, the local university had a surplus materials auction, and I went to it to get some bargains I could otherwise have never been able to afford, including some large wooden office desks at $2 each, floor lamps at $1 each, and several shelf units. My secret was to bid first with a very low bid, and not to raise it. They usually had several lots of each item in the auction, and I often got the second or third lot because nobody else bid.

    I also bought electronic parts and equipment. My best scores were a teletype machine for $1 in 1981 (my first computer printer), a Dynaco PAT-4 preamp for $10 in 1976, and for $1 in 1980, a group of 10 large cardboard boxes full of unused transformers, capacitors, resistors, rheostats, coils, switches, and many other electronic parts. Nobody else bid on any of these except the preamp. Included in the boxes of parts were most of the parts used in this project.

    The key parts I needed that were in those boxes were a pair of high power audio output transformers that each had two 8-ohm output windings. They had a high winding count and low DC resistance that made them stable for the purpose I used them for.

    The two transformers mentioned in the box on the right were the key to the design. On each transformer, I connected the two 8-ohm windings together to produce a phase inverter. To keep the primary winding from developing high voltages, I put a load resistor on each one. These were the central components of my design.

    Using coils and capacitors, I turned each transformer into two ψ (psi, or frequency-dependent) phasor units spaced 90 degrees apart. I fed one from the left channel input and one from the right channel input. I used L-C circuits, rather than the R-C circuits in most phasor circuits, because the outputs had to drive low-impedance speakers.

    I used rotary switches and the basic circuits of the UQ-1 decoder (with some preset rheostats) to complete the decoder. It decodes the following matrix systems:

    1. QS
    2. Dynaquad
    3. Stereo 4
    4. Compatiquad (CQ - see above)
    5. SQ
    6. EV Universal
    7. UQ Equal Separation

    Four more rotary switch positions provide the following variable matrix settings. The Width and Depth controls from the UQ-1 design allow adjusting each matrix:

    1. Variable Basic Matrix
    2. Variable RM
    3. Variable CQ
    4. Variable SQ

    In addition, I added a switch to let me decode BMX. It trades the left front and left back outputs. Using the Variable SQ position with full Width and no Depth provides the signals. The listener faces the left front speaker instead of the front. I did not yet have the details of Matrix H or UHJ at the time I built this.

    I also built in a few accessories because I had the parts:

    1. Phase Reverse of left back speaker (known difference between some systems)
    2. Front and Back Autovary (see above)
    3. Front Phased Crossblend (to partly get rid of side imaging problem)
    4. Back Filter (later found out it was exactly what was needed for Dolby Surround)
    5. Bass Booster (fed some front bass to back channels)
    6. Speaker Orientation Rotation (like on Sansui QS-1)
    7. Discrete Input
    8. Headphone outputs with Fixler Matrix and Bauer 16  Headphone Circuits
    9. Oscilloscope output for 4-channel display

    The UQ-44 is a cube about 1 foot on a side and weighs almost 20 pounds. The transformers were the size-determining factor.

    The Problem:

    After I got this working, I looked up how much it would cost to build another one. The results were shocking:

    • Many parts in the phasor units (especially coils) were unavailable unless a production run of at least 4000 of each kind is ordered.
    • Assuming I could buy coils at the equivalent wholesale unit price, all of the parts in one UQ-44 cost over $1000 (new parts, 1981 dollars).
    • Removing the items listed in the accessories (except the phase switch) lowered the price to about $600.
    • Removing the preset rheostats and adjusting Width and Depth controls for each matrix reduced the cost to about $450.
    • The transformers alone were $100 each. This set a floor for the cost.
    • None of these prices included the case or the labor to put it together.

    I then figured that nobody would want to buy one. It was cheaper to buy a second amp than to buy this. But I enjoyed mine from 1981 until 1993 when I moved. I added Dolby Surround run through the discrete inputs, but used UQ-44 for older matrix records.

    To contrast this, I built the first UQ-1 for less than $20 (1973 dollars).

    The details of the UQ-44 will be revealed on this page: UniQuad UQ-44

  51. My 4-Channel Sound in 2-Channel Headphones

    I built three different headphone adaptors for quadraphonics:

    I didn't have access to the Bauer articles until 1980.

  52. Some anomalies in listening to stereo records with a quadraphonic system

    I made some strange discoveries while listening to stereo records on the UQ-44:

    In many of these cases, the records were made before records made in those quadraphonic systems mentioned were released to the public.

    What was going on? I did some investigating, and learned the following:

  53. Record Companies and Stereo Manufacturers Discontinue Quadraphonics

    Even before Dolby Surround appeared, many manufacturers discontinued quadraphonic products because they were not selling. There were several reasons:

    1. The economy was in a recession, and people were not buying more expensive records and equipment. Most record companies charged a dollar more (about 20%) for quadraphonic records.
    2. In 1975, many record companies stopped recording in quadraphonics because the records weren't selling. Too many people thought you had to have a quadraphonic system to play the records. But the only quadraphonic products that would not work with a stereo player were the discrete quadraphonic tapes and CD-4.
    3. Record stores were putting quadraphonic releases in a special "quadraphonic" bin in the special products part of the store, instead of putting them with the other records that artist recorded. This caused record companies to stop labeling the quadraphonic records as quadraphonic.
    4. Many record companies and stereo manufacturers did not want to produce quadraphonic products because there was no standard. Unlike the greed for royalties in the quadraphonic market, the Westrex 45/45 easily became a standard because the concept was patented by Alan Blumlein in 1933, and the patents had already expired (because nobody saw any commercial value to it until there was interest in stereo in the 1950s).
    5. The marketing "experts" totally misread the market for quadraphonics. Sales of discrete 4-channel reel-to-reel tape recorders exceeded all expectations. But when other quadraphonic products appeared on the market, they didn't meet sales expectations.

      It turned out that most of the 4-channel reel recorders were not going into home quadraphonic music systems. Musicians were buying them to create homebrew multitrack recording studios. Of all the manufacturers, only TASCAM figured it out.

      The only discrete 4-track recorder I own is used for recording studio purposes. It has never been used for discrete quadraphonic playback, although it was used extensively to record and encode matrix surround sound.

    Once Dolby Surround showed performance that none of the quadraphonic systems could match, most record companies stopped recording quadraphonic records:

  54. Well - sort of....

    Even though quadraphonic was "dead" in the markets, many die-hards kept it alive:

    1. One company kept selling quadraphonic recordings of passing trains for years - in CD-4.

      I probably would have bought some of these records if they had been recorded in matrix instead of CD-4.

    2. Many records are covertly recorded in either quadraphonic sound (usually QS) or Dolby Surround. These include:
      • Many new CD releases of old quadraphonic records still have the encoding.
      • Many movie albums are in Dolby Surround because the audio comes from the film. This is not usually mentioned
      • Engineers recording classical music use extra microphones to capture the concert-hall ambience. This is usually recorded out of phase in the recording, producing a Dynaquad recording.
      • Some engineers know that many recordings will be played through a Dolby Surround system, and provided a recording with suitable content.
      • Many recording engineers like the sound of QS when it is played in stereo, with the reverb and harmony parts spread wide.
      • Note that the CD has no standardized playback equipment for discrete surround sound available to the public. So any desired surround sound must be recorded with a matrix system (usually Dolby Surround).
    3. Many recordings have been made in surround sound, but are totally unlabeled.
    4. A new recording made in QS was released in 2018. It costs over $200, but comes with a working QS Variomatrix decoder on a PC board.
  55. Patents and Copyrights Kill Off Standardization

    The problem with many innovations is that there is no standard. Every company hopes that its own patented development will bring it royalties, and every company wants to avoid paying royalties to competing companies. We have seen the same kind of market battles dividing various industries over and over again. Here is a list of battles over the years:

    1. The battle between AC power and DC power: This was short-lived in most locations because AC was cheaper to make and distribute. But it continued for years in New York City, where Consolidated Edison continued to supply DC. 0 
    2. The battle between laterally recorded sound on records (the direction the stylus vibrates) and vertically recording records: Note that, as soon as all of the patents expired, all record companies switched to lateral records. 0 
    3. The companies could not even agree on what speed records should rotate at, with speeds ranging from 70 RPM to 120 RPM (80 RPM being the norm). The National Association of Broadcasters (NAB) finally forced a standard speed of 78.26 RPM in 1928. They declared that all electric radio station turntables would turn at that speed, an average of Columbia (80 RPM) and Victor (76.59 RPM) speeds. They also declared that most radio station turntables would play only lateral records. 0 
    4. Disagreement over the recording equalization for records: At least 20 different curves were used. Trying for a standard, the NAB and the Audio Engineering Society (AES) proposed very different curves, furthering the disagreement. The Recording Industry Association of America (RIAA) produced a compromise curve that ultimately became the standard for microgroove records. It became the standard in the US in 1957, and in Europe in 1962. Before that, people needed record players with switchable equalization. 0 
    5. Columbia and RCA had a battle over whether microgroove records should turn at 33.33 RPM or 45.00 RPM (the famous "Battle of the Speeds"). For a while, RCA did what they did with 78 RPM records, releasing classical music on 45 RPM records (with the same annoying side breaks 78s had). This was one of the few cases where each company adopted the other's technology by trading patent rights. The 45 was used for singles, while the 33 was used for albums and classical works. But if it hadn't been for the proliferation of 45 RPM jukeboxes, we might have had a standard speed of 33 and a standard hole size. 0 

      I do wish they had agreed on the size of the center hole. It would have made using my record changer that can change mixed speeds easier.

    6. A battle emerged between CBS, NBC (RCA & Westinghouse), and CTI (Color Television Inc.) over how color TV should be broadcast. CBS used a spinning color wheel in front of the camera and in front of the picture tube. It didn't work very well and was not compatible with existing black and white TV, but the FCC approved it in 1951. This was later revoked due to Korean War production restrictions, letting RCA show its fully compatible (with black and white TV) system that doesn't use more bandwidth. It was adopted in 1953, and is still in use, but was replaced by incompatible digital TV for many countries in 2007. 0 
    7. Several different open reel tape track formats competed for standardization. Two systems that were incompatible with each other were finally chosen for mono voice and stereo music formats. 0 
    8. Several different broadcast video tape formats competed for standardization. The spinning head system won over the high speed linear system. 0 
    9. Several different methods for making stereo records were proposed. These battled from about 1952 until 1957. Among them were the Minter (Components Corporation) FM carrier in the groove system (see above), the Cook dual groove band system (two arms or a forked arm), the RCA side-by-side dual groove system, The Blumlein groove on each side of the record system, the Blumlein vertical-lateral system, and the Westrex 45/45 system. The Westrex system was superior, but it was adopted only because Blumlein's already expired 1933 patents had priority, so no royalties would be paid by anyone to record records in stereo. 0 
    10. Several different methods for broadcasting FM in stereo were proposed, including the Crosley system, a Minter system, and the GE-Zenith system. The FCC was required to decide before any broadcasting could be done. To everyone's surprise, the FCC chose the GE-Zenith system because it had a much lower probability of an accidental out-of-band event. 0 
    11. Three different car cartridge tape players battled for the market in the 1960s. The winner was the Lear Jet 8-track tape format. 0 
    12. The quadraphonic record format battle this page is about.
    13. Four different video cassette formats battled for market supremacy, with VHS the winner. 0 
    14. A similar quadraphonic FM broadcast format battle started, but the FCC decided that matrix was good enough, and didn't approve any discrete system. 0 
    15. The battle over different AM stereo systems: No system was ever chosen. 5 different systems were allowed to coexist, with the radio station choosing which to use. 0 
    16. Many market battles have occurred since the 1970s, including the various formats for digital recording, digital TV, and computer data storage. All of them are detrimental to consumers. We could have had compatible high definition television if Microsoft had not used its clout to force its incompatible formats upon us. 0 

    It is time to remove the power of patents and copyrights that keep the best systems from being adopted and cause the removal of old systems from the market. Their periods should be shortened, the royalties should be reduced to amounts equivalent to the mechanical royalty, and licensing must be compulsory.

  56. UHJ Ambisonics

    Ambisonics stylus motions Michael Gerzon 22  and others started developing Ambisonics in 1974. It is yet another matrix system that can have additional transmission channels added to increase separation.

    This is derived from the BBC Matrix H. It is designed to further remove the phasiness heard during normal stereo playback of the recording. It also has mono playback compatibility, with no sounds encoded as vertical stylus motions.

    A small group has continued to make recordings in Ambisonics, and equipment is still available to play it. Some recordings are released as ordinary CDs.

    This can be played on a normal stereo, or with an SQ decoder with both back speakers connected to the right back output. A Dolby Surround, RM, or QM decoder will also work, but not as well. This is a good design for adding mono compatibility that is hampered by lack of available equipment.

    I didn't have access to the article above until 2006.

  57. Circlesurround

    Circlesurround stylus motions Sound Retrieval System (SRS) owns Circlesurround, which was introduced in the mid 1990s. It was introduced to provide a matrix method of having two different surround speaker signals for Dolby Surround in theaters, and on VHS and DVD. Movies have been encoded in Circlesurround; Theaters have been equipped with circlesurround decoders; and many receivers and decoders have circlesurround capability. Dolby Surround decoders can also play Circlesurround, but without the separation between the surround speakers. 0 

    Circlesurround has also been sold for automotive surround sound. It does synthesize surround sound from ordinary stereo. It has a pleasing surround effect.

    Circlesurround makes no sense to me, because the encoding holes at the left side and right side encode the sound closer to center front than the left front and right front signals are encoded. This system is nothing but SQ with the left and right back signals traded and moved forward. It is essentially the front half of SQ with the channels traded.

    You can play Circlesurround with an SQ or EV Universal decoder by trading the left back and right back speakers. Dolby Surround also plays it adequately.

  58. Surround Field Recording

    surround field stylus motions In 1996, I was recording a soloist rehearsing a speech. I was using some microphones on a 3-mic surround stand I had made a few weeks earlier. The speaker was about two feet from the L and R mics. The soloist practiced the part a few times before the first take. Then we recorded the take.

    I rewound the tape to play it through the monitor speakers (in regular matrix), and started the tape playing at the beginning. Then the following conversation took place:

    It sounded so real that I didn't realize it was the tape playing. I thought it was the soloist practicing again.

    After this, I continued to experiment and perfect the system over several years. In one of the experiments, I had someone walk around the mic cluster at different distances, speaking as he walked (he kept saying, "Can you hear me now?" in a gag reference to a cell phone ad). On playback, I could hear not only the direction but the approximate distance of his voice.

    This system closely mimics both the shadowing effect of the head on the ear farthest from the sound (which a panpot does) and the delay of the sound from one ear to the other. These combine to produce a stable image no matter which direction the listener is facing. It also produces a correct image to the side of the listener with a quadraphonic (RM) speaker layout, again without regard to the direction the listener is facing.

    Spheround stylus motions Another effect this system produces is a steering effect that guides the ear to the correct direction. This happens because the mics farthest from the sound pick up the sound too, and the echoes from that sound, and present them delayed in the opposite speakers.

    I have heard many different attempts at realistic sound, using speakers or with headphones. But this is the only one that has a "you are there" quality I have never heard elsewhere. I call the process "Surrfield".

    The sound images are perfectly located without any separation enhancement, even when the individual instruments are panned to locations different from the general location of the entire band.

    I devised a 3D version of this called Spheround. The stylus motions are at right.

    See these pages for more on this process:

  59. Separation Enhancement 5: Enhancement in the Recording

    The fifth form of separation enhancement was putting enhancement in the recording. There have been several different attempts to do this:

    1. Binaural - This was an attempt to use a dummy head with microphones in ears to record a realistic surround sound. It worked quite well if your head was the same size as the dummy head and your ears had the same shapes.
    2. Ambisonics - This attempts to create a stable image through phase changes and multiple speakers.
    3. Sound Retrieval System - This system creates a surround effect through stereo speakers. The devices have this logo "(•)" on them. But if you turn to look to the left or the right, the effect disappears.
    4. My surround field recording system (above)
  60. Was CD-4 the end of the phonograph record?

    CD-4 died long before the phonograph record did, but something with the initials "CD" did kill off the phonograph record: The Compact Disc (CD).

    I prefer the phonograph record over the CD.

    Note that the matrix systems work just fine with CDs. I have several CDs that are marked QS, one that is marked SQ, several in unmarked SQ, and quite a few marked as being in Dolby Surround. In addition, many of the reissues on CD of records that were originally encoded in a matrix are also encoded on the CD. Many soundtrack albums are in Dolby Surround. And some record producers are also making CDs in Dolby Surround.

    Some companies are still making records. I bought a new one in 2014, and several more in later years.

    A new recording made in QS was released in 2018. It comes with a working QS Variomatrix decoder on a PC board.

  61. Lack of Equipment to Play Older Recordings

    People who collect recordings are finding that there is a lack of working equipment for playing older recordings. In addition, many of the recordings themselves are deteriorating:

    1. Many electronic devices 15 years old or older have quit working. There are several things that can go wrong with them:
      • The electrolytic filter capacitors in the power supplies go bad. Many of them dry out and have no capacitance at all. Others "reform," increasing their capacitance while reducing the voltage they can stand. This usually happens if the equipment is not used for many years. When turned on after many years of disuse, the voltage from the power transformer might be too high for the capacitor. It shorts, and may explode. Sometimes this also burns out the power transformer.
      • Tubes go bad. Except for a few types used in guitar amps, replacements have not been made for many years.
      • Many devices used proprietary integrated circuits that are no longer available.
      • Other parts (particularly potentiometers) are oxidized by the air and fail or become noisy.
    2. New reel-to-reel, cassette, and VCR players are rare, if they are sold at all.
    3. New reel-to-reel, cassette, and VCR tapes are no longer sold.
    4. The rubber belts and drive wheels in record players and tape recorders go bad. Often the parts are no longer available.
    5. Many of the better turntables have customized pickup cartridges that are not made anymore.
    6. Styli for many pickup cartridges are no longer made. Many pickup cartridge companies have gone out of business or have stopped making record playing equipment.
    7. Often the 78 RPM stylus is no longer made for the cartridge, even if the microgroove stylus is still available.
    8. Nobody makes the CD-4 pickups and styli anymore.
    9. The heads go bad in tape recorders and VCRs.
    10. The LASER heads in CD and DVD players go bad.
    11. The glue holding the oxide to recording tape dries up and the oxide falls off the tape.
    12. The glue holding the oxide to recording tape absorbs moisture and becomes sticky, causing a problem called "sticky-shed". This causes the oxide to stick to the tape heads, fouling them and keeping the tape from moving.
    13. New players no longer can play older formats. This was first seen when many turntables made in the 1970s no longer had the 78 RPM speed. One would wonder if the cheap 3-speed turntables sold today have the 78 RPM stylus as well as the 78 RPM speed.
    14. Nothing sold today can play the quadraphonic matrix systems (except that Dolby Surround systems can play the RM and QM formats).
    15. The special replacement stylus for playing CD-4 records is no longer made.
    16. The special turntable cables for playing CD-4 records are no longer made.
    17. Replacement IC chips for quadraphonic decoders are no longer made. Fortunately, the early decoders used common transistors that are still available.
    18. New home theater systems use digital connectors that are incompatible with quadraphonic equipment.

    The problem is that all manufacturers make things that will sell in large quantities, not what people need.

  62. Loss of Standards Again

    With the advent of digital formats for video recording (DVD and Blu-Ray) came a caboodle of new discrete digital sound encoding techniques that are incompatible with each other. We lost the simplicity of one standard that Dolby Surround provided for more than 25 years.

    Unless it is deliberately encoded into the discrete recording, we also lost the side image location fix that Dolby Surround provided.

    There should be a law requiring any manufacturer producing a new product that changes or removes an existing standard to either keep making equipment for the old standard or to pay for conversions of all old software and recordings to the new standard, ensuring the compatibility of old recordings or software with the new standard.

    One suggestion is a multichannel digital to matrix converter. Connect it to the discrete outputs of a DVD or Blu-Ray player and use it with your old receiver.

  63. MP-3 Destroys Surround and Hall Ambience

    The compression methods used to shrink the music in a computer file for MP-3 also remove some information from the file. This often removes information from the recording, including precise pan position, surround encoding, and concert-hall ambience.

    I took some of the matrix-encoded recordings I made and converted them to MP-3 format to enter them in an original recordings contest. A flute part I added to change the timbre of an organ part totally disappeared from the MP-3 version. The MP-3 encoder treated that entire flute part as harmonics of the organ part, and thus, MP-3 removed it as "unnecessary information". It also changed the panning of the reverb (panned into the surround speakers) into only the right channel, destroying the surround effect.

  64. My Decaphonic Setup

    I built a 10-channel matrix switching system to be able to decode any of the matrix systems ever used. The details are here.

    With it, I discovered that the location of a sound becomes more distinct when more channels are used, even though they are just decoded at different directions in the same matrix.

    With the decaphonic system, I finally got to try out the octophonic system I sketched out in 1970, but with adjustable matrix parameters. It would have produced better sound images than any quadraphonic system has made.

    This system can play all of the following matrix systems:

  65. Separation Enhancement 6: Many Channels

    The sixth form of separation enhancement was using many channels with decoding coefficients close to each other. Some of today's movie theater systems use multiple discrete channels to achieve this, but it works just as well with matrix systems.

    This idea seems counterintuitive, but it works. My page on Surround Fields shows how this works. The use of the surround field recording method makes it work even better, because the direction the listener is facing does not matter.

    Provision of many channels keeps the ear from finding the speaker location instead of the sound location.

    With the discrete systems, several speakers in different directions carry the information for the human ear to locate the sound. It also works, no matter which way the listener is facing.

  66. Investigating separations between signals and speakers (part 2)

    I did the calculations for the new matrices and added them to the ones I knew about earlier, creating a new a table showing how well each system would work with various kinds of music. Systems no longer being considered in 1975 that were in the earlier list were removed:

    System Quadraphonic Separation Stereo Synth Separation Center
    Back −
    Mono ¤
    Music Performance Original
    FrontBackSides FrontBackMono-
    play ¤
    E-V Stereo-4 8.3 dB0.2 dB4.9 dB 14 dB4.1 dB19 dB40 dB BetterGoodGoodBetterBad BlurCenter Back
    Dynaquad 25 dB1.2 dB1.2 dB 25 dB4.8 dB12 dB40 dB FairFairFairGoodBad BlurCenter Back
    Sansui QS 3.0 dB3.0 dB3.0 dB 8.3 dB8.3 dB8.3 dB40 dB FairGoodGoodGoodBad ◊ BlurBoth Sides
    CBS SQ 25 dB25 dB3.0 dB 25 dB3.0 dB3.0 dB40 dB BadGoodFairBadBad BlurBoth Sides
    CBS SQ Blend 14 dB3.2 dB3.6 dB 20 dB3.0 dB8.1 dB40 dB FairGoodFairFairBad BlurBoth Sides
    EV Universal 8.3 dB3.0 dB5.2 dB 14 dB3.0 dB8.3 dB40 dB GoodGoodGoodFairBad BlurBoth Sides
    UQ equal sep. 4.8 dB4.8 dB4.8 dB 11 dB3.0 dB6.8 dB40 dB GoodGoodGoodFairBad BlurBoth Sides
    Denon BMX 3.0 dB3.0 dB3.0 dB 8.3 dB8.3 dB3.0 dB3.0 dB PoorGoodGoodAwfulBest BlurBoth Sides
    Dolby Surround 25 dB0.0 dB3.0 dB 25 dB3.0 dB25 dB40 dB GoodGoodGoodGoodBad GoodBoth Sides
    CircleSurround 25 dB25 dB0.7 dB 25 dB8.3 dB3.0 dB6.0 dB FairGoodGoodFairGood FairBoth Sides
    BBC Matrix H 3.0 dB3.0 dB3.0 dB 8.3 dB8.3 dB6.0 dB8.3 dB FairGoodGoodFairFair BlurBoth Sides
    Ambisonics UHJ 12 dB3.0 dB3.3 dB 12 dB3.3 dB3.6 dB5.4 dB FairGoodGoodGoodGood FairBoth Sides
    Spheround on QS 3.0 dB3.0 dB3.0 dB 8.3 dB8.3 dB8.3 dB~5 dB FairGoodGoodGoodGood § BestBoth Sides
    System Quadraphonic Separation Stereo Synth Separation Center
    Back −
    Mono ¤
    Music Performance Original
    FrontBackSides FrontBackMono-
    play ¤
    QS Variomatrix 15 dB15 dB15 dB 15 dB15 dB20 dB40 dB BetterBestBetterGoodBad BlurBoth Sides
    CBS SQ F-B Logic 25 dB25 dB15.0 dB 20 dB3.0 dB15 dB40 dB AwfulGoodFairAwfulBad BlurBoth Sides
    CBS SQ Variblend 20 dB15 dB15 dB 20 dB8.0 dB15 dB40 dB GoodGoodGoodPoorBad BlurBoth Sides
    EV Universal Logic 8.3 dB4.7 dB4.9 dB 14 dB4.1 dB19 dB40 dB GoodGoodGoodGoodBad BlurBoth Sides
    UQ Autovary 10 dB10 dB5.3 dB 11 dB3.0 dB12 dB40 dB GoodGoodGoodGoodBad BlurBoth Sides
    Denon UD-4 20 dB*20 dB*20 dB* 8.3 dB**8.3 dB**3.0 dB**3.0 dB Better*Better*Better*AwfulBest BlurBoth Sides
    JVC CD-4 20 dB†20 dB†20 dB† 0.0 dB GoodBetter†Better†None BlurNone ‡
    Dolby Pro Logic 25 dB0.0 dB20 dB 25 dB8.0 dB25 dB40 dB BetterBetterBetterGoodBad GoodBoth Sides
    CS Logic 25 dB25 dB10 dB 25 dB15 dB15 dB6.0 dB BetterBetterBetterGoodGood FairBoth Sides
    Dolby Digital 25 dB25 dB25 dB 0.0 dB BetterBetterBetterNone None ‡

    * Separations are at 3 KHz and below. Separations above 3 KHz are as in BMX.
    ** UD-4 uses BMX values for synthesis from stereo.
    † Depends on the condition of the carrier.
    ‡ Not a matrix system. Does not synthesize from stereo, have a hole, or lose sound in mono.
    ◊ This system provides best mono play by equally mixing decoder outputs.
    ¤ This is how each system plays on a normal mono player.
    § Front mics get delayed version of back sounds.
    ≈ Varies with how the recording was made.
    ~ Varies with how much of the back sounds get into the front mics.

  67. Mono Compatibility Problems (Part 2)

    In the separation table above, the "Center Back − Mono" entry shows how much of the center back signal gets to mono playback.

    Most of the systems described above still have the same problem when the record is played through a monophonic radio or record player. When correctly encoded (as opposed to an error in encoding caused by an encoding hole) any sound panned to center back disappears from mono playback.

    The stylus vector diagrams of most of the systems discussed so far still show a vertical line for the violet vector for center back. That means that it will disappear (except some crosstalk or distortion) from mono play.

    Again note that in some of the diagrams, the blue vector and the magenta vector follow the same path (but with opposite rotation), and they seem to combine to produce a violet trace on a low-resolution monitor. Again, right-click on an image and click "view image" to display a larger version to see the two colors. Ignore such color combinations here.

    Only UMX/BMX, Matrix G, Matrix H, and UHJ have center back signals that do not disappear in mono play. These are the mono compatibilities mentioned above. And in Spheround, the image steering signals of a center-back sound do not disappear.

  68. Comparing Systems for Concert Hall Ambience (Part 3)

    Adding the new systems to the table of separations critical to the quality of concert hall ambience:

    System Separations to LB Separations to CB .. Ambience Worst Case
    Pan LF 22.5° LPan CF22.5° R Pan RF Pan LF 22.5° LPan CF22.5° R Pan RF Wd LBWd CB Nr LBNr CB
    E-V Stereo-4 4.9 dB10.1 dB19.0 dB11.2 dB5.3 dB 5.1 dB10.7 dB40.0 dB10.7 dB5.1 dB 4.9 dB5.1 dB10.1 dB10.7 dB
    Dynaquad 1.2 dB4.3 dB11.7 dB17.7 dB6.0 dB 3.0 dB8.3 dB40.0 dB8.3 dB3.0 dB 1.2 dB3.0 dB4.3 dB8.3 dB
    Sansui QS 3.0 dB5.1 dB8.3 dB14.2 dB40.0 dB 8.3 dB14.2 dB40.0 dB14.2 dB8.3 dB 3.0 dB8.3 dB5.1 dB14.2 dB
    SQ 3.0 dB3.0 dB3.0 dB3.0 dB3.0 dB 3.0 dB8.3 dB40.0 dB8.3 dB3.0 dB 3.0 dB3.0 dB3.0 dB8.3 dB
    SQ 10-40 3.7 dB6.4 dB8.3 dB6.4 dB3.7 dB 4.0 dB9.4 dB40.0 dB9.4 dB4.0 dB 3.7 dB4.0 dB6.4 dB9.4 dB
    EV-U Enh On 5.0 dB10.3 dB19.4 dB10.3 dB5.0 dB 5.1 dB10.7 dB40.0 dB10.7 dB5.1 dB 5.0 dB5.1 dB10.3 dB10.7 dB
    EV-U Enh Off 4.4 dB6.9 dB8.3 dB6.9 dB4.4 dB 5.1 dB10.7 dB40.0 dB10.7 dB5.1 dB 4.4 dB5.1 dB6.9 dB10.7 dB
    BMX 3.0 dB5.1 dB8.3 dB14.2 dB40.0 dB 8.3 dB14.2 dB40.0 dB14.2 dB8.3 dB 3.0 dB8.3 dB5.1 dB14.2 dB
    Dolby Surround 3.0 dB8.3 dB40.0 dB8.3 dB3.0 dB 3.0 dB8.3 dB40.0 dB8.3 dB3.0 dB 3.0 dB3.0 dB8.3 dB8.3 dB
    BBC Matrix H 3.0 dB5.1 dB8.3 dB14.2 dB40.0 dB 8.3 dB14.2 dB40.0 dB14.2 dB8.3 dB 3.0 dB8.3 dB5.1 dB14.2 dB
    Ambisonics UHJ 1.3 dB2.5 dB4.3 dB4.3 dB4.1 dB 4.0 dB6.1 dB8.5 dB6.1 dB4.0 dB 1.3 dB4.0 dB2.5 dB6.1 dB
    Hall Ambience 8.3 dB14.2 dB40.0 dB14.2 dB8.3 dB 8.3 dB14.2 dB40.0 dB14.2 dB8.3 dB 8.3 dB8.3 dB14.2 dB14.2 dB
    System Separations to LB Separations to CB .. Ambience Worst Case
    Pan LF 22.5° LPan CF22.5° R Pan RF Pan LF 22.5° LPan CF22.5° R Pan RF Wd LBWd CB Nr LBNr CB
    QS Variomatrix † 15.0 dB15.0 dB15.0 dB15.0 dB15.0 dB 15.0 dB15.0 dB15.0 dB15.0 dB15.0 dB 15.0 dB15.0 dB15.0 dB15.0 dB
    EV-U Enh Auto † 5.0 dB10.3 dB19.4 dB10.3 dB5.0` dB 5.1 dB10.7 dB40.0 dB10.7 dB5.1 dB 5.0 dB5.1 dB10.3 dB10.7 dB
    Dolby Pro Logic † 15.0 dB15.0 dB15.0 dB15.0 dB15.0 dB 15.0 dB15.0 dB15.0 dB15.0 dB15.0 dB 15.0 dB15.0 dB15.0 dB15.0 dB
    CD-4 *‡ 30.0 dB30.0 dB30.0 dB30.0 dB30.0 dB 30.0 dB30.0 dB30.0 dB30.0 dB30.0 dB 30.0 dB30.0 dB30.0 dB30.0 dB
    Denon UD-4 *‡ 30.0 dB30.0 dB30.0 dB30.0 dB30.0 dB 30.0 dB30.0 dB30.0 dB30.0 dB30.0 dB 30.0 dB30.0 dB30.0 dB30.0 dB
    Dolby Digital ‡ 40.0 dB40.0 dB40.0 dB40.0 dB40.0 dB 40.0 dB40.0 dB40.0 dB40.0 dB40.0 dB 40.0 dB40.0 dB40.0 dB40.0 dB
    Scheiber Logic Ambiance is drowned out by the separation-enhancement logic.
    SQ F-B Logic Ambiance is drowned out by the separation-enhancement logic.
    SQ Variblend Ambiance is drowned out by the separation-enhancement logic.


    • Wd = The orchestra is recorded wide, between the LF and the RF speakers.
    • Nr = The orchestra is recorded narrow, restricted to 22.5° on each side of CF.
    • LF, CF, and RF are either real speakers or phantom images when no speaker is there.
    •   *   = Figures assume no carrier damage. Damage introduces snapping or rushing sounds that hide or destroy ambience.
    • † Separation depends on program content.
    • ‡ Not a matrix system. Separations don't depend on location.


    The systems are sorted from best to worst for each of 5 categories.

    Systems with equal performance are listed alphabetically.

    The categories are:

    Sorted best to worst
    # System  Wide  
    ----- # System  Wide  
    ----- # SystemNarrow
    ----- # SystemNarrow
    ----- # SystemStereo
    1Dolby Digital40.0 1Dolby Digital40.0 1Dolby Digital40.0 1Dolby Digital40.0 1Dolby Pro Logic15.0
    2CD-430.0 2CD-430.0 2CD-430.0 2CD-430.0 .QS Variomatrix15.0
    .Denon UD-430.0 .Denon UD-430.0 .Denon UD-430.0 .Denon UD-430.0 3Hafler (3 spkr)14.2
    .Discrete Tape30.0 .Discrete Tape30.0 .Discrete Tape30.0 .Discrete Tape30.0 .Hafler (4 spkr)14.2
    5Dolby Pro Logic15.0 5Dolby Pro Logic15.0 5Dolby Pro Logic15.0 5Dolby Pro Logic15.0 .Hall Ambience14.2
    .QS Variomatrix15.0 .QS Variomatrix15.0 .QS Variomatrix15.0 .QS Variomatrix15.0 .Sansui QS14.2
    7Hafler (3 spkr)8.3 7BBC Matrix H8.3 7Hafler (3 spkr)14.2 7BBC Matrix H14.2 .Scheiber14.2
    .Hafler (4 spkr)8.3 .BMX8.3 .Hafler (4 spkr)14.2 .BMX14.2 8Ambisonics UHJ10.7
    .Hall Ambience8.3 .Hafler (3 spkr)8.3 .Hall Ambience14.2 .Hafler (3 spkr)14.2 .E-V Stereo-410.7
    10EV-U Enh Auto5.0 .Hafler (4 spkr)8.3 10EV-U Enh Auto10.3 .Hafler (4 spkr)14.2 .EV-U Enh Auto10.7
    .EV-U Enh On5.0 .Hall Ambience8.3 .EV-U Enh On10.3 .Hall Ambience14.2 .EV-U Enh Off10.7
    12E-V Stereo-44.9 .Sansui QS8.3 12E-V Stereo-410.1 .Sansui QS14.2 .EV-U Enh On10.7
    13EV-U Enh Off4.4 .Scheiber8.3 13Dolby Surround8.3 .Scheiber14.2 13SQ 10-409.4
    14SQ 10-403.7 14E-V Stereo-45.1 14EV-U Enh Off6.9 14E-V Stereo-410.7 14BBC Matrix H8.3
    15BBC Matrix H3.0 .EV-U Enh Auto5.1 15SQ 10-406.4 .EV-U Enh Auto10.7 .Dolby Surround8.3
    .BMX3.0 .EV-U Enh Off5.1 16BBC Matrix H5.1 .EV-U Enh Off10.7 .Dynaquad8.3
    .Dolby Surround3.0 .EV-U Enh On5.1 .BMX5.1 .EV-U Enh On10.7 .SQ8.3
    .Sansui QS3.0 18Ambisonics UHJ4.0 .Sansui QS5.1 18SQ 10-409.4 18BMX3.0
    .Scheiber3.0 .SQ 10-404.0 .Scheiber5.1 19Dolby Surround8.3 .Denon UD-43.0
    .SQ3.0 20Dolby Surround3.0 20Dynaquad4.3 .Dynaquad8.3 20Scheiber Logic0.0
    21Ambisonics UHJ1.3 .Dynaquad3.0 21SQ3.0 .SQ8.3 .SQ F-B Logic0.0
    22Dynaquad1.2 .SQ3.0 22Ambisonics UHJ2.5 22Ambisonics UHJ6.1 .SQ Variblend0.0
    23Scheiber Logic0.0 23Scheiber Logic0.0 23Scheiber Logic0.0 23Scheiber Logic0.0 23CD-4-0.1
    .SQ F-B Logic0.0 .SQ F-B Logic0.0 .SQ F-B Logic0.0 .SQ F-B Logic0.0 .Discrete Tape-0.1
    .SQ Variblend0.0 .SQ Variblend0.0 .SQ Variblend0.0 .SQ Variblend0.0 .Dolby Digital-0.1
  69. What Surround Sound Enthusiasts can do Today

    There are many options available for enjoyment of surround sound:

  70. Putting a Live Band or DJ in Live Surround Sound

    The following methods can be used to create surround sound for a live audience:

  71. Panning Philosophy for Surround Sound

    The following are panning philosophies I have collected or formulated over the 40+ years of surround sound.

  72. Fitting Surround Sound Into a Room.

    Part of the problem with surround sound is fitting into an average room. Actually, the biggest obstacle to overcome is a spouse who loves to rearrange the furniture periodically.

    Here are some suggestions to ease the burden of having a quadraphonic or surround sound system in an average room:

  73. Diagrams Showing the Room Size Expected from a Quadraphonic System.

    EV matrix room In his book, "Four Channel Sound", Leonard Feldman had a diagram 23  showing "apparent room sizes" for the QS and old EV matrix systems. I wanted to display similar diagrams for all matrix systems. So I developed a method to make similar diagrams. The diagram for the original EV matrix is at right.

    I originally developed this idea in 1988, but the printer I was using quit in that year and I no longer have equipment needed to read the disks. So I had to re-create the design from memory in 2018.

    The diagrams are on this page: Quadraphonic Systems

Works Cited

On my lack of article references:

When I was in high school and college, I didn't have the money to buy every magazine that had an interesting article in it. Instead, I went to the library and copied just the one article on the copying machine. Many of the copies I have do not identify the magazine or issue.

In addition, I did have some magazines that had articles that I built devices from. The problem is that I had to get rid of a lot of magazines when I moved in 1993. So I no longer have some of the magazines containing articles I did use. I have searched online and reconstructed what I could. Assistance in identifying articles is welcome. Articles without known references are identified by a 0 footnote.

0. The source for this has not been rediscovered (See above).

1. "A New Quadraphonic System; David Hafler,
Audio 07/1970 p. 24

2. "The Four Channel Disc" Larry Klein,
Stereo Review 01/1970 pp. 68-69

3. "The Scheiber 4-Channel Stereo System" Milton Snitzer,
Electronics World 09/1970 pp. 43, 69

4. "How Four Channel Programs are Encoded" author unknown,
This was part of a packet sent to me by Sansui. It covers the technical details of QS. It contains no credit references at all (It might be part of the QS-1 user manual).

5. "A Compatible Stereo-Quadraphonic (SQ) Record System" B.B. Bauer, D.W. Gravereaux, & A.J. Gust,
Journal of the Audio Engineering Society 09/1971 V 19 pp. 638-646

6. "A Discrete 4-Channel Disc and its Reproducing System" T. Inoue, N. Takahashi, & I. Owaki,
Journal of the Audio Engineering Society 07-08/1971 V 19 pp. 576-583

7. "The Compatible Stereo-Quadraphonic 'SQ' Record" Benjamin B. Bauer,
Audio 10/1971 pp. 34-40

8. "Analyzing Phase-Amplitude Matrices" Peter Scheiber,
Journal of the Audio Engineering Society 11/1971 V 19 pp. 835-839

9. "Discrete-Matrix Multichannel Stereo" D.H. Cooper & T. Shiga,
Journal of the Audio Engineering Society 06/1972 V 20 pp. 346-360

10. "Advances in SQ Encoding and Decoding Technology" B.B. Bauer, R.G. Allen, G.A. Budelman, & D.W. Gravereaux,
CBS Laboratories, presented 02/1973, reprinted as Appendix 3 of the book:
"Four Channel Stereo From Source to Sound"
G/L Tab Books, 2nd Edition 1974, Appendix 3, pp. 230-247

11. "4-2-4 Matrix Systems: Standards, Practice, and Interchangeability " John Eargle,
Journal of the Audio Engineering Society 12/1971 V 20 pp. 809-835

12. "A Geometric Model for Two Channel Four Speaker Matrix Stereo Systems" Michael Gerzon,
Journal of the Audio Engineering Society 03/1975 V 23 pp. 98-106

13. "Anomalies in the CBS SQ Stereo/Quadraphonic System" Michael Gerzon,
Paper presented to the Mathematical Institute, Oxford England.

14. "The Sansui QS Matrix and a New Technique to Improve its Inter-Channel Separation Characteristic." R. Itoh & S. Takahashi,
Audio Engineering Society 42nd Convention May 2-5 Preprint F6

15. "104 Easy Projects for the Electronics Gadgeteer" Robert M Brown,
Tab Books 1970 pp. 96-97, Project #62 Tubeless Audio Squelch

16. "Stereophonic Earphones and Binaural Loudspeakers" Benjamin B. Bauer,
Journal of the Audio Engineering Society 04/1961 V9 pp. 148-151

17. "SQ Dichophony-Quadraphonic Earphone Listening" Benjamin B. Bauer,
Journal of the Audio Engineering Society 06/1976 V24 p. 387

18. "Four Channel Sound" Leonard Feldman,
Howard W Sams & Co. Inc 1973, pp. 32-80

19. "Four Channel Sound" Leonard Feldman,
Howard W Sams & Co. Inc 1973, p. 45

20. "The Subjective Performance of Various Quadraphonic Matrix Systems" T.W.J. Crompton and BBC Research Department,
British Broadcasting Corporation, Report RD1974/29, 11/1974

21. "Developments in Matrix H Decoding" P.S. Gaskell & P.A. Ratliff,
British Broadcasting Corporation, Report RD1977/2, 2/1977

22. "Ambisonics in Multichannel Broadcasting and Video" Michael Gerzon,
Journal of the Audio Engineering Society 11/1985 V 33 pp. 859-873

23. "Four Channel Sound" Leonard Feldman,
Howard W Sams & Co. Inc 1973, p. 62

Appendix: The Basic Idea of the Matrix

Dolby Surround

Note how phase and amplitude control the direction the sound comes from with the RM system:

Other matrix systems interpret amplitude and phase in different ways.