Aqualung and Warchild aree CD-4 DChannel Discrete Quadradiscs
new Digital AV ramps are not true Quad but close, here is some info
What you need to play back your Quadraphonic Recordings
There where many formats created to reproduce sound over more than 2
speakers, Now called surround sound, back in the '70's called
Quadraphonics.
DISCRETE TAPE FORMAT - Quad reel-to-Reel, Quad 8-Track
4-Channel tape decks where developed in order to deliver 4 channels of
audio into the consumers home. The formats where reel to reel and the
8-track cartridge. Special 4-channel reel-to-reel's and 8-track decks
were created. These decks could also play back stereo tapes as well a
the new Quadraphonic recordings. A 4-channel reel to reel plays only in
one direction as opposed to its stereo cousin, where you flip the tape
over to play the other side. You must have a 4-channel reel to reel in
order to play the 4 tracks in one direction to reproduce Quadraphonics.
A 4-channel 8-Track has only two program tracks, each consisting of
4-channels, as opposed to its stereo cousin that has 4 programs each
consisting of 2 channels. You must have a 4-channel 8-track in order
to reproduce Quadraphonics.
Quad 8-track head layout
MATRIX FORMATS - SQ, QS, EV, Dynaquad
Another way of getting 4-channels delivered into the consumer's home was
to matrix or mix the 4 channels down to two, thus utilizing the existing
stereo LP, radio and tape formats. All that is needed in the home is a
decoder to separate the two channels back to four. In order to playback
a matrixed recording, you need a decoder for that system. Your 2-channel
source (LP, Tape of FM Radiobroadcast) is input into the decoder. The
4-channel output of the decoder (Front Left, Front Right, Rear Left and
Rear Right) is then sent to a 4-channel amplifier or two-stereo
amplifiers (front and rear). Although the various formats are similar,
they are different. In order to hear what the recording engineer
intended you must have the same format decoder as the matrix format you
are playing from LP, tape or radio. If you are playing an SQ recording,
you need to have an SQ Decoder, a QS or EV or other decoder will work,
but only get you close to what you are supposed to be hearing. You can
play matrixed recordings over a dolby surround or pro logic system. The
effect will be in no way what the band or engineer intended, however,
you will hear more information out of the rear channels compared to a
stereo recording.
DISCRETE VINYL FORMATS - CD-4 (Also known as Quadradisc), UD-4 (Also
known as UMX)
Another method of delivering 4-channel sound to the home via the vinyl
record format was labeled as a discrete format, but is actually a
combination of matrixing and discrete channels. This method required
a special cartridge and Stylus that extended the frequency response
from 20k of a typical stereo cartridge to 45-50k for CD-4 and up to
35-40k for UD-4.
This enabled the cartridge to pick up a sub-carrier frequency embedded
in the record grooves, much like an FM broadcast. Playback of this
system also required a Demodulator (a box to send the sound to the
correct channels).
It was later learned that a special stylus was also needed to play back
CD-4 recordings. The shape of an elliptical stylus did not allow all
the tiny modulations in the grooves to be read and allowed dirt and
grim to collect in the grooves and hide the subcarrier signal.
The UD-4 format was a little less cumbersome as it did not require a
demodulator and special cartridge, but with those produced better
results. UD-4 enabled the user to just use a regular matrix decoder
(RM or Regular Matrix was Sansui's early version of the QS format)
to decode or extract the 4-channels. But by adding the special
cartridge and demodulator, separation and performance of the system
increased.
JVC's CD-4 Quadraphonic Compatable Disc Format
CD-4 Quadraphonic Equipment
MATRIX FORMATS & RECORD LABELS
SQ - Developed by CBS, Record companies who adopted this format include:
Angel, Capitol, CBS, CTI, Columbia, EMI, Epic, Eurodisc, Harvest,
HMV, Seriphim, Suprophon, Vangaurd
QS - Developed by Sansui, Record companies who adopted this format
include: ABC, Advent, Bluesway, Candide, Command, Decca, Impulse,
Longines, MCA, Ovation, Pye, Turnabout, Vox
EV - Developed by Electro Voice, also known as Stereo-4, Very few items
are encoded in this format.
DY - Developed by Dynaco, also known as Dynaquad, Very few items are
encoded in this format.
To playback the matrix formats, all you need is the appropriate decoder.
It can be a separate box or built into a 4-channel amplifier.
DISCRETE FORMATS
CD-4 - Developed by JVC/RCA, also known as Quadradisc, Record companies
who adopted this format include: Arista, Atlantic, Capricorn,
Elektra, Fantasy, Grunt, JVC, Nonsuch, RCA, Reprise.
UD-4 - Developed by Nippon/Columbia, Very few items are encoded in this
format.
To playback the discrete vinyl format of CD-4, you will need a special
cartridge that can pick up frequency's up to 45,000 hz, A special cut
diamond stylus and a demodulator. The stylus shape created by JVC back
in the '70's was called the "Shabata". A "Microline" stylus currently
available will also do the job. The demodulator can be a separate
box or built into a turntable or 4-channel amplifier. The Shabata or
Microline stylus will protect the disc from damage from dirt build up
over a period of time or number of plays and will pick up the tiny
modulations in the grooves. It is believed that a standard Eliptical
stylus will pass over these tiny modulations and trap dirt in the
grooves. To playback the discrete vinyl format of UD-4, You can use
a Regular Matrix decoder. by adding a special cartridge and a UD-4
demodulator, separation and performance of the system increased.
UD-4 is rather rare in the states as it was marketed in the U.K.,
Europe and Japan.
CD-4 and UD-4 also made the requirement that special low capacitance
leads (wires) from the head shell to the demodulator be used. I have not
had any problems with any leads from turntables and believe that this
requirement was only stated due to the use of cheap ceramic cartridge
turntables in use at the time.
PLAYBACK ALTERNATIVES
If you cannot find Quadraphonic equipment to playback your matrix
recordings, you do have other options. You can use your Dolby Surround
decoder for playback of SQ, QS, EV or DY. You will not hear what was
intended, but the effect is still quiet pleasing. CD-4 and UD-4 also
offer good rear channel information over a matrix system when compared
to a stereo counterpart played over a matrix system.
A Circle Surround decoder also does a nice job with matrixed Quad.
Or you can make what is called a Hafler circuit, Chris Kantack's
Surround Sound Information Source web page has a good explanation and
diagrams. Back in the early days of Quad, one could by a box for around
$20 made by Dynaco, Lafayette & others to do the same thing that these
diagrams show. You connected the box to your 2 speaker outputs on your
stereo receiver and your 4 speakers to the box, this enabled a person
getting started for little money, later if it seemed worthy, one could
splurge on an Active decoder as opposed to this passive approach.
Chris Kantack's Surround Sound Information Source web page
home.earthlink.net/~kantack/surround2.htmPLAYBACK RECOMENDATIONS
Should you buy vintage quad gear from ebay? That depends on what
you really want. If you are looking to play Quad 8-Tracks or reel to
reels, you could by vintage equipment. A modern alternative for playing
Quad 8-Tracks exists by purchasing a Fostex 1/4" 8-Track reel to reel,
then bust open the 8-track cartridge and string it up on a reel to play
on the Fostex. This is of coarse is left to a die-hard fan or an expert.
4-Track reel to reels were made well into the late 80's for home studios.
These are much quieter than decks made in the '70's, but the tape bias of
these decks are usually setup for more modern tape formulas, therefore
playback bias should be adjusted for the older tape formula you wish to
play.
For matrixed Quad recordings, there are a few choices.
I myself loved the gargantuan receivers made in the '70's,
but unfortunately, the decoders built during the height of quad were not
the best. It was not until Quad was waning and the public lost
interest, that good matrix decoders were on the market. By then the
public had had enough.
One reason for purchasing original equipment from the time period is so
that you could match the proper decoder with the matrixed recording you
wish to play. The problem is that equipment from the '70's is extremely
noisy compared to modern digital equipment.
If you are a casual listener or collector and not a real diehard Quad
fanatic, I would recommend not spending your money on ebay buying vintage
gear unless you really know what you should be buying. I often have folks
contact me after purchasing an old quad receiver off ebay with terrible
decoders, lots of system hiss and noise.
They are all excited and want to know where they can find recordings to
play over there new system. I never have the heart to tell them that the
decoder in their receiver only produces anywhere from 3db to 15db of
separation between channels, which does not create a very spatial
effect were one can clearly say where the sound originates from.
Some of the decoders, either separate or in a receiver, built in the
late '70's or early '80's could achieve as much as 50db of separation
between channels, and are fairly quite in regards to noise.
My recommendation to the average person would be to buy a new digital
receiver.
While the decoders in new receivers are different than the ones in the
days of old, they still are pretty close. The draw back is, when
playing a Quad matrixed recording over a new surround system with
Dolby Pro-Logic II, Neo-6 or Circle Surround II, You will not hear
exactly what the engineer originally intended. But the effect is pretty
accurate. With new receivers, you can turn of the center channel and
subwoofer if you do not want to use them. The other advantage with a
new receiver is that you can also enjoy the new formats of Dolby Digital
and DTS, or use the analogue 6 channel inputs to connect your new
DVD-Audio or SACD disc player. The greatest advantage is that you can use
these inputs to connect your old Quad 8-Track player or Reel to Reel and
not have the hiss that old receivers produced.
My personnel favorite decoding option is Circle Surround II. While I like
Dolby Prologic II and Neo-6, Circle Surround is more aggressive in its
rear channels, but not to a point that is distracting.
Kenwood and Marantz have receivers with Circle Surround II.
