originally published in Studio
Sound magazine (now defunct), June 1975
on any image to see an enlarged version
Floyd were among the earliest innovators to use four channel sound,
and more recently Dark Side of the Moon won many awards, including
several for engineering, on its way to being one of the best-know albums
of all time. The author, who engineered these and many other sessions
for the band, discusses the quadraphonic record production, and contrasts
it with the presentation of multichannel sound on stage.
Many years ago, in the earlier
part of their career, Pink Floyd had been experimenting with a device
inscrutably known as the Azimuth Coordinator. It was not a magic box
for aligning type machine heads as the name might suggest but a very
glorified term for what we now know as a quad pan pot. Its use at live
concerts at that time very likely inspired considerable audience interest
in multichannel sound systems and in a mild way may have contributed
towards the now booming industry of quadraphony. Many groups have recently
adopted quadraphonic pa systems for live shows, the size and power of
which seem to be increasing. Quadraphonic record sales are also on the
increase, despite the indecision both on the part of the public and
record companies about which of the various systems provide the best
results and compatibility.
all non-classical recordings are made using close mic techniques in
relatively dead studio acoustics and later premixed to a stereo master
tape. Exactly the same recording procedures can apply for a quadraphonic
record except that, because the master reduction is made to four channels
rather than two, the multitrack layout must allow an effective distribution
of sounds for adapting to quad. There are obviously more possible
positions in a four channel remix, and conflict may arise with track
groupings organized with stereo on mind. Although Dark Side of the
Moon was monitored in studios equipped for stereo reproduction, many
sections were recorded with regard to the eventual quadraphonic reduction,
even though this took more track space than would have been necessary
for stereo. For example, the clock sounds for Time were built in an
imaginary quad picture on to four tracks of the 16 track master. The
sounds heard on the introduction to Money were also distributed
across four tracks to enable the spatial shifts of the quad reduction.
This involved transfer from an edited tape loop on a four track machine
to the 16 track for subsequent overdubs so that each sound issued
from a different speaker.
Merely redistributing the sound
for the quad mix, however, is not the end of the story. The various
quad systems for which the album is intended have to be
in mind. EMI have adopted the SQ system for disc issues. As with all
matrix systems it has specific limitations. For example, if signals
are positioned anywhere in the area between centre-of-the-roon and
center back they are likely to be out of phase to some degree when
encoded and cut in two disc channels. This results in a considerable
drop in level, due to the difference channel limitations or even a
total disappearance of the signal in mono, so this has to be avoided
wherever possible, although a pan through this center area might pass
unnoticed since level variations would be less objectionable in a moving
When approaching the quad mix of the album it had to be emphasized
that the contents should be unchanged musically, but be a showcase for
the quad medium and avoid the more obvious gimmicks of panning etc.
The requirements were a discrete master for tape systems, and an encoded
SQ master for disc transfer. It was thought that two separate remixes
would be the ideal situation, for in that case each system could be
used o its fullest capabilities without compromise on account of the
other. However, there might have been such huge differences in quad
effect between the two that they might have been incompatible with
each other musically; for example, in the effect of following disc
and tape cartridge.
Another considered alternative
was to remix to discrete and SQ simultaneously. This would have
presented a considerable demand on machinery, especially as many
other tape machines would be in use for quad echo delay, automatic
double-tracking (a technique using a fast delay) and so on. Every
edit would then
to be duplicated on both systems; crossfades would be a nightmare,
needed three four track machines and three stereo machines quite
apart from the extra time involved and the multiplication of
lineup procedures. It was eventually decided to work with one
discrete four track tape and monitor it in such a way that assured
a reasonable result for both systems, in other words bearing
in mind the compromises in the subsequent two-channel processing.
The quad remix room at EMIs Abbey Road Studios
has the convenient facility to monitor a discrete tape passed
through a back-to-back SQ encode/decode arrangement, and also
the stereo result direct from the two matrix channels without
decoding. Thus, we can monitor discrete, SQ and stereo from just
one four track tape. An SQ master was to be prepared simply by
making a copy of the final edited and crusaded four track tape
through the SQ encoder. This extra generation could be saved
if it was felt necessary by direct transfer from an advance head
four track machine to disc via an encoder, although normal practice
is to prepare an intermediate two channel tape: azimuth and generation
difficulties can be overcome by careful engineering. Having determined
the manner in which the various systems could be handled for
the reduction, the problem of quad positioning arose.
On the stereo version the basic instrument positions were arranged
as in fig. 1 Additional sounds such as synthesizers, extra guitars
and backing vocals were spread across the picture in various combinations
for maximum filling out of the music stage. The stereo remix was by
no means a simple one, many tracks having to be potted for
just a bar or two. The 16 track master itself was derived from an earlier
16 (down to nine or ten tracks on the second in some cases) in order
to make spare tracks available for further overdubs. This did not make
the quad picture design any easier. For instance, the drums
had been mixed to stereo on the second generation 16 track which, owing
to SQ limitations, had to be spread from left to front right, leaving
bass drum and snare center front and tom toms spread in stereo across
the front of the room. The bass guitar also had to remain center front
for the sake of the SQ, but this was no great problem as bass frequencies
have little directional characteristics and the harmonics and attack
of the instrument are not particularly strong here. Guitar was placed
rear left and the electric piano rear right.
The reverberation system used throughout the quad reduction was two
EMT reverb plates: one was spread across the front channels and one
across the rear both fed from the same source. This gave a very
full inside the chamber effect and helped to minimize the
hole in the middle of the room caused by the absence of
direct sounds there.
piano on The Great Gig in the Sky is a natural quad recording
made in Abbey Road Studio One (while bass and drums were playing simultaneously
in Two) using two distant microphones for back channel reverberation.
The four tracks were simply combined for the stereo version.
In Time the roto-toms (tom-toms tuned by rotating drums on a
pivot to stretch the head) were spread across the back channels while
most of the remaining instruments were distributed across the front.
The recording technique and studio layout for the basic backing tracks
were nothing especially unusual except that maximum possible separation
was attempted. Poor separation for a quad remix of this type could
probe very disturbing. This was no problem in most cases, as many instruments
were overdubbed rather than laid down on the basic track. The Kepex
system was used as a noise gate on all the 16 tracks for the reduction,
and also in the earlier stages to improve separation between individual
drums on the basic recording. Further use of Kepex enabled decay times
of various tracks to be altered; the heartbeat on the introduction
to the album was, in fact, a Kepexed bass drum.
The positioning for quad remix was effected by means of an external
insertion unit containing sixteen dual-concentric pan pots (front to
back and left to right). These were then fed into channel faders on
the mixing console in the normal way. Any movement or panning was arranged
by patching in external joystick panpots to the appropriate tracks
and then again returned to channel faders.
and Them is probably the most involved piece of quad technique
on the album. On the stereo version a vocal line is repeated by means
of a very long tape echo which moves from the left towards the right
on each successive repeat. In order to achieve an interesting effect
in quad, each repeat was returned to a different channel which entailed
using a different tape system for each repeat rather than recycling
one signal back through the same system, as one would for a normal
tape echo or digital loop. In order to do this a hookup had to be arranged,
with an eight track machine as in fig. 3.
It will be noted that each repeat
involves two record-replay stages. This was necessary to attain the
length of delay needed for the piece and in fact to
the delay still further the tape speed of the machine was lowered.
By the time the fourth repeat had arrived about four seconds after
the original signal it had passed through eight stages of tape, so
machine and Dolby line up were extremely critical. This caused troubles:
originally, the record/replay equalization was accurately set, as usual,
but the relatively slight speed deviation meant that, at the changed
speed, slight top lift occurred. After eight repetitions this became
rather unusable. It will also be noticed that the repeat from track
eight is fed back into the record stage of track one so that a further
cycle takes place. Thus: fifth repeat returns left front, sixth right
front and so on. The result is a round-and-round-the-room effect. The
system is operated below unity gain however, and the sixth and seventh
repeats are barely audible.
A similar type of delay is used in Any Color You Like on synthesizers.
Richard Wright, when overdubbing on to the section, heard the tape
repeat in earphones, and played in such a way that the result was canonic.
Owing to the sheer complexity of some of the procedures involved in
the recording of Dark Side, many of the sounds would be impossible
to reproduce live, even with the most involved equipment. It is for
this reason that Pink Floyd use a number of prerecorded tapes, reproduced
in quad on a Teac four track machine, for their concert programs. The
tape is operated at the mixing desk which is situated within the hall
in the audience area. One unusual point about the quadraphonic layout
for Floyd concerts can be seen in fig. 4. Rather than use a conventional
double stereo set up, ie front left, right front, left back and right
back, the whole system is rotated 45º. This has many advantages over
a normal system.
The main stereo pa is extremely large and powerful (approve 8 kW).
To set up an equally powerful system at the rear corners of a concert
hall would be a mammoth task, and very impractical. Even with the layout
shown, road crews have a hard time humping huge cabinets to the sides
and back of the hall, especially when the auditorium is on several
levels. This involves speaker stacks on every level together with their
associated cables, which have to be kept out of the way of the audience.
It has been found very effective to have the quad output stacks on
a level somewhat above that of the stage, especially since the system
is used frequently to simulate movement.
This applies more especially to the stack behind the stage, of course,
which in most cases would be drowned by the more powerful independent
stereo stage pa. The stage quad stack also serves as an aural cue to
the band, who might otherwise find it difficult to hear the other quad
channels, which could literally be hundreds of feet away from the stage.
Any attempt to duplicate the quad picture from the recorded version
would be disastrous. The delay from front to back in a large hall could
be as much as half a second, and in tight rhythmic sections this would
be very unpleasant to listen to, quite apart from the band finding
timekeeping very difficult with their own sound coming back at them
from al directions with various erratic degrees of delay.
the quad system for a live hall has to be used in a rather subtle manner,
the aim being in this case to add impact at relevant points in the
piece being performed. In the long introduction to Dark Side,
the heart beat fades on slowly as the house lights dim and synthesizers
and voices swirl around the hall. In one of the Floyds old favorites
the effect is slightly less subtle: in Careful With That Axe Eugene the
quad carries no sound at all until the famous horrific scream at which
every amplifier and speaker is driven to its absolute maximum, accompanied
by an explosion of flash powder behind the stage.
Any individual instrument carrying a microphone to the mixing console
can be individually switched into the quad system. This is used to
the most advantage on quiet passages where the main stereo pa can be
virtually shut down and the maximum use made of quad pan pots for movement.
With domestic quadraphonic systems, seating position is very important.
In a concert hall, however, this is not as critical owing to the greater
distances involved between channels. It is an unfortunate fact, however,
that some unlucky concert goers have to sit directly underneath a quad
stack and get themselves deafened which is as good a reason
as any for not using the quad too much throughout the concert. In the
film Earthquake the noise issues from huge cabinets at both ends of
the theater, and the author was unlucky enough to find himself sitting
near one of the rear stacks at a showing in the West End.
Pink Floyd have recently used back projected film behind the stage
with a 35 mm four channel sound track. This has proved very successful
but problems do arise with run-up-times of up to ten seconds when attempting
to bring in a sound on a musical cue. Film and multichannel sound are
now commonplace of course, as in the new Ken Russell picture of Tommy and
its use of a quintophonic system doubtless an
indication of things to come.
Sound at the Stereo Society:
Surround Sound, an Introduction
by Mike Thorne.
Where are we now?
and Music (1974)
by Mike Thorne.
Originally published in Hi-Fi News and Record Review Annual, UK, 1974
About the musical
possibilities of quadraphonic surround sound, and some speculation about
potential future developments. The ideas still apply in today's 5.1
surround sound environment.
by Paul Myers (Director, CBS International
Masterwork) and Bob Auger (Bob Auger Associates).
Originally published in Studio Sound, UK, June 1975.
In fall 1974, in one of the most complex sessions London has seen, Gurrelieder was recorded by CBS for stereo and eventual quadraphonic release. The musical,
production and engineering background is covered, from both stereo and quadraphonic
To Four Sides
of the Moon
by Alan Parsons.
Originally published in Studio Sound, UK, June 1975.
Pink Floyd were among the earliest innovators to use four channel sound, and
Dark Side of the Moon has won many awards, including several for sound
engineering. The author, who engineered these and many other sessions for
the band, discusses the quadraphonic record production, and contrasts it with
the presentation of multichannel sound on stage.
To the Production
of Quadrafile (2001)
by Mike Thorne.
Four sides and four quadraphonic systems, this double album released in 1975
had identical musical sides which differed only in their quadraphonic surround
system. The music varied from Pink Floyd's Money to a special remix
of parts of Tubular Bells. It sounded really good, but then quad
went and died on us.