Please see the Post above for the
DISCRETE article.
MATRIX:
Note; There was a subscription card that blocked the last sentence of the “Editor’s Note.” The beginning of the “Matrix” article on Page 3 was covered by the card. The beginning of the “Discrete” article from Page 3 was partially recovered, but with some incomplete sentence between these two symbols: [ ].
A quick proofread of the two articles was performed, and I did go word by word. But, there’s bound to be mistakes. The original article scans are not the best. But, it’s a fascinating read about the state of Quad and Quad radio in 1978.
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January 7, 1978
FCC's 'Q' Dilemma
EDITOR'S NOTE: As the FCCS Jan. 30 deadline approaches to hear arguments for and against quad discrete and matrix broadcasting systems, the conflict between the different systems has moved out of the laboratory and into the public anca. In a move to provide a plusform for both sides before the government decides which quad system will become the standard, Billboard offers viewpoints on ma-
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MATRIX
Continued from page 3
But first, if you are not now a quadraphile, permit me to explain what l assume that you will want Q sound in the future. With Q sound for the first time you will be able to reproduce music as it is heard in the orchestral stage in front with surrounding ambience, or the enveloping reverberation in a cathedral or even an avant-garde rock performance played through individual loudspeakers spaced around You.
These are real live sounds and we know from experience that the most realistic the most natural, sound reproduction ultimately wins out. Harry Maynard, the noted writer and radio commentator on hi fi, tells us that 95% of Q listeners who write him on "the pros and cons of living with quadraphonic sound" say they will never go back to stereo.
Furthermore, I have noted the way you have been buying equipment in attempt to approach spatial realism-like stereo loudspeakers which bounce sounds off the walls and delay lines feeding rear loudspeakers to simulate concert hall reverberation--all producing only an imitation of the real Q sound. I am convinced that eventually you will want the real thing. A single standard is needed to reestablish confidence and the vigorous growth of 4-channel sound.
And, not only should such a standard offer the best system to be heard, but it must be a single inventory standard, also satisfying all stereo and mono listeners.
As I shall prove to you, only SQ has the ingredients for such a standard. There is an important factor that most people don't realize: every discrete 4-channel program- even one which starts as a 4-channel tape-must be matrixed into 2-channels prior to broadcasting or recording on a disk This combined sound is what the stereo and mono listeners hear. Upon reception by the 4-channel listener, the mainxed program is converted back to Q sound. The same, of course, is true of SQ starting with discrete 4-channels, the program is matrixed by a special encoder into SQs 2-channels ecording and broadcasting. Stereo and mono listeners hear this SQ program directly as regular stereo and mono. For Q listening the matrixed signals are changed back to 4-channels.
Now you may ask, "If both discrete and matrix are first matrixed to
2-channels and then converted back to four, what is the difference be tween the two svstems?
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Well, the conventional matrix used in "discrete" systems cannot be converted back to Q without the aid of two added auxiliary matrixed signals. These are inscribed in the form of ultrasonic modulations in a disk or in an FM broadcast are placed on added subcarriers. Upon replay or reception, these auxiliary signals are combined with the conventional matrix to produce Q sound.
By contrast, the SQ matrix encoded signals carry within them all the information needed to convert them back to Q sound. At the same time, these signals are excellent for stereo or mono. To convert the SO encoded signals back to Q sound, an SQ decoder is used containing a
"logic" which is able to "place" the encoded signals in their proper speaker or speakers.
Therefore, an SQ record or broadcast serves both as a conventional stereo program and with the aid of a decoder, a Q program. Perhaps the next question then is, "If a matrix must be used with either discrete or SQ, which of these do listeners prefer?”
Until recently, no one could prove this one way or another. We said "ours" and they said "theirs." But now, at last, a competent government authonty -the FCC Laboratory has compared them and extensively tested them and made its pronouncement. In one test phase, the FCC compared the ideal discrete not a discrete record or broadcast, mind you, but a 1-inch, 4-channel 15 ips, master tape, no less. (which they called 4-4-4) against SQ, the H of BBC, and the QS of Sansui, all four matrixed to stereo, using the most thorough, totally anonymous identically administered,
"A-H” musical preference test. And what was its verdict?
SQ was preferred for stereo listening over all others, in this order, SQ,
4-4-4, H, QS.
"But, what about me?" you ask. “I have a mono FM in my car and my portable FM set is mono also. Which system will work best for me?
The FCC also was interested in this question. It connected the above stereo outputs to a single loudspeaker. The result? Identical to that given above SQ, 4-4-4, H, QS.
"Granted," yoU say, "but, how
about 4-channel performance?”
Surely the pure discrete is best?” Well, the fact is that at this point no one can prove this one way or another. The FCC did not perform a Q test of an SQ record versus a CD-4 discrete record or an SO broadcast versus a discrete broadcast.
What it did was compare the output of a 1/2 inch, 25 i.p.s. 4-channel master tape against an encoded/decoded output of three matrix-with logic systems - SO, H and QS. A "4-3-4" matrix (without logic) system, furnished by RCA, also was tested.
Naturally, the source master was preferred to every encoded/decoded system, but its margin of preference over SQ was, in the FCC’s very own words,
“very slight”
52% : 48%. Startling, however, was the comparison of SQ against all the other matrix systems.
Prefer SQ
58%
62%
77%
Prefer Other System
42% (BBC H)
38% (RCA 4-3-4)
23% (Sansui QS)
Thas, ladies and gentlemen of the jury, your choice is clear. For the stereo and mono audience no other system is as good as SQ, which, in turn, according to the FCC, is also the closest to the master tape in 4-channel performance of all the systems tested. And what additional expense does the broadcaster have to go to broadcast SQ? Nothing.
The SQ record simply takes the place of the stereo record. There are no changes needed in the pickup, the turntable, the audio console, the studio/transmitter link, or the transmitter, itself. And, by adding an SQ encoder, the broadcaster can convert his entire existing stereo record library to quad.
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The author is vice president, general manager of the CBS Technologs Center.
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The home listener can readily convert his stereo receiver to Q by adding a decoder and two amplifiers and loudspeakers, and he can use the same decoder to either reproduce his SQ records in the surround sound mode or Q enhance his home library. But. - suppose, instead, that the FCC opts for the discrete system. All the simplicity of SQ goes out the window. The broadcaster now must buy a 4-channel tape player or a special pickup for playing CD-4 records followed by a CD-4 demodulator.
And since the vast majority of Q records available are SQ records, he also must buy an SQ decoder to use decoded SO as a source of discrete broadcasts. Then he finds he needs a new 4-channel console, plus a 4-channel link from the studio to the transmitter, (Four 15 kHz matched phone lines? 4-channel microwave link? No one knows). Next, a new exciter for the transmitter. And what about the SCA? It becomes obsolete, or it has to be moved to a higher frequency, which means changing all the SCA receivers. The total cost? Somewhere around $20.000, perhaps more.
And what does the broadcaster get for this investment? According to the FCC tests, the stereo and mono listeners won't like the result as much as they like SQ. Furthermore, the mono signal in the outiying areas will suffer a signal-to-noise ratio loss of up to 4.7 dB, corresponding to a loss of coverage of 25%.
Then, the many listeners who already have SQ decoders will not receive the discrete broadcasts as Q programs. And, as to the prospective discrete listeners-what will they use? To date no receivers have been designed, and no conversion of existing stereo receivers to discrete Q is possible. And even when discrete receivers become available, they will still need added decoders to play Q records.
“I will grant you now that SQ is best of all the systems tested. But what about the 2% difference? If SQ is within 2% of the master tape quality, are you closing the door on perfection?” you say.
Happily, no. Let us assume that the FCC were to approve discrete broadcasting in the future. In that case, it will always be possible to design the transmitter exciter to simultaneously broadcast fully discretiable SQ, for continued superior reception by stereo, mono, or SO, equipped receiver, and, at the same time, to transmit auxiliary signals so that totally discrete reception with a specially designed receiver will also be possible.
