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Tell me about QS regular matrix system in laymaup terms.

We'll try to make it as non-technical as possible. First, the name QS regular matrix system is a name given to a comprehensive system of encoding all of the original sound field information to 2-channel, and then decoding those 2-channel signals to four signals for reprodution from four speakers in a listener's room. In short, it consists of an encoder and a decoder.

The QS vario matrix circuit, in contrast, is a new technique we've developed for the decoder. It improves the inter-channel separation of reproduced 4-channel sound, with, if we may say so, revolutionary results. Now, let's take the circuit elements one by one.

Fig-2 is the basic QS decorder, or rather, a block diagram of it. What it does is exactly the opposite of encoding ..... for it unscrables the left-total and right-total signals back into the original four signals.
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Any matrix encoder that encodes four signals into two must encode the two rear (back) signals in reverse phase (i.e., 180 degees out of phase with each other). However, if we fed these two encoded signals to a decoder, the two rear speakers would be in reverse phase also, creating undersirable results.
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To see the compatibility of the QS regualr matrix 4-channel system with regular 2-channel stereo playback, let's examine how 4-channel signals are positioned in 2-channel playback.

We saw in the preceding discussion of the stylus tip movements that the cutting system for QS 4-channel stereo is compatible with the cutting system for the conventional stereo disc. That is, you can play a QS-encoded 4-channel disc via an ordinary 2-channel stereo system for ordinary stereo reproduction. In this case, all 4-channel signals are perfectly reproduced, as you can see in Fig. 5. The signals which would be positioned in the back of the reproduced 4-channel sound field will then spread outside of the left and right stereo speakers. This creates a rich sense of stereo perspective, more so than the conventional stereo disc. It also adds a great sense of pressence.

Now, let's return to the main theory of the QS regular matrix system with QS vario matrix circuit. Let us first suppose that a sound is generated at left front, and that the resultant signal is encoded through the QS encoder. If we used the basic QS decoder to reproduce that signal, part of the signal will leak out to the two adjacent channels. The sound pressure response diagram in Fig-6 shows this situation. In a matrix 4-channel system, the position of each signal is thus always established by the interrelationship of three speakers. This sound pressure response pattern is true for signals at all positions in the original 360-degree sound field.

Fig-7 shows for comparison purpose, the sound pressure response pattern for the same left front signal as achived by discrete 4-channel tape recording.

Could you explain about the new QS vario matrix in more detail? How it works, what it actually does and so forth?

Yes. First of all, let me make the following points very clear.
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• (1) The QS vario matrix circuit is a technique to improve the decoding effectiveness of the QS regular matrix system. It does not change the system itself, and the QS encoder remains unchanged.
• (2) When we say it improves the decoding effectiveness, we mean that it does away with the classic drawback of matrix 4-channel systems - i.e., insufficient inter-channel separation.
• (3) The QS vario matrix circuit reduces the interchannel crosstalk by automatically controlling the matrix parameter, but does not tamper with the amplitude gain in each channel at all. It is in this respect that it differs entirely from the so-called gain control logic decoders. What this means is that, if a separate, independent signal existed simultaneously in a channel where the crosstalk from the main channel if appearing, that signal would not be cancelled but would be reproduced in full.
• (4) For this reason, we believe the QS vario matrix to be a most effective decoding technique, totally retaining the musical qualities of the program source.
• (5) Thex cost of the QS vario matrix circuit is inexpensive. It is expected that it will be made into an integrated circuit (IC) in the near future; it will then cost less and become smaller in size.

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Fig. 9 shows the actual control of the sound pressure response curve. In this illustration, it is assumed that we want to reduce the 0.7 crosstalk of the LF signal appearing in the RF and LB channels to, say, 0.2.

We can do this by changing the matrix parameter instantaneously so that we derive the RF' and LB' signals from two points close to the RB' position where there is no crosstalk whatsoever from the LF signal. These two points, for instance, can be located where the two dotted lines join the circle shown in Fig-9. The function of the QS vario matrix circuit is to do this task automatically according to each input signal.

Fig. 10 shows the operation of QS vario matrix circuit against simultaneous multiple input signals.

Actually, the QS vario matrix operates in much the same manner. But if these multiple input signals were of different levels and directionalities - as the signals A, B, and C are in Fig. 10 - then the directionalities of the weaker signals - B and C - would be somewhat obscured ..... at least in terms of physical measurements.
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It was said that the QS vario matrix is a technique to cancel the inter-channel crosstalk without altering the gain in each channel. This, I understand, is the theory of directional masking. What is directional masking?

As stated in the preceding discussion pertaining to Fig. 10, when a number of signals enter the decorder simultaneously (which is the case in music), the QS vario matrix controls the matrix in such a way as to accentuate the directionality of the louder signal (and thereby create greater inter-channel separation). But in the process, it would somewhat obscure the directionalities of the weaker signals.
However, the human ear does not sense this obscuring of the directionalities of the weaker sign is.

This is because, when a number of sounds arrive at our ears simultaneously from different directions, our sense of hearing is momentarily fixed on the loudest of these sounds. And it is insensitive to the directions from which the weaker sounds come. In the terminology of psycho-acoustics, this phenomenon is called directional masking. Thus, to our ears, the 4-channel sound field reproduced by the QS vario matrix circuit sounds almost identical to the original, live, multi-dimensional sound field.
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Electonically, speaking, how is the QS vario matrix circuit constructed?

I understand the QS vario-matrix circuitry synthesizes regular 2-channel recordings with startling effect. Coult you expalin why and how it is so?

The availiability of 4-channel stereo sources is expanding rapidly, but is still rather limited both in qunatity and variety as compared to conventional stereo sources (records, tapes, etc.). It therefore is to the immense advantage of music fans to be able to transform these popular stereo sources into 4-channel sound. Today.

From the beginning, Sansui's QS 4-channel decoders and this 'synthesizing' capability. But now, with the invention of the QS vario matrix technique and the addition of a supplementary circuit called 2-4 Synthesizer Encoder, it is far more effective.

Actually, the new synthesizer offers two 4-channel effect - surround and hall.
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1. Surround: As the name suggests, the sound surrounds the listener to make him feel as if he were participating in the performance. This mode ideal for rock and pop music.
2. Hall: Again as the name suggests, the acoustic effect of a concert hall is closely simulated in this mode, with the stage in front of the listener and the ambience around him. Many listeners prefer Hall for classic music, big band jazz and live recordings.

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Fig. 13 shows the relationship between the standard 2-channel stereo perspective and a 4-channel sound field.

This diagram shows where the various positions of the line between the left and right stereo speakers are located in the "synthesizea" 4-channel sound field when a 2-channel stereo record is converted to 4-channel by the QS Synthesizer.

The upper curve represents the original 2-channel stereo perspective. The line below it shows the adjusted perspective ..... as expanded by the new 2-4 Synthesizer Encoder. As you can see, the entire line is stretched and bent to create a 4-channel sound field.

Why & how does the QS vario-matrix decode SQ records without infringing upon original SQ decoding technology?

SANSUI ELECTRIC CO., LTD. 14-1, 2-CHOME, IZUMI, SUGINAMI-KU, TOKYO 168, JAPAN/TELEPHONE: 323-1111/TELEX: 232-2076
SANSUI ELECTRONICS CORPORATION 55-11 QUEENS BLVD. WOODSIDE, NEW YORK 11377, U.S.A./TELEX: NEW YORK 422633 SEC Ul
SANSUI AUDIO EUROPE S.A. DIACEM BUILDING, VESTLNGSTRAAT 53-55, 2000 ANTWERP, BELGIUM/TELEX: ANTWERP 33538

• Anmerkung : Ich glaube, da ist heute niemand mehr, um Ihre Fragen zu beantworten. Sparen Sie das Geld für gute Musik.

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