DISCRETE FOUR-CHANNEL STEREO This is the most authentic system of four-channel stereo, since the original four-channel signals are transmitted in four independent ways and will pass through four independent amplifiers to drive four speakers Four-channel tapes (open reel and cartridge) are (he most popular program sources of discrete four-channel now on the market. and these sources .ire distinguished by a distinctive separation of sound among four independent channels The discrete CD-4 discs were marketed froth the midclfe of 1972 However. to hear discrete four-channel reproduction requires the use of a four-channel tape deck (for discrete tapes) and a CD-4 disc demodulator Ito! discrete discs). in addition to a four-channel amplifier or receiver and four seers At present. discrete FM broad casts are still pendingt in the United States. although there have been some experuitental broadcasts DISCRETE FOUR-CHANNEL DISC • The CD-4 disc. is a unique four-channel discrete record that has compatibility with both mono or stereo records. In the CD-4 disc four independent signals are recorded by using special modulation techniques The disc maintains the con ventional 45"/45 record groove. but on the Inger groove wall the lett channel sum signals (channel 1+ channel 2) are engraved while on, the outer wall the right channel sum signals (channel 3+ channel,4l are engraved. in much the same way as conventional two-channel stereo records. These signals can be heard directly when they, pass through con ventional two-channel equipment However, on the CD-4 disc. real channel signals are also engraved on the two disc groove walls as differential signals (channel 1 channel 2) as well as (channel:3 channel 41 These differential signals are carried by the inaudible subcarrier in the sound ranges from . 2oKHz to 45KHz in the form of modulated signals These signals with extended frecluency response in the high ranges. cannot be heard directly, and this IS the reason why a CD-4 demodulator and special phono cartridge are necessary to play CD-4 records. The differential signals are demodulated by the demodulator. and when we matrix the sum signals and demodulated differential signals. we obtain four inde pendent signals, as indicated in this diagram. QUAD RECORDS F l it& NOW! POSITIONING SPEAKER SYSTEMS This is a-very important aspect of the entire new format. Speaker positioning can do much to determine just how you can e.,noi your new%ystern 20 maximum advantage Here are four different POssitiihties 2-2 system 2.2 System Regular 4 corner position Front .2 system: Best for symphon widely accepted as "standard" Most res. operas. chamber music and big effective for listening to mood music, band jazz rhythm and blues. vocal numbers and "recorded live" records. Note: Whatever your preference, better effect can be obtained by &ono the front two speaker systems on the floor :tightly m from the extreme left and right corners of the room, and by elevating the rear systems about three feet off the floor E=III Front 2-2 system ch 1 • Ch 2 Ch I•Ch 21 - ten I - 211 = 2 Ch 3•Ch 4 area S'gnal‘- liCh 3 • Ch 4) • (Ch 3 - Ch 411= Ch 3 co 1 - Ch 2 I Modulated Storm , . +IlCh 3 + Ch 41 - ICh 3 - Ch 411= Ch 4 Ch 3 - Ch 4 REGULAR MATRIX FOUR-CHANNEL STEREO The most reasonable and inexpensive system of four-channel stereo is called-regular matrix. in which the original tour channel signals are converted into conventional two-channel signals and then played back again in four-channel For reproduction of this system, your present turntable or tuner or tape deck is suitable for sound transmission. What will be required is a four-channel amplifier or receiver with built-in regular matrix decoder and another two speakers for the rear channels With the regular matrix decoder, converted two-channel signals are decoded back into the proper four channel by a decoder that recreates the original four-channel stereo sound field. It is even possible. with quality regular matrix decoding equipment. to achieve certain four-channel sound effects from conventional two-channel tapes and discs. iiiiMi SO MATRIX FOUR-CHANNEL STEREO The one matrix four-channel system' that has no cornpapthty with any of the others is called the SO 'system Since its matrix encoding/decoding principle is quite. different from other regular matrix systems. a special SO decoder is re quired in order to reproduce an SO disc or an FM broadcast utilizing an SO disc Pioneer's four-channel receivers are equipped with this SQ decoding circuit as well as regular _ matrix decoding circuit. , - ,'''' , :--: -, ;•As, ...,_____., ::, 1 7" ...,,,,, i .. LED ®, II • • '-' , t i i l L"I sTO CM LEM • • 1 -- ~] , _____l cam ' --. 7' i , 2-2/Front 2-2 compatible systems 1"I Front 1211\1 li> Rear (A) 1 4 ':iVRectri61 Ideal Posrtronong Method In vn've rt , /. use Of shr , veaker 4•t you ceoord the regtaar 2 or . ruirt 2 2 system by the ,trllol4, of the rear Speakers Sear, h 45• . e..\\N ,‘‘ Outer Wall 7 ......... - - ......N lA \c Ch iSul 4111 .. I • ' MHZ 301012 45rir12. \,..,..,,.......2...._71-12 r 3 Cr,. ll The first is called discrete four-channel stereo (4-ch. tape, CD-4 disc). the second is the regular matrix system, and third is the SQ matrix system. In discrete four-channel, the original , four-channel signals are transmitted by four independent sound sources, say four tracks of a tape, and four indepen dent playback amplifiers. In the CD-4 disc, four independent signals are recorded by using special modulation techniques. The regular matrix system uses four signals recorded% the form of four-channel stereo and then fad through a 'special encoder to be converted into two-el - fennel signals. When you playback these signals through the decoding circuitry of four-channel equipment ,the record - originates" its original tour-channel sound field This system is called the matrix, or 4-2-4 system, and, when used, does not require a special tape deck or demodulator as is the case of discrete stereo. The SQ matrix system is also a 4-2-4 system, although its encoding/decoding function is much different than the regu lar matrix system. To play SQ records requires a special SO decoder. . P m i Front P .I \,I listening Area ‘ 17 ...11. 4>Rear 2.2 Front 2.2 Cornp3lstde FosMon log Method Vnth th e . .",., Ith , Co.l, fee rt• rt• oU • •I ropy both the r .II the Froot 2 2 • v , ;er , D v point A to oolot Four-channel stereo is an impressive, effective way to re create the original sound field of a concert hall right in your own home listening room. Better yet. it makes possible a new sound of music that cannot be obtained from conventional two-channel stereo. There are many different types of four-channel stereo systems novit' available. although they can be clasqlhed into three categories.
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