Pioneer qx 747 brochure

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pioneer qx 747 brochure

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rlx-747 BUILT.IN CD-4 DEMODULATOR Because the discrete four-channel disc (CD-4), unlike other matrix four-channel discs, employs a special modulation technique for engraving four-channel signal information onto one disc groove, a special demodulator is necessary to achieve perfect four-channel performance from these discs. The QX-747 has this special demodulator built-in. This demo- dulator section employs an advanced circuit technology for stability and reliability, including PLL lC and FETs. lt is not an "extra" piece of equipment adding to the cost of your four-channel investment. Playing CD-4 records with the QX-747 is accomplished with ease. Clear sound localization, one of the major virtues of CD-4, is achieved by simple manipulation of the separation controls and carrier level control by the use of the CD-4 test record that is included without cost with each receiver. These adjustments may be observed on the striking four-channel level indicator, another feature that is new and exclusive with the QX-747. REGULAR MATRIX AND SQ MATRIX DECODERS BUILT.IN The two other prominent four-channel systems for matrix decoding are also built-in to the QX-747 -regular matrix and SQ matrix. This means that this new Pioneer receiver gives you a choice of all the important four-channel program sources, and has all the important four-channel circuitry built-in. The regular matrix position can be used to reproduce the majority of four-channel discs now available, and is equally effective in achieving excellent four-channel sound effects from your conventional two-channel discs or tapes. The SQ matrix posi- tion is used for ex- clusive playback of all SQ encoded pro- gram sources. (1) SOPHISTICATED FM FRONT END The important FM front end of the QX-747 contains a dual- gate MOS type FET (fietO Effect Transistor) and a frequency linear four-gang variable capacitor. These solid state devices contribute immensely to the unit's high sensitivity of 1.9,tV (lHF), its more than 80dB image rejection, and more than 100d8 spurious rejection. FM reception at all times is both stable and sensitive, attesting to the precision manufacture.-., of the QX-747. (2) F|VE-STAGE LTMTTER rN THE FM rF SECTTON The lC used in the QX-747's FM lF section is exclusive, designed to improve the lF performance characteristics. The limiter stage gives a capture ratio of 1dB (lHF), signal-to- noise ratio of 70dB and AM suppression of 55d8. The linearity of the detector circuit is most important for sound quality. ln the QX-747 a quadrature detector circuit is employed for excellent linearity and low-distortion characteristics. (g) EXCCLLENT PHASE LINEARITY AND HIGH SELECTIVITY So that inferior phase characteristics will not adversely influence sound quality, Pioneer has used "phase-linear" ceramic filters in the FM lF section. Two ceramic filters, each with two elements, are employed to improve the unit's selec- tivity characteristics more than 60dB (lHF) while suppressing distortion. (4) HIGH.PERFORMANCE MPX IC The double-balanced differential demodulator circuit used by Pioneer in the QX-747 remarkably improves MPX performance. Separation is wide, more than 40dB at 1KHz, and more than 30dB within 50 to 10,000H2. Additionally, this type of MPX circuit is not influenced by SCA beat interruption. The sharp low-pass filter employed in this section suppresses carrier leakage to a minimum. (5) EFFECTIVE FM MUTING SWITCH The QX-747 is equipped with an FM muting switch withou--., 5- AM/FM STEREO TUNER SECTION

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noise and also suppresses undesirable inter-station noise when stations are tuned. This device also eliminates the annoying pop noise that often occurs when stations are tuned on or off. (C) IIruENR FM DIAL SCALE AND TUNING METER The FM dial scale of the QX-747 is the extra-wide linear type that facilitates easy and precise tuning of your favorite FM stations. The unit also features a dual-purpose tuning meter that acts as the center-tuning meter for FM as well as the siqnal strenqth meter for AM recention (Z) OUTSTANDING AM SECTION AM tuner reception is nearly the equal of FM reception in terms of tonal quality. An AM lC combined with ceramic filters ensures fine AM sound. AMPLIFIER SECTION (1) DIRECT-COUPLED OCL POWER AMPLIFIER The power amplifier stage of the QX-747 is equipped with two separate DC power supplies and also features an all- stage direct-coupled OCL circuit. The use of the direct- coupling design means that coupling capacitors are elimi- nated between individual stages; it also results in a super wide frequency response curve ranging from near DC to well ... _.eyond the audible sound range. The entire power bandwidth from 7 to 40,000H2 (8 ohms, four-channels driven), is charac- terized by harmonic distortion of 0.5o/o. And in terms of power, the QX-747 produces 20W x4 of continuous RMS power (8 ohms, four-channels driven, H.D. 0.5%), the minimum guaranteed figure within the 20 to 20,000H2 range. The 20 to 20,000H2 sound range, of course, is the most critical of all the specifications, since it is only within this range that the human ears are capable of hearing. lt is by far the best evaluation of a receiver or amplifier's true performance. (2) UNIOUE POWER BOOSTING CIRCUIT When used in the four-channel mode, the QX-747 delivers 20W x4 of continuous RMS power. But when you choose to use it to play conventional two-chan- nel sources, the unit's special "Power Boosting Circuit" con- :rts this four-channel power -) even greater two-channel power- up to 40W x 2 of continuous RMS power. This power conversion can be done by changing the 2-CH/4-CH selector plug on the rear panel. This circuit device employs a micro power switch so that conversion can be accomplished even when the amplifier's power is turned on. Moreover, since this "Power Boosting Circuit" is not a BTL type, it is thus free from the BTL circuit's drawbacks, as the PBC does not employ the complicated circuitry of the BTL amplifiers. The QX-747 assures stable performance in both the two-channel or four-channel mode. (g) AOVNNCED PROTECTION CIRCUIT The power amplifier section of the QX-747 includes an automat- ic protection circuit to protectyour speak- ers and valuable pow- er transistors from potential DC shock. This protection circuit also acts as a muting circuit to eliminate the irritating pop- noise that often occurs when you turn the power switch on. (4) TOTAL 30,000pF ELECTROLYTIC CAPACITORS The power supply section of the QX-747 employs large elec- trolytic capacitors to reproduce the extremely low-sound range with stability at high output power levels. These capa- citors are the 15,000pF x 2 (total 30,000pF) types chosen for their extra power margin and for dynamic sound reproduction over the entire sound range. (S) NTE (NEGATIVE FEEDBACK) TYPE TONE CONTROLS WITH CLICK.STOPS Bass and Treble tonal adjustment in the QX-747 may be independently applied to both front and rear channels. These NFB (Negative Feedback) type controls operate with meas- ured click-stops to offer accurate tonal adjustment. OTHER QX.747 FEATURES (1) FOUR.CHANNEL LEVEL INDICATOR A unique four-channel level indicator is employed on the front panel of the QX-747 to permit you to observe the output levet of each of the four-channels appearing on the viewing screen. The level of each channel may be adjusted by using the level controls provided near the indicator. You will find the indicator to be valuable for all channel level adjustments. CD-4 sepa- ration adjustment, for example, is easily achieved by viewing the screen, which is also a beautiful display device. lndication level (sensitivity) of the indicator can be set to OdB (normal), -10d8, -20d8, -30d8, according to the volume level and the balance of each of the four-channels. (2) REAR SPEAKER SELECTION You can connect up to three pairs of speaker systems with the QX-747, one for the front channels and two for the rear channels. This versatility gives you the choice of either A