What is stereo?

There are now two system of high fidelity, monophonic (monaural) and stereophonic. Monophonic is a system that starts from one microphone and is fed through a single high fidelity set. Stereophonic is a double system. Two separate microphones are placed at different sides of the orchestra and two different systems are used to keep the two signals or channels separated. Two separate speakers are used, placed on different sides of you room. Stereo is much like 3-D photography, two slightly different sound reach your ears giving you a new dimension in sound.

H.H. Scott '59

Pioneer QX-747 (1974)

Pioneer has studied the problem of quadraphonic receivers with the aim of enabling you to play every four channel program source a available today - and tomorrow, and they have succeeded, it's all four channel in four different ways.

The Latest CD-4 Demodulator

Playing CD-4 records with full fidelity and space expanding four channel realism is easy with the Pioneer QX-747. They have a built-in CD-4 demodulator of the latest design, clear sound localisation in the four channels is achieved by simple manipulation of CD-4 separation controls.

SQ Full Logic Matrix Decoder

Newly developed integrated circuits for the matrix logic and gain control section of this advanced full logic SQ decoder help to obtain the very best separation between the front and rear, as well as the left and right channels, essential for the true to life reproduction of sound field when you play an SQ encoded four channel record throught either the Pioneer QX-747 .

Regular Matrix (RM) Decoder

The RM position on the four channel mode selector of both Pioneer QX-747 is to be used when you play any matrix four channel record other than SQ or wish to synthesise four channel stereo from a normal stereo disc.

Other Four Channel Features:

A 4 CH-MPX out terminal is located on the back panel enabling you to hook up an FM four channel adaptor to receive FM discrete four channel broadcast when they become available in the future.

A four channel level indicator

All The Power You Need For A BIg Four Channel Sound

QX-747 A produces 20 watts per channel at 8 ohms (four channels driven) 20 Hz to 20 kHz with a total harmonic distortion of 0,5%

Specifications QX-747 A

Audio Section

Continuous power:

4 x 30 W; 2 x 55 W (1 kHz, 4Ω)

4 x 25 W; 2 x 45 W (1 kHz, 8Ω)

4 x 20 W; 2 x 40 W (20 - 20,000 Hz, 8Ω)

45 W/ 4-ch.; 65 W/2-ch. (each channel driven DIN 1kHz, 4Ω)

THD at rated output power 1 kHz, 8Ω (IHF): <0,5%;

THD at 4 x 50 mW, 8Ω, 1 kHz (DIN): <0,2%

Power bandwidth 4 channels driven: 7 Hz - 40 kHz

Frequency response at AUX input DIN: 10 Hz - 25 kHz (+0,5 dB, -1 dB)

Input sensitivity impedance:

Phono: 2,2 mV/50 kΩ

Tape monitor, Tuner, Aux: 140 mV/100 kΩ

Bass control (100 Hz): ±10 dB

Treble control (10 kHz): ±10 dB

CD-4 Demodulator Section

Input sensitivity: 2,5 mV

Input impedance: 100 kΩ

Distortion: 0,07%

Signal-to-noise ratio: >70 dB

Separation 1 kHz: 50 dB (left to right); 30 dB (front to rear)

Frequency response: 20 Hz - 15 kHz

FM Section (87,5 to 108 Hz)


IHF: 10,8 dBf

DIN (26 dB S/N ratio, 40 kHz dev.): 1,3 μV

Capture ratio: 1 dB

Selectivity (±400 kHz): 60 dB

S/N ratio (mono): 70 dB

Image rejection: >80 dB

THD (stereo) 1kHz: <0,4%

Stereo separation 1 kHz (DIN): >40 dB

Subcarrier suppression: 65 dB

MW Section (525 - 1605 kHz)

Sensitivity (IHF): 15 μV/m

Image rejection: >45 dB

IF rejection: >55 dB

S/N ratio: 50 dB

Power consumption: 340 W

Dimensions (W x H x D): 550 x 160 x 420 mm

Weight: 19,1 kg

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