Pioneer QX-704

Commentary

A 4-channel receiver equipped with 3-way 4-channel playback function.

4 ch playback of 3 systems (CD-4, RM/SQ) is possible.
The CD-4 Demodulator is designed with consideration for frequency characteristics and separation by using PLL and FET. It also has an ASC circuit that automatically compensates for noise even in frequently used records to improve S/N. Separation and carrier level can be adjusted using the attached test record.
RM/SQ4ch playback has built-in decoders for efficient playback of RM/SQ records. In addition, 2 ch records, tapes, broadcasts, etc. can also be played through the matrix decoder to get a sense of presence.

The power amplifier section uses a pure complimentary service OCL circuit directly connected to all stages.

A 15,000 μ Fx2 power Fx2 power supply capacitor.

Equipped with a power boosting circuit, it is possible to enhance the output during 2 ch playback by switching the switch on the rear panel.
The ordinary BTL circuits, the circuit used in the QX 704 can be driven by a 4 Ω speaker.

The equalizer amplifier section is a 3-stage direct connection type.

The control amplifier is an NF type with a 3-chip configuration and has excellent control characteristics.
Front and rear can be adjusted independently of each other.

Equipped with a protective circuit that combines a power relay and an electronic circuit.
This circuit also functions as a power muting, and reduces shock noise when the power is turned on.

The front-end section of the FM tuner uses a frequency-linear 4-row varistor and a MOS FET. In addition, high-integration ICs for FM and the IF section of a 5-stage limiter that employs a phase-linear ceramic filter, a highly linear quadrature detection circuit, and ICs for FM MPX are used to improve the performance.
It also has an FM muting switch and a 4 ch MPX output terminal.

Equipped with a 4-channel level indicator that allows you to see the output level at a glance and allows you to accurately adjust the level during 4-channel playback.
The indicator sensitivity can be switched in 4 stages according to the volume level.

Model Rating

4-channel receiver
FM Tuner Section
Practical sensitivity (IHF)	1.9 μ V
Capture Ratio (IHF)	1dB
Effective selectivity (IHF)	60dB
S/N	70dB
Image Interference Ratio (82 MHz)	85 dB or more
IF Interference Ratio (78 MHz)	100 dB or more
Spurious interference ratio (82 MHz)	100 dB or more
AM suppression ratio	55dB
Harmonic distortion factor	Mono : not more than 0.2% Stereo : not more than 0.4%
Frequency characteristic	20 Hz to 15 kHz + 0.2 -2.0 dB 50 Hz to 10 kHz + 0. 2-0. 5 dB
Stereo separation	40 dB or More (1 kHz) 30 dB or More (50 Hz to 10 kHz)
Carrier leak suppression ratio	65dB
Antenna	300 ohm balanced 75 Ω Unbalanced Type
Muting	ON/OFF enabled
<AM Tuner Section>
Practical sensitivity (IHF)	15 μ V 300 μ V/m (bar antenna)
Selectivity	35dB
S/N	50dB
Image interference ratio	45 dB or more
IF interference ratio	55 dB or more
Antenna	Ferrite bar antenna
Power Amplifier Unit
Circuit system	Pure complimentary service OCL
Effective power	20 Hz to 20 kHz, 4-ch drive : 25Wx4 (4 Ω) 20Wx4 (8 Ω) 1 kHz, 4-ch drive : 30Wx4 (4 Ω) 25Wx4 (8 Ω) 1 kHz, 1 ch drive : 45W/45W/45W/45W / 45 w (4 Ω) 33W/33W/33W/33W / 33 w (8 Ω) 2 ch power boosting circuit time 20 Hz to 20 kHz, 2-ch drive : 50W + 50W (4 Ω) 40W + 40W (8 Ω) 1 kHz, 2-ch drive : 55W + 55W (4 Ω) 45W + 45W (8 Ω) 1 kHz, 1 ch drive : 65W/65W (4 Ω) 50W/50W (8 Ω)
Harmonic distortion factor	0.5% or Less (Effective Output) 0.05% or Less (at 1Wx4 Output)
Cross modulation distortion factor	0.5% or Less (Effective Output) 0.05% or Less (at 1Wx4 Output)
Output Bandwidth (IHF, 4-ch drive)	7 Hz ~ 40 kHz (Distortion Factor 0.5%)
Damping factor (1 kHz, 8 Ω)	35
Residual noise	1 mV or less
Input Sensitivity / Impedance	Phono : 2.5mV/50k Ω Aux, Tape (2 ch, 4 ch) : 140mV/100k Ω
Phono maximum allowable input (rms/p-p)	100mV/280mV
Output Level / Impedance	Tape rec (2 ch, 4 ch) : 140 mV Speaker : Front 1 set, Rear 2 sets (4 Ω ~ 16 Ω) Headset : Front, rear (4 Ω - 16 Ω)
Frequency characteristic	Phono (RIAA deviation) : 30 Hz to 15 kHz ± 1 dB Aux and Tape : 10 Hz to 25 kHz + 0.5 -1dB
Tone control	Bass : ± 10 dB (100 Hz) Treble : ± 10 dB (10 kHz)
Loudness contour (at Volume -40dB)	+ 6 dB (100 Hz), + 3 dB (10 kHz)
S/N (IHF, short circuit, A-network)	Phono : 70 dB or more Aux, Tape : 90 dB or more
CD-4 Demodulator Part
Input Sensitivity / Impedance	2.5 mv (1 mv ~ 5 mv variable) / 100k Ω
Distortion factor	0.07%
S/N (IHF, A Network)	70 dB or more
Separation (when standard signal 1 kHz is applied)	Left to Right : 50 dB Front to Rear : 30 dB
Frequency characteristic	20 Hz to 15 kHz
<General>
Power consumption	150W (rated) 340W maximum
External dimensions	Width 550x Height 160x Depth 420 mm
Weight	19.1kg