Beautiful and extremely rare Sony receiver with possibility of 4-channel rendering. The SQ circuit is built in. This circuit turns a 2 channel signal into a 4 channel signal. This super receiver also has, in addition to FM an MW reception, options for cassette deck, tape recorder and record player. This receiver was prized for its sound quality where many receivers from this period could not match it. Really very beautiful and very good sounding receiver for the lover of gorgeous vintage audio or a beautiful sound. Pure quality! The front consists of 2 parts and are made of metal, not plastic. This translates to the fact that the edges are undamaged. The lighting is great of course, and just look at the meters, of which 1 is slightly less bright, but that can probably be fixed. Model 2ch/4ch receiver Integrated Systems 4ch Receiver: SQ decoder and decoder system, including RM Power amplifiers: quasi-complimentary SEPP OTL scheme FM Receiving frequency 76MHz ~ 90MHz Antenna terminal 300Ω balanced Intermediate frequency 10.7MHz Sensitivity 2.2μV (IHF) 1.7μV (S / N: 30dB) Image Rejection 55dB IF Rejection 90dB Spurious Rejection 78dB AM suppression 55dB Kyapuchareshio 1.5dB Selectivity 70dB (IHF) S / N 68 dB Frequency 30Hz ~ 15kHz, +1-2dB Distortion mono: 0.3% (400Hz, 100% modulation) stereo: 0.8% (400Hz, 100% modulation) Stereo separation 35dB (400Hz) AM Antenna terminal Built Ferit antenna bar With external antenna terminal Sensitivity 48dB / m (when using the antenna bar) 30μV (when using external antenna) S / N 50dB Distortion 0.8% Amplifier Output (0.8% harmonic distortion) Dynamic power: (IHF, law constant voltage supply) 4ch Speaker Output: 56W (8Ω) 96W (4Ω) Hi-Power 2ch Speaker Output: Total 90W (8Ω Effective output (1kHz): 4ch Speaker Output： 4ch Speaker Output: 8W +8 W +8 W +8 W (8Ω) 11W +11 W +11 W +11 W (4Ω) Hi-Power 2ch Speaker Output: 25W +25 W (8Ω) Characteristics of the output bandwidth (IHF) 10Hz ~ 40kHz Output Level / Impedance Recording terminal Rec Out: 250mV/10kΩ Recording connector Rec / PB: 30mV/82kΩ Headphone Jack: 8Ω ~ 10kΩ 4ch speaker terminals: 4 ~ 16Ω meet 2ch speaker terminals: 6 ~ 16Ω meet Harmonic distortion 0.8% or less (at rated output) 0.2% or less (1W output) Intermodulation distortion (60Hz: 7kHz = 4:1) 1.0% or less (at rated output) Less than 0.5% (1W output) Frequency Phono: RIAA standard, ± 1dB AUX, Tape, Rec / PB, 4ch Input: 20Hz ~ 50kHz, +0-3dB Input sensitivity / impedance (At rated output) Phono: 2.5mV/47kΩ AUX, Tape, REC / PB, 4ch INPUT: 250mV/100kΩ S / N Phono: 60dB AUX: 70dB Tape, REC / PB, 4ch INPUT: 80dB Damping Factor 35 (8Ω) Tone control Treble: 10kHz, ± 10dB Bass: 100Hz, ± 10dB High Filter 6dB/oct, 5kHz Loudness switch (-30dB attenuation) 50Hz, +8 dB 10kHz, +4 dB Volume knob Independent channels available around Balance knob Independent channels available around General Using semiconductor Integrated receiver: 1FET, 66 transistors Circuit included: four transistors 37 diodes Power AC100V, 50Hz/60Hz Outlet 300W, Non-linked: 1 line Power 85W Dimensions Width 434 × height 144 × depth 345mm Weight: 9.5kg A link to more information about this great and very special receiver: http://jbmanuals.free.fr/Sony/SQR-6550/Sony%20SQR-6650.html