Quad 303 Power Amplifier

Peter Walker founded the Acoustical Manufacturing Co. in 1936, and since then all Quad products have displayed originality in design. What we have here is a 303 power amplifier that is fully working and in superb overall cosmetic condition for its age – see our images. It will be professionally packaged, coming with mains cable, interconnects and as always, our standard three month warranty.
Quad Say….
The Quad 303 power amplifier Is intended for normal domestic use with loudspeakers of moderate efficiency, but is also used by broadcasting and recording studios, groups, and discotheques worldwide, who appreciate its excellent performance and dependability.
The outstanding performance of the Quad 303 is largely due to the unique output circuit developed by Quad. The circuit employs symmetrical triples, greatly reducing distortion and rendering the quiescent current independent of output transistor temperature. This development enables the designers to reduce distortion to any desired degree without sacrificing stability, and to maintain this excellence under all dynamic conditions. To put this in perspective, the lowest theoretical distortion present on the very best tape and disc will still be some hundred times greater than that of the Quad 303. Such a level is, of course, completely inaudible no matter how refined the test. The use of triples, permits simple and effective control of the output current and since the voltage is also controlled, the output transistors are completely protected and must always operate within their ratings with the obvious advantages of greatly improved reliability under all conditions, without the use of elaborate and expensive circuitry. The amplifier cannot be upset even when overdriven by an asymmetrical signal or by shorting or disconnecting the loudspeakers.
The Quad 303 is normally used with the Quad control unit but can readily accommodate other signal sources. Since it has no controls, it can be mounted out of sight in a well ventilated cabinet.
The amplifier won a Council of Industrial Design Award in 1969.
Specifications:
Power output: 45 watts per channel into 8 Ω (stereo)
Frequency response: 30 Hz to 35 kHz
Total harmonic distortion: 0.1%
Input sensitivity: 0.5 V
Signal to noise ratio: 100 dB
Speaker load impedance: 4 Ω to 16 Ω
Dimensions: 120 (W) x 324 (D) x 159 (H) mm
Weight: 8.2 kg