Quad 33 Preamp and 303 Amplifier // Vintage Stereo combo

The Quad 33 preamp and 303 power amp are true icons of British hi-fi—mid-century modern design wrapped around gear that helped define the sound of the late ’60s and ’70s. The 33 preamp, with its orange pushbuttons and modular plug-in boards, feels charmingly retro yet still clever in its simplicity, while the 303 power amp delivers a solid 45 watts per channel with Quad’s trademark smoothness and musicality. Together, they serve up a sound that’s warm, un-fatiguing, and wonderfully human—less about slam and fireworks, more about flow, texture, and long-haul listening comfort. Whether you love them for their distinctive industrial design or their easygoing sonic character, the 33/303 combo remains a cult classic that’s as much art object as stereo equipment.

S/N: 20948 / 23826

RESTORATIONS

• Replaced electrolytic capacitors in Quad 33 preamplifier
• Resoldered weak connections where found
• Cleaned control contacts
• Verified inputs and outputs
• Unit accepts moving magnet type phono cartridges
• Comes with input adapter cables for connecting components with RCA connectors
• Verified power and distortion for the Quad 303 at 1kHz:
• Right Channel 46.0 watts RMS into 8 ohms @0.061% THD+N
• Left Channel 45.6 watts RMS into 8 ohms @0.069% THD+N

 

FACTORY SPECS

Quad 303

Type   Solid state stereo amplifier

Power output   45 watts per channel into 8Ω (stereo)

Frequency response   30Hz to 35kHz

Total harmonic distortion   0.1%

Input sensitivity   0.5V

Signal to noise ratio   100dB

Speaker load impedance   4Ω to 16Ω

Dimensions   4.72"W x 6.25"H x 12.75"D

Weight   18 lbs.

Quad 33

Type   Solid state stereo preamplifier

Frequency response   30Hz to 20kHz

Total harmonic distortion   0.02%

Input sensitivity   2mV (MM), 100mV (ceramic), 100mV (line)

Signal to noise ratio   70dB (MM), 85dB (line)

Output   100mV (line), 0.5V (Pre out)

Dimensions   10.25"W x 3.62"H x 6.5"D

Weight   6.6 lbs.

LINER NOTES

The Quad 303 is a two channel power amplifier primarily designed for high quality domestic installations. It is ideally suitable for driving loudspeakers in the 4-16 ohm range and will provide an output of up to 45 watts per channel depending upon the load impedance. The input required for full output is 0.5 Vrms unbalanced. Transistor triples are employed in an original circuit to provide a completely symmetrical output stage, quiescent current independent of junction temperature and symmetrical current and voltage limiting. Harmonic and intermodulation distortion products in the audio range are so low that they are difficult to measure in meaningful terms. The amplifier is unconditionally stable and may be used with any load.

The Quad 33 selects and controls the radio tuners, gramophone pickup and tape recorder connected to it and feeds the loudspeakers via the power amplifier, providing for stereo, mono on either or both channels, from all inputs, plus monitoring and track selection facilities for tape.It removes surface noise, tracing distortion and similar shortcomings in the upper frequency range of the recording or broadcast, and the two control filter system achieves this to a very fine degree without intruding unnecessarily into the harmonic range so essential for realistic reproduction.