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.
- Production
- 1967-84
- Condition
- 8/10
- Serial No.
- 20948 / 23826
- Orig. MSRP
- $499 (amp) $399 (pre)
- Restoration
- 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 umbilical and 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.
- Documentation
Quad 303 Owner's Manual
Quad 303 Service Manual
Quad 303 Brochure
- The History of Quad
- The company was founded by Peter J. Walker in 1936 in London, and was initially called S.P. Fidelity Sound Systems. In 1936 the name was changed to the Acoustical Manufacturing Co. Ltd. The company moved from London to Huntingdon in 1941 after being bombed out of London in World War II....
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- 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.
- Stock No.
- 9084266152157
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.
Production
1967-84
Condition
8/10
Serial No.
20948 / 23826
Orig. MSRP
$499 (amp) $399 (pre)
Restoration
- 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 umbilical and 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.
Documentation
Quad 303 Owner's Manual
Quad 303 Service Manual
Quad 303 Brochure
The History of Quad
The company was founded by Peter J. Walker in 1936 in London, and was initially called S.P. Fidelity Sound Systems. In 1936 the name was changed to the Acoustical Manufacturing Co. Ltd. The company moved from London to Huntingdon in 1941 after being bombed out of London in World War II....
[ Read More ]
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.
Stock No.
9084266152157
