NEW > QUAD 33 Preamplifier and QUAD 303 Stereo Power Amplifier

Born in the swinging sixties, QUAD’s famous 33 preamp and 303 power amp return in fresh, revitalised form to delight a new generation of music lovers seeking a retro-modern twist

Cambridgeshire, England – One of the most celebrated amplifiers of all time – the 33/303 two-box pre/power amp system from QUAD, Britain’s original high-end hi-fi brand – makes a triumphant return 57 years after it first recalibrated expectations for transistor-based sound.

Teased in prototype form at the High End audio show in Munich in May, the reimagined QUAD 33 preamplifier and QUAD 303 stereo power amplifier are already among the most hotly anticipated hi-fi launches of 2024. This reflects not only the appeal of retro-modern design in audio, but also the high esteem in which the original amps are held – the 33 and 303 remain among the most sought-after ‘vintage’ amplifiers on the second-hand market.

Upon their launch in 1967, their innovative circuit design elevated transistor-based amplification to new heights. The new 33/303 contain highly evolved versions of the same signature technologies, wrapped in an industrial design that echoes the past and embraces the future.

Design evolution of QUAD 33 in QUAD 303

QUAD’s decision to revisit the 33 and 303 was in no small part due to the continuing demand for these amps on the second-hand market some four decades after they were discontinued in the 1980s. What a tempting proposition, to take such an iconic design and update it inside and out, creating a new amp pairing that is unmistakably a QUAD 33/303 yet benefitting from the advances in design, engineering and manufacturing in the 57 years since the original was first realised.

To achieve this vision, QUAD assembled a formidable in-house team at its HQ in Huntingdon, Cambridgeshire, led by four esteemed individuals:
Jan Ertner: lead electronics designer for QUAD and sister-brand Audiolab.
Rob Flain and Paul McConville: QUAD’s most experienced service engineers – nobody knows the innermost workings of QUAD amplifiers past and present better than these two gentlemen.
David McNeill: QUAD’s industrial design chief for the last two decades.

Technology – the new QUAD 33

The original 33 preamplifier was launched at a time when vinyl was king and digital audio was still some 15 years away from entering the domestic scene in the form of CD. It offered several vinyl-oriented facilities for users to tailor the sound, including 5k, 7k and 10k filters, accessed via the buttons beneath the rotary controls for bass, treble and slope adjustment. These filters were intended to remove record surface noise and high frequency distortion when used in concert with the slope dial.
The new 33 remains a staunchly ‘analogue’ preamplifier, with no built-in DAC for digital sources, but its facilities have been adapted to better suit contemporary requirements. For a start, the filters for vinyl have gone and the bass, treble and slope dials have been replaced by bass, tilt and balance.
The ‘Tilt’ control was created by QUAD’s founder Peter Walker as a more sophisticated form of tone control. It was introduced in 1982 on the QUAD 34 preamp, which succeeded the 33; although not contemporary to the original 33, it is considered a classic QUAD feature that remains highly useful and so has been added to the new 33.

Technology – the new QUAD 303

The original 303 stereo power amplifier was (and still is) admired by hi-fi enthusiasts and studio professionals alike for three reasons: its exceptional reliability, the positional flexibility permitted by its compact form, and its smooth yet energising and richly detailed sound. All these attributes are equally applicable in a modern context to the new 303,
which evolves the core circuit design of QUAD’s innovative original with today’s techniques and technologies.
Peter Walker’s great circuit innovation for the 303 – the ‘triples’ output stage – remains at the new amplifier’s heart. A breakthrough in transistor amp design, it effectively forms a feedback amplifier-within-an-amplifier, requiring far less negative feedback, possessing exemplary thermal stability (meaning the current in the output stage is practically
immune to temperature fluctuations) and producing lower distortion.
Whilst updated with the finest modern circuit components, the new 303’s ‘symmetrical triples’ design is faithful to the original, providing a completely symmetrical output stage and rendering the resting current independent of output transistor temperature.
Distortion is reduced to emphatically low levels without sacrificing stability, maintaining this performance under all dynamic conditions.

History elevated

Together, the new 33 preamp and 303 power amp offer a compact and cool-running analogue pre/power pairing that is both faithful to the iconic originals yet thoroughly updated inside and out. The fact that vintage 33/303 units made in the 1960s and ’70s are still in use today, and their sound still much admired, is testament to the original design.
The new editions maintain and elevate these core attributes in every respect. They capture the originals’ silky sonic delivery that set them apart from transistor-based amps of the time, adding greater clarity, detail, bandwidth and dynamic impact. This pre/power amp combination is a joy to listen to, track after track, symphony after symphony, thoroughly engaging the listener whether the volume is set low or high.

Quad 33
Quad 303
Quad 33 + Quad 303