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What’s Old is New Again:
Quad 33 Preamplifier

For over eight decades, Quad Electroacoustics has defined the pinnacle of British high-fidelity audio. Founded by Peter Walker in 1936, the company is built on the legendary ethos of “the closest approach to the original sound.” Quad revolutionized the industry with the world’s first full-range electrostatic loudspeaker—the iconic ESL-57—which remains a benchmark for transparency and detail today. Quad also produced some superb amplifiers, one of which is the subject of this “What’s Old is New” feature.

Quad brochure showcasing their “closest approach to the original sound” ethos and a few of their iconic products
Quad founder, the late great Peter Walker

The Old: QUAD 33 Control Unit (Preamplifier)

The Quad 33 Control Unit, released in 1967, remains one of the most distinctive and influential preamplifiers in high-fidelity history. Clad in its iconic metallic-grey finish with bold orange and yellow accents, it represented a radical departure from the clinical aesthetic of its era. Beyond its looks, the 33 was a masterpiece of modular engineering, designed to pair perfectly with the Quad 303 power amplifier.

Quad 33 Control Unit

Its primary innovation lay in its versatility. It featured a unique plug-in board system, allowing users to swap modules to match different phono cartridges or tape levels—a forward-thinking move toward future-proofing. The control layout was equally legendary, particularly its sophisticated filter system. Unlike modern “straight-wire” designs, the 33 offered granular control over high-frequency “cancel” points and slopes, which was essential for getting the best sound out of variable-quality vinyl pressings and radio broadcasts of the time.

Rear panel of the Quad FM3 tuner (top) and 33 control unit (bottom). The 33 is equipped with “tape adapter” and “disc adapter” portals where the user could plug in modules to match their tape and phono equipment.

Sonically, the Quad 33 is celebrated for its smooth, non-fatiguing character. While it may lack the ultra-wide transparency of modern digital-age preamps, it possesses a musical warmth and “British” refinement that still captivates enthusiasts. It isn’t just a piece of vintage gear; it is a functional sculpture that defines the golden age of transistor design.

An “All Quad” system comprising a FM3 tuner (top), 33 control unit (bottom), and 33 power amplifier (right)
A beautifully restored Quad 303 and 33 combination
One more view of the 33/303, this time showing the “business end” of the 303

Back in the 1960s, the Quad 33/303 would have been a great match for the Quad ESL-57 speaker, shown here.

The legendary Quad ESL-57 full range electrostatic loudspeaker

The New: Quad 33 Preamplifier

The new Quad 33 (2024 Edition) is a masterful “reimagining” that preserves the soul of the 1967 original while completely modernizing the internal architecture. Visually, it is instantly recognizable, retaining the compact form factor and iconic orange-accented aesthetic. However, the dated “taupe” finish has been replaced by a more contemporary titanium metallic sheen, and the original mechanical buttons have been swapped for high-quality, microprocessor-controlled switches.

The “new” Quad 33 preamplifier was introduced in 2024
The new version keeps the original aesthetic of the original, with some modern updates

Technically, the new 33 is a purely analog powerhouse. It does without an onboard Digital-to-Analog Converter (DAC) to avoid digital noise, focusing instead on a brand-new Moving Magnet (MM) and Moving Coil (MC) phono stage, and a dedicated current-feedback headphone amplifier. Connectivity is significantly upgraded with the addition of balanced XLR inputs and outputs, moving past the finicky DIN sockets of the past.

Inside view of the new Quad 33 preamplifier
Rear view showing the wide range of inputs using a mix of RCA and XLR connectors

A standout feature is the return of Quad’s unique tone control approach, now complemented by a subtle orange-backlit LED display that indicates adjustment levels. This form of equalization allows you to warm or brighten the sound without coloring the frequency extremes. Paired with a motorized ALPS volume pot and a full-function remote, the 33 reissue delivers a refined, transparent, and musical performance that bridges the gap between mid-century charm and modern high-end fidelity.

The new 33 would make an ideal perfect match for Quad’s new version of the 303 amplifier, shown here.

A new Quad 33 matched with a pair of Quad’s new 303 power amplifiers

And if you are a big fan of this updated 1960s aesthetic, Quad has released a couple of other products including the 3CDT Compact Disc Transport and Model 3 Integrated Amplifier.

Quad 3CDT Compact Disc Transport is a thoroughly modern machine….
….as is the Quad 3 integrated amplifier

More about QUAD

Renowned for their timeless industrial design and engineering innovations, Quad consistently bridges the gap between technical precision and musical soul. For audiophiles who value heritage without compromising on modern performance, Quad remains an enduring icon of sonic purity.

The QUAD ESL-57 electrostatic loudspeaker was inducted into the Hi-Fi Hall of Fame in 2023. If you’d like to read our profile of this groundbreaking speaker, just click on this link: hifihalloffame.com/equipment/quad-esl-57-loudspeaker/

And if you’d like to see the entire QUAD lineup, here’s a link to the company’s website: quad-hifi.co.uk/