QUAD 33/303 Pre/Power Amplifier Review

By the beginning of the nineteen-sixties, QUAD could do no wrong. Peter Walker's company had launched its ESL-57 electrostatic loudspeaker just three years earlier, which proved to be a groundbreaking design and one of the finest loudspeakers in the world. The 1953 QUAD II valve power amplifier was still widely respected, too, for its sweet sound and fine build quality, so replacing it wasn't going to be easy.

Given the rush to transistorisation at that time, the II's successor would naturally have to be solid-state. The problem was that the technology was still in its infancy, and many such amps had a reputation for sounding harsh and grainy. Launched in 1967, the new 303 power amplifier used a clever 'triples' transistor output stage that carefully controlled output current and accounted for the operating temperature of the output devices. A technical tour de force, it won a Design Council award in 1969.

The matching 33 preamplifier was arguably no less impressive, and a significant advance over the outgoing 1953-vintage QC-II that it replaced. Sporting a distinctive fascia with unusual but effective tone controls and filtering options, it was a flexible control centre for home audio systems of that era. With inputs for multiple sources from (moving magnet) turntables to tuners and tape decks, it was finished in a (then) contemporary shade of taupe. This matched the purposeful-looking 303 power amp with its front-facing heatsinks. The combination was so aesthetically innovative that it went on display in New York's Museum of Modern Art.

So, it's hard to overstate the importance of QUAD's 33/303 combo when it was launched. It consolidated the company's reputation as an innovative, premium hi-fi manufacturer, loved by well-heeled audiophiles and professional sound engineers alike. Finally discontinued in the early eighties, the 303 sold over 100,000 units and went on to become an iconic audio product. And now, QUAD has decided to reimagine it – and its partnering 33 preamp – for today's hi-fi world.

Instead of remanufacturing the original design, the circuitry has been gently tweaked and some modern twists added. So, these new amps are not the 1967 models reborn, but neither are they brand-new designs with only retro styling retained. Instead, the design team, comprising Rob Flain, Paul McConville, Jan Ertner, Peter Comeau, and David McNeill, has chosen a sensible middle path. It's worth noting that some of the aforementioned gents are QUAD veterans and have a combined total of 200 years of engineering experience.

The 33

The original 33 was designed for the new breed of audiophiles emerging in 1967, who played new-fangled stereo LP records or had open-reel tape recorders and FM tuners. To wit, it had several inputs, including one for moving magnet phono. With its taupe metal case, orange and white buttons, and flush-mounted rotary controls, it seemed quintessentially modern, as futuristic as cars such as the NSU Ro80, which launched that same year. Unusually, it offered bass and treble controls with variable slope, as well as 5kHz, 7kHz, and 10kHz filters to suppress tape hiss and record scratches.

The new 33 is similarly compact but features a matte silver finish, an anodised front panel, and a metal chassis. The orange fascia accents remain, but there's now an orange backlit LC display too.

The tone controls have been changed, so there's only bass (±3dB below 50Hz), and tilt (700Hz, ±3dB), plus a balance control. The filters have now gone, and the volume control is motorised. Although moving coil cartridges did exist in 1967 – Ortofon's SPU being a prime example – the original 33 was centred around moving magnet pickups; this new one offers a switchable MM/MC phono stage with adjustable settings. There's also a headphone amplifier and remote control.

All preamp settings are controlled by a microprocessor, but the signal path remains analogue and there's no built-in DAC. Gone are the DIN sockets, as the new model sports three RCA line-level inputs and one balanced XLR, plus RCA and XLR outputs, an aux out and a headphone out. The toroidal transformer and multiple regulated supply rails – among other things – make this a much quieter preamp than the original, and there's better headroom to handle the 2V output of modern CD players and DACs. Overall, it's lovely to use, and looks distinctively different to any other modern preamp – although classic QUAD purists may not like the display.

The 303

In the early days of solid-state power transistors, they were primitive devices, and complementary types were not readily available. This is why the original 303 used a so-called quasi-complementary output stage. Obviously that's no longer the case, so the new model uses has a fully complementary output stage, which is more linear and stable with modern transistors.

That's also partly why the latest model produces a claimed 50W into 8 ohms (70W into 4 ohms) of Class AB power, compared to the original's 45W into 8 ohms.

The new 303 is said to have no problems driving low-impedance speaker loads and can also be bridged for 140W into 8 ohms and 170W into 4 ohms. In the standard non-bridged configuration, the 303 should be good for driving a wide range of speakers.

Thanks to its sturdy anodised aluminium chassis and chunky 200VA toroidal power transformer, the new 303 weighs a solid 8.4kg. This is quite a lot for such a compact design, albeit still slightly larger than the original. The heatsinks on either side make the casing stiffer to minimise resonance, as well as keeping the amp cool – it never got more than slightly warm during the review period. This power amp is designed to partner the new 33 preamplifier for a perfect aesthetic and electrical match, although you can use it with pretty much any modern preamp via its single-ended RCA or balanced XLR inputs.

The Listening

QUAD's new 33/303 is a fine pre/power amplifier combo, boasting a host of endearing attributes, including good power delivery, a clean and spacious sound, and a pleasing rhythmic gait that makes music fun to listen to. You wouldn't call it as beguiling as valve-powered equivalents, but it's still less mechanical than many solid-state designs, old or new.

Tonally it is warm in a subtle way that doesn't appreciably colour the sound. You can cue up, for example, ABBA's Eagle and this already rose-tinted disco-era recording gets just a teensy bit sweeter. Play the hard, jangling indie pop of Felt's Primitive Painters, and the steely coldness of the recording softens just a touch, making it more pleasant to listen to. Play a crystal-clear recording such as Kate Bush's 2011-vintage Snowflake, and it loses a fraction of its edge, making the music just a wee bit gentler.

Yet that's not to say that this amplifier combination sounds dull or opaque. It has a good deal of insight into the busy mix of the aforementioned Felt track, letting you hear the texture of the powerful bass guitar line with ease, and the grittiness of Liz Frazier's vocals. It doesn't airbrush things in the way that some valve amplifiers can, or even some solid-state Class A designs. Instead, you're able to follow the undulations of the song in sharp relief. The QUAD also locks everything into position in the soundstage admirably well – way better than the original 33/303 by the way. Through a new pair of Wharfedale Super Linton speakers, this makes for a large, expansive recorded acoustic on the Kate Bush track, for example.

Glen Campbell's classic Wichita Lineman sounds delightful through the new 33/303; it's a brilliant recording that's hugely expansive, and the QUAD combo showcases it clearly. There's a decent degree of depth perspective, although you'll do better with a high-quality, premium integrated system, such as Audiolab's 9000A here. Likewise, this pre/power doesn't quite have the forensic focus of the aforementioned one-boxer or more expensive rivals.

Yet its enjoyably natural and authentic way of making music makes the simple, nineties singalong Britpop of Wonderwall by Oasis flow so well. This combo performs enjoyably across a wide range of musical genres, constantly distinguishing itself as a good performer at the price.

The Verdict

This new, reimagined version of the classic QUAD 33/303 retains the original's gentle, lucid and slightly warm presentation, while adding a shot of extra clarity and insight, plus a grippier bass and additional power. Both the new preamp and power amp also have usefully revised features that make them far more relevant to the modern world. Factor in the fine build and striking retro-modern styling, and this classy combination will win many friends. 

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