Quad 1963“Peter Walker had it in his mind that technology really was there to be used to achieve a result – low distortion and tonal accuracy – hence the slogan, ‘the closest approach to the original sound’”, says Quad’s Peter Comeau. “He grew up in an era when a lot of people were playing at making hi-fi, thinking they were doing good things, but he went after all the technical flaws and found very elegant answers to them. Everything he did was clever, and moved the game along. Even in Quad now, everything we do is about good solid engineering, offering an elegant solution to the problems out there…”

Peter J. Walker founded S.P. Fidelity Sound Systems in London in 1936, but soon changed the name to the Acoustical Manufacturing Company. “He was an electronics engineer by training, but came from a position of having worked in dance bands and was a musician, so he was very well rounded. These were the days when Public Address systems were very limited and crude, and he had to come up with a sound that was able to fill a dance floor. A lot of work he came up with in valve amplifiers were practical solutions of getting more power, which were very restricted in those days. He was thrown in the deep end really, long before he made hi-fi…”

An exceptionally talented electronics designer, he had his very own distinctive approach. “He was obviously making things which sounded very good,” says Peter Comeau, “but certainly placed more emphasis on measurements that he did on listening. He was from the old school that didn’t spend a lot of time listening to equipment, instead devoting it to measurement to ensure it did what exactly he wanted. He did listen to music a lot for pleasure, but it wasn’t a big part of his testing routine.”

That’s not to say Walker was crudely deterministic about measurements though. “If he had just chased low distortion for its own sake, his products would have sounded less good. He was sophisticated in his approach and, for example, didn’t believe zero distortion was a necessity. He knew perfectly well that if you have second harmonic distortion below 1% for example, you can’t actually hear it. He knew what you have to do ensure something sounded good, but he didn’t actually tweak things too much, he just did what was necessary to get the job done. Like many engineers of his generation, the subjective approach was less important for him.”

Walker’s PA experience proved invaluable when he moved into the domestic sound reproduction equipment field. “He was one of the few real technical innovators of his era, and that came out of his professional audio origins. I think when you’re making equipment that you’re taking out on the road that gets battered and bashed and still has to work at the end of the car journey, that’s when you learn about how to make things so they survive. And that experience gave him a leg-up when it came to production engineering hi-fi. The equipment was always extremely well made and made to work well within its limits. There weren’t any fancy components, rather he worked with everyday components and made sure they worked and continued to work – and then backed that up with a legendary service department.”

In 1949, Walker’s company introduced its first hi-fi product, the QA12/P 12W mono valve amplifier. Sound quality was excellent by the standards of the day, and the amplifier naturally ended up being used by the BBC. However, the first amplifier to wear the company’s now iconic brand name was the QUAD 1, the name itself being an acronym for ‘Quality Unit Amplifier Domestic’. The company duly renamed itself QUAD Electroacoustics Ltd., and didn’t look back. Peter Walker, observes Comeau, “was a great self-publicist.” He pithily observed that an amplifier should be “a piece of wire with gain”, and had the ability to make the weather in the hi-fi world. In 1953, the QUAD II power amplifier arrived, and proved outstanding in several respects. It pioneered cathode feedback through the output transformer, which reduced harmonic distortion dramatically, and created a headache for Walker when the time came to replace it, such was its fine, sweet sound.

“Peter Walker produced a very high quality speaker called the Model CR (Corner Ribbon), which in itself was highly innovative – using a ribbon that went down to about 1.5kHz and then handed over to a twelve inch bass unit. Even that was loaded by a double-ported bass chamber which was a very elegant solution for getting good bass from a relatively small cabinet. The whole speaker was superbly well engineered but cost a fortune – 83 Pounds was a lot of money in those days. It got fabulous reviews but even then he knew there were flaws in it, so he looked around how to improve on it. The ribbon had obviously given him the idea that you could better moving coil drivers.”

“There were electrostatic tweeters around at the time, but they were single ended – in other words, they have a diaphragm and one plate; as the former moved away from the latter obviously it reduced the effect of the charge and the distortion increased. For a tweeter that wasn’t too bad because the diaphragm displacement is relatively small, but nobody could come up with a solution about how to make a full range electrostatic where the displacement is relatively large. So he sat down and worked it out, with the help of D.T.N. Williamson and Peter Baxandall. Together they conceived the concept of the full-range, push-pull electrostatic. It was a brilliant idea, and arguably the most important hi-fi product of the twentieth century…”

The new Quad ESL 57 loudspeaker was a revelation – and in many respects still outperforms most modern loudspeakers even today. Using an ultra-light plastic film in its diaphragms, vibrating between two charged plates to produce sound, there was simply nothing else like it. The ’57 gave a dramatically cleaner and clearer sound than the moving coil speakers of its day. With striking modernist looks and revolutionary technology, it embodied everything that was great about the company. “He took the prototype to the London hi-fi show before the launch, and people flocked to hear it,” says Comeau. “Of course the loudspeaker manufacturers of the day all came to hear this thing – Gilbert Briggs, Stanley Kelly and Harold Leak. In fact, there’s a quote from Briggs that said when he and Kelly heard it they solemnly agreed that they would ‘change into black and meet in due course at the workhouse’…”

The invention of the transistor in 1947 was something that was always going to shake up the hi-fi world, and for years manufacturers wrestled with the new technology to get it sound good, as well as deliver its promised benefits of miniaturisation and reliability. QUAD was again at the cutting edge of this, with its controversial 303. Arguably the first truly modern power amp, it was claimed to be the world’s first low-distortion transistor amplifier. An expensive product for 1967, it nevertheless found itself on the BBC’s shopping list, and garnered widespread critical acclaim. Peter Walker did find himself answering criticism about the amount of time the company had taken to get to the solid-state table however, and replied. “We are sometimes accused of being slow to take up transistors, but in fact early transistor amplifiers were inferior to good valve amplifiers and it has been necessary to develop a fundamentally new approach to circuit design to overcome this. The result is that the Quad 303 is superior to the best of valve designs in every respect.”

The 303 was revolutionary in both its design and its packaging. With no controls, the amplifier was designed to be hid away discreetly. “Almost every amplifier is long, low, silver and black,” argued Walker. “We have tried to give our equipment a distinctive appearance which will not date as the fashion changes, and which will fit in with the modern surroundings in which it will be used.” He was right, and many 303s still run today in an unerringly fuss-free way. The amplifier’s new output ‘triples’ transistor configuration meant that less negative feedback was needed, whilst giving lower distortion and greater thermal stability. The idea won a Design Council Award in 1969, causing one magazine to call it “the god of amplifiers”.

If the 303 was the first modern solid-state power amp, the 405 launched in 1975 set the blueprint for all future Quad designs. It introduced the principle of ‘Current Dumping’, whereby two amplifiers were effectively used per channel, rather than one. A low powered Class A amplifier provides an ultra-low distortion signal, backed up by a ‘current dumper’ high power Class B stage. Walker came up with the concept of a bridge that balances the high powered output with the Class A amplifier. Any resulting distortion is automatically balanced by the bridge and fed forward into the audio path, in such a way that the high power audio amplifier achieves a very low distortion figure, even at high power levels. Ingeniously clever, it earned the Queen’s Award for Technological Achievement in 1978.

“Walker was again very innovative in his thinking with the 405,” says Peter Comeau. “His way of designing this amplifier would result in extreme consistency, in the way it performed when you first got it home, then after five, ten or fifteen years down the line this thing would still perform exactly the same as when it was left the factory. The circuit is still remarkable today, and that’s why we still use it, because it’s the only output stage where you can say that it remains unchanged in its performance over time. Because it’s a bridge formation, it will always perform exactly as it was designed, and will never shift. It’s a brilliant way to drive a loudspeaker as well, and Quad has rightly been held in high regard for that for many years. Quad distributors, retailers and owners are all fanatical about these amps…”

The 405 was ingenuous, but didn’t quite manage rave reviews from everyone at the time. Comeau attributes this to a combination of factors. “In the whole realm of Quad products, the 44/405 wasn’t the best pairing. The 44 preamplifier used CMOS integrated circuits to do its switching, and they weren’t good sounding. Also, the 405 was slammed by the subjective press at the time because it wouldn’t drive really low impedance loads – some reviewers used Linn Isobariks at that time as reference speakers, and the first version of the 405 just couldn’t hack it. Peter realised it pretty quickly, and with the Quad 405-2 he put it right, adjusting the bridge system so it could drive lower impedance loads; it was a much better amplifier. The 34 that followed was a better preamp too, and everything went much better. We could really see the good sides to the design.”

Quad’s next step was to upstage the brilliant ESL-57, which had been in production for no less than eighteen years at that time. The new ESL-63 was launched in 1981, and was a worthwhile refinement of the electrostatic loudspeaker, but didn’t reinvent the wheel. A full-range design featuring two sets of concentric annular electrodes fed through sequential delay lines, it used this patented system to reproduce a true point source. It delivered an exceptionally clean and uniform sound, whilst offering valuable extra headroom compared to the ESL 57. By the mid eighties, Quad was seemingly at the height of its game – making excellent amplifiers and loudspeakers that were bold and innovative, yet quite unlike anything else on sale.

Whilst hi-fi went through a distinctly minimalist phase in the latter part of the nineteen eighties, Quad continued to offer the same proposition to the customer. The 66/606 was an update of the 45/405 with sleeker ergonomics and more power, controlled by a sophisticated, intelligent two-way remote control, and proved justifiably popular. The 77 system followed in 1996, the company’s first to be integrated as an interlinking whole – with the CD player, amp and tuner linked by a bus system called QUADLINK. The 77 integrated won ‘European Amplifier of the Year’ award, and used a pioneering and unusual pure Class B circuit designed by Jan Ertner, with an efficient method of solving the problems of crossover distortion. The 99 series followed in 1999, carrying these designs forward further.

Peter Walker died in 2003 at the age of 87. He had retired in the late nineteen eighties, then turning management over to his son Ross Walker. Soon after the launch of the 66 series, Quad was bought by Verity Group plc, and in 1989 the brand was purchased by International Audio Group with production transferred to China, at a time that Verity decided to focus on NXT flat panel loudspeakers. Since that time, Quad has come up with a plethora of interesting products. The ESL 63 electrostatic received a light rework to become the 988, and the option of an extra pair of bass panels made the 989. The company launched the QUAD QC-24 Control Unit in 2000, with input from the tube guru Tim de Paravicini, alongside the Quad II-Forty valve power amplifiers. The mighty 11-Eighty power amplifiers followed, giving even more power.

The ESL-2805 and ESL-2905 followed in 2006, a clever repackaging of the 988 and 989, with improved structural rigidity and power handling. Around about the same time, Quad added a range of small, affordable moving-coil loudspeakers, called the L series. This has burgeoned, and been joined by the S-series and Z-series, which like the classic Corner Ribbon from all those years ago, use wide range ribbon tweeters. The latest ESL-2812 and ESL-2912 are the finest expression of the electrostatic line, with super-rigid frames and excellent power handling. The Elite series of separates offers fine sound in a neat, slim package and the Vena is a retro-styled yet ultra-modern integrated that’s hugely versatile. Most interesting of all in Quad’s diverse and eclectic product range though, is Artera…

“Artera delivers a common-sense approach to hi-fi,” says Comeau. “Like all Quad gear, you take it home, plug it in and it carries on working – and if it ever needs servicing you go to the service department and they’ll quickly restore it to as-new spec. All of Quad’s products, including the ESL-57, are still serviced by the Company’s Service Department in Huntingdon. When we sat down and mapped out what we wanted Artera to do four years ago, we were thinking how can we make hi-fi simple, because so many things in hi-fi are just getting more and more complicated. We wanted something that is not off-putting to work with or to look at. We needed a fresh approach, so we made something that looks so stunning and sounds so good. In a way, Quad has become more mainstream again. Quad is very special, a rare no-nonsense approach to hi-fi…”

QUAD classics
1949 QA12/P integrated amplifier
1949 Acoustical Corner Ribbon loudspeaker
1951 Q.U.A.D. 1 control unit and power amplifier
1953 QUAD QC-II and Q-II power amplifier
1957 QUAD ESL 57 electrostatic loudspeaker
1967 QUAD 33/303 preamp/power amplifier
1975 QUAD 405 power amplifier
1981 ESL-63 electrostatic loudspeaker

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