The history of Quad is one of technical achievement in the field of sound reproduction. It's a story which began with the Quad 1 amplifier, which brought the benefits of 15 years knowledge and experience in professional audio and industrial products to the task of making the most accurate domestic audio amplifier of its age.
In 1953 the product which set the standard for amplifiers was the Quad II Power Amplifier; also the time of HRH Queen Elizabeth II's coronation, and the year in which Mount Everest was finally conquered. The Quad II amplifier pioneered the principle of cathode coupling through the output transformer to reduce harmonic distortion to almost negligible levels. Such was its clear superiority this model remained in production for 18 years.
Three years later, in 1956, Quad demonstrated the first true full-range electrostatic loudspeaker. This remarkable product, known later as the ESL 57, used a virtually massless plastic film as a moving diaphragm between two charged plates. Compared to moving coil loudspeakers, the ESL 57 was free of unwanted colourations and distortions. This landmark product remained in production, virtually unchanged, for 28 years.
In 1967 Quad introduced their first transistorised amplifiers, the 33 Control Unit and the 303 power amplifier. These amplifiers introduced a new triple output stage which solved all the thermal instability problems which plagued early transistor designs. Radical in both circuit design and appearance, this pre/power amplifier combination went on to win a Design Council Award in 1969.
Amplifier performance took a further step forward in 1975 with the arrival of the Quad 405 current-dumping amplifier. This remarkable new circuit topology remains one of the few truly original amplifier designs and has featured in Quad products ever since. For this technology Quad was awarded the Queen's Award for Technological Achievement in 1978.
In 1981 Quad announced the ESL 63, a full-range electrostatic loudspeaker based upon two sets of concentric annular electrodes fed through sequential delay lines. This patented system produces a sound pressure pattern identical to the theoretical ideal of a point source origin. Once again a Quad electrostatic loudspeaker became the reference standard throughout the world.
Quad II Classic Integrated Amplifier
The arrival of the radical 77 Series in 1994 introduced the concept of a fully integrated sound system operated with a two-way remote control system. The system boasted numerous new types of circuit technology, as well as an example of the most advanced control software seen in a consumer product. Two years after its launch, Quad was presented with the European Amplifier of the Year award for the 77 Series Integrated Amplifier.
In 1999 Quad launched the successor to the 77 series, the 99 series, and supplemented this with a range of moving-coil loudspeakers, the L series, and two new models of electrostatic, the ESL 988 and ESL 989. Quad's latest version of the highly acclaimed ESL series, the ESL 2812 and ESL 2912 are a celebration of a classic. Using the signature mylar diaphragm, while re-evaluating all circuitry and components, the result is an authentic ESL experience, incredible full-range accuracy, and startling realism.
Have you ever wondered why valves are considered by many to be better for reproducing music and presenting it in a truly high-end manner? The reasons are probably as numerous as the number of valve amps on the market and Art Audio don't pretend for a second every valve amp is good. Nor would they say all solid state amplifiers are bad, but overall they accept a good thermionic valve will beat a sliver of silicon every time. Many have argued this is due to the fact valve distortion tends to be even ordered, and therefore remains in tune with the primary sound. This means the low level harmonic distortion all amplifiers produce is, in valve amps, 2nd and 4th harmonies which are indeed harmonic, whereas in solid state amps they tend to be odd values, such as 3rd and 5th, which are out of tune with the original sound. Even though this is demonstrably and measurably true, can it be the whole answer? When you look at the infinitesimally low distortion figures of many solid state amplifiers you would think the difference should be pretty negligible.
Art Audio Opus 4 Power Amplifiers
Art Audio think it is a combination of many things, including the large voltage envelope available to a well designed valve amp which allows great scope for the speaker cones to be moved accurately. Contrary to the opinions of others, Art Audio claim valves don't sound warmer and may be as detailed as any solid state device. What they have is the ability to produce all the timbre and tonality of the original music. If there is warmth in the original sound, such as a cello or viola, then it is there, but give them blasting and dynamic brass and they can shake it up with the best. Then there is the transformer matching. Most valve amplifiers utilise transformers to connect the output to speakers. If these transformers are well designed it means the drive can be almost effortless, straining none of the components in the system.
Indeed, much of the extra circuitry within transistor amplifiers is there simply to cope with the inherent problems of the devices, and it is this very complexity which robs their musical reproduction of life. Also, there's the question of linearity, that is to say, how accurately the device passes the signal through itself whilst adding gain. All materials in the signal path alter the sound in some way and Art Audio readily admit valves possess their own characteristics.
However, thermionic valves are inherently more accurate than silicon semi-conductors as electrons only have to pass through a vacuum which by its nature will not effect the signal, whereas transistors and op amps will always have a hysteresis curve and will effect the sound. Simply put, you have a valve where the signal passes through vacuum within a glass envelope, probably made of sand, or you have a transistor where the signal is effectively passing through the sand itself. Instinctively, the valve approach seems more sensible.
Of course, valves do go off and burn out over time, but normally not for many years and Art Audio's self-biasing system keeps them at optimum performance throughout their life. However, when failure does occur the sound is easily re-established by re-valving, which means you effectively get the sound of a new amplifier for a very small percentage of the original cost.
Possibly the most important thing with valve amps is their sheer simplicity, because every component in the way of the music degrades the signal. With a well designed valve system there is much less to get in the way of the music. If you couple that to exemplary manufacturing quality, as with all Art Audio equipment, you have a winning combination.