This is a faithful reproduction of the original mono amplifier – the Quad II Classic offers audiophiles the chance to recreate the spirit and atmosphere produced by one of the most famous amplifiers in audio history.
The original Quad II was first launched in 1953, designed by Peter Walker. At the time, many of his contemporaries were also producing good quality valve amplifiers. The Quad II looked, in comparison, very simple and unassuming, but its performance was far beyond that which its diminutive dimensions might suggest.
The property which set the Quad II amplifier apart from the other amplifiers of the time was its output stage. it was arranged such that the cathode coupled circuit emulated the performance of triode operation, but with the size and efficiency characteristics of pentode operation. It was this breakthrough that ensured the Quad II was to remain in continuous production until 1970.
Peter’s circuit, notably the design of the output transformer, has become the stuff of legend amongst electronics engineers. Studied and analysed by the finest minds in the industry, the elegance and coherence of the design is still regarded as a reference today. Given the quite modest components of the day, he was able to engineer something which was literally greater than the sum of its parts.
The Quad II classic has been recreated accurately with input and output valves the equivalent of those used in the original design. The same balancing act has been employed to ensure the same wealth of detail and gentle tone of the original.
The output valves produce around 15 W per channel, operating in Class A, which allows for a gloriously sweet and refined sound with appropriately matched contemporary loudspeakers.
The history of Quad is one of technical achievement in the field of sound reproduction. It is a story that 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.A few years later, in 1953, the product which set the standard for amplifiers was the Quad II Power Amplifier, the time of Queen Elizabeth’s Coronation and the year in which Mount Everest was finally conquered. This amplifier pioneered the principle of cathode coupling through the output transformer to reduce harmonic distortion to almost negligible levels. Such was its clear superiority that 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 mass-less plastic film as a moving diaphragm between two charged plates. Compared with moving coil loudspeakers, the ESL 57 was free of unwanted colourations and distortions. This landmark product remained in production, virtually unchanged, for 28 years.
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