In 1967 Quad introduced its first transistorised amplifiers, the 33 Control Unit and the 303 power amplifier. These amplifiers introduced a new ‘Triples’ output stage that solved all the thermal instability problems that plagued early transistor designs. Radical in both circuit design and appearance, they 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. Numerous other prestigious awards were presented to Quad from all over the world. 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 around the world.