Amplification
Following the mass production of 'stereo' vinyl records in 1958, the QC 22 control unit was developed and released in 1959.[4] This was a stereo control unit that was designed to be used with a pair of QUAD II mono power amplifiers. To complement the QUAD II, the company also produced AM and FM tuners for use with the QC II & 22 control units.[4]
The company made the transition to transistor-powered models in 1966 with the "professional" QUAD 50 monobloc which had a tapped transformer output, and in 1967 the consumer Quad 33 preamplifier and 303 stereo power amplifier combination.
Quad I Control Unit - 1951 to 1953 - 2000 units[4] Quad QCII Control Unit - 1953 to 1959 - 20,000 units[4] Quad 22 Control Unit - 1959 to 1967 - 30,000 units[4] Quad 33 – 1967 to 1982 – 120,000 units[4] Quad 34 – 1982 to 1995 – 41,000 units[4] Quad 44 – 1979 to 1989 – 40,000 units[4] Quad 66 – 1986 to 1997 – 12,000 units[4] Quad 99 - 1999 to at least 2003[4] Quad QC-twentyfour - 2000 to at least 2003
Quad 303 – 1967 to 1985 – 94,000 units[4] Quad 77 - 1996 to 1999 - 2,500 units[4] Quad 99 - 1999 to at least 2003 [4]
Quad I - 1951 to 1953 - 2,000 units[4] Quad II - 1953 to 1970 - 90,000 units[4] Quad 50E - 1966 to 1983 - 12,000 units[4] Quad 99 - 2000 to at least 2003 [4]
Quad 405 – 1975 to 1982 – 64,000 units[4] Quad 405–2 1982 to 1993 – 100,000 units[4] Quad 306 – 1986 to 1995 – 25,000 units[4] Quad 606 – 1986 to 1997 – 27,700 units[4] Quad 707 - 1997 to 1999 - 4,500 units[4] Quad 909 - 1999 to at least 2003[4] Quad 909 Mono - 1999 to at least 2003[4]
Quad QA12/P - 1949 to 1951 - 1,000 units[4] Quad 77 - 1994 to 1999[4] Quad 99 Stereo - 1999 to at least 2003[4] Quad 99 Mono - 2000 to at least 2003[4]
- Control Unit – Pre-amplifiers
- Monobloc Power Amplifiers
- Current Dumping Power Amplifiers
Tuners
Quad HR1 - 1949 to 1951 - 500 units[4] Quad /R - 1951 to 1955 - 1,000 units[5] Quad AM - 1954 to 1970 - 2,500 units[4] Quad AMII - 1960 to 1969 - 10,000 units[4] Quad AM3 = 1969 to 1973 - 2,000 units[4]
Quad FM - 1955 to 1967 - 25,000 units[4] Quad FMII - 1968 to 1971 - 7,500 units- [4] Quad FM3 - 1971 to 1982 - 50,000 units
CD players
Quad 66 CD - 1989 to 1994 - 13,000 units[4] Quad 67 CD - 1993 to 1996 - 6,100 units[4] Quad 77 CD - 1996 to 1999 - 3,500 units[4] Quad 99 CD - 1999 to at least 2003[4]
Loudspeakers
In late 1949 (or early 1950), the company launched the CR corner ribbon loudspeaker. This used a Goodmans Axiom 150 cone loudspeaker for the lower frequencies and an electromagnetic ribbon loudspeaker, designed by Acoustical, for the higher frequencies. Fewer than one thousand units were sold.
In 1957, they released the Quad Electrostatic Loudspeaker (ESL), the first production full frequency range electrostatic loudspeaker renowned for sonic transparency and very low distortion. Its sonic neutrality and transparency were offset by its extreme directionality, moderate power handling, the need for a large room, and moderate bass extension; its novel electrical characteristics could render some amplifiers unstable, which could result in damage to either or both.
The ESL was quickly adopted by the BBC for monitoring the sound quality of their broadcasts. The BBC eventually replaced them with moving coil based monitor speakers developed by several manufacturers, such as the highly successful LS3/5A, that were more easily transported and stored, and were more representative of typical contemporary hi-fi speakers.
Quad launched ESL-63, successor to the original ESL, in 1981. The newer design featured larger panels and an innovative stator design, made up of eight concentric rings fed from the centre outwards through analogue delay lines, so that the audio signal radiated out as though emanating from a single point. Subsequent electrostatic models, the 988/989, the 2805/2905 and then the 2812/2912 were successive refinements of the ESL-63 design, featuring increased power handling and output levels, more sophisticated overload protection, and greater structural rigidity.
Following the Verity acquisition, Quad developed and market a range of conventional electrodynamic loudspeakers alongside its electrostatic line, available in both passive and active (i.e. featuring in-box amplification) configurations.
