Quad was established in 1936 in London by Peter J. Walker, initially called 'S. P. Fidelity Sound Systems' before quickly being renamed 'Acoustical Manufacturing Co. Ltd'. The company was established to produce public address systems, but after the Second World War, began producing equipment to be used in the home, soon focusing on audio systems. After their London factory was bombed in the Second World War, they moved to Huntingdon where the company still resides today.

The Quad brand name was first used with their Quad 1 amplifier, released in the early 1950s. Quad stood for "Quality Unit Amplifier Domestic" and became a naming convention used with all of their products. By 1983, the company had become synonymous with the brand name Quad, and so changed their name from 'Acoustical Manufacturing Co.' to 'Quad Electroacoustics Ltd'.

During the 1990s, the company swapped ownership a few times. They became owned by the Verity Group plc in 1995, and then became part of the International Audio Group in 1997.