ATC S50/S85 (1978)

After a few years making drive units, ATC produced its first speaker systems in 1978: the bass-reflex S50 (pictured right) and infinite baffle S85, which established the company’s naming tradition representing the internal volume of the speaker. Inside the plywood-based 50- and 85-litre cabinets were 25mm soft-dome tweeters, a 75mm soft-dome mid driver and a 22.5cm woofer (two in the S85).

Unusually, the crossover arrangement allowed for true active tri-amping. Owners could use a rotary switch either to access the internal passive crossover or to use an external electronic crossover.

Formed in 1974 by Billy Woodman to manufacture drive units, and making its mark with the 12″ PA75-314 driver, ATC went on to make both domestic speaker systems like this S50 in 1978, and high-powered PA speakers — Pink Floyd and Supertramp were among Woodman’s early customers.