ADC 303 (ca. 1964–1972)

Known variants: 303A “Brentwood,” 303B
Price: $95 (303A, 1964); $80 (303B, 1972)
Dimensions (303B): 21½ × 11⅞ × 10 inches

Not much is documented about the ADC 303 beyond a handful of period reviews and advertisements. The record shows a compact speaker system in at least two named variants - the 303A “Brentwood” and the 303B - spanning roughly a decade. The early 303A Brentwood was advertised in Audio (October 1964, p.97) at $95. The ad claimed lab measurements showed lower distortion than the reviewer had measured on many larger and more costly speakers. A later review of the 303B in High Fidelity (March 1972, p.44) listed it as a full-range speaker in an enclosure measuring 21½ by 11⅞ by 10 inches, priced at $80. The same review noted excellent transient response at both low and high frequencies, with only a slight ringing at 3,000 Hz that likely contributed to a perceived brightness. ADC was no newcomer by then. The company began in 1935 as the Audio Development Company, making jacks and jack panels for broadcast and telephone use, and later introduced innovations such as the Bantam jack. The 303 line appears to have been one of their early forays into consumer loudspeakers. No production years, driver specifications, impedance, or exact crossover details have survived in the available sources.