FM4

About the FM4

The Quad FM4 is a self-powered stereo FM tuner manufactured by Quad (Acoustical Manufacturing Co. Ltd.) from 1982 to 1995. It is designed to match the Quad 44 preamplifier and 405-2 power amplifier. The FM4 covers the FM band from 88 to 108 MHz with seven presets and a manual tuning knob. It uses traditional analog tuner technology with a digital microprocessor controlling the display and station preselection. The tuner includes a balanced mixer, IF amplifier with ceramic filter, LC filter for channel separation, and a phase-locked stereo decoder. It features automatic locking to tuning frequency and muting between stations. The unit is compact (321 x 64 x 207 mm), solidly built (3 kg), and styled in the simple, no-nonsense Quad aesthetic. It accepts only a 75 ohm coaxial antenna input and achieves a noise ratio of 70 dB with signals between 1 mV and 100 mV. The FM4 is known for its sensitivity (2.7 µV FM), selectivity (53 dB), low distortion (0.15%), and frequency response of 20 Hz to 15 kHz. It is recommended to check the power supply and digital display condition when buying used, as some components like the IF amplifier IC may require replacement. The tuner was never fully digital, maintaining analog signal processing despite having a digital display.