Harman Kardon SR-900 (c. 1964–1966)

The Harman Kardon SR-900 was an early all-transistor stereo receiver, part of the company’s Stratophonic Series. HiFI-Stereo (November 1964, p.113) announced the series as fully transistorized. Many receivers still used vacuum tubes then. The SR-900 put an FM stereo tuner, preamplifier, and amplifier on a single chassis.

High Fidelity (April 1965, p.70) described the front panel. It had an easy-to-read station dial with a logging scale, a stereo signal indicator, a station-tuning meter, and an amber power button that glowed when the unit was on. Below those sat a six-position function selector. The settings were stereo and mono tape head, phono, FM mono with automatic stereo switching (labeled “stereologic”), FM stereo, and an auxiliary high-level input. One volume control adjusted both channels at once.

A year later Harman Kardon released the upgraded SR-900B. High Fidelity (June 1966, p.21) advertised 100 watts total, a bandwidth of 5 to 60,000 cps at full rated power, and distortion of just 0.2%. The receiver could feed stereo to one or two rooms, separately or at the same time. HiFI-Stereo (May 1966, p.30) noted that the SR-900B raised power to 100 watts and extended the bandwidth to 5 to 100,000 cps at 50 watts per channel. The tuner section stayed unchanged from the original SR-900.

Little detailed documentation survives for the SR-900 beyond these period reviews. Known specifications gathered from the contemporary press:

All-transistor (solid-state) design, no vacuum tubes
FM stereo tuner with automatic mono/stereo switching
Power output: 50 W per channel (SR-900B), 100 W total
Frequency response: 5–60,000 cps at full power (SR-900B); 5–100,000 cps at 50 W/ch
Total harmonic distortion: 0.2%
Inputs: stereo tape head, mono tape head, phono, FM, auxiliary
Two-zone speaker switching for separate or simultaneous stereo in two rooms
Front-panel controls: volume, six-position function selector, tuning, amber power indicator