Heathkit AA-20 (c. 1968–1970)
The Heathkit AA-20 was a compact solid-state integrated amplifier from the late 1960s, offered as a kit. Documentation on this model is thin, but the record that survives paints a picture of a modest, budget-oriented stereo amp typical of Heathkit's approach at the time: build it yourself, save money, and get perfectly respectable performance.
The AA-20 was built around a simple semiconductor complement — 4 ICs, 4 transistors, and 4 diodes — and delivered roughly 24 to 25 watts per channel into 8 ohms. Both sources in the archive agree on the key performance figures: total harmonic distortion under 0.3%, frequency response from 5 Hz to 60 kHz, phono input sensitivity of 2.0 mV, and high-level input sensitivity of 150 mV. The amplifier offered two RCA phono inputs and one high-level RCA input, with a tape output and preamp output. It weighed 11 pounds and measured 406 x 103 x 238 mm — a compact, unassuming box.
The year of introduction is disputed: one source says 1968, another 1970. Given the component mix (early IC usage alongside discrete transistors), either date is plausible; the truth likely sits in between. No original price and no circuit topology details have surfaced. Period Heathkit advertising promoted the company's kits as costing half what you'd expect to pay for comparable components High Fidelity (June 1960, p.33). It appears to have been a straightforward, economical entry point into stereo — the kind of kit Heathkit sold by the thousands, and which few thought to document in detail. What we know of it comes down to the specs above, and the quiet assumption that it did its job well enough to be forgotten.
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