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Vintage Dynaco ST-80 Stereo Power Amplifier - 40 Watt Solid State AmpFully tested and 100% functional; the classic ST-80 is a cool little 40 watt amp. Cosmetically, it exhibits some wear from over the years but is overall very good.SpecificationsPower output: 40 watts per channel into 8Ω (stereo)Frequency response: 10Hz to 50kHzTotal harmonic distortion: 0.5%Damping factor: 40Input sensitivity: 1.3VSignal to noise ratio: 90dBSpeaker load impedance: 4Ω to 16ΩSemiconductors: 12 x transistors, 10 x diodesDimensions: 14 x 8 x 4 inches
At US$248, this sits above the recent used median of US$194 and even above the 75th percentile of US$221, so it reads as a bit ambitious rather than a bargain. It is not wildly out of line for a desirable vintage power amp, but there is no obvious price cushion here unless the condition, cosmetics, or service history are unusually strong.
The ST-80 is well liked for straightforward, punchy vintage stereo power and a sound that pairs well with efficient speakers and classic systems. If this one is clean, original, and has been serviced or lightly used, it can still be a worthwhile buy for someone who wants the Dynaco character and a tidy period piece; if not, the price leaves little room for age-related maintenance.
Independent perspective — not a price guarantee. Always verify condition, accessories and provenance before purchase.
Dynaco emerged in 1955 from Philadelphia, Pennsylvania, when hi-fi pioneer David Hafler partnered with engineer Ed Laurent to form the Dyna Company. Hafler brought expertise from his earlier Acrosound venture, which produced high-quality output transformers starting in 1950. The duo targeted the burgeoning hi-fi market with affordable, DIY-friendly kits, launching the Mk II 50-watt tube amplifier shortly after incorporation and relocating to a former chocolate factory for expanded operations.
The brand specialized in tube amplifiers that defined its legacy, including the iconic Stereo 70—over 350,000 units sold—alongside models like the Mk III. Dynaco expanded into FM tuners such as the FM-1, bookshelf speakers like the A-25, solid-state amps, and innovative systems like the Dynaquad for simulated four-channel sound. Late-1970s efforts included the Phase III speakers, though the company shifted toward kits and components emphasizing value and performance.
Dynaco holds a revered position as the era's top-selling tube amp maker, beloved by budget-conscious audiophiles for reliable, high-value hi-fi. Liquidated in 1980 after Hafler's sale to a toy firm, its vintage gear remains a collector's staple, with later revivals by Panor Corporation producing replicas for tube enthusiasts seeking that classic warmth and build-it-yourself appeal.
See all Dynaco listings on RADAR.
