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The Dynaco ST-70 is a legendary 35-watt per channel stereo tube amplifier produced from 1959–1970s, renowned for high-fidelity stereo sound using EL34 tubes. Known in some circles as a "poor man's McIntosh" it features 4-16 output taps and a classic, warm, detailed sound, often restored or modified due to its enduring popularity. This one is in Good condition, with definite signs of wear: faded chrome, a chip out of the bakelite fuse housing (pic) and mild corrosion in spots (pix) but, overall, this amp sounds warm and toasty and looks good. On both sides of the chassis, there are three flathead screws that hold the cage to the amp, one screw on each side is missing, but the two other screws do an adequate job of holding the cage on (see pix).Tubes/Valves: 2x Philips 34167/7199 (US Made)2X Mullard EL34 (Russian-made)2X (Svetlana) EL341X JJ (US Made) GZ34/5AR4Specs:Power Output: 35 watts RMS per channel into 8 or 16ΩTube Complement: 4 x EL34 (output), 2 x 7199 (driver), 1 x GZ34/5AR4 (rectifier)Design: Push-pull ultra-linear design with A-470 output transformersFrequency Response: 10Hz to 40kHzInputs: Dual RCA inputs on the front, with a Stereo/Mono switchWeight: 32 lbsService History: No service records were included from the prior owner. Here at the shop we did routine testing, cleaning and inspection.Cosmetic Condition: Overall we rated this at Good.In the Milwaukee Area? Stop in our shop to inspect/demoSee our feedback and thank you for considering. All the gear we sell is packaged with great care for safe arrival in the condition advertised.
Timing matters here because this is an older Dynaco monoblock design, and with vintage amps the real value is mostly in condition, originality, and whether it’s been serviced. At US$700, it sits just above the US$672 median and well below the US$900 75th percentile, so this reads as a fair-to-strong asking price rather than an aggressive one.
What makes it appealing is the usual Dynaco formula: respected, musical tube-era power, simple circuits, and a huge parts/service ecosystem that keeps these relevant long after many contemporaries faded. If the unit is clean, original enough to matter, and not hiding transformer or power-supply issues, there’s real upside here; if it’s fully sorted or comes with matched accessories, that’s even better. Since condition is listed as unknown, I’d want a careful look at cosmetic state, modification history, and whether it powers up safely.
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.
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