Dynaco 400 (1974)
The Dynaco 400 came out in 1974. It was the heavyweight of the Dynaco solid-state line, a power amplifier that sat at the top of the transistor lineup. Damping factor was rated at greater than 200, and sensitivity was 1.5V for rated output.
The period advertising leaned hard on the "ultimate" angle. Dynaco's own ads in Audio (September 1974, p.19) touted 400 watts at 8 ohms and 600 at 4. Those figures appear to reflect peak or bridged performance rather than the continuous per-channel rating, though the source doesn't clarify. The same campaign pushed "unsurpassed stability with any speaker," massive cooling capacity, and unmatched protection for both amplifier and speakers. High Fidelity (April 1975, p.37) covered the 400 as a "super amplifier kit" in their consumer's guide. It listed a 17 by 7 inch front panel, 14 inches deep, and a price of $499 in kit form.
It's a big amplifier: 19 x 7 x 12 inches and 60 pounds, with a massive power transformer and a large capacitor bank inside. Inputs are single unbalanced RCA and balanced XLR. It drives dual speaker terminals.
The historical record is thin from here. The archive documents no original selling price for the assembled version, no common failure points, and no current market values. The 400 was Dynaco's answer to the high-power solid-state era, and it has a clean reputation among collectors.
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