Denon PMA-400 (1978–1979)
The Denon PMA-400 is an integrated transistor amplifier from the late 1970s, made between 1978 and 1979. In certain regions it was sold as the PMA-501. Denon listed it in its own "Hifi-Program 1978/79" catalog. Past that, documentation is thin. No service manual has surfaced, and what exists is a patchwork of listings, forum posts and a few spec sheets.
Here is what is known. The PMA-400 delivers 50 watts per channel into 8Ω. Frequency response is rated from 5Hz to 100kHz, and total harmonic distortion is 0.05%. Input sensitivity is 2.5mV for MM phono and 150mV for line. Signal-to-noise ratios are 76dB (MM) and 100dB (line). It measures 430 x 146 x 321mm and weighs 13kg. One German-language source lists a sine output of 2 x 85W at 4Ω and 1000Hz. That is a different measurement condition, not a contradiction. A Gumtree listing mentions a "unique crosstalk canceller circuit" on the phono input. Nobody has located detailed documentation of that circuit.
Owner reports are few but positive. A forum user called theirs "very nice," and noted a missing low-cut filter switch that had been glued for strength. An Avito seller said the unit "works perfectly" with cosmetics "very good for its age," and mentioned a 220V version brought from Germany. One UK listing asks £1,050, but that is a single asking price, not a market trend.
- Power output: 50W/ch into 8Ω
- Frequency response: 5Hz–100kHz
- THD: 0.05%
- Input sensitivity: 2.5mV (MM), 150mV (line)
- S/N: 76dB (MM), 100dB (line)
- Dimensions: 430 x 146 x 321mm
- Weight: 13kg
The PMA-400 comes from the late-'70s Denon lineup. It clearly had some clever technology inside, even if the full story hasn't survived in the documentation.
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