Denon PMA-830 (1978)
The Denon PMA-830 is a pre-main (integrated) amplifier released in 1978 at ¥89,000. Some sources list the release year as 1979. The big feature is the Class A / Class B switch, a real dual-mode design. In Class A it delivers 15W + 15W into 8Ω (THD 0.005%). In Class B it steps up to 65W + 65W into 8Ω (THD 0.01%) or 90W + 90W into 4Ω. That's an unusual feature for an integrated amp of the period.
The circuitry descends from the PMA-850, which introduced a symmetrical push-pull circuit adopted across all stages. The 830 carries that same architecture forward. The power amplifier section adds a Class A DC amplifier alongside the Class B DC amplifier. The equalizer stage uses a newly developed ultra-low-noise transistor that brings noise down to -142dBV. The power supply is built around an ultra-large toroidal transformer with strict multiple shielding to suppress leakage flux. Signal-to-noise is rated at 122dB, and the damping factor is 100. It weighs 16.5kg (though one source lists 9800g) and measures 434 x 164 x 400mm.
The aluminum front panel was styled so the lower portion looks like plastic, a deliberate choice from an era when that look was fashionable. The toggle switches sit against this darker lower section and can read as buttons from a distance. A Russian-language source describes the overall design as "post-tube classic with an industrial slant."
The phono stage is well equipped for the era. There are two phono inputs at 2.5mV/50kΩ, with a maximum allowable input of 200mV and RIAA deviation within ±0.2dB. You also get a subsonic filter at 20Hz (6dB/oct), tone controls with defeat, a -20dB mute, and a continuously variable volume with a special balance curve for fine channel adjustment. The pre-out delivers 1V rated (25V max) into 50kΩ.
The record on this model is thin. No period reviews turned up in the major English-language hi-fi press, and most of the detailed technical information comes from Japanese-language documentation. The PMA-830 sits between the PMA-850, which introduced the symmetrical push-pull topology in 1977, and the PMA-630, which shares a fundamentally similar circuit. Collectors regard it well. One Russian listing calls it "a wonderful top amplifier from a respected company," and it appears to have been built to a high standard, with everything functioning well for its age.
- Type: Pre-main (integrated) amplifier
- Class A output: 15W + 15W (8Ω, 20Hz–20kHz, THD 0.005%)
- Class B output: 65W + 65W (8Ω, 20Hz–20kHz, THD 0.01%); 90W + 90W (4Ω, 1kHz)
- S/N ratio: 122dB
- Damping factor: 100
- Phono inputs: 2 (2.5mV/50kΩ)
- Dimensions: 434 × 164 × 400 mm
- Weight: 16.5kg (one source lists 9800g)
- Price (1978): ¥89,000
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