Denon PMA-700mkIII (1977)
The Denon PMA-700mkIII is a pre-main (integrated) amplifier released in 1977 at ¥149,000. It is the third generation of Denon's 700 series. The model description says this generation brought "improved physical characteristics and sound quality" over its predecessors. It's a big, serious piece of stereo gear: 70W + 70W into 8Ω (0.1% THD) and 85W + 85W into 4Ω, with a damping factor of 100 and residual noise of just 0.5 mV. The power amp section is an OCL, twin power line, all-stage DC, fully complementary circuit. The whole unit weighs 12.5 kg (430 × 140 × 350 mm).
The preamp section is where the 700mkIII gets interesting. It has a dedicated MC head amplifier - a newly designed, low-noise class A push-pull design using four PNP and four NPN transistors per side - giving the MC-2 input a sensitivity of 0.32 mV. The MM inputs accept 3.2 mV/50kΩ, and line inputs 320 mV/90kΩ. RIAA deviation is held to ±0.2 dB (20Hz-20kHz). The tone controls step in precise 2 dB increments through an 11-contact rotary switch, with switchable turnover frequencies. The filters are 18 dB/octave Butterworth types (15 Hz low cut, 9 kHz high cut). There's also a loudness control (+6.5 dB at 100 Hz, +6 dB at 10 kHz), a -20 dB mute, and pre-out/main-in jacks.
The vintageknob.org describes this as professional-grade consumer gear, "made to function day-in, day-out with no problems whatsoever, ever." It was sold as consumer equipment, but it carried a little of Nippon Columbia's studio DNA. The same source also flags a possible "semi-equivalent" under the Monarch brand (Series 8 Model 8000) with the same layout and specs, though this is unconfirmed.
Surviving documentation is thin. No professional reviews have surfaced, and production years beyond the 1977 release aren't confirmed. The few used-market listings that appear (Yahoo Auctions Japan, Mercari) suggest working units changing hands in the ¥15,000-¥16,500 range.
**Known specs:**
- Rated output: 70W + 70W (8Ω, 0.1% THD, 20Hz-20kHz); 85W + 85W (4Ω, 0.1% THD)
- Power amp THD: 0.05% or less
- Frequency response: DC–100 kHz (+0/−1 dB at 0.5W)
- S/N ratio (IHF-A): 115 dB or more (power amp)
- Damping factor: 100 (8Ω/1kHz)
- Phono MM: 3.2 mV/50kΩ; Phono MC: 0.32 mV (at 40Ω cartridge impedance)
- Dimensions: 430 × 140 × 350 mm; 12.5 kg
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