Denon PMA-701 (1976–1978)
The Denon PMA-701 is a pre-main (integrated) amplifier from the very start of the "power race" of the late 1970s. It was introduced in October 1976 and produced through 1978. It was the top model in a two-amp lineup alongside the smaller PMA-501, and it was sold with the matching TU-701 tuner. It sold reasonably well in Europe, though it's now far less remembered than Denon's next mid-end generation, the PMA-850/TU-850.
The PMA-701's party trick was PCC - Phono Crosstalk Canceller. It's an analog circuit that adds reverse crosstalk to cancel the crosstalk inherent in phono pickup cartridges. It uses two wide-bandwidth phase-shifting circuits that track clicks and pops on each stereo channel, reverse phase when needed, then matrix the two signals to cancel the pops out of the music. Pop sensitivity is adjusted separately for the L-to-R and R-to-L signals, and Denon supplied an adjustment record to set it up. The vintageknob notes that Denon's PCC was all-analog, and that the concept was fairly short-lived - gone from Denon's lineups by late 1978. It resurfaced in the 1980s and early 1990s with Marantz's SX-72 "scratch remover" and Philips' IS5022. Denon even made a dedicated PCC-1000 outboard unit, described as "an extra-rare rarity."
Beyond PCC, the 701 is a serious piece of 70s engineering. It uses a DC-DC pure complimentary OCL circuit with full DC differential amplifiers throughout. The power supply has three transformers - one for each channel plus a separate one for the preamp section - and four big 10,000µF filter caps. The output stage uses new double-epitaxial and triple-diffusion power transistors, and there's a fast protection circuit with a specially structured relay. The phono input is wired directly to the equalizer amplifier, which avoids shielding wire and stray capacitance. It also has a low-cut filter, three-stage tone controls, three-step muting, and outputs for three loudspeaker pairs. The smaller PMA-501 shares the same construction but has two transformers instead of three, smaller 6,800µF caps, no low-cut filter, and standard (not black anodized) heatsinks.
The specs are solid for the era. Power is 70W + 70W into 8Ω and 85W + 85W into 4Ω (rated, both channels driven, 20Hz - 20kHz), with 0.05% THD at rated output. Dynamic output is rated at 220W IHF (110W + 110W into 8Ω). Frequency response extends to 100kHz (+0/-1dB), S/N ratio is 116dB or more (IHF, A-network), and output impedance is 0.16Ω or less.
The original Japanese price was ¥89,800. The unit is 430mm wide, 147mm high and 310mm deep, and it weighs 13kg, which one Russian owner noted is "enough for 70W." Current asking prices in classified listings range from 75,000 to 90,000 rubles. No damping factor or residual noise figures were ever published, and documentation is thin. No service manual has surfaced on the usual archives.
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