Marantz 2640 (1982–1984)

The Marantz 2640 is a solid-state FM/AM receiver made from 1982 to 1984. It listed at $535. It's rated at 45 watts per channel into 8 ohms with 0.02% THD. For its output class it's fairly compact, at 440 × 125 × 343 mm and 9.2 kg.

The FM tuner section is where the documentation gets tangled. HiFi Engine and Hifi-Wiki both describe a quartz PLL synthesizer design. Radio Museum lists a conventional FM/AM dial, and Hifi-Wiki's own spec table also mentions a 5-gang variable capacitor - which can't coexist with PLL tuning. This page leaves the tuning mechanism out of the spec list rather than guess which description is right. The sources do agree on the rest: FM sensitivity of 13.2 dBf mono and 37.2 dBf stereo for 50 dB quieting, signal-to-noise of 76 dB mono / 70 dB stereo, and selectivity of 70 dB. The AM tuning range is documented (530-1600 kHz), but no source gives AM sensitivity figures.

The amplifier specs are cleaner. The phono stage takes MM cartridges at 2.5 mV sensitivity, with 76 dB S/N and 36 dB gain at 1 kHz. There's a CD/AUX input at 150 mV sensitivity, which fits the era, since CD players were just appearing. Also on board are tape in/out with one-way dubbing, a pre-out, and two switched speaker pairs rated for 8-16 ohm loads. Tone controls give ±10 dB at 50 Hz and 20 kHz, and loudness is fixed at +6 dB at 100 Hz. Power consumption is rated at 250 W.

Radio Museum lists an LED signal-strength/center-tuning meter among the front-panel features, which was a notable inclusion for the period. The front panel also carries bass, treble, balance, volume, input selector, speaker A/B switching, loudness, muting, and preset/up-down tuning controls. A single source lists the semiconductor complement as 1 IC, 1 FET, and 10 transistors.

Output: 45 W/ch into 8 ohms, 20 Hz–20 kHz, both channels driven
THD: 0.02%
FM sensitivity (50 dB quieting): Mono 13.2 dBf / Stereo 37.2 dBf
FM S/N: Mono 76 dB / Stereo 70 dB
FM THD: Mono 0.3% / Stereo 0.5%
Selectivity: 70 dB
Dimensions: 440 × 125 × 343 mm; 9.2 kg

No owner commentary, market-reception notes, or common repair issues surfaced in the research. The 2640 appears to have been a straightforward mid-line Marantz receiver of its generation — competently specified on paper, but with little surviving documentation about how it was received or how it holds up today. A period review of a related Marantz product noted the company's professional line was aimed at field recording applications, illustrating the brand's broader market presence at the time EQ Magazine (February 2002, p.104).