Marantz PM420 (1982)
The Marantz PM420 is a compact pre-main (integrated) amplifier released in 1982, originally priced at ¥45,800 in Japan. The documented record on this model is thin — nearly everything known comes from a single database entry plus scattered owner reports and classified listings. What the record does show is a modest, well-featured amplifier of the early 1980s, rated at 35W + 35W into 8Ω (20 Hz–20 kHz) with total harmonic distortion of 0.025% at rated output. Frequency response is listed at 10 Hz to 40 kHz ±1 dB. The phono stage accepts 2.5mV at 47kΩ, and there is also a mic input (0.3mV/10kΩ) — an unusual inclusion on an integrated amp of this class. Signal-to-noise on phono (IHF-A) is rated at 80dB, and power consumption at 110W. Physically it is a compact unit: 416mm wide, 73mm high, 300mm deep, weighing 5.7kg.
One period database describes the PM420's "fantastic LED display" as allowing you to check all functions at a glance. It came in two finishes, gold and silver. Owners report a quirk: the volume buttons drive a small motor that turns the potentiometer, instead of a conventional direct-control knob. Motorized volume was something of a Marantz signature of the era. That mechanism has proven to be a common failure point. At least one owner on a repair forum (June 2024) reported volume control issues, and another reported that only one of the four speaker outputs worked, with the headphone output likewise dead on one side.
Current used-market prices vary widely. Listings observed include $164, €120 (Kleinanzeigen, 2023), €240 (a Swedish hifi dealer), and 350 lei in Romania. One price-aggregation site estimates a €95 median based on 17 listings, though that figure should be treated with caution. The PM420 is often found paired with period Marantz tuners. The ST320L, ST 430L, and ST 521L have all appeared alongside it in bundle listings, though no official pairing is documented. Service manuals and schematics do circulate among collectors.
Known Specifications
- Rated output: 35W + 35W (8Ω, 20 Hz–20 kHz)
- THD: 0.025% (8Ω, rated output)
- Frequency response: 10 Hz–40 kHz ±1 dB
- Input sensitivity/impedance: Phono 2.5mV/47kΩ; Tuner/Aux/CD/Tape 150mV/27kΩ; Mic 0.3mV/10kΩ
- Phono S/N (IHF-A): 80dB
- Power consumption: 110W
- Dimensions: 416 × 73 × 300 mm (W×H×D); weight 5.7kg
- Finished in gold or silver; LED function display; motorized volume control
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