Marantz ST320 (1982–1984)
The Marantz ST320 is a slimline FM/AM analogue tuner from the early 1980s. It was sold alongside a long-wave variant, the ST320L, aimed at European markets where LW broadcasting still mattered. Both are Japanese-built and date to roughly 1982-1984. The "L" suffix is generally read as "long wave," but no source states that outright. It's an inference, not a documented fact.
The service literature is the most solid part of the record. The Marantz service manual covers the ST320 and ST320L together. It lays out the chassis as a set of plug-in boards: a main tuner board, a selector switch board, a muting/mode switch board, a power switch board, an LED board, and a de-emphasis board. That last one is marked "ST320 Only," which suggests the L variant handled de-emphasis differently. The manual also documents the alignment procedures for FM, the muting circuit, the multiplex section, and AM. It specifies the bench gear Marantz expected a warranty station to have on hand: a Sound Technology 1000A FM/MPX generator, a 1700A distortion analyzer, a Tektronix T932 or Philips 3232 scope, a Fluke 1900A frequency counter, and a Simpson 1379 AC wattmeter, among others.
On specifications, the record is thinner than it looks. The base ST320's published figures are patchy — most of the hard numbers in circulation belong to the ST320L, which Audio Trader lists at 2.0 µV sensitivity, 66 dB signal-to-noise, 0.35% distortion, 65 dB selectivity, and a 30 Hz–15 kHz frequency response, covering FM 87.5–108 MHz, MW 525–1605 kHz, and LW 150–350 kHz. Those are the L's numbers, not necessarily the base model's, and shouldn't be read across. What's consistent between the two is the physical package: a compact, low-profile chassis weighing 2.4 kg, with an illuminated dial window, a weighted tuning dial, and LED tuning aids on the front panel. Owners describe the dial action approvingly, and the tuner turns up on the secondhand market with some regularity, frequently from European sellers — unsurprising given the LW variant's market. Expect parts units as often as working ones; that's normal for a forty-year-old tuner.
Several things aren't documented: no period review, no confirmed original price, no circuit topology beyond the board layout in the manual, and no reliable account of common failure modes. If you own one and can add to any of that, the archive would be glad to hear it.
- Type: Slimline FM/AM analogue tuner; ST320L adds LW
- Years: c. 1982–1984
- Bands (ST320L): FM 87.5–108 MHz; MW 525–1605 kHz; LW 150–350 kHz
- ST320L specs (Audio Trader): 2.0 µV sensitivity; 66 dB S/N; 0.35% distortion; 65 dB selectivity; 30 Hz–15 kHz
- Weight: 2.4 kg
- Front panel: Illuminated dial window, LED tuning aids, weighted tuning dial
- Service manual: Covers ST320/ST320L; full alignment and board-level documentation
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