Harman Kardon S100M (c. 1980)
The S100M is an unusual one - a bookshelf speaker from around 1980 with a rear-firing ambience driver on a rotating baffle. Documentation is thin, but what survives shows clearly what Harman Kardon was trying to do.
The idea was sound-field control. A 21.1 cm polypropylene cone woofer and a 2.54 cm polypropylene dome tweeter handle the front. A 6.5 cm cone driver sits on a rotating panel on the rear. You can angle that rear driver depending on whether the speaker stands vertically or lies horizontally, and internal faders let you balance the energy between the front and rear speakers to tailor the ambience effect to the room. The enclosure has a walnut wood-grain finish. The Russian listing that surfaced this unit compared the approach to Bose's controlled acoustic field work, though no specific Bose model was named.
Specs are modest: 100W maximum input, 6 Ω impedance, 87dB/W/m sensitivity, 245 × 436 × 230 mm, 8.45 kg. Original price in Japan was ¥49,500 per unit.
Surviving information is thin. No frequency response, crossover point, or production figures have been documented. What is known comes largely from Japanese equipment databases and a single Russian classifieds listing that described the unit as "extremely rare collectible vintage acoustics of the late 70s" in ideal cosmetic and technical condition. A pair surfaced on Yahoo Auctions Japan, and one unit sold on Youla (a Russian marketplace) in April 2022 for 20,000 rubles. The Avito listing from St. Petersburg has since been removed.
Known specs:
- Type: 2-way, 3-speaker, bookshelf
- Woofer: 21.1 cm polypropylene cone
- Tweeter: 2.54 cm polypropylene dome
- Rear ambience driver: 6.5 cm cone on rotating baffle
- Max input: 100W
- Impedance: 6 Ω
- Sensitivity: 87dB/W/m
- Dimensions: 245 × 436 × 230 mm; 8.45 kg
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