Kenwood LS-990AD (1986)
The Kenwood LS-990AD is a three-way, three-speaker bookshelf system introduced around 1986 at ¥59,800 per unit. It belongs to Kenwood's LS series and carries that line's technology, plus the company's plasma diamond diaphragm. That is diamond ion-plated onto a titanium base, and Kenwood used it for both the tweeter and the midrange dome.
The driver lineup is big for a bookshelf design. The woofer is a 33 cm cone with a reinforced carbon cone and a large strontium magnet. The midrange is a 10 cm semi-dome with a three-layer sandwich cone. The tweeter is a 2.5 cm hard dome. Kenwood rated the system at 200W (EIAJ) maximum input, 6 Ω impedance, and 92 dB/W/m sensitivity, with a claimed frequency range of 28 Hz to 47 kHz. Crossovers sit at 600 Hz and 5 kHz. The cabinet measures 355 × 671 × 321 mm and weighs a hefty 22 kg. All three drivers use what Kenwood called a Class A suspension. The crossover network is split onto separate boards per driver to minimize interference, with independent ground lines for the network and the drivers.
Documentation on this model is thin. A Russian owner paired the LS-990AD with a Kenwood KA-1100D amplifier and reported being satisfied with the sound, though he had replaced the crossover filters. That suggests the originals may be a weak point with age. One Japanese listing notes the LS-990AD cost 5,000 yen more than the related LS-990A/AD/D/HG variants, but the relationships between those models aren't documented. No production end date, market values, or common failure information beyond the crossover work has surfaced.
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