Kenwood KA-990SD (circa 1984–1985)
The Kenwood KA-990SD is a SuperDLD integrated amplifier from the mid-1980s. It belongs to Kenwood's 990-series line, which also included the Trio KA-990, KA-990D, and KA-990EX. One Russian seller calls it the best amplifier of the 990 series and warns buyers not to confuse it with its siblings. Production dating is slightly fuzzy: sources say "around 1984" and "Japan, 1985."
The headline feature is the Super DLD (Dynamic Linear Drive) circuit. Conventional DLD designs switch between high- and low-power amplifier stages, each with its own dedicated power supply. The Super DLD adds a "supercharger" that lets the unused high-power supply feed the low-power stage when it's operating. Same efficiency idea, more muscle. The amp also has a CD direct switch that bypasses the input selector, mode, subsonic contact switches, and balance control in the signal path. The Σ drive concept is kept in "Type B" form. It extends the NF loop to the speaker terminals and puts all ground lines at one point on the terminal to cut mutual interference. Kenwood used an ICL High GmFET differential input and an IC-based equalizer amplifier. It even specified the internal grounding wire: 26 strands of 0.26 mm wire, with six times the cross-section of conventional runs.
The figures look very good on paper. Power is 125W + 125W into 6Ω (THD 0.007%) and 105W + 105W into 8Ω (THD 0.004%) from 20 Hz to 20 kHz, with 150W + 150W into 4Ω at 1 kHz. Damping factor is rated at 1000, slew rate at ±100 V/µs, and frequency response runs from DC to 200 kHz (+0/ - 3 dB). Signal-to-noise is 108 dB on line inputs and 88 dB on phono MM. Both MM (2.5 mV/47 kΩ) and MC (0.2 mV/100 Ω) phono stages are built in, and the MC stage accepts up to 15 mV at 1 kHz. It draws 230W and weighs 11.0 kg, in a 440 × 143 × 383 mm chassis. Black and silver finishes were offered.
Documentation is mostly service-manual material. Schematics and manuals circulate among collectors, and the model appears in period parts databases. Market listings show it selling with matching tuners and CD players in Russia for around 43,000 rubles, and in Bulgaria for roughly 330 EUR. One eBay listing offers a unit "for parts or repair." The original price was ¥79,800 (around 1984). No production run or period magazine reviews have surfaced in the record.
- Type: SuperDLD integrated amplifier
- Output: 125W + 125W (6Ω, 20 Hz–20 kHz, 0.007% THD); 105W + 105W (8Ω, 0.004%); 150W + 150W (4Ω, 1 kHz)
- Phono: MM 2.5 mV/47 kΩ; MC 0.2 mV/100 Ω
- S/N: 108 dB (line), 88 dB (MM), 70 dB (MC)
- Damping factor: 1000 (50 Hz)
- Dimensions/Weight: 440 × 143 × 383 mm; 11.0 kg
- Finish: Black and silver
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