Kenwood KA-990V (1985)
The Kenwood KA-990V is a heavyweight integrated amplifier from the mid-1980s. It weighs 13.9 kg, which says plenty about the transformer and heatsinking inside before you read a spec. It was released in 1985 at ¥79,800. It comes from the period when Kenwood was taking the high-end Σ drive technology from its flagship L-02A and putting it into more attainable components.
The technical headline is the VIG / DLD circuit. The VIG (Voltage Isolation Ground) stage sits between the power supply and the amplifier stage and is designed to block power-supply noise from reaching the amp. It presents low impedance toward the amplifier side and high impedance toward the supply. The power supply backs it up with a large transformer that has extra laminated core material and lower winding impedance, plus four 10,000 µF Chemi-Con filter capacitors. The equalizer section gets its own dedicated winding. The output stage uses discrete high-performance transistors.
It also uses what Kenwood called "Σ drive typeB," a refinement of the Σ drive topology from the L-02A. Here the negative feedback loop extends all the way to the speaker terminals, which puts the parts that cause distortion and coloration inside the feedback loop. All ground lines converge at a single point on the speaker terminals to suppress mutual interference. Kenwood also applied vibration analysis to the chassis design, aiming to avoid resonance from speaker sound pressure or floor vibration.
On the front panel, the KA-990V has eight inputs, including the then-new CD and Tape-C positions. A CD direct switch bypasses the input selector, mode switch, subsonic filter contacts, and balance control to shorten the signal path for digital sources. The three tape loops (A, B, C) allow dubbing in any direction - A→B/C, B→A/C, C→A/B - and you can record from the same source to two decks at once.
The specs are strong for the era. Rated output is 110W + 110W into 8Ω (THD 0.004%) and 130W + 130W into 6Ω (THD 0.006%), with 1kHz figures of 115W into 8Ω and 155W into 4Ω. Frequency response runs from 1 Hz to 180 kHz (+0/-3 dB), damping factor is 1000 at 50 Hz, and slew rate is rated at ±100 V/µs. The phono stage handles both MM (2.5 mV/47kΩ) and MC (0.2 mV/100Ω) cartridges, with RIAA accuracy of ±0.3 dB. Signal-to-noise is 108 dB on line inputs, 88 dB phono MM, and 70 dB phono MC. Tone controls give ±10 dB at 100 Hz and 10 kHz, and there's a subsonic filter at 18 Hz (6 dB/octave).
Documentation on this model is thin. There's no surviving period magazine review in the Archive's collection, and owner opinions are limited to sales listings. One Polish seller called it "the ideal stereo amplifier," and a Dutch listing praised its stable power supply and extremely low distortion. Production years are variously given as 1985-86, 1985 only, and 1986-87. The 1985 launch date is the best-supported. If you own one and have the owner's manual or service literature, the Archive would welcome it.
Known specifications, in brief:
- Output: 110W + 110W (8Ω, 20 Hz–20 kHz, THD 0.004%); 130W + 130W (6Ω); 155W + 155W (4Ω at 1 kHz)
- Frequency response: 1 Hz–180 kHz (+0/−3 dB)
- Damping factor: 1000 (50 Hz)
- S/N ratio: 108 dB (line), 88 dB (MM), 70 dB (MC)
- Phono: MM 2.5 mV/47kΩ; MC 0.2 mV/100Ω
- Dimensions: 440 × 158 × 420 mm; 13.9 kg
- Original price: ¥79,800
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