Kenwood KA 9900 (1978)
A high-power integrated amplifier from Kenwood/Trio, released in 1978. It has a DC-coupled design and exceptional measured performance.
Overview
The Kenwood KA 9900, also known as the TRIO KA-9900, is an integrated amplifier from Kenwood/Trio, released in 1978. It pairs a high-power amplifier section with advanced preamplifier circuitry, built for low distortion and wide bandwidth. It is a variant of the Kenwood KA-907, specifically the "Trio KA-9900 Japan execution," which reflects its regional specification.
Specifications
| Exact product name | TRIO KA-9900 |
| Manufacturer | TRIO |
| Product type | Integrated amplifier |
| Released in | 1978 |
| Original price | ¥ 200,000 |
| Rated output (8 Ω) | 150W + 150W (20 Hz to 20 kHz) |
| Rated output (4 Ω) | 180W + 180W (1 kHz) |
| Total harmonic distortion (8 Ω) | 0.01% (20 Hz to 20 kHz at rated output, Vol-20dB) |
| Total harmonic distortion (8 Ω) | 0.004% (1 kHz at rated output) |
| Frequency response (DC on) | DC ~ 400 kHz -3dB |
| Frequency response (DC off) | 1 Hz ~ 400 kHz -3dB |
| Output bandwidth (IHF) | 5 Hz to 100 kHz (8 Ω, 0.03% distortion) |
| Damping factor | 100 (8 Ω, DC to 20 kHz) |
| Input sensitivity / impedance (Phono MM) | 2.5mV / 33k, 47k, 100k Ω |
| Input sensitivity / impedance (Phono MC) | 0.1mV / 100 Ω |
| Input sensitivity / impedance (Tuner, Aux, Tape) | 150mV / 50k Ω |
| Signal-to-noise ratio (IHF-A, Phono MM) | 90 dB |
| Signal-to-noise ratio (IHF-A, Phono MC) | 70 dB |
| Signal-to-noise ratio (IHF-A, Tuner/Aux/Tape) | 105 dB |
| Tone control (Bass) | ±7.5 dB (150 Hz, 75 Hz) |
| Tone control (Treble) | ±7.5 dB (10 kHz, 20 kHz) |
| Loudness control | +3 dB, +6 dB, +9 dB |
| Rise time | 0.8 μs (Tuner, Aux, Tape → SP) |
| Slew rate | ±230 V/μs (Tuner, Aux, Tape → SP) |
| Phono RIAA deviation | ±0.2 dB (20 Hz to 20 kHz) |
| Output level / impedance (Tape rec) | 150mV / 180 Ω |
| Output level / impedance (DIN) | 30mV / 80k Ω |
| Output level / impedance (Pre out max) | 9V / 750 Ω |
| Power amplifier THD | 0.005% (rated output, 20 Hz to 20 kHz, 8 Ω) |
| Power amplifier S/N ratio | 110 dB (IHF-A) |
| Power amplifier input sensitivity / impedance | 1.0V / 50k Ω |
| Power amplifier rise time | 0.6 μs |
| Power amplifier slew rate | ±230 V/μs |
| Power outlets | 2 systems (power switch interlock) |
| Power supply voltage | 100 VAC, 50Hz/60Hz |
| Rated power consumption | 400W |
| Colour | Silver |
| External dimensions | 460 x 161 x 463 mm |
| Weight | 25.8kg |
Design
The KA 9900 combines DC amplifier and high-speed amplifier technologies. It uses TRIO's original straight DC amplifier design, with no low-frequency cut capacitor between the Tuner (Aux) input and the speaker terminal. The MC phono stage is DC-configured, with an all-stage complementary push-pull circuit and parallel low-noise transistors in the first stage. The equalizer amplifier is a cascode differential design with ultra-low-noise FETs and a current mirror, which keeps gain high without degradation. The volume control is a four-connected conductive plastic type, for smooth operation and a better S/N ratio. The tone control uses TRIO's NF-CR circuit with ultra-low-noise ICs, giving linear, phase-correct adjustment. The power amplifier is DC-coupled with three differential stages, a cascode FET input, current mirror loads, and super linear transistors in parallel for high output and low distortion. Dual power transformers and four 18,000 μF capacitors feed the left and right channels separately, which reduces dynamic crosstalk. Separate windings and a constant voltage supply serve the preamp and tone sections.
Market
A working Kenwood KA 9900 was listed for $400 by an established dealer, shipping included. That suggests a current market value in that range for functional units.
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