Kenwood KA-8100 (1978)
A high-speed DC integrated amplifier from Kenwood’s classic KA series, built with dual power supplies and precision phono stage circuitry.
Overview
The Kenwood KA-8100 is a DC-coupled integrated amplifier released in 1978 by Trio-Kenwood. It features a straight DC signal path with no capacitors in the low-frequency circuitry, designed for accurate audio reproduction. This model supports both moving magnet and moving coil phono inputs, with a dedicated low-noise MC head amplifier. It was part of the export-focused x100 series and positioned as a slightly less powerful sibling to the flagship KA-9100, sharing much of its high-quality construction.
Specifications
| Type | Integrated amplifier |
| Rated output (RMS, both channels, 8Ω, 20Hz–20kHz) | 75 watts per channel |
| Rated output (RMS, both channels, 4Ω, 20Hz–20kHz) | 90 watts per channel |
| Total Harmonic Distortion (at rated output, 8Ω, 20Hz–20kHz) | 0.08% |
| Total harmonic distortion (Tuner/Aux/Tape, 8Ω, 1kHz at rated output) | 0.004% |
| Total harmonic distortion (Tuner/Aux/Tape, 8Ω, 20Hz–20kHz at 1/2 rated output) | 0.01% |
| Total Harmonic Distortion (at 1 watt output, 20Hz–20kHz) | 0.008% |
| Cross modulation distortion factor (Tuner/Aux/Tape, at rated output) | 0.004% |
| Frequency Response (Aux, DC on) | 5Hz to 100kHz, +0 -1dB |
| Output Bandwidth (IHF, 8Ω at 0.03% distortion) | 5 Hz ~ 40 kHz |
| Damping Factor (8 Ω) | 50 |
| Input Sensitivity / Impedance Phono MM | 2.5mV/47k ohms |
| Input Sensitivity / Impedance Phono MC | 0.1mV/100 Ω |
| Input Sensitivity / Impedance (Tuner, Aux, Tape) | 150mV/47k ohms |
| Signal-to-noise ratio (IHF-A) Phono MM (2.5 mV input) | 80dB |
| Signal-to-noise ratio (IHF-A) Phono MC (0.1 mV input) | 68 dB |
| Signal-to-noise ratio (IHF-A) Tuner/Aux/Tape | 100dB |
| Tone Control Bass | ±10dB at 100Hz |
| Tone Control Treble | ±10dB at 10kHz |
| Loudness Control (volume at -30dB) | +6dB at 100Hz, +3dB at 10kHz |
| Transient response Rise time | 0.9 μs |
| Transient response Slew rate | ± 110 V / μ s |
| Phono maximum allowable input MM (1 kHz, 0.01% distortion) | 220 mV |
| Phono maximum allowable input MC (1 kHz, 0.01% distortion) | 8 mV |
| Phono RIAA deviation | 20 Hz to 20 kHz ± 0.3 dB |
| Output Level / Impedance (Tape rec) | 200mV/120 Ω |
| Subsonic Filter | 18Hz, 12dB/oct. |
| Power outlets (switched) | 2 |
| Power outlets (unswitched) | 1 |
| Power supply voltage | 100 VAC, 50Hz/60Hz |
| Rated power consumption | 150W |
| External dimensions | 440 x 150 x 370mm |
| Weight | 15.5kg |
Design
The KA-8100 uses a high-speed DC amplifier configuration with no low-frequency cut capacitors in the signal path or feedback loop. It features dual power supplies for left and right channels, each with a large transformer and four 6,800μF capacitors, plus a separate regulated supply for the preamplifier stage. The MC phono input uses a complementary push-pull circuit with a low-noise transistor first stage. The design includes an attenuator-type volume control with gain and loudness controls, and ensures clear separation between high-current and low-current circuit areas.
Product Family
The Kenwood KA-8100 was part of the export-only x100 series, which included the KA-9100, KA-7100, and KA-6100. It was a smaller sibling to the flagship KA-9100, offering slightly lower power but similar build quality and circuit design.
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