Kenwood Model Seven (1958–1959)
The Kenwood Model Seven is one of the earliest integrated amplifiers to put a tube preamp and power amp in a single chassis. It came out at the dawn of the stereo era and was among the first Japanese-made integrated amplifiers sold in the U.S. under the Kenwood brand. Trio Electronics built it in Japan, and it was sold domestically as the Trio Model 7.
It's a push-pull EL84 design with four output tubes (push-pull per channel), and it uses 12AX7 and 12AU7 tubes for preamp/driver duty. The chassis is steel with a brushed brass face, which Vintage Knob describes as a "champagne gold faceplate." Wiring is point-to-point, done by hand throughout. It also used a silicon solid-state rectifier instead of a tube rectifier, which was forward-looking for the late 1950s.
Audio Heritage lists the power output at 15 watts per channel continuous. Other period sources disagree: Classic Audio says 12 watts per channel, and Vintage Knob cites 10 watts RMS. That kind of conflict is typical of early stereo-era marketing. Whichever number is right, this was never a powerhouse, and it was positioned as Trio's entry-level push-pull amplifier. Frequency response was rated at 20Hz to 20kHz with less than 1% THD, a damping factor of 10, and hum and noise at -70dB.
Inputs are Phono (2mV sensitivity), Tuner, Aux, and Tape. Speaker outputs are on 4, 8, and 16 ohm taps, and there are also Tape Out and Preamp Out jacks. Controls are bass and treble tone controls, a loudness switch, balance, input selector, and volume. It measures 14½" W × 6½" H × 10" D and weighs 28 lbs.
The original price was $229.95. Audio Heritage describes the Model Seven as "an excellent example of early Japanese hi-fi construction," and it's often praised for its warm, tube-era sound and build quality. The Trio/Kenwood Model Eight followed in 1959. HiFI-Stereo (August 1975, p.14) noted the Model Seven in a new products column, so the unit was still of interest to enthusiasts well into the 1970s.
No production numbers, current market values, or common maintenance issues are documented in the available record.
- Output: 15W/ch continuous (Audio Heritage); 12W (Classic Audio); 10W RMS (Vintage Knob)
- Tubes: 4× EL84 output, 12AX7 and 12AU7 preamp/driver
- Frequency response: 20Hz–20kHz, THD under 1%
- Inputs: Phono, Tuner, Aux, Tape; speaker taps 4/8/16 ohms
- Dimensions: 14½" W × 6½" H × 10" D; 28 lbs
- Price: $229.95
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