Kenwood KA-907 (1979–1980)

At 25.8 kg, it doesn’t just sit on the shelf—it stakes a claim.

Overview

The Kenwood KA-907 isn’t an amplifier so much as a declaration. Built during the final surge of Kenwood’s “monster” period, it represents the brand’s most ambitious foray into high-end integrated design—a last, full-throated statement before the market pivoted toward compact separates and digital sources. Marketed as a High Speed DC Integrated Amplifier, the KA-907 was engineered to eliminate every trace of signal path compromise, from input to output. Owners report it was assembled with a level of internal rigor rarely seen in an integrated unit: dual mono construction, discrete all-DC circuitry, and a power delivery system that borders on overkill. It wasn’t just meant to compete with the elite from Accuphase, Luxman, and Yamaha—it was meant to out-engineer them.

Despite its integrated form, the KA-907 functions more like a preamp/power amp combo in disguise. The design isolates left and right channels completely, with independent power supplies, massive transformers, and FET-based Class A driver stages. This isn’t subtle engineering—it’s brute-force precision. The front panel, all aluminum with a semi-matte “frosted” texture, signals a shift in Kenwood’s aesthetic language, introducing angular knobs and switches that feel more surgical than decorative. This is gear for people who believe that if you can’t measure it, you shouldn’t hear it.

Specifications

Key Features

Dual Mono Design with Independent Power Supplies

The KA-907 doesn’t merely claim dual mono construction—it enforces it. Each channel runs off its own regulated power supply, fed by what owners describe as “two massive” transformers. Four 18,000µF capacitors provide reservoir capacity that rivals standalone power amps of the era. This isn’t just about power headroom; it’s about preventing any crosstalk or channel interaction, even under dynamic load. The result is a soundstage with exceptional focus and separation, where instruments don’t bleed into one another, even at high volumes.

All-DC FET/Class A Pre and Driver Circuitry

True DC coupling extends from input to output, eliminating coupling capacitors that can color or slow the signal. The preamp and driver stages use FETs in Class A configuration, minimizing crossover distortion and ensuring linearity across the entire dynamic range. This contributes to the amplifier’s famously low THD and IMD figures, but more importantly, it delivers a sense of immediacy—transients arrive without hesitation, and decay trails fade into true silence. The design philosophy is clear: remove every obstacle between the source and the speaker.

Four-Parallel-Pair Output Stage with High-Speed Transistors

The output stage uses four parallel pairs of 2SA165 and 2SC2489 transistors—high-speed devices rated at 50MHz—configured with cascode bootstrap, current mirror, and constant current drivers. This isn’t just about power; it’s about control. The high damping factor of 100 ensures tight grip over speaker cones, especially with demanding loads. Bass is not just deep but articulate, with punch that doesn’t blur into bloat. The slew rate of ±230V/µs means the amplifier can track even the fastest musical transients without smearing.

Discrete, Symmetrical MC and MM Phono Stages

The phono section is a standout, especially for an integrated amp. The MC stage employs a three-stage symmetrical complementary circuit with low-noise transistors in the first stage, followed by a common emitter and emitter follower. Negative feedback links the first and third stages, while supplementary feedback from the second stage is applied to the first, reducing distortion and output impedance. The MM stage uses a DC-coupled FET input, offering high overload capability and excellent signal-to-noise performance. Both stages are fully discrete, avoiding ICs in favor of precision-matched components.

ALPS Conductive Plastic 4-Gang Motorized Attenuator

The volume control is a high-grade ALPS conductive plastic 4-gang potentiometer, motorized for remote operation. Two gangs are placed on either side of a buffer amplifier to improve linearity and reduce distortion at low listening levels. While owners report the motorized mechanism can develop noise over time, the core potentiometer itself is robust. When functioning properly, it delivers smooth, precise attenuation with minimal channel imbalance.

Frosted Aluminum Front Panel and Industrial Aesthetic

The KA-907 marks the beginning of Kenwood’s “frosted” design language—thick aluminum front panel with a semi-matte texture, angular knobs, and flush-mounted switches. It’s a stark departure from the brushed finishes and rounded controls of earlier models. This isn’t just cosmetic; the chassis is engineered for rigidity, minimizing microphonics and vibration. The build quality is industrial-grade, with a heatsink mass that suggests this unit was built to run hard, not just look good on a shelf.

Historical Context

The KA-907 arrived in 1980 as Kenwood’s flagship integrated amplifier, positioned as the ultimate expression of their analog engineering prowess. It shares significant design DNA with the earlier Model 600 series, effectively serving as a refined, updated version of that platform. The amplifier, along with the KT-917 tuner, represented a final, high-water moment before Kenwood shifted focus. Its production run was brief—1979 to 1980—and quantities were limited. A European variant, reportedly only 100 units, featured gold trims and knobs, distributed primarily in Germany. Collectors note this was the last of Kenwood’s “monster” amplifiers—overbuilt, uncompromising, and technically audacious.

Collectibility & Value

The KA-907 is considered one of the finest integrated amplifiers of its era, and its rarity amplifies demand. Due to aging components, particularly electrolytic capacitors in the power supply and protection circuits, fully functional units in original condition are uncommon. The motorized volume control is another known failure point, often requiring cleaning or replacement. Restoration is possible but labor-intensive, given the amplifier’s complexity and dense layout. Despite these challenges, working examples command strong prices, with collectors valuing its combination of performance, build quality, and historical significance. No original pricing data is available, but current market interest remains high, with owners noting difficulty finding units even on secondary markets.

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• Akai AM-2850 (1975)
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