Kenwood KA-4002

A 42-watt entry point into Kenwood's late-seventies lineup. It does best with the loudness engaged.

Overview

The KA-4002 was the gateway model, the one Kenwood hoped would pull budget-conscious listeners into the brand. At 42 watts per channel into 8Ω, it had enough power to make that work. That's not headline-grabbing output for the era, but it's usable, and it drives a wide range of speakers. The 4 to 16Ω output impedance range gives owners more flexibility than entry-level units often had.

The KA-4002 weighs 8 kg (17.6 lbs) and measures 420 x 146 x 270mm. The chassis is a straightforward late-seventies Kenwood design, with controls laid out for daily use. Inside is a Class AB amplifier with an FET-based phono stage, and the whole package draws 130W from the wall. Production ran from 1976 to 1980 according to most sources, though some documentation suggests a 1975 start. The discrepancy is minor.

Kenwood sold this unit in Europe under the Trio badge, where it carried a 1977 price of 259 Deutsche Mark (approximately $132.50). In the US the asking price was reportedly higher at $299.95, though the exact figure is harder to pin down. A 1971 advertisement in HiFI-Stereo (September 1971, p.19) promoted the KA-4002 as an 80-watt (IHF) stereo amplifier with a price of $139.95.

Key Features

42W/ch Class AB Output Stage

The amplifier section delivers 42 watts per channel into 8Ω, which is plenty for most home setups. Total harmonic distortion sits at 0.3%, respectable for the era and still listenable today. The Class AB topology keeps heat manageable and gives clean output through the midrange, where this amp does its best work. Owners consistently describe the sound as warm with a slight mid-forward character, a voicing that suits jazz and vocals.

FET-Based Phono Stage

The phono section is built around FETs. It accepts moving magnet cartridges only, with an input sensitivity of 2.5mV, and delivers a signal-to-noise ratio of 72dB on the MM input. That's not reference-grade quiet, but it's clean enough for daily listening, and owners describe the FET front end as acceptable for MM cartridges. The line inputs are quieter at 90dB S/N, and the 150mV line sensitivity makes the KA-4002 easy to match with nearly any source from the period.

Loudness Control with a Purpose

Owner reports consistently note that the bass is a bit soft at low volume. The loudness circuit exists to fix exactly that. Engage it when listening quietly and the low end firms up considerably. Leave it off at higher volumes and the amp's natural balance takes over.

Flexible Input/Output Arrangement

The KA-4002 offers inputs for Phono, Tuner, Aux, Tape 1, and Tape 2, with recording outputs for both tape decks. Two tape loops meant you could dub between decks or keep a dedicated processor in the chain. Two tape monitors were usually reserved for higher-end models.

Historical Context

The KA-4002 was introduced as the entry-level model in Kenwood's 1976 lineup, positioned below the KA-6002 and KA-8002. Being the budget option didn't mean being stripped down. Kenwood gave it the same design philosophy as its bigger siblings, just with less power and fewer frills.

In Europe, the same unit appeared as the Trio KA-4002, a badge that carried weight in markets where the Trio name was better established. The 1977 German price of 259 DM positioned it competitively against the Japanese rivals entering the European market at the time.

Production dates are a point of mild contention among collectors. Most sources cite 1976 to 1980, though hifi-wiki lists 1975 to 1978. The earlier date possibly reflects European availability ahead of the US launch.

Collectibility & Value

The used market for the KA-4002 is accessible. Units in decent condition routinely sell for €80 - €150 depending on condition and location, which makes this one of the more affordable ways into vintage Kenwood ownership. The pricing reflects that it's a working amplifier, not a collector's trophy piece.

At that price, expect to do some work. The most common issues are aging capacitors and scratchy pots and switches, the standard complaints for any amplifier of this vintage. Owners recommend replacing the electrolytic capacitors as a matter of course, and recapping is frequently mentioned as the single most impactful maintenance step. Some units surface as "for parts not working" due to blown output transistors. That's a more serious repair, but not necessarily a dealbreaker for someone comfortable with a soldering iron.

One owner described the sound as "warm with a slight mid-forward character; good for jazz and vocals," with a "natural, dynamic timbre with a slightly dark treble." The preamplifier section is reportedly clean, while the phono stage is described as "acceptable for MM carts." Owners suggest pairing it with efficient speakers and a good moving magnet cartridge.

For the buyer willing to do basic maintenance, the KA-4002 represents one of the better values in vintage integrated amplifiers. It's cheap to acquire, straightforward to service, and delivers a sound that punches well above its price point — provided you remember to engage the loudness when the volume drops.