Kenwood LS-X700 (1987)

At 13 kilograms and with a 27 cm woofer crammed into a bookshelf footprint, this Japanese oddball means business - even if its ambitions outpace its category.

Overview

The Kenwood LS-X700 was released in 1987 as part of a domestic-market LS-X series. It's a 3-way, bass reflex speaker system built to deliver dynamic low end and extended highs. Kenwood marketed it as a bookshelf model, but its 530 mm height and 13 kg mass say it was never meant for actual shelves. Dedicated stands or heavy-duty furniture are more like it. The design is late-'80s Japanese engineering maximalism: overbuilt drivers, exotic materials, and magnetic shielding for CRT-era TV compatibility, all in a utilitarian enclosure with rounded baffles to minimize diffraction.

Kenwood positioned the LS-X700 as a technically advanced speaker for audiophiles chasing transient speed and frequency extension. The 27 cm cone woofer dominates the front baffle, flanked by a 10 cm midrange and topped by a 2.5 cm hard dome tweeter. It isn't balanced elegance. It's a front-loaded assault on what a passive bookshelf speaker could attempt in the analog-digital transition era. The specs are 30 Hz to 40 kHz playback, 91 dB/W/m sensitivity, and a 160 watt (EIAJ) power handling rating. Behind the numbers is a design that prioritizes measurable performance over tonal refinement, which was common among Japanese high-end models of the period that aimed to out-spec the competition.

Specifications

Key Features

27 cm Woofer with HR Carbon Diaphragm

The most striking feature is the oversized 27 cm low-frequency driver, unusually large for a bookshelf format. It uses a "New HR carbon diaphragm," a proprietary Kenwood material touted for excellent transient response and high propagation speed. The goal was a "sharp rising sound," which suggests an emphasis on attack and clarity over warmth or bloom. The material's real-world performance is undocumented beyond promotional claims. The carbon fiber hints at a move toward stiffness and low mass, in line with contemporary high-end trends.

Dual Magnetic Circuit & Voice Coil Structure

Kenwood used an unconventional motor system where the voice coil operates within two magnetic circuits formed by dual magnets. Two voice coils are wound to match two timing gaps, and their outputs are "effectively added." This push-pull-like setup aims to reduce distortion and improve control, particularly in the critical mid-bass region. Whether it gives measurable linearity or just added complexity remains unverified.

Class A Suspension System

Kenwood's "original Class A suspension" uses two suspensions that cancel each other's non-linear distortion, theoretically ensuring linear diaphragm motion. This dual-suspension approach is rare and mechanically intricate, likely increasing production cost and potential failure points. The principle is sound, since opposing non-linearities can yield net linearity, but real-world durability and alignment sensitivity are unknown. No reports confirm long-term reliability. The design clearly prioritizes theoretical performance over serviceability.

2.5 cm Plasma Diamond Dome Tweeter

The high-frequency driver is arguably the most audacious part of the LS-X700: a 2.5 cm hard dome tweeter with a "plasma diamond diaphragm." According to documentation, this is a composite material with titanium ion-plated onto a diamond surface, offering high rigidity, no resonance peak, light weight, and good heat dissipation. The claim of "no resonance point" is extreme, since all physical diaphragms resonate. The material likely pushes breakup modes well beyond 40 kHz. Whether that gives smoother in-band performance or merely shifts problems higher is undocumented.

Push-Pull Tangential Edge Design

The tweeter's edge uses a "push-pull tangential edge" to maintain linearity across signal levels. This likely refers to a dual-roll surround or symmetrical suspension that resists deformation under excursion, improving performance at both low and high volumes. It's another case of Kenwood applying mechanical fixes to linearity problems. The actual sonic benefits are speculative without listening reports or measurements.

Separated Crossover Network & Round Baffle

The crossover network is physically separated, possibly meaning components are isolated or housed independently, to reduce mutual interference. This suggests Kenwood was concerned about electromagnetic crosstalk or thermal drift affecting performance. The enclosure uses rounded baffles to minimize edge diffraction, a well-understood acoustic benefit that smooths off-axis response. Unlike many boxy Japanese designs of the era, this points to a more sophisticated approach to baffle geometry, even if the overall form remains utilitarian.

Collectibility & Value

The LS-X700 launched in 1987 at ¥39,800 per unit in Japan. Current market activity is sparse. Limited auction data suggests used pairs trading at low levels, with bids as low as 7,000 to 13,111 yen for a pair on Japanese resale platforms. Whether these are actual sale prices or just starting bids is unclear. Replacement parts are occasionally listed, including a dedicated woofer (KENWOOD/ケンウッド LS-X700用ウーファー T10-0310-03), so some serviceability remains possible. No widespread reputation for failure modes or maintenance issues has emerged, likely due to limited ownership outside Japan and an absence of user reviews.

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