Kenwood LS-550 (circa 1986)

At 8.5 kg and nearly half a meter tall, these bookshelf speakers were big for the class, and they cost ¥55,000 in 1986.

Overview

The Kenwood LS-550 speaker system came out around 1986 as a high-fidelity bookshelf design. It sold for ¥55,000 per pair at launch, which put it in the mid-tier of Japan's booming hi-fi market. It's a bookshelf speaker in name only. Each one stands 480 mm tall and weighs 8.5 kg. The design is 3-way with 3 speakers, so each driver handles its own band, which cuts intermodulation and improves clarity.

Kenwood fitted the LS-550 with a 22 cm cone-type woofer using a polypropylene (PP) cone. That material reportedly adds rigidity and reduces cone breakup at higher excursions, which helps tighten the bass in a bass reflex design. The enclosure is symmetrical, which may help reduce internal standing waves and panel resonance, and it has a reflex port for extended low-frequency output. The speaker is also magnetically shielded, so it can sit near CRT televisions without color distortion. That made it handy for TV-audio setups.

Frequency response runs from 35 Hz to 25 kHz, which is wide bandwidth for a bookshelf model of its time. Whether real-world performance reaches 35 Hz depends on room placement and the amplifier. Sensitivity is rated at 90dB/W/m, so the speakers are reasonably efficient and work with a wide range of amplifiers, including modestly powered receivers. Nominal impedance is 6 Ω, a manageable load for most solid-state and many tube amps. Owners should still watch for impedance dips near the crossover points.

Crossover frequencies are 5 kHz and 10 kHz, dividing the work between the 5 cm semi-dome midrange and the 2.5 cm dome tweeter. A semi-dome midrange suggests a balance between dispersion and directivity, and it may give smoother off-axis response than a pure cone. The tweeter is small but is tasked with reaching 25 kHz. That is likely more about headroom and transient response than audible ultrasonic output. A level control is included, presumably to adjust tweeter or midrange output for the room or the listener. Speakers at this level don't always have one.

Specifications

Manufacturer	Kenwood
Model	LS-550
Product type	Speaker system
Original price	¥ 55,000 (per pair, circa 1986)
Configuration	3-Way, 3-Speaker, Bass Reflex, Bookshelf Type
Woofer	22 cm cone type
Midrange	5 cm semi-dome type
Tweeter	2.5 cm dome type
Frequency response	35 Hz to 25 kHz
Maximum input power	150W
Nominal impedance	6 Ω
Sensitivity	90dB/W/m
Crossover frequencies	5 kHz, 10 kHz
Dimensions (W x H x D)	270 x 480 x 216 mm
Weight	8.5 kg

Key Features

22 cm PP Cone Woofer for Enhanced Rigidity

The 22 cm cone-type woofer uses a polypropylene (PP) cone, a material increasingly favored in the 1980s for its stiffness-to-mass ratio and damping. This reportedly reduces cone flex and breakup, giving cleaner bass and better transient response. Combined with the bass reflex enclosure, the woofer aims for a deep, controlled low end from a bookshelf footprint.

Magnetic Shielding for CRT Compatibility

Kenwood included magnetic shielding in the LS-550, which helps anyone using the speakers in a video setup. They can sit near CRT televisions without distorting the picture. That was a small but useful detail in the mid-1980s, as audio and video were coming together in home entertainment.

Symmetrical Bass Reflex Enclosure

The cabinet is a symmetrical bass reflex design, which may help balance internal pressure distribution and reduce cabinet-induced coloration. The reflex port improves low-frequency efficiency and extends bass below what a sealed enclosure of similar size could manage. The exact tuning frequency isn't documented, but the claimed 35 Hz lower limit suggests a relatively deep alignment.

Level Control for Tonal Adjustment

The LS-550 has a level control, likely for the high or mid frequencies, to match the speaker to room acoustics or personal preference. This is uncommon in similarly priced bookshelf models of the era and suggests Kenwood expected varied installation environments.

Collectibility & Value

The Kenwood LS-550 was priced at ¥55,000 per pair around 1986. Used units show up regularly on secondhand markets, including eBay, Facebook, and over 400 used hi-fi sites tracked by Hifi Shark. No current market prices are documented, and there is no information on common failures or maintenance requirements. Original manuals, including owner's, service, and brochure materials, are reportedly available in digital form through enthusiast networks, which may help with servicing and restoration.