Sony APM-8 (1980s)

Name: Sony apm-8
Brand: Sony

Flagship loudspeaker from Sony’s Advanced Polymer Matrix line, featuring square flat diaphragm drivers and a sealed enclosure.

Overview

The Sony APM-8 is a 4-way sealed loudspeaker developed in the 1980s as the flagship model of Sony’s APM (Advanced Polymer Matrix) speaker line. It features a full complement of square flat diaphragm drivers: a 30 cm (12") woofer, 12 cm (5") midrange, 5 cm (2") tweeter, and 2.5 cm (1") super-tweeter. Designed for accuracy and speed, the APM-8 delivers a frequency response from 20 Hz to 50 kHz and is noted for tight, articulate bass and exceptional transient response. The speaker’s performance is highly dependent on amplifier quality and room placement, with some listeners describing the tonal balance as analytical or bright when paired with revealing electronics.

Specifications

Enclosure type	Sealed (acoustic suspension)
Driver complement	4-way
Woofer	30 cm (12") square flat diaphragm
Midrange	12 cm (5") square flat diaphragm
Tweeter	5 cm (2") square flat diaphragm
Super-tweeter	2.5 cm (1") square flat diaphragm
Crossover frequencies	200 Hz, 1 kHz, 8 kHz
Frequency response	20 Hz - 50 kHz
Nominal impedance	6 ohms
Sensitivity	89 dB (2.83 V/1 m)
Power handling	150 W
Dimensions (H x W x D)	750 x 450 x 380 mm (29.5" x 17.7" x 15.0")
Weight	45 kg (99.2 lbs)

Design

The APM-8 uses Advanced Polymer Matrix drivers with flat, square diaphragms constructed from a honeycomb polymer sheet covered with a thin aluminum foil skin. All drivers are flush-mounted to the baffle to minimize diffraction. The cabinet is built from thick particleboard with extensive internal bracing to reduce resonance. The crossover network incorporates high-grade components, including air-core inductors and polypropylene capacitors, and the speaker is equipped with gold-plated multi-way binding posts for secure connections.

Market

A working pair of APM-8 speakers in good cosmetic condition typically sells for $1,500–$2,500 USD on the used market. The foam surrounds on the APM drivers are prone to deterioration over time, requiring replacement. Refoaming is a specialized task due to the drivers’ unique square shape and construction.