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 from the 1980s. It was the flagship of Sony's APM (Advanced Polymer Matrix) line. Every driver has a square flat diaphragm: a 30 cm (12") woofer, 12 cm (5") midrange, 5 cm (2") tweeter, and 2.5 cm (1") super-tweeter. Frequency response runs from 20 Hz to 50 kHz. The bass is noted as tight and articulate, and the transient response as exceptional. The speaker depends heavily on amplifier quality and room placement. Some listeners call the tonal balance analytical or bright when it is 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 drivers use flat, square diaphragms made from a honeycomb polymer sheet covered with a thin aluminum foil skin. All of them are flush-mounted to the baffle to minimize diffraction. The cabinet is thick particleboard with extensive internal bracing to reduce resonance. The crossover uses air-core inductors and polypropylene capacitors, among other high-grade parts. The binding posts are gold-plated and multi-way.

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 tend to deteriorate over time and need replacing. Refoaming is a specialized job because of the square shape and construction of the drivers.