Pioneer PW-A31

A 30 cm cone woofer unit built in Japan with a high-efficiency magnetic design and low distortion features

Overview

The Pioneer PW-A31 is a 30 cm cone woofer made by Pioneer in Japan. It belongs to the A series of cone woofers and was designed for high-fidelity audio systems. The cone material and magnetic circuit are built to cut harmonic distortion while keeping strong output and controlled resonance.

Specifications

Model Rating Type	30 cm Cone Woofer
Impedance	8 Ω
Lowest resonance frequency (fo)	20Hz
Reproduction frequency characteristic	Fo ~ 3 kHz
Max Input	80W
Rated input	40W
Output sound pressure level	93dB/W/m
Crossover frequency	3 kHz or less
Qo	0.27
Total flux	178,000maxwell
Magnetic flux density	10,700gauss
Equivalent mass	57gr
Baffle opening	270 φ mm or 310 φ mm
External dimensions	Diameter 340x Depth 156.5 mm
Weight	6.7kg

Design

The cone is a selected fiber material with a high Young's modulus and moderate internal loss. The surround is a high compliance type roll edge. The magnetic circuit uses a large ferrite magnet and a long voice coil, which gives good magnetic efficiency and uniform flux even at large amplitudes. A pure copper cap on the pole piece suppresses harmonic distortion.

Market

The Pioneer PW-A31 was originally priced at ¥14,000 around 1974, with a later listing at ¥16,700 around 1978. It appears as a listed item for sale on eBay, which points to ongoing collector interest.