Acoustic Research M4
Little is documented about the Acoustic Research M4. The record shows a speaker made during AR's "Holographic Imaging" era of the early 1990s, when the company was actively promoting its approach to stereo imaging. Audio (October 1991, p.319) ran an advertisement for the Holographic Imaging line that year, and Audio (October 1991, p.319) published a similar ad quoting Julian Hirsch's praise in Stereo Review. The ads touted the "Filtered Suspension" woofer loading, which AR described as an acoustic-suspension enclosure firing into a filtered chamber for tight bass.
Beyond those promotional materials, the M4 shows up in a single test report. HiFI-Stereo (June 1991, p.44-46) measured a two-driver configuration - a 6-inch bass/midrange driver in a sealed acoustic-suspension enclosure, with a carbon and mica-filled polypropylene cone, and a lower bass driver. The review noted the bass/midrange had a well-damped resonance and response within ±1 dB from 65 to 400 Hz, rolling off at 12 dB per octave below 65 Hz. At 1,000 and 10,000 Hz, the test amplifier clipped at about 1,200 watts before the speaker reached its limits.
No production years, original price or full specifications have been confirmed. Surviving documentation is thin.
eBay Listings
As an eBay Partner, we earn from qualifying purchases. This helps support our independent vintage technology research.