Model Allison One Speakers by Roy F. Allison for Allison Acoustics, 1976, Set of 2

Allison Model ONE

Allison models one through four were developed as rational answers to real problems that are important and audible to everyone. Every aspect of their design is functional and they are highly accurate reproducers of sound in the only environment that really matters: a room for listening to music.
More than a year of full-time research into room-speaker interaction has shown that the impedance reflected from the confines of the room increases the power output of a conventional loudspeaker at very low frequencies, but decreases it significantly in the low-mid range.
Another unique aspect of all of these systems is the non-directional dispersion of the mid and high frequencies from the drivers at relatively high output levels. This is achieved with a new type of diaphragm, convex in overall profile, that is superior to small dome radiators in dispersion, but equals the efficiency of normal cone drivers of comparable size.

The ALLISON: ONE system is a flagship, combining maximum frequency range, power output capability and placement flexibility. High Fidelity magazine said it is ''the kind of extremely accurate sound reproducer that would appeal to the serious listener who is both musically oriented and technically astute enough to appreciate a truly refined sound.''

An ALLISON: ONE system should be used with the back close to the wall of a room (but not in a corner), and with the bottom resting on the floor or near the ceiling. Full design performance will be maintained if the cabinet is positioned within three inches of the boundaries of these two rooms (thus allowing for recessed baseboards and radiators) and if the center of the cabinet is more than two feet from a side wall. Because the system is non-directional in the front hemisphere, it does not need to be ''facing'' the listeners. A stereo pair of these systems can be used on the same wall, on a pair of adjacent walls, or even on opposite long walls at the far end from the main listening area.

In Allison; Quattro systems this placement is facilitated by the location of the woofer in the top panel of its bookcase-sized cabinet, rather than in the normal front panel position. The distance from a room boundary (the wall behind the cabinet) is therefore kept to an absolute minimum, which maximizes possible distance rations. The smoothness of bass output in practical use of the system is significantly better than any conventional bookshelf model. Only the larger Allison systems are better in this respect than the Quattro.

Specifications

Speaker Complement:
Two 10'' (254 mm) woofers;
Two 3½ ''(89 mm) convex diaphragm midrange units;
Two 1'' (25 mm) convex diaphragm tweeters
Crossover frequencies: 350 and 3,750 Hz
Crossover network:
LC semisection at both crossover frequencies. Air-core inductors and non-polar computer capacitors are used. Three-position control switch (accessible from front) provided for selection of system acoustic power response from nominally flat to concert hall balancing slope.
Impedance: 8 Ω nominal (7 Ω minimum at any balance switch setting)
Efficiency: Better than 0.7% when placed at floor-to-wall intersection.
Minimum amplifier power: 30 watts per channel to produce a sound pressure level of 100 dB in most home environments.
Acoustic power output capability: minimum 0.5 acoustic watts, across the frequency range, with peak input of 70 watts.
System resonant frequency: 45 Hz, nominal
Effective system Q: 1.0. Low-frequency response -3 dB at 35.5 Hz, -6 dB at 29.5 Hz
Enclosure: sealed acoustic suspension with radiation stabilized loading.
External dimensions: 40'' high by 19'' wide by 10¾'' from front to back (1002 cm by 483 mm by 273 mm). Interior volume: 2,550 cubic inches (41.8 liters).
Material: high density particle board walnut veneer, oiled finish
Weight: 67 pounds (30.4 kg)