Unlike many other
loudspeaker systems of recent years which depart from a conventional box
format, the Allison models One through Four are not clever solutions looking in
vain for problems to be solved. Instaed they were developed as rational answers
to real problems that are important and audible to anyone. Every aspect of
their design is functional, and they are uniquely accurate sound reproducers in
the only environment that really matters: a room for listening to music.
More than a year of
full-time research on the room-loudspeaker interaction has shown that reflected
impedance from the room boundaries increases a conventional loudspeaker's power
output at very low frequencies, but decreases it significantly in the middle-bass
range.
ALLISON:THREE
systems have flat bass power output in room corners, a capability shared only
by huge corner horn systems. The cabinet should rest on the floor or, with the
system inverted, it can be put close to the ceiling. Full design performance
will be maintained if the distance to these room surfaces does not exceed three
inches.
A pair of these
systems can be used at opposite ends of a wall, with spacing considerably
greater than is common for stereo speakers. Because of the extremely wide
dispersion the stereo image will be maintained even when the angle from a
listener to the two speaker systems is much wider than normal.
Alternatively, one
ALLISON:THREE system can be used as a main stereo speaker with an ALLISON:ONE
or ALLISON:TWO system as the other main speakers - a combination that solves
many practical placement problems. Finally a pair of ALLISON:THREE systems have
unique advantages as back speakers in four-channel and ambience-synthesis
systems of all kinds.
Specifications
Speaker complement:
One 10" (254
mm) woofers;
One 3½" (89 mm) Convex Diaphragm mid-range
units;
One 1" (25 mm) Convex Diaphragm tweeters
Crossover
frequencies: 350 and 3,750 Hz
Crossover network:
LC half-section at
both crossover frequencies. Air-core chokes and non-polar computer-grade
capacitors are used. Three-position control switch (accessible from front)
supplied for selection of system acoustic power response, from nominally flat
to concert-hall balance slope.
Impedance: 4 Ω
nominal (3,5 Ω minimum at any setting
of balance switch)
Efficiency: better than 0,7% when placed at floor-wall
intersection.
Minimum amplifier
power: 30 watts per channel to produce
100 dB sound pressure level in most domestic room environments.
Acoustic power
output capability: 0,5 acoustic watt
minimum , over full frequency range, with 70 watt peak input.
System resonance
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: Stabilized Radiation Loading sealed acoustic
suspension design.
Outside
dimensions: 40" high by 15¼" wide by 10" front to back (1002 cm
by 387 mm by 254 mm).
Occupies
10⅞"(209 mm) of wall space minimum.
Internal
volume: 1,275 cubic inches (41,8
liters).
Material: High density particle board veneered with
walnut, oiled finish
Weight: 45 lbs (20,4 kg)
Full Waranty for
Five Years
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