What is stereo?

There are now two system of high fidelity, monophonic (monaural) and stereophonic. Monophonic is a system that starts from one microphone and is fed through a single high fidelity set. Stereophonic is a double system. Two separate microphones are placed at different sides of the orchestra and two different systems are used to keep the two signals or channels separated. Two separate speakers are used, placed on different sides of you room. Stereo is much like 3-D photography, two slightly different sound reach your ears giving you a new dimension in sound.

H.H. Scott '59

Allison THREE

 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.
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 10"(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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