Acoustic Research AR M4 Holographic Imaging Speakers. Absolutely fantastic and rare speakers. These speakers were designed and built with sound excellence in mind. I just re-foamed the woofers and they sound incredible. Acoustic Research Holographic Imaging Series of loudspeakers was designed to create a more natural and believable sound stage, or stereo image, than conventional speakers do. To achieve this effect, all six models in the series have the driver that handles the musical midrange at the top of the cabinet, angled upward at about 30 degrees. The tweeter is just below that driver, offset a few inches to the outside, so that the tweeters are spaced slightly farther apart. According to AR, the upward-firing drivers provide improved hall-simulating midrange reverberation through ceiling reflections. The output from the tweeters slightly favors the inward direction, toward the listening area, creating a clear center stage in the sound field. The upper half of the cabinet is a sealed acoustic-suspension enclosure for the 6-inch bass/midrange driver, whose carbon and mica-filled polypropylene cone has a 32-Hz free-air resonance. The driver’s response is allowed to roll off naturally at low frequencies. At 3,600 Hz there is a crossover, with 12-dB-per-octave slopes, to the 3/4-inch soft-dome tweeter, whose voice coil is cooled by ferro-fluid. The lower half of the cabinet contains a separate sealed enclosure for the 6-inch low-bass woofer. Although the woofer is the same size as the midrange driver, it has a relatively massive paper cone with a free-air resonance of 28 Hz, and a series inductor rolls off its output above 100 Hz. The output below 100 Hz emerges from two rectangular ports on the sides of the enclosure. The two cone drivers have different low-frequency resonance, or “Q, ” characteristics, as well as different resonant frequencies, so that their outputs combine to produce a strong, uniform response down to 50 Hz. The speaker is recommended for use with amplifiers designed to drive loads of 4 to 8 ohms and with power ratings of 20 to 150 watts. This item is in the category “Consumer Electronics\Vintage Electronics\Vintage Audio & Video\Vintage Speakers”. The seller is “mitchelwestberr0″ and is located in this country: US. This item can be shipped to United States.
- Brand: Acoustic Research
- Model: Acoustic Research AR M4 s