Acoustic Research AR-9
4-Way Floor-Standing Loudspeaker System (1979)
In the Acoustic Research AR-9, for the first time we have a system that is virtually flat down to 28Hz, comes in with a more than acceptably low Q of 5, and reproduces bass frequencies with startling power and clarity.
How have AR engineers managed to bend the laws of physics?
First, the AR9 uses two 300mm (12 inch) woofers connected in parallel. At any volume setting each of them moves only half the distance a single driver would have to move to produce the same volume level. Thus the woofers are able to handle more power without distortion or break-up.
Second, a large enclosure (120 litres) is used to create a system with a low resonant frequency.
Third, and the real secret weapon, is a sophisticated new crossover network - an important step ahead in speaker design. This crossover is designed with special circuitry that acts like an automatic transmission and helps control bass response. It allows the system to have maximum damping at the resonant frequency (thus low Q) while maintaining bass output. Above the resonant frequency it shifts electronically to maintain flat response across the bass spectrum.
Type: 4 way, 5 driver loudspeaker system
Frequency Response: 18Hz to 30kHz
Power Handling: 175W
Recommended Amplifier: 400W (maximum)
Crossover Frequency: 200, 1200, 7000Hz
Bass: 2 x 300mm acoustic suspension
Midbass: 1 x 200mm acoustic suspension
Midrange: 1 x 38mm dome
Tweeter: 1 x 19mm dome
Dimensions: 1340 x 381 x 402mm
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