Wednesday, March 07, 2007

The Loudspeaker Part 3

Twenty years later after much well-marketed but insubstantial change in speaker technology, somebody finally brings the goods. In 1954 Edgar Villchur develops the acoustic suspension principle. As great as speakers were for making things louder the bass just sucked man. The sound reproduction was very treble heavy. Villchur's work made your subwoofer possible and by extension the song Low Rider with his patent No. 2,775,309. Great Stereophile article here.

What I like about Villchur is that he was really one of us radio geeks. he ran a radio shop on West 4th Street, in Manhattan building and repairing custom hi-fi sets. He taught at NYU and wrote two books on the reproduction of sound. One of which, his 1965 book, Reproduction of Sound in High-Fidelity & Stereo Phonographs, is still in print today.

Acoustic suspension principle is a mathematical model of woofer behaviour in tandem with the air in a speaker cabinet, it provides a way to design a small speaker system. Before this to produce bass sounds accurately required ridiculous Frigidaire sized chassis. This allowed the development of effective and linear low frequency response in a small chassis. Suddenly with a two way system (woofer and tweeter) a output of 35 to 40 Hz from a box of only two cubic feet or so was possible. Without getting into the math, the idea is as follows:
1. Small cabinet size
2. Tight, clean bass response.
3. improved efficiency
4. The smaller woofer
5. Controlled response below the system resonance

Eddie's company, Acoustic Research introduced the small AR-1 bookshelf loudspeaker that used the this principle. that puppy cost $185 retail. This was followed by the $89 AR-2 in 1956 and eventually by the AR-3 with improved domed tweeters in 1958. The Acoustic Research brand of Hi-Fi loudspeakers became famous with their AR-3 loudspeaker. These had 12-inch woofers and a dome midrange speaker to compliment the high frequency tweeter.

The company prospers even now as they sully their brand name with tiny crappy speakers for the Ipod. But why not, Villchur sold Acoustic Research in 1967. He took the dough and founded the Foundation for Hearing Aid Research. His non-profit foundation developed a prototype device whose basic design is used widely in today's hearing aids.

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