Downsizing Again

Bose is up to its old tricks. The company first pulled the faux speaker cabinet caper on audio journalists back in the late 1980's when it introduced the Acoustimass system. Lee Ritenour's On the Line came pouring  out of a sub box and a pair of tiny cube speakers hidden behind curtains, but the company made it first appear that a pair of towering floorstanding speakers was delivering the driving jazz tune.

The company put on a similar ruse yesterday at its Framingham, MA, headquarters where it took the wraps off new PC speakers called MusicMonitors ($399 a pair). Bose set designers placed a sub box beneath a desk in a home office environment with two aluminum miniature satellites positioned on either side of a monitor.

Turns out the sub box was just a prop. All the sound, including some surprising bass, came from a tweeter and a pair of 1 3/4-inch passive radiators mounted in opposition to each other inside the rigid aluminum cabinet. By using two small passive radiators, Bose engineers could achieve the surface area required to move a lot of air for low-frequency sound, yet keep the compact size people want today from their PC speakers.

Putting the passive radiators face to face and porting the sound out a slot in the side of the cabinet has a physical benefit, too. It cancels out mechanical vibrations from one to the other keeping the speakers stationary on a desk. Bose designers gave reporters a peek at what would happen of the passive radiators were mounted in the same direction: the demo speaker took a small excursion across the table in the Bose auditorium.

Credit Class D switching amplifier circuitry and digital signal processing for keeping the speakers compact, too. Chip-based technologies handle functions handled in the analog world by resistors, capacitors and other components.

We expect to see more from this design down the road.--Rebecca Day