Sunday, July 13, 2008

Class D Amplifiers Are Shrinking and Greening Your Electronics

Class D amplifiers, the first real advance in speaker design in decades. These amps were once thought to be appropriate only for low-end audio devices like cellphones. But with continuing refinements they have started showing up in everything from flat panel televisions and computers to high-end sound systems.

'Imagine a light bulb in your house,' said NHT audio engineer Gordon Chang. 'If you turn it on all the way, it's too bright, and if you turn it off, it's too dim. Now if you turn it on and off really quickly, you can get the light to look like it's halfway between on and off.'

Traditional amplifiers achieve the same effect using electrical resistance, similar to a dimmer switch that controls the light. Those resistors turn valuable electricity into unwanted heat, which necessitates bulkier design. Ever wonder why your ultra-thin panel television sounds so great despite having so little real estate dedicated to audio? The Class D amplifier, which is having a massive, albeit largely unacknowledged effect on consumer audio devices, is responsible.

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