Class T amplifier

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A Class T amplifier is an audio amplifier product developed primarily by Adya Tripathi and Cary Delano of Tripath Technology. Rather than being a separate "class" of amplifier, Class T is a registered trademark for Tripath's amplifier technologies. It is an implementation of Class D amplifiers, but uses a sophisticated control scheme to provide very high quality audio amplification. Rather than using digital signal processing, class T amplifiers use an overall loop that is similar to a higher order Delta-Sigma (ΔΣ) (or sigma-delta) modulator. While it is called a digital amplifier, the class T amplifier is almost entirely analog; the amplifiers use a digital clock internally only to control the sampled comparator. The two key aspects of this topology is that (1) feedback is taken directly from the switching node rather than the filtered output, and (2) the higher order loop provides much higher loop gain at high audio frequencies than would be possible in a conventional single pole amplifier.

Despite superlative performance, the cost of the Class T amplifier approach appears to have limited its acceptance. Financial difficulties have caused Tripath to file for Chapter 11 bankruptcy protection on 8 February 2007. Sales in the 10's of millions of dollars per year, and owneship of several patents, suggest that Tripath designs will continue in production, even if the company is reorganized during Chapter 11.

Tripath sells the amplifiers as chips, or as chipsets, to be integrated into products by other companies. For example:

Sony, Panasonic and Blaupunkt use them in several car stereos and integrated home cinema systems
Apple Computer used them in their Power Mac G4 Cube, Power Mac G4 (Digital audio), eMac and iMac (Flat Panel) computers
Sonic Impact manufactures an inexpensive portable battery powered amplifier based on the technology. It has received very good reviews from the audiophile press despite its plebian origins and marketing.