Originally Posted by kloneman
One variation (Class G, I think) uses multiple sets of power supplies that are switched in as the signal swings toward the normal power supply limit, to extend the output signal beyond it.
Class G is being used by Fosgate for their multi-channel amps. They are one of very few companies building HT amps with Class G design.
Below is what they have to say about it.
"The new FAA 1000.5, incorporating the acclaimed Trans•ana circuit topology in a new Class-G version, delivers a level of audio performance previously available only in much more expensive and exotic products.
JFET input stages dramatically reduce noise modulation and cross-products which can cloud amplifier detail and clarity on complex musical material.
MOSFET power output devices assure high output current, fast transient response, reliability and transparent sound quality.
Trans•ana output topology is configured for “voltage gain,” allowing a simple signal path.
Output topology is dual-voltage-rail type, with soft transition between levels (Class-G), allowing cooler operation at typical 1/8 to 1/3 power levels. 4:1 power headroom (average) allows sustained high output levels -- a highly desirable characteristic for reproduction of movies or music. The FAA 1000.5 is virtually immune to thermal shutdown and meets UL and other regulatory requirements.
A real-time protection system continuously computes MOSFET power dissipation. Combined with the unique load-impedance selector switches, optimum operation is attainable with any type of loudspeakers."
Kloneman, I knew you could not resist this discussion. . .