Class H amps?


Just came across 'Class D' (after years of A, AB, not really B). 

So what is Class H? How does it differ from Class D?

 

kraftwerkturbo

The output transformers are valves between 2 voltage rails. Say, + and - 10 V.

In A, B and A/B those rails are fixed values. Classes G and H vary those rail voltages. Carver and NAD got famous on G. The idea is that minimizing the difference between the rails and raising them only when needed minimizes heat of the output transistors.

NAD continues to dabble with their hybrid Class D amps today.

Wikipedia is your friend:

 

As an aside, an audio buddy is using a pair of Benchmark AHB2 Power Amplifiers to drive his SoundLab electrostatic speakers to great effect.

Benchmark's specs state it: “combines class-AB, and class-H topologies, using a feed-forward error correction system” (https://benchmarkmedia.com/products/benchmark-ahb2-power-amplifier).  My buddy is using two AHB-2’s that are in bridged mode to output enough power for his SoundLabs.