Amplifier Efficiency Classes
Class A:
η_max = 25% (resistive load)
η_max = 50% (tuned load)
P_dissipated = P_supply − P_output ≥ P_output × 3
Class AB:
η_typical = 50–65%
P_dissipated ≈ P_output (at max output)
P_dissipated = P_output × (1/η − 1)
Class D:
η_typical = 80–92%
P_dissipated = P_output × (1/0.85 − 1) = P_output × 0.176 (at 85%)
Example comparison — 1000W amplifier:
| Class | Input Power | Heat Dissipated |
|---|---|---|
| Class A | 4,000W | 3,000W |
| Class AB | 1,667W | 667W |
| Class D (85%) | 1,176W | 176W |