English 
French
A Class-D amplifier, also known as a switching amplifier, transforms the analog input signal into a PWM (pulse-width modulation) signal, a sequence of pulses representing the amplitude and frequency of the original signal. The PWM signal is then amplified and, before being sent to the loudspeakers, low-pass filtered to reconstruct the audio waveform and remove unwanted ultrasonic components.
The major advantage of Class-D amplifiers is their extremely high efficiency, reaching values around 90%, significantly higher than those of Class-AB amplifiers (around 50 – 70%). In practice, they are able to convert almost all the energy absorbed from the mains into usable power.
Thanks to this feature, Class-D has established itself in the professional field: it allows for very high power outputs, even thousands of watts per channel, with smaller dimensions, lower heat dissipation, and, in some cases, without the need for large heat sinks or cooling fans.
Today, almost all power amplifiers (in our industry) use Class-D circuits, with rare exceptions.
