What are Class D Amplifiers?

HowToAV talks to AVIXA audio expert Chuck Espinoza about Class D Amplifiers and how they differ from the more conventional A, B & C class amplifiers.

What is a Class D Amplifier?

A Class D Amplifier is also known as a 'switching power amplifier'. Class D amplifiers work off pulse width modulation, it converts the input signal into a stream of pulses.

Pulse width modulation diagram example:

Class D Amplifier Diagram

What are the pros and cons of Class D Amplifiers?


  • They are efficient - unlike Class A Amplifiers which are constantly at full power, Class D Amplifiers power switches on and off.
  • They can be smaller as they do not have a big transformer and capacitors.
  • Easy to install and easy to store away as they don't get hot like a Class A Amplifier would.
  • Does the job for most things!


  • Some people do not like the sound the Class D Amplifiers give as it can sound very digital.

Efficiency v.s. Distortion diagram:

Efficient diagram

What is a Class A Amplifier?

Class A Amplifiers are the most common used and simplest form of a power amplifier, they have both output stages of the device constantly at full power. 

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