What is a Class D Amplifier?

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.

Understanding Class D Amplifiers

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.

Class D Amplifiers are often misinterpreted as digital amplifiers - or at the very least - 'two levels better' than a conventional Class A amplifier.

The reality is that Class D technology is increasingly being adopted for traditionally bulky heavy and inefficient power amplifiers in large scale public address, voice reinforcement and live sound systems.

Pulse width modulation diagram example:

Class D Amplifier Diagram

What are the benefits of a Class D Amplifier?


  • 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. 

Conventional analogue amplifiers are extremely reliable but are well known for their weight and bulk due to the copper wirings of the transformer(s) - and ofcourse, the more powerful the amplifier the larger and heavier it will be.

So in large scale PA and sound reinforcement systems - often with 1000's of watts of output and multiple channels - the resulting audio rackbuild quickly becomes quite significant, to the point of 300 high racks requiring lifting equipment to position them in the final resting place!

And as an inefficient technology, conventional analogue amplifiers develop a lot of heat which needs to be managed - requiring even more space and energy for temperature conditioning.

CIE professional audio system design - contact the team

Need help with your AV-over-IP products or system design?

CIE is one of the UK's leading Audio distributors and has over 50 years experience in supply and system design for many of the UK's largest, highprofile audio projects; our AV experts provide a unique level of technical support and customer service.

If you would like assistance, please call our team today on T. 0115 9770075 or email us now.

HowToAV.tv free audio visual training channelGot a question for the HowToAV team?..

HowToAV.tv provides a whole host of tips, tricks and technology know-how for the professional audio visual industry.
Subscribe to our YouTube channel now at howtoav.tv for all the latest video casts or send us your questions to [email protected]

Featured Products

Inter-M - PM Series Class-D Mixer Amplifiers
view product
Inter-M - DPA300Q 4x 300W 100v Power Amplifier
view product
Inter-M - DPA300D 2x 300W 100v Power Amplifier
view product
Inter-M - DPA900S 1x 900W 100v Power Amplifier
view product
< Back