What's the difference between amplifier classes? | Crutchfield

Class D, Class AB, Class A...what's the difference between these amplifiers, and why would you want one over another for different applications?

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Amplifiers use different designs to perform their primary job: to increase voltage in order to combine with an audio signal to play over a set of speakers. There are different ways to achieve this, and depending on what you're asking your amp to do, one design may be better for you than another.

Amplifier class designation refers to how that particular amp combines the power and signal. The classes differ on how efficient they are, how much room they take up, how they handle the heat generated by amplification, and the fidelity of sound they produce.

Class A amps offer the highest audio fidelity, but they're inefficient and rare, and due to the heat they generate they are not used in car audio.

Class B amps run much more efficiently than Class A amps, but due to their two-transistor design they produce crossover distortion. Pure Class B designs are exceedingly rare.

Class AB amplifiers take the best of Class A and Class B to produce a fairly efficient amp with high fidelity sound. Most home theater amps and stereo amps use a Class AB design.

Class D amps are very efficient, and can take on a much smaller form since they are not producing as much waste heat. This makes them great for car audio and PA systems, though Class D amps don't output as high-fidelity a sound as Class AB. The trade-off for car audio is well worth it, though, because Class D amps don't draw as much power and you don't need to worry as much about keeping them cool.

Which one's best? That depends on what you plan to do with your amp. As always, if you have questions, just call Crutchfield or chat online with one of our product advisors. They'll be happy to recommend something for you.

Read our excellent article about amplifier classes: https://www.crutchfield.com/i-rYTVc2R...

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0:00 Intro
0:20 Amplifier basics
1:06 Class A amplifiers
1:48 Class B amplifiers
2:10 Class AB amplifiers
2:58 Class D amplifiers
4:19 Other amplifier classes
4:45 Should I care?
5:18 Recap and contact info