Originally Posted by speedfreak28

Ill keep it simple because it can get more complicated than what is neccessary to explain the uses in car audio. Ill break it down into classes real quick.

Class A/b amplifiers were the main stay in car amplifier technology for a long time because its not very complex. They are still used today in a lot of audiophile installations because of the output and ability to reproduce higher frequencies cleaner and with less distortion. A big disadvantage is that they are pretty inefficient and as far as car audio is concerned, class A/B could involve costly upgrades to the vehicles electrical system to provide proper current.

Class D has been the main stay in car audio for most of the past 10 years. Mainly because it is cheaper and more efficient( basically you need less voltage across the board to maintain the given rms of the amp) and the efficiency reduces heat. A disadvantage is that audible distortion can occur at lower frequencies than in A/B applications. This is why class D technology is commonplace in high powered woofer applications.

Newer to the car audio market is class GH ( G and or H ) The output of the amplifier is similar to class A/B but is more efficient in terms of power consumption. The technology is newer to car audio applications but I believe will end being very common because you don't have to trade sound quality for efficiency like class D applications.

Hopefully I didn't bore you too bad, How the different topologies achieve their output is a lot more complicated but I don't feel its neccessary to get into here. Hopefully this helps