While selecting amplifiers for your car audio system, you need to navigate through several types.
However, the choice usually boils down to 2 most popular categories – class AB and class D amplifiers. To make an informed decision, you have to clearly understand the difference between class D and class AB amps.
Class AB consists of the most prominent representative of 2 separate groups (A & B) with their strong points preserved. Similar to class A, these amps let the current smoothly flow through output transistors, but the level of electricity, in this case, is significantly lower in the idle mode. Thus, AB amplifiers ensure a higher level of audio fidelity (class A trait), while staying cooler and more efficient (identical to class B).
Class D amps boast an even higher efficiency level while preserving low temperature. Such amplifiers are equipped with transistors that actively switch back and forth from receiving power and being activated to receiving no power and being off.
Of course, higher efficiency is a solid argument in class D vs. class AB amplifiers stand-off. But it comes at an additional cost. Because of constant on and off switching, there appears more distortion. Fortunately, this effect occurs at very high frequencies, so you can use a low pass filter to eliminate it.
Manufacturers have done their best to improve class D amplifiers, so nowadays, you can find really decent options. However, there are people, who claim that such amps degrade the quality of the sound, so they don’t even want to switch a car radio on. Anyway, there are still users who don’t notice any difference.
All in all, average listeners as well as audiophiles are likely to be disappointed with class D amplifiers, especially when it comes to entry-level, cheap models that produce noise.
AB amplifiers are based on older technology, which doesn’t mean outdated, but rather tested and approved. They have been around for a while and are a go-to option for many car owners. If you are OK with lower efficiency, then AB amps are a sure way to go. Besides, they are easier to install and guarantee clearer sound.