You’ve most likely heard amplifiers referred to in “classes”, such as “A”, “B” and so forth. Although some manufacturers might indulge in a bit of “this Class is better than that Class” type of marketing, the truth lies in the definition of each of these classes, and how they apply to the type of audio system you want to design.
The primary difference in these classes is how the internal circuitry operates. Let’s look at these differences, and how they might apply to your system.
Class A amplifiers always have current flowing through their output transistors. This design results in a physically large and usually heavy component. They also tend to generate a good amount of heat. Although these may be undesirable attributes to some, the most significant benefit is fidelity. Class A amplifiers tend to sound the best and have the least amount of distortion. So if you have ample space for ventilation and size or weight is not an issue, you can’t go wrong with Class A.
Class B amplifiers only send current through the output stage when a signal is present. This greatly improves on the efficiency of the amplifier, but can generate some distortion as the amp is always switching the output transistors on and off.
Class AB is basically a combination of Class A and Class B, as you might infer. Instead of switching output transistors off completely when no signal is present, they simply power down slightly and then return to full output. This mitigates the switching distortion and maintains a respectable level of efficiency. Truly the best of both worlds, Class AB amplifiers constitute many of the full-range amps on the market.
Class D amplification, also known as “Digital” amplification, is where the output transistors themselves operate as electronic switches, instead of the linear gain associated with other, traditional amplifiers. Basically, a Class D amp takes the input signal and applies it (very rapidly) to pulses of current generated by the amp’s power supply. Any distortions are typically well above our hearing range, power output can be quite impressive, size and heat signatures are minimal, and the prices are great. Class D amplifiers have carved a very comfortable niche in the world of car audio for the reasons outlined herein.
Communications Center knows car audio amplification. We can set you up with the best amps for your particular vehicle, and ones that will work great with the rest of your equipment.
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