In electronics, amplifier classifications are often letter codes applied to various power amplifier classes. The class provides a broad overview of the features and functionality of an amplifier. In most cases, it is assumed that each amplifier in a given system can be placed in one of the class levels. However, the level of power amplification needed by a device, for the system to operate normally, may require the use of more than one amplifier from a given category. Likewise, in some cases, one or more amplifiers of a given class may be required for a given application. Regardless, of whether the device requires high power output, low power output, or a combination of the two; the appropriate class of amplifier should be chosen and implemented for the application. If you want to get a unique amplifier, go for class a amplifier.
Amplifier Class A - An amplifier classified in this level offers a maximum output power level of zero ohms. These devices are often small single-ended or true multichannel audio amplifiers. They are intended for desktop and smaller application. As their name suggests, Class A amps are designed for high efficiency performance at a low wattage. They are typically used in portable devices and industrial applications where high power output is a requirement.
Class B - An amplifier classified in this level offers a minimum total harmonic distortion level at all frequencies above the rated power. They are usually manufactured by true single-ended audio amplifiers or by true multi-ended devices. They are preferred over Class A audio amplifiers as they offer increased power handling capability over a smaller space. Some Class B amp models have switched circuit baring board technology. Other features that distinguish a Class B amplifier from a Class A amplifier include switching options, input and output power controls, high level outputs, and idle current shutoff.
Class AB - An amplifier classified in this level offers a wide range of features and benefits. Compared to Class A, they are larger in size and are more efficient, but are normally not as affordable as Class C and D amplifiers. However, most power amplifiers in this class are of the true single-ended design. Some advantages that distinguish a Class AB amplifier from a Class B amplifier include discrete power amplifiers, true constant power supplies, and dual frequency protection.
Class C - This class of amplifier is the cheapest of the three. It offers low distortion and high efficiency. In addition, they usually incorporate quartz control technology which offers high reliability. However, most Class C amplifiers offer only limited audio quality due to their lack of voltage drive ability. As an alternative, many Class C amplifiers offer DC drives. You also need to have ideal vacuum tubes to use with an amp.
Class D - True Constant Power (TCP) amplifiers are ideal for powering electric machines such as VCRs, DVD players, and other electronic devices. Because they require no separate power supply, they eliminate the need for separate power cables. The advantage that TCP amplifiers offer over Class C and AB amplifiers is their high efficiency and low distortion. However, they are also priced a little too high.