Describes the method used by an electronic component’s output devices to amplify signals; common classes are Class A, Class B, and Class AB. Class is most often used in relation to amplifiers but is also applicable to preamplifiers, CD players, or almost any other electronic device. lass A provides the best sound quality and frequency regularity thanks to its always on status, the output devices that provide power never shut down regardless of what part of the signal is being amplified. By contrast, a Class B device shuts down its output producers when they are not called upon to reproduce a signal (if a negative signal is presented, the positive output device will shut off until a positive signal is presented and vice versa). Class A provides smooth, continuous power while Class B provides intermittent power only as needed. Class B electronics function efficiently but produce poor quality results thanks to their start and stop nature. Conversely, Class A components produce superior quality but run inefficiently producing large amounts of heat and necessitating massive power supplies and associated build quality. s a compromise between Class A and Class B, the Class AB design retains power at all times but decreases output when a signal is not present. In this way, Class AB devices are able to save power output like a Class B design without suffering from the severe start and stop distortions that plague Class B designs. Amplifiers and other audio electronics typically are of the Class A or Class AB design type. Class B designs are used primarily in two-way radios and other applications where quality is of lesser importance compared to efficiency. In addition to the classes listed above, there are a number of others used most often in subwoofer amplifiers.