Which Amplifier Class Is Best? Part 1

For consumers and audio enthusiasts looking for a good sound system to achieve high-quality sound, the power amplifier (POWER AMP) is a key piece of equipment and one of the main factors in getting high-quality sound.

Power amplifiers come in several classes, with each class divided according to the working characteristics of the power amplifier design technology and the improvements made to the various internal circuit stages to make them more efficient. They are named after their power amplifier class. In the past there were 3 classes of power amplifier: Class A, Class B, and Class AB, but today there are also Class D, Class T, Class G, Class H, and others. Let's get to know each class and how each should be used to be best suited.

Amplifier Class A

Class A power amplifiers emphasize sound quality, with low distortion and little noise, but they have the drawback of running fairly hot because current is fed to the transistors at all times, even when there is no input signal, and the output power obtained is fairly low. This type of amplifier is therefore suited to listeners and consumers who value the detail of mid-high frequencies rather than loud, booming sound.

Amplifier Class B

Class B power amplifiers divide the operation of the transistors in the output amplification stage into 2 halves: one side works on the positive (+) portion and the other side works on the negative (-) portion, dividing the work between them, which gives fairly high efficiency. However, they have a drawback: at the point where operation switches between the positive and negative portions, the transition is not smooth and can be called distorted, known as crossover distortion, which is the distortion that occurs during the switching of the transistors' operation. This results in poor-quality sound, and today this class of power amplifier may no longer be produced.

Amplifier Class AB

Class AB combines the advantages and disadvantages of both Class A and Class B. That is, when the input signal is weak the output stage works in Class A mode, but when the input signal grows stronger the output stage works in Class B mode. This gives an amplifier with low distortion and high efficiency. Today the Class AB power amplifier is the most popular type of power amplifier, and it can drive both mid-high speakers and subwoofers (low-frequency speakers).

Today we covered 3 amplifier classes and what kind of use each class is suited to. In the next article we will talk about the remaining 4 amplifier classes and a table comparing each class.