What are the Types of Power Amplifiers?

A power amplifier, commonly known as an "amplifier", its function is to amplify the weak signals from the sound source or pre-amplifier to drive the speakers to produce sound. In a good sound system, the role of the power amplifier is indispensable. The power amplifier is the most basic device in a sound system. Its task is to amplify the weak electrical signals from the signal source (in a professional sound system, from the mixer) to drive the speakers to produce sound.

Now, as SISCO will introduce the classification of power amplifier, let's first understand more about the power amplifier itself. The power amplifier, abbreviated as PA, can be regarded as the largest family among various audio equipment. Its main function is to amplify the relatively weak signals input by the sound source equipment and generate a large enough current to drive the speakers for sound reproduction. Considering factors such as power, impedance, distortion, dynamics, and different usage scopes and control functions, different power amplifiers vary in internal signal processing, circuit design, and production processes.

Classification by the Conduction Mode of Power Transistors

1. Class A Amplifier: In a Class A amplifier, during the entire period of the signal (both the positive and negative half-cycles of a sine wave), no power output components in the amplifier will experience current cutoff (i.e., stop output). Class A amplifiers generate a lot of heat during operation, resulting in low efficiency. However, their inherent advantage is the absence of crossover distortion. Single-ended amplifiers operate in Class A mode. Push-pull amplifiers can operate in Class A, Class B, or Class AB mode.
2. Class B Amplifier: In a Class B amplifier, the positive and negative half-cycles of the sine signal are alternately amplified and output by the two "arms" of the push-pull output stage. Each "arm" conducts for half a cycle of the signal. The advantage of Class B amplifiers is high efficiency, while the disadvantage is that crossover distortion occurs.
3. Class AB Amplifier: Class AB amplifiers are between Class A and Class B. Each "arm" of the push-pull amplification conducts for a time greater than half a cycle and less than one cycle of the signal. Class AB amplification effectively solves the crossover distortion problem of Class B amplifiers and has higher efficiency than Class A amplifiers, so it has been extremely widely used.
4. Class D Amplifier: Also known as a digital amplifier, a Class D amplifier uses a very high-frequency switching circuit to amplify audio signals. It has the advantages of high efficiency and small size. Many Class D amplifiers with a power of up to 1000W are only as large as a VHS video cassette. This type of amplifier is not suitable for use as a wide-band amplifier but is more commonly used in active subwoofer speakers.

Classification by the Number of Amplifying Elements in the Output Stage

1. Single-ended Amplifier: The output stage of a single-ended amplifier consists of one amplifying element (or multiple elements connected in parallel as a group) to complete the amplification of both the positive and negative half-cycles of the signal. Single-ended amplifiers can only operate in Class A mode.
2. Push-pull Amplifier: The output stage of a push-pull amplifier has two "arms" (two sets of amplifying elements). When the current of one "arm" increases, the current of the other "arm" decreases, and their states alternate. For the load, it is as if one "arm" is pushing and the other "arm" is pulling, jointly completing the current output task. Although Class A amplifiers can adopt push-pull amplification, it is more common to use push-pull amplification to form Class B or Class AB amplifiers.

Classification by Function

1. Power Amplifier (Also Known as Rear Stage): Abbreviated as PA, it is an electronic device used to enhance the signal power to drive the speakers to produce sound. A power amplifier without auxiliary functions such as signal source selection and volume control is called a rear stage.
2. Pre-Amplifier (Also Known as Front Stage): It is the pre-amplification and control part before the power amplifier, used to enhance the voltage amplitude of the signal and provide functions such as input signal selection, tone adjustment, and volume control. The pre-amplifier is also called the front stage.
3. Integrated Amplifier: An amplifier that installs the pre-amplification and power amplification parts in the same chassis is called an integrated amplifier. The power amplifiers commonly found in our homes are generally integrated amplifiers.

Classification by Application

1. AV Power Amplifier: Specifically designed for home theater purposes, an AV power amplifier generally has four or more channels and surround sound decoding functions, and is equipped with a display screen. The main purpose of this type of power amplifier is to realistically create the ambient sound effects of movies to allow viewers to experience the theater effect.
2. Hi-Fi Power Amplifier: Designed to reproduce the original appearance of music with high fidelity, an Hi-Fi power amplifier is generally designed with two channels and has no display screen.

In words, the diverse classifications of power amplifiers cater to a wide range of applications and user preferences. Whether it's the pursuit of high fidelity in music listening with Hi - Fi amplifiers, or the immersive experience of home theaters with AV amplifiers, there's an amplifier type to suit every need. As technology progresses, we can expect further refinements and innovations in amplifier design, promising even better audio experiences for all. Keep exploring our latest offerings power amp to stay ahead of the curve and unlock the full potential of your audio setup.