Basic knowledge about amplifiers
Active and passive. The active speaker is equipped with a built-in power amplifier. Due to the special matching design, these power amplifiers can drive the driving unit in the speaker well, and the user does not need to consider how much the power of the power amplifier or the impedance match. Passive speakers do not have built-in amplifiers, so they need to be used with external amplifiers. When choosing an external power amplifier to be used with passive speakers, first of all, you must clarify the impedance load and rated power of the passive speakers. If one of these two parameters does not match, it will cause great damage to your speakers.
Bi-amplifier. As the name implies, a bi-amp speaker has two power amplifiers: one to power the high-frequency unit and the other to power the low-frequency unit. By separating the frequencies before reaching the power amplifier, the bi-amp speakers can effectively eliminate the main source of crossover distortion. Therefore, the sound will be more open and clear. The other two variants of this configuration are three-amplifier and four-amplifier designs, which can provide three and four amplifiers, respectively, and can provide separate power for each drive unit in the speaker.
rated power. Rated power refers to the continuous power that the power amplifier can output or the continuous power that the passive speaker can handle. Generally speaking, the rated power is roughly half of the peak power.
Peak power. Peak power refers to the maximum power that the amplifier can provide or the maximum power that the passive speaker can handle instantaneously without being damaged. It should be noted that the speaker will burn out after running for a few seconds under peak power load.
Class A amplifier. Class A amplifiers are the simplest type of amplifier. For any output waveform, the transistors in the output stage are always on (not completely turned off). Because Class A amplifiers can provide very low distortion, they are very popular among enthusiasts, but because of their extremely low power efficiency, they are not suitable for professional audio application scenarios.
Class B amplifier. The output stage transistor of the Class B amplifier is only turned on during the half cycle (180 degrees) of the signal waveform. In order to amplify the entire signal, two transistors are used, one for the positive output signal and the other for the negative output signal. The efficiency of Class B amplifiers is much higher than that of Class A amplifiers, but due to the crossover point between the two transistors from on to off, crossover distortion will occur, especially at low signal levels.
Class AB amplifier. As the name implies, Class AB amplifiers are a mixture of Class A amplifiers and Class B amplifiers. In the case of low level, its function is basically the same as the class A amplifier, ensuring low crossover distortion; in the case of high level, it will be converted into class B amplifier mode. The advantages of this design can be well reflected in high-frequency playback. For this reason, PreSonus air series speakers use Class AB amplifiers to power high-frequency drive units. Therefore, its high-frequency sound will be more natural, without the sharp and harsh sound that Class D amplifiers will produce.
Class D amplifier. Class D amplifiers use pulse modulation of the input signal to control the output. The pulse controls the output voltage and current. Class D amplifiers are highly efficient and lightweight, making them ideal for portable speakers. It is the most commonly used amplifier type in active professional speaker design.