How much do you know about amplifiers

                                               How much do you know about amplifiers

First of all, we are very familiar with speakers and know that speakers use electromagnetic principles to produce sound. The electrical energy is converted into magnetic energy, and the magnetic energy is converted into mechanical energy. The speaker can make sound by compressing the air. The device that processes the electrical signal into a sound that can drive the speaker is the power amplifier.

In front of the power amplifier is the sound source, such as CD player, tape player, computer, TV, mobile phone, etc. are all sound sources. When the signal from the audio source is sent to the power amplifier, what kind of changes have occurred?

First, the power amplifier performs high and low impedance conversion. The signal input to the power amplifier is a relatively weak electrical signal, and the input impedance is relatively high. The speaker is loaded behind the power amplifier, and the output impedance is relatively low. The power amplifier has carried out the appropriate high and low impedance conversion.

Second, the electrical signal input to the power amplifier needs to be purified and the timbre adjusted. This process is a bit like the preliminary work of cooking - sorting and washing dishes. The purpose of washing vegetables is to remove the sediment on the vegetables and remove the inedible parts. Similarly, the power amplifier also needs to purify the signal, filter out the noise in the electrical signal, and polish the sound signal to a certain extent. This process determines the quality of the tone.

Third, a clean signal is still a weak signal and cannot be used to drive the speakers. Therefore, the power amplifier also needs to amplify the electrical signal. We operate the volume controller to start the amplification process of the electrical signal. First, the voltage is amplified by the voltage amplification stage, then the voltage and current are further amplified by the push stage, and finally the current is amplified by the output stage to generate enough power to drive the speaker to sound . Fourth, the significance of power amplification is not only to make the speaker sound, but also to have a major impact on the sound quality, such as the dynamic performance of the sound, the balance of the sound, the stability of the sound, etc. Relatively speaking, the power amplifier with larger power, The sound performance is better than that of a less powerful amplifier.

To sum up, the power amplifier has done two aspects of work: first, it has done the work of signal processing, filtering noise, beautifying the sound and amplifying the voltage of the electrical signal. These tasks are extremely important, it is an important guarantee of the tone color, and it is also a necessary preparation before the power amplification of the electric signal. We call its work the pre-amplification, and the part that completes this work is called the pre-amplification part, or the pre-amp for short. Second, the current amplification based on the signal processed in the previous stage realizes the power amplification, and such an electrical signal can drive the speaker to sound. This part of the work is called power amplification, and the part that completes this work is called the post-amplification part, or simply the post-stage.