Main performance indicators of loudspeakers

The main performance indicators of loudspeakers are: sensitivity, frequency response, rated power, rated impedance, directivity, distortion and other parameters.
1. Rated power
The power of loudspeakers is divided into nominal power and maximum power. Nominal power is called rated power and undistorted power. It refers to the maximum input power allowed by the loudspeaker within the rated undistorted range. The power marked on the trademark and technical manual of the loudspeaker is the power value. Maximum power refers to the peak power that the loudspeaker can withstand at a certain moment. In order to ensure the reliability of the loudspeaker, the maximum power of the loudspeaker is required to be 2~3 times the nominal power.
2. Rated impedance
The impedance of the loudspeaker is generally related to the frequency. Rated impedance refers to the impedance measured from the input end of the loudspeaker when the audio is 400Hz. It is generally 1.2~1.5 times the DC resistance of the voice coil. Common impedances of general dynamic loudspeakers are 4Ω, 8Ω, 16Ω, 32Ω, etc.
3. Frequency response
When an audio signal of the same voltage but different frequencies is applied to a loudspeaker, the sound pressure generated will change. Generally, the sound pressure generated by the mid-range frequency is larger, while the sound pressure generated by the low and high frequencies is smaller. When the sound pressure drops to a certain value of the mid-range frequency, the high and low frequency range is called the frequency response characteristic of the speaker.
The ideal speaker frequency characteristic should be 20~20000Hz, so that all the audio can be reproduced evenly, but this is impossible. Each speaker can only reproduce a certain part of the audio better.
4. Distortion
The phenomenon that the speaker cannot reproduce the original sound realistically is called distortion. There are two types of distortion: frequency distortion and nonlinear distortion. Frequency distortion is caused by the strong playback of some frequency signals and the weak playback of other frequency signals. Distortion destroys the original ratio of high and low sound levels and changes the original sound tone. Nonlinear distortion is caused by the fact that the vibration of the speaker vibration system and the fluctuation of the signal are not completely consistent, adding a new frequency component to the output sound wave.
5. Directivity characteristics
It is used to characterize the sound pressure distribution characteristics of the speaker radiating in all directions in space. The higher the frequency, the narrower the directivity, and the larger the paper cone, the stronger the directivity.