The main performance indexes of loudspeaker include: sensitivity, frequency response, rated power, rated impedance, directivity, distortion and other parameters.
1. Rated power
The power of loudspeaker can be 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 specification of the loudspeaker is the power value. Maximum power refers to the peak power that the speaker can withstand at a certain moment. In order to ensure the reliability of the hoister, the maximum power of the loudspeaker is required to be 2 ~ 3 times of the nominal power.
2. Rated impedance
The impedance of loudspeaker is generally related to frequency. Rated impedance refers to the impedance measured from the speaker input when the audio frequency is 400Hz. It is generally 1.2 ~ 1.5 times the DC resistance of voice coil. The common impedances of general dynamic coil speakers are 4 Ω, 8 Ω, 16 Ω, 32 Ω, etc.
3. Frequency response
When audio signals with the same voltage and different frequencies are applied to a speaker, the sound pressure generated will change. Generally, the sound pressure produced by medium audio is larger, while the sound pressure produced by low audio and high audio is smaller. When the sound pressure drops to a certain value of medium audio, the high and low frequency range is called the frequency response characteristic of the speaker.
The ideal speaker frequency characteristic should be 20 ~ 20kHz, so that all audio can be played back evenly, but this is impossible. Each speaker can only replay a part of the audio well.
4. Distortion
The phenomenon that the loudspeaker can not reproduce the original sound realistically is called distortion. There are two kinds of distortion: frequency distortion and nonlinear distortion. Frequency distortion is caused by strong playback of signals at some frequencies and weak playback of signals at other frequencies. The distortion destroys the proportion of the original high and low loudness and changes the original timbre. The nonlinear distortion is caused by the incomplete consistency between the vibration of the speaker vibration system and the fluctuation of the signal, which adds a new frequency component to the output sound wave.
5. Pointing characteristics
It is used to characterize the sound pressure distribution characteristics radiated by the loudspeaker in all directions of space. The higher the frequency, the narrower the directivity, and the larger the paper basin, the stronger the directivity.