The main performance indicators of the speaker are: sensitivity, frequency response, rated power, rated impedance, directivity, and distortion.
Speaker power is divided into nominal power and maximum power. Nominal power is rated power and undistorted power. It refers to the maximum allowable input power of the speaker within the rated undistortion range. The power marked on the speaker's trademark and technical specifications is the power value. Maximum power refers to the peak power that the speaker can withstand at a certain moment. To ensure the reliability of the speaker, the maximum power of the speaker is required to be 2 to 3 times the nominal power.
Speaker impedance is generally frequency dependent. The rated impedance refers to the impedance measured from the speaker input when the audio frequency is 400Hz. It is generally 1.2 to 1.5 times the DC resistance of the voice coil. Common dynamic coil speakers have 4Ω, 8Ω, 16Ω, 32Ω and so on.
When an audio signal with the same voltage and different frequencies is applied to a speaker, the sound pressure produced by the speaker will change. Generally speaking, the sound pressure generated during middle audio is relatively high, while the sound pressure generated during low audio and high audio is small. The high and low frequency range when the sound pressure drops to a certain value of mid-range audio is called the frequency response characteristic of the speaker.
The ideal speaker frequency characteristic should be 20 ~ 20KHz, so that the entire audio can be reproduced evenly, but this is not possible. Each speaker can only play back a good portion of the audio.
The phenomenon that the speaker cannot reproduce the original sound realistically is called distortion. There are two types of distortion: frequency distortion and non-linear distortion. Frequency distortion is caused by strong playback of signals of some frequencies and weak playback of signals of other frequencies. Distortion destroys the original ratio of high and low sound and changes the original sound color. The non-linear distortion is caused by the vibration of the speaker vibration system and the signal fluctuation not being completely consistent. A new frequency component is added to the output sound wave.
5, Pointing characteristics
It is used to characterize the sound pressure distribution characteristics of speakers radiating in various directions in space. The higher the frequency, the narrower the directivity, and the larger the paper cone, the stronger the directivity.