What are the Performance Indicators of Loudspeakers Related to?

A speaker is a transducer device that converts electrical signals into acoustic signals. The performance of the speaker has a great influence on the sound quality. Its performance index are related to the following parameters:

1. Rated power

The power of the amplified speaker is divided into the nominal power and the maximum power. Nominal power is also called rated power or undistorted power. It refers to the maximum input power allowed by the amplified speaker in the rated non-distortion range, which is marked on the amplified speaker's trademark and technical specification. The maximum power refers to the peak power that a amplified speaker can withstand at a certain moment. In order to ensure the reliability of the amplified speaker, its maximum power of is required to be 2 to 3 times of the nominal power.

2. Rated impedance

The impedance of the amplified speakers is generally related to its frequency. The rated impedance refers to the impedance measured from the input when the audio frequency is 400Hz. It is generally 1.2 to 1.5 times the DC resistance of the voice coil. Common impedances of moving coil speakers are 4Ω, 8Ω, 16Ω, 32Ω, etc.

3. Frequency response

The produced sound pressure will change when audio signals with the same voltage but different frequencies are applied to a amplified speaker. Generally, the sound pressure generated in the mid-range is relatively high, while the sound pressure generated in the low-range and high-range ranges is relatively small. When the sound pressure drops to a certain value of the mid-range, the frequency range between high and low frequencies is called the frequency response characteristic of the speaker.

The ideal frequency characteristic of the amplified speaker should be 20~20000Hz, so that all audio can be reproduced evenly, but this is impossible. Each amplified speaker can only reproduce a certain part of the audio well.

4. Distortion

The phenomenon that the amplified 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 reproducing of signals at certain frequencies and the weak reproducing of signals at other frequencies. Distortion destroys the original high and low sound intensity ratio and changes the original tone. The non-linear distortion results from the lack of complete consistency between the vibration of the speaker vibration system and the fluctuation of the signal, so a new frequency component is added to the output sound wave.

5. Pointing characteristics

It is used to characterize the sound pressure distribution characteristics radiated by the speaker in all directions in space. The higher the frequency, the narrower the directivity; the larger the cone diameter, the stronger the directivity.