The principle of speaker sound is not complicated, it is to convert the audio signal into an electrical signal, and drive the speaker to vibrate after amplifying the electrical signal through the power amplifier, so as to emit sound, and the structure is also very simple from the appearance, that is, a box, on which one or several speaker units are installed. However, when playing the same music, the sound of different speakers is completely different, and the world is different, what affects the sound of the speaker?
Speaker unit:
The speaker unit, which we often refer to as the speaker, is the key to the sound of the speaker. The structure of the speaker unit is also relatively simple, usually three large pieces (magnet, voice coil, diaphragm), when the audio signal current passes through the voice coil of the speaker, the alternating magnetic field generated by the audio current in the voice coil and the strong constant magnetic field generated by the ring magnet interact to make the voice coil vibrate mechanically, the voice coil will be pulled in or pushed out, and its amplitude will change with the direction and size of the current, and the up and down vibration of the voice coil will drive the diaphragm closely connected with it to move, so that the surrounding large area of air will vibrate accordingly, and the mechanical energy will be converted into sound energy.
As can be seen from the above figure, the speaker is composed of diaphragm, magnet, coil and other materials, and its various material parts have an important impact on the characteristic curve and quality of the speaker. Therefore, it is very wrong to judge the sound quality of the external diaphragm material and the size of the speaker. For example, if there are two woofers with the same cone but different sizes, it is not possible to achieve better low-frequency results with a larger speaker, because the smaller speaker may have better low-frequency characteristics than a larger speaker because it has a larger magnet inside, which has a higher magnetic flux density. With such a developed industry, it is easy to produce a loudspeaker unit, but it is even more difficult to ensure that the sound emitted by the loudspeaker unit is consistent with the sound information stored in the original audio signal!
The frequency of sound waves that the human ear can hear extends from 20Hz to more than 20KHz, in the process of enjoying music, different musical instruments or vocals have different frequency responses, and due to the physical characteristics of the speaker, no matter how good the speaker is, there is no way to cover the sound waves of the full range, so several speakers are often designed on a speaker to be responsible for replaying high-frequency, medium-frequency, and low-frequency sound waves.
Crossover:
Since most loudspeakers are designed with two or more loudspeaker units to achieve multi-way crossover reproduction, the crossover is also an indispensable part of the speaker. The crossover is a kind of circuit device in the speaker, which is used to separate the input music signal into different parts such as high, medium and low sound, and then send them to the corresponding high, medium and low speaker units for replay. If the full-band signal is fed directly into the high-, mid-range and woofer units without separation, the part of the "redundant signal" outside the frequency response range of the unit will adversely affect the signal restoration in the normal frequency band, and may even damage the high-range and mid-range drivers.
The crossover is the "brain" of the speaker and is crucial to the quality of the sound. Only by scientifically, rationally, and rigorously designing the crossover of the speaker can we effectively modify the different characteristics of the speaker unit and optimize the combination; make each speaker unit develop its strengths and avoid its weaknesses, and give full play to its due potential; make the frequency response of each frequency band become smooth and the sound image phase accurate; make the music played by high, middle and bass clearly layered, harmonious and clear, and reproduce the comfortable, wide and natural sound quality effect.
Speaker Cabinet:
The function of the speaker cabinet is to isolate the sound waves on both sides of the speaker paper cone to avoid the phenomenon of "sound short circuit", so as to ensure the reproduction effect of low-frequency signals, and the cabinet of the speaker can effectively control the resonance of the sound, increase the sound damping effect, and make the sound more beautiful and beautiful. The low-frequency re-release limit of a loudspeaker is generally determined by the resonant frequency of the subwoofer unit used, so in order to reduce the distortion of the subfrequency speaker at the resonant frequency, it is necessary to try to suppress the impedance peak of the loudspeaker unit at the resonant frequency and reduce the amplitude of the cone. When the subwoofer unit is installed in a cabinet with a suitable internal volume, the stiffness of the air in the box will have a suppressive effect on the movement of the diaphragm, which can effectively suppress the impedance peak of the subwoofer unit at the resonant frequency and reduce the distortion of the entire loudspeaker. By selecting a reasonable cabinet structure and parameters, the purpose of broadening the low-frequency response can also be achieved.
In addition, in order for the loudspeaker to be able to effectively reproduce the signal over a fairly wide frequency range, it is necessary to use two or more loudspeaker units to replace a single loudspeaker unit in some way, so that each loudspeaker unit only operates in a narrow frequency band in the entire audio range, and then reasonably combine them through a crossover network. Therefore, another function of the loudspeaker is to place more than 2 speaker units with different frequency ranges on the same cabinet in a fixed way, so that it has a fairly wide range of amplification frequencies to form a speaker system.
From the above introduction, it can be seen that the role of the speaker cabinet is not only to install and fix the speaker, but also to increase the sound power of the speaker, expand the frequency range of the reproduced sound, and improve the playback frequency characteristic curve of the speaker.