The speakers on the market come in all shapes and colors, but no matter which one, they are composed of the two most basic parts of the speaker unit (the term is called the speaker unit) and the cabinet. In addition, most speakers use at least two or more The speaker unit implements the so-called multi-channel crossover playback, so the frequency divider is also an indispensable part of the telegraph. Of course, there may be other components in the speaker, such as sound-absorbing cotton, inverted tube, folded "labyrinth pipe", reinforced plate/reinforced partition, but these components are not indispensable to any speaker, the most basic composition of the speaker The element has only three parts: speaker unit, cabinet and crossover.
Why do some speakers use two speaker units, while some use three, and some use four or five, and use one?
The speaker unit plays the role of electric-acoustic energy conversion and converts the electric signal sent by the power amplifier into sound output. It is the most critical part of the speaker. The performance index and sound quality of the speaker greatly depend on the performance of the speaker unit. , The prerequisite for making a good speaker is to select a speaker unit with excellent performance. In summary, the performance requirements of the speaker unit mainly include high carrying power, low distortion, wide frequency response, good transient response, and high sensitivity. However, it must take into account distortion at the same time in the wide frequency range of 20Hz-20KHZ. Performances such as, transient, and power are very difficult. Just like road police, if you manage too wide, you will definitely lose sight of one another, and it is much easier to manage one section of each section. The same is true for the speaker unit. The most effective solution is sub-band playback. For this reason, the speaker factory has produced different types of units. Some are only responsible for playing bass, called woofer, midrange is called midrange, and tweeter is only responsible for treble. In this case, a targeted design can be adopted. The performance of this unit is better.
Therefore, although a full-band speaker can be used to design the speaker, for the above considerations, the design method of using a combination of multiple units to cover the entire audio frequency band still accounts for the vast majority. The specific number of units used depends on the frequency division method of the audio range. If it is a simple split treble and bass (or mid-low) two speakers, it is enough; if it is a three-way frequency divided into high, medium, and low Loudspeakers must use at least three units. Now the design of two low-frequency units working in parallel is also very popular, so the total number of units may reach four; some large-scale speakers have a finer frequency division, if you use more units With the design of parallel operation, the total number of speaker units will be more. There is usually a program such as "X way X unit" in the information or manual of the speaker, which is a specific description of the number of frequency divisions of the speaker and the total number of units used. For example, "three-way four-unit" means that this is a three-way design. For the speakers, a total of four speaker units are used, and the rest can be deduced by analogy.
What is the purpose of the divider?
Since almost all current speakers adopt the design method of multi-unit sub-band playback, there must be a device that can divide the full-band music signal sent by the amplifier into treble, bass output or treble, midrange, and bass output as needed. In order to connect with the corresponding speaker unit, the crossover is such a device. If the full-band signal is directly sent to the high, medium, and woofer unit without distribution, the part of the "excess signal" outside the frequency response range of the unit will have an adverse effect on the signal restoration in the normal frequency band, and may even cause The tweeter and midrange unit are damaged. From the perspective of the circuit structure, the frequency divider is essentially an LC filter network composed of capacitors and inductance coils. The treble channel is a high-pass filter, which only allows high-frequency signals to pass through and blocks the low-frequency signals; the bass channel is just the opposite, it Only let the bass pass and block the high-frequency signal; the midrange channel is a band-pass filter, except that the frequency between the two crossover points of one low and one high can pass, high-frequency components and low-frequency components will be blocked. In the actual frequency divider, sometimes in order to balance the sensitivity difference between the high and woofer units, an attenuation resistor is also added; in addition, some frequency dividers also add an impedance compensation network composed of resistors and capacitors, the purpose of which is Make the impedance curve of the speaker psychologically flat, so that it can be driven by the power amplifier.