Detailed explanation of the working principle of the speaker crossover

The speaker divider divides the sound signal into several frequency bands. For example, the divide-by-2 is composed of a high-pass filter and a low-pass filter. A three-way frequency band adds another bandpass filter. The crossover is the "brain" in the speaker, which is very important for the sound quality.

Problems with the use of the frequency divider The audio technology frequency divider is an audio device that can divide the sound signal into several frequency bands. We know that the frequency range of the sound is between 20Hz and 20kHz. It is hoped that using only one speaker will ensure that a wide frequency sound such as 20Hz-20kHz is difficult to achieve, because this will be technically different. A variety of problems and difficulties. Therefore, under normal circumstances, in order to ensure the frequency response and the frequency bandwidth of the reproduced sound, in the professional range, the high-bass split speaker is mostly used for sound reproduction, and when the high-bass split type speaker is used for sound transmission, It is necessary to use a frequency divider.

The speaker crossover adopts the structure of the following figure, and the specific analysis:

The circuit that connects the tweeter: let the current flow through the capacitor first, block the low frequency, let the high frequency pass, and the horn is connected in parallel with a coil to make the coil generate a negative voltage. This voltage is exactly a voltage compensation for the tweeter, so it can The sound current is reduced approximately realistically. Connect the woofer circuit: the current flows through the coil first, so that the high frequency part is blocked, and the low frequency band passes smoothly because the coil is basically not obstructed. Similarly, the woofer is connected in parallel with a capacitor, which is to use a capacitor to generate a high frequency. The voltage is used to compensate for the lost voltage, which is the same as the tweeter.

It can be seen that the characteristics of the capacitor and the coil that are fully utilized by the frequency divider are divided. However, the coil and the capacitor still consume the voltage in the respective blocked frequency bands, so the circuit divider will lose a certain sound, and there are many compensation measures. Because the author has insufficient knowledge, it is difficult to say clearly. The electronic crossover solves this problem. When the sound is input to the power amplifier, the frequency is divided first, and then a special amplifier circuit is used to amplify the different frequency bands, so that the sound distortion is small and the reproduction is realistic. But the circuit is complicated and expensive.

The speaker crossover is able to separate the frequency of the sound signal, distinguish the sound signals of different frequency bands, and then amplify and send them to the speakers of the corresponding high and low frequency bands. The effect of achieving different high and low sound quality is the speaker frequency divider.

1. When playing music, due to the capabilities and construction limitations of the speaker unit itself, it is difficult to cover all the frequency bands with only one speaker, and if the full-band signal is directly sent to the high, medium and low-range units without allocation, in the unit The local "excess signal" outside the frequency response range can adversely affect signal recovery in the normal frequency band, possibly causing damage to the treble and midrange units. For this reason, designers must divide the audio frequency band into several segments, and different frequency bands stop sounding with different speakers. This is the origin and role of the divider.

2. The crossover is the "brain" in the speaker, which is crucial to the quality of the sound. The music signal output by the power amplifier must be disposed through the filter components in the fire frequency device, so that the signals of specific frequencies of each unit pass. It is necessary to scientifically design, rationally and rigorously design the frequency divider of the speaker to effectively modify the different characteristics of the speaker unit, optimize the combination, so that each unit can develop its strengths and avoid weaknesses, and exert its potential as much as possible to make the frequency response of each frequency band change. Smooth, accurate phase of the sound image, in order to make the music level played by high, medium and low sound clear, co-shoot, clear, warm, wide and natural sound quality.

3. In the practical crossover, sometimes in order to balance the flexibility difference between the high and low woofer units, it is also necessary to participate in the attenuation resistor; in addition, some frequency dividers also participate in the impedance compensation network composed of resistors and capacitors. The purpose is to make the impedance curve of the speaker psychologically flat to facilitate the power amplifier drive.

From the working principle, the frequency divider is a filter network composed of a capacitor and an inductor. The treble channel only allows the high-frequency signal to pass through and blocks the low-frequency signal; the bass channel is just the opposite, only the bass passes through and blocks the high-frequency signal; the mid-range channel is a band-pass filter, except for one low-high two-frequency point The frequency between them can pass, and both the high frequency component and the low frequency component will be blocked.

It seems simple, but in the practice of the crossover, in order to balance the difference in flexibility between the up and down units, manufacturers need to participate in different types of attenuation resistors or impedance compensation networks composed of resistors and capacitors according to different conditions. Different design and consumption processes naturally make the seemingly inconspicuous component of the crossover have different effects in the speaker. These details, the formal pursuit of all HIFI equipment, this is the fundamental difference between HIFI and ordinary civilian equipment.

1. The general fault of the frequency divider is that the capacitor, resistor and inductor are burnt out, and the same data should be exchanged. If you can't see the original data after burning, you can only open another speaker to view the corresponding component data. Can not find the same data components, can be obtained in series, parallel, the power can only be large and not small. The inductor can only be re-wound after it has burned out.

2. Find the plastic pipe with the outer diameter of about +25mm, take 20mm-50mm as the skeleton sleeve, and temporarily add two baffles with diameter greater than φ50mm on both sides. According to the original coil turns, use φ1.0-1.2. The mm enameled wire is wound. After the winding, the baffle is removed, and the coil is temporarily bound by four parts of the enameled wire, and then the paint is immersed. After the coil is dry, remove the temporarily bundled enameled wire and attach it to the crossover board.