Mixer tutorial for crossovers, speakers and speakers
1. Frequency division and frequency divider Frequency division refers to dividing the audio signal into high frequency band, middle frequency band and low frequency band.
In the process of increasing its sound output power, the dynamic speaker has narrowed its frequency coverage due to its structural characteristics. In order to achieve full-band high-power sound output, speakers must be made in separate frequency bands and then combined to play sound. To give full play to the sound efficiency of speakers in various frequency bands, the question of frequency division is involved. There are two commonly used frequency division methods in sound reinforcement: electronic frequency division and power frequency division. The former is suitable for occasions with high sound quality requirements, such as song halls, concert halls, and disco halls, and the latter is suitable for ordinary karaoke halls. , Ballroom dance hall and multi-function hall.
1. Electronic frequency division Electronic frequency division is also called active network frequency division. Its frequency division system needs to be added with power. Its frequency division method is shown in Figure 3-1.
It can be seen from the figure that the sound signal is divided before entering the power amplifier. The advantage is that the sound generation efficiency is high, and the power signal sent by each power amplifier gives sound to the corresponding frequency band speakers. At the same time, no nonlinear components are added behind each power amplifier except the speaker, so the nonlinear distortion is small and the sound is beautiful. However, the number of power amplifiers used is large. The main sound reinforcement system is divided into left and right channels. Three power amplifiers are required. If an auxiliary sound reinforcement system is also configured, three power amplifiers are required. In this way, the cost is very high. Figure 3-2 shows the function keys of the front panel and rear cover of the Mu-CO31 electronic crossover. Set the mode switch to the 1 position for stereo sound reproduction at the frequency of 3; place the mode switch at the 2 position for stereo sound reproduction at the frequency of 2; mode switch at the 3 position for monophonic sound at the frequency of 3. The phase reversal key is generally not used. Only when the two channels of corresponding frequency bands are in reverse phase, you can press one of them to get the same phase.
After the electronic crossover is connected to the sound reinforcement system, its cross-point frequency must be adjusted, otherwise there will be some speakers silent, the cross-point frequency can be determined in two cases, to determine the cross-point frequency (low Cross-point frequency), using mid-range and low-band speakers to play sound, turn the low-end cross-point frequency adjustment knob from left to right, then from right to left. When tuned to a certain point, both speakers sound louder, then this The adjustment point frequency is the low-end cross-point frequency. In the same way, the mid-high frequency speakers play the sound, rotate the high-end cross-point frequency adjustment knob, from right to left, and then from left to right. When adjusted to a certain point, the two speakers When the sound is large, the frequency of this adjustment point is the high-end crossover frequency.
2. Power frequency division The power frequency division is also called passive source network frequency division, it does not require power supply, and its frequency division method is shown in Figure 3-3.
It can be seen from the figure that the sound signal is first amplified by power, and the amplified power signal is sent to the corresponding speakers through high pass, band pass, and low pass, respectively. This frequency division method is simple, easy to connect, less power amplifier consumption, low cost, but because the frequency division is divided after the power amplifier, the frequency division network will always consume some power, making the speaker sound efficiency is low. In addition, the capacitors and inductors used in the crossover network belong to non-linear components, which have non-linear distortion, and the sound quality is not as good as electronic crossover. This is a disadvantage of power crossover. Commonly used power frequency division and frequency division are divided into unit type and dual element type.
The power frequency division dual-element type is clearer than the unit model in terms of frequency band division, and the frequency division effect is better. Some power dividers use a combination of single and double components, and some use two-way frequency division, that is, the woofer takes into account the mid-bass sound, and the tweeter takes into account the mid-high sound. For example: JBL826 type is easy to work is a two-frequency system combining single and dual components. The treble part adopts dual components, the bass part adopts unit parts, the treble part speakers play both middle and high sounds, and the bass part speakers play middle and low sounds.
Second, the speaker The speaker is an electro-acoustic conversion component, which converts the sound electrical signal into sound. From the perspective of development history, there have been various speakers, such as: electrodynamic speakers, electromagnetic speakers (that is, reed speakers), crystal speakers, electrostatic speakers, etc.
The principle of the sound of the electric speaker is that the coil of the alternating current signal moves in the magnetic field to vibrate the diaphragm connected to the voice coil, which involves the vibration of the paper cone, and then transmits the sound wave through the air medium.
The electromagnetic speaker generates sound by generating an alternating magnetic field through a coil with an alternating current signal, attracting the repelling magnetic sheet, causing the diaphragm and paper cone to vibrate, and then transmitting the sound through the air medium.
The sound of the crystal speaker is caused by the electric expansion and contraction effect of the crystal piece, which causes the diaphragm to vibrate, and then the sound is transmitted through the air medium.
The static speaker sound is generated by the attracting and repelling effect of static electricity accumulation, making the diaphragm vibrate, and then transmitting the sound through the air medium.
Among these speakers, in addition to motorized speakers, other speakers are eliminated because of the narrow frequency range of radiated sound and small radiated sound power. The remaining motorized speakers, because their radiating frequency range can reach the entire audio range, and the sound power can be very large (you can make high-power speakers by dividing the frequency band and use the combined sounding method to form a full-band playback), so you get widely used.
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