The role of frequency divider: In a speaker system, people call the cabinet, frequency dividing circuit, and speaker unit as the three major parts of the speaker system, and the frequency dividing circuit plays a role in whether the speaker system can restore the electroacoustic signal with high quality. Extremely important role. Especially in the middle and high frequency parts, the role played by the frequency dividing circuit is more obvious. Its role is as follows:
Reasonably divide the working frequency band of each unit;
Reasonably allocate power to each unit;
Make each unit have a proper phase relationship to reduce the acoustic interference distortion of each unit in operation;
Use the characteristics of the crossover circuit to make up for the acoustic defects of the unit in a certain frequency band;
Connect each frequency band smoothly and smoothly.
Obviously, these functions of frequency dividing circuits have been recognized and accepted by people.
Choice of crossover point:
1 Consider the practical boundary frequency f = 345 / d (d = effective diameter of the unit diaphragm) for the directivity of the middle and low units. Generally, the boundary frequency of the 8 "unit is 2k, the boundary frequency of the 6.5" unit is 2.7k, the 5 "unit is 3.4k, and the 4" unit is 4.3k. In other words, when using the above units, the crossover frequency cannot be greater than the practical boundary frequency corresponding to each unit.
2 Considering the resonance frequency of the tweeter, the crossover frequency should be greater than three times the resonance frequency. In other words, from the point of view of the tweeter, the frequency division point should usually be greater than 2.5k.
3 Consider the mid-bass unit high-end response Fh, usually the crossover frequency should not be greater than 1/2 Fh. In fact, the above conditions for two-way speakers are difficult to meet at the same time. At this time, the designer should have a better choice among the three. However, it must be emphasized that the first condition, that is, the practical boundary frequency should be satisfied first.
4 In the case of three-way frequency division, usually the farther the two frequency division points should be separated (should be more than three octave bands), the better the combined system response will be. Otherwise, complex interference radiation will occur.
5 The crossover point of bass and midrange should consider the problem of vocal sound image localization. The reproduction of vocals should be undertaken by the mid-range unit as much as possible to avoid excessive changes in the sound localization tone of the vocals. This is often easily overlooked by designers. Usually this crossover point should be 200-300Hz.
The following is the crossover of Meixin
DS1073 3V, EconOscillator / divider
| The DS1073 is a fixed frequency oscillator and requires no external components. Using the internal programmable prescaler and frequency divider can provide a variety of operating frequencies in the range of approximately 27.3kHz to 100MHz. DS1073 uses the main oscillator, prescaler and programmable frequency divider structure. The prescaler and programmable frequency divider are set by the user to the desired value, and the value can be stored in non-volatile memory. This allows users to purchase existing devices on the market and program them before they become board-level products. You can modify the design (or reprogram the programmed device) by programming different values ​​within the device. The DS1073 is configured at the factory to half the maximum operating frequency. If special programming devices are needed, you can contact the factory. As a board-level oscillator, you can select an external clock signal or crystal oscillator as a reference. The reference source (internal or external) is selected by the user during programming (or when the chip is not working, if the SEL mode is selected). DS1073 uses dual-effect I / O pins. If the device is started in programming mode, this pin can input serial data to the register. After writing the command, the data is stored in non-volatile memory. When the chip is powered on in the working mode, these values ​​will be automatically stored in the internal register, at this time the I / O pin becomes the oscillator output. The DS1073 can operate in the commercial temperature range (TA = 0 ° C to 70 ° C) or the industrial temperature range (TA = -40 ° C to + 85 ° C). The AC and DC electrical characteristics of the chip when operating in these temperature ranges are given at the end of the data sheet. The DS1073 is available in an 8-pin DIP or SO package, which can generate clock signals simply and economically, and takes up the least board area. |
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