As we all know, capacitor (c) and inductor (L) form an LC network (Network) on the sound line, which is used to divide the frequency line - the output integrated signal of power amplifier. When passing through this LC network, each high and low frequency will be separately transmitted to different speakers (such as tweeter, mid-range, worker, sub-woofer, etc.) according to the designed frequency division point and sound path
According to the design of engineers in various factories, the LC network can range from the simplest two-way high / low, universal three-way high / medium / low, advanced four way high / medium / low / subwoofer or ultra-high / high / medium / low, to the top five way ultra-high / high / medium / low / subwoofer, and even more·
The circuit of LC network is also designed by the engineers of each factory. Each sound path has from the most basic one capacitor, one inductance, two capacitors and two inductors to several capacitors and several inductors·
Because the signal passes through the capacitor and its phase reverses by 90 degrees (if the capacitor has no loss - in fact, this is impossible), and the signal passes through the inductor and its phase advances by 90 degrees, in order to restore the signal phase to the original phase, usually each sound path of the complete frequency division line must use the same number of capacitors and inductors... (of course, some people insist on using different numbers as the signal phase difference)
Because all sounds from the power amplifier to the speaker pass through the LC network (except for the sunny type), the importance of these two components to sound can not be ignored. It is not too much to say that they are the same as single speakers or speakers·
Relationship between capacitor and sound:
As mentioned earlier, the LC network composed of capacitors and inductors is a frequency division line, and its formula is
F (frequency division) = 2 π√ (L x C)
Therefore, the frequency division of the classification point should be accurate, and the capacitance value of the capacitor should be relatively accurate. Therefore, the error value of the capacitor used in the frequency
Signal and capacitor polarity:
Because the output of the power amplifier is the signal voltage (also known as AC), the capacitor used on the frequency division line must be non-polarized·
Signal and capacitor withstand voltage (WV):
In order to carry the signal voltage output by the power amplifier, the withstand voltage value of the capacitor used on the frequency division line must be higher than the output signal voltage PP (peak-peak) value designed by the power amplifier, which is generally 30% - 40% higher than the safety value (it is not necessary to require too high withstand voltage value to avoid unnecessary cost) · the signal voltage output by most power amplifiers does not exceed 30vac, so the withstand voltage value of 50V can be used, Of course, the withstand voltage value of 100V is more safe·
**The carrying power has no effect on the withstand voltage value of the capacitor, but is related to the allowable ripple current of the capacitor, that is, the loss factor·
Loss angle between signal power and capacitor:
In a word, the carrying power of the capacitor is related to the loss angle value. The lower the loss angle value, the greater the carrying power, and the higher the loss angle value, the smaller the carrying power·
What is the loss factor (DF)? The angle between the phase angle of the signal passing through the capacitor and - 90 degrees is called the loss factor (also referred to as DF) · the phase angle of the standard capacitor is negative 90 degrees (the loss angle is zero, and the ESR impedance value is also zero), and the lower the DF value, the lower the ESR impedance value·
For example, the phase angle of the signal through standard capacitor is negative 90 degrees, so the closer the phase angle of the capacitor is to - 90 degrees, the lower the loss angle value and the greater the carrying power. If there is a standard capacitor, because its phase is - 90 degrees, that is, the loss angle value is zero and the ESR impedance value is zero, so it can carry infinite power·
Tone and capacitor loss angle:
The loss angle value is directly proportional to the level series internal resistance (ESR) of the capacitor. The lower the loss angle value is, the lower the internal resistance value is. The higher the loss angle value is, the higher the internal resistance value is. Therefore, the sound quality is inversely proportional to the loss angle value. The lower the loss angle value is, the lower the internal resistance value is. Therefore, the sound quality is better. The higher the loss angle value is, the higher the internal resistance value is, so the sound quality is worse·
Frequency response and loss angle of capacitor:
When the same capacitor works at different frequencies, its loss value and capacity value are different. Generally speaking, the higher the working frequency is, the greater the loss angle value will be (the smaller the capacity value will be). The change rate is directly proportional to the loss angle value of the capacitor. The lower the loss angle value is, the smaller the change rate is, the higher the loss angle value is, the greater the change rate is. Therefore, the frequency response is closely related to the loss angle value of the capacitor, The lower the loss angle value, the smaller the change rate of the loss angle value and capacity value when working at various frequencies, so the smoother the frequency response (the wider the frequency can be passed), and the opposite is true for the capacitor with higher loss angle value·
**Most frequency division capacitors can specify the maximum allowable loss angle value (e.g. 10% 5% 4% 3% 1%...) under the test frequency of 120Hz or 1kHz, However, in order to make the frequency response more flat and perfect (generally, the curve of high frequency or high pitch should not be pulled down), The capacitor can also be required to specify that its test frequency is at a higher frequency (for example, at 3kHz, 6KHz, 10kHz or even 20kHz, preferably at the same frequency as the set frequency division point). Set the maximum allowable loss angle and rated capacitance - on this point, the capacitor manufacturer of sound specialty can cooperate to meet this requirement·
Loss angle between speed of transmission and capacitor:
For example, the above loss angle value is directly proportional to the level series internal resistance (ESR) of the capacitor. Therefore, in addition to the quality of sound and the loss angle value, the sound transmission speed is also closely related to the loss angle value. The lower the loss angle value is, the lower the internal resistance value is, so the transmission speed is also faster. The higher the loss angle value is, the opposite is true·
From the above, we should understand that the quality of the capacitor is closely related to the sound horn (whether for household or vehicle use). The capacitor is like the artery of sound, and a good sound frequency division line should have a good capacitor - that is, the error value of the capacitor should be accurate, the withstand voltage value should be sufficient, and the loss angle should be low·
Briefly describe the capacitors used in various frequency division lines:
Types and of capacitors
Its maximum DF value @ 1kHz
General capacity range and
Tolerance value
characteristic
PP plastic film
0.04% ━ 0.10%
zero point zero one μ F ~ 47 μ F
± 1% ~ ± 10%
The loss angle is the lowest, the speed is the fastest, and the frequency is the highest
The clearest sound and the highest cost
Applicable to: UHF high-power top products
PE plastic film
0.4% ━ 1.00%
zero point one μ F ~ 100 μ F
± 1% ~ ± 10%
Low loss angle, fast speed and high frequency
Bright sound and high cost
Applicable to: high frequency, medium and high power high-grade products
Low loss NP electrolysis
2% 3% 4%
5% 6% 10%
one μ F ~ 300 μ F
± 2% ~ ± 10%
The loss angle is low and the speed can be medium and high
Soft sound and moderate cost
Applicable to: medium and high frequency, medium and high power high-grade products
General NP electrolysis
10% 12% 15%
one μ F ~ 1000 μ F
± 10% ~ ± 20%
Low loss angle, high speed, low frequency
Lowest cost of sound paste
Applicable to: low power ordinary products
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