Impedance matching: In the audio system, almost all equipment uses a cross -connection method, that is, the output impedance design of the device is very small, and the input impedance is large. This is because in the system, unless the signal is transmitted long -distance transmission, it is generally treated as a short -term processing. And the signal level bottom, the signal is required to transmit high quality, and the change of the load basically does not affect the quality of the signal. When the signal source is designed to a constant voltage source, or the load is far greater than the internal impedance of the signal source, the above requirements can be met. In fact, the impedance of professional audio equipment is designed in accordance with the above principles. The device interconnection is adopted by a cross -connection method. This is the impedance matching of the audio equipment. When designing the soundplacement system, that is, when a signal source drives several loads, the active or source -free signal distributor must be used to meet the requirements of the equipment impedance matching (if it is two devices, it can generally be directly and in the front stage directly and in the front stage The output end of the device) The amplifier and speakers are connected according to the output impedance of the nominal and the input impedance of the speaker. The output impedance of the amplifier is 4Ω and 8Ω, you can connect 4Ω speakers or 8Ω speakers. When connecting the 4Ω speaker, the power amplifier's output power is larger than 8Ω. Two 8Ω speakers can be connected to the amplifier output end, which is 4Ω working. It must be noted that when the speaker is connected, the impedance will reduce its minimum output impedance that is not as small as the power of the power amplifier. When a 4Ω load impedance is used, the required transmission line impedance is doubled than 8Ω. In a high -quality audio system, the transmission impedance during 4Ω output does not exceed 0.2Ω (excluding the internal resistance of the large device). If the transmission is less than 100m, the cross -sectional area can be reduced by half. The contact resistance at both ends of the transmission line is also required. In a performance preparation of the audio system, it was found that the connection of the transmission line at both ends of the transmission line was replaced with a better plug -in.2, level matching: When the audio equipment is interconnected, the matching match is equally important. If the matching is not good, or if it will be insufficient, or if the overload will occur, it will cause serious distortion, which will make the system unable to work normally. To achieve the level matching, not only should it be matched in the rated signal state, but the signal does not have a peak, but also does not occur. The peak factors of the high -quality system are considered at least 10db. Modern audio devices are designed according to standards. Just pay attention to the selection of the book and the system tuning to meet the requirements of the level matching.