Selection of transmission cable for sound equipment

It is necessary to interconnect signals between analog devices or digital devices in the audio equipment system. Whatever system type and configuration of the system, the cables used are very important. Sometimes in practice, the communication characteristics of the cables and the transmission characteristics of various uses are neglected. No matter how good an analog/digital audio equipment is, it is impossible to achieve the best skill characteristics without choosing appropriate audio cables and connectors that match the communication characteristics, and the undesirable consequences will occur. Therefore, according to the professional theory and practice of many years of audio skills, talk about the selection of transmission cable for audio equipment, for the reference of audio skills operators.

1, digital audio cable

Commonly used digital audio cable can be used with analog audio same connector, such as Kanongkou XLR, Lotus mouth RCA, BNC and so on. The use of analog cable to replace digital cable can also signal the transmission, but it will affect the transmission quality.

The output impedance of analog cable and digital equipment is more severe than that of cable impedance. No matter how long the analog cable is, the impedance of the analog cable is 600_at each point of the cable. The input and output impedance of the analog equipment is less than 600_when the level matches, the sound quality of the analog audio will not be affected. Assuming that the digital audio signal is a pulse data stream with a high frequency of operation, it is necessary for the cable to match the transmitting and receiving equipment in order to transmit the signal accurately, and the impedance of the start-to-end cable must adhere to common specifications, such as digital AES/EBU, I/O interface specifications. The transmission medium of cable is coaxial cable or twisted pair cable. The characteristic impedance of twisted pair cable is 110_. Otherwise, the transmission of digital signal will be damaged and the system will not work properly.

It is assumed that the characteristic impedance of a digital cable replaced by an analog cable does not match because the frequency of the digital signal is very high, and the skin effect of the current on the conductor will be deeper when the characteristic impedance matches, and the deeper the transmission, the better. The shallower the skin will be, the worse the transmission effect will be. This is because most of the current in the cable reflects. Standing wave will occur, which consumes signal energy and distorts the waveform of digital pulse signal. Because the dispersed capacitance, inductance and resistance of the cable can directly affect the frequency response of the signal when the impedance of the cable is not matched, the rising edge and falling edge of the pulse are affected (i.e. the symbol is "1" or "0"). There is a level jump at the beginning and end of each data bit cycle, and the mismatch will affect the frequency response. In the receiving end of the transmission, the decoding of the digital signal will present error code. Assuming that the time of pulse rising and falling edges shift forward and backward, the trembling time will be long and the audio quality will be degraded, even noise will occur.

In recording and manufacturing various programs, audio cables are needed for the combination of audio system equipment. In addition to the digital mixer, there are many digital and analog peripheral equipment such as various types of microphones, equalizers, delays, actors, composers, D/A converters, audio processors, digital audio recording and playback equipment, listening box and other equipment. It is possible to ignore the program quality transmission policy if it is considered to be connected. Assuming that the equipment skill policy is not high and the lack of cables is not obvious, assuming that the equipment policy in the recording room is all upgraded equipment, the use of impedance matching cables becomes an important part of the audio policy. The result is that it is necessary to use transmission cables that match the equipment, and at the same time, the input and output levels of the equipment must be properly matched (this is no longer within the planning).

2. Imitate the audio cable.

The analog audio cable can be broadly divided into microphone cable, transmission line cable and speaker cable. The audio cable has single core wire, two core wire and three core wire. Core wire is the conductor of audio signal; the outer layer of the conductor is a shielding metal wire composed of braided mesh and the outer skin of the maintenance layer, which shields from external electromagnetic interference and can be used as a signal ground. The outer layer of the shielding layer is covered with non-conductive plastic or rubber, which acts on the tensile force of the shielding wire of the inner conductor and maintains the shielding layer free from electromagnetic interference. It is corroded; the outermost outer skin can maintain the inner layers to make the cable durable. Audio cable also considers skin effect, generally using copper wire silver or tin as conductor, because of its low cost, good conductivity, easy to move.

Simulates the audio cable to use several typical plug-in methods, the Jane generally uses the Canon port (XLR) or (RTS) 6.25 large three-core (that is, 1/4 inch), the unbalanced multi-use (RS) large two-core 6.25 or Lotus mouth (RCA) plug-in. Loudspeaker cables usually have large diameter and many strands of copper strands, sometimes with banana plugs or other self locking plugs. When plugs and sockets are connected, they must adhere to the tightest connection. Analog and digital equipment on the use of the cable is slightly different in appearance, careful point to distinguish between omnipotent, in the selection principle, must not be turbid or misused, this is also a decision on the audio system equipment quality and operation policy, a very important audio equipment skills operation.