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Introduction of microphone cable

Updated:05-08-2021
Summary:

The microphone cable is mainly used for the connection […]

The microphone cable is mainly used for the connection of microphones and audio equipment. It should be classified as a weak current control cable in the cable category, and the single-core or double-core outer shielding method should be adopted.

It is mainly divided into two categories: balanced (double-core outer shielding) and unbalanced (single-core outer shielding). The former is used for long-distance transmission, and the latter is used for short-distance long-distance transmission within 5-10 meters. The microphone cable can usually transmit up to hundreds of meters away. The microphone input is an electrical signal of 1 millivolt (0.001V), and the microphone impedance is about 600 ohms. The microphone is an energy provider. Because its working voltage is extremely weak, the wire needs to be used Two methods to deal with the problem of interference. They are:
1. a pair of twists
2. Shield
Pair-twisting can only be used on balanced two-wire transmission signal lines. Because the signal is extremely weak, interference will inevitably be encountered during transmission. Therefore, at the microphone end, a transformer is used to convert the signal to a positive and a negative signal for simultaneous transmission. When subjected to external interference, the two wires will cancel the interference to eliminate the interference and obtain the required signal. In order to make the interference into the cable evenly, the wire pairs need to be twisted. A better twist may be as fine as 30mm. Similar anti-interference techniques are used in both network cables and HDMI. For related entries, please refer to: Differential Mode Signal
The following is an introduction to some shielding methods:
1. Coated copper wire: Copper wire is generally used to wind the inner quilt. When it is bent, it is easy to cause poor shielding. Most of it is used for short-distance microphone cables.
2. Braided copper wire: The copper wire is woven into a net in a manner of multiple strands. Its shielding characteristic is much higher than that of winding. It is used in professional stage performances and equipment that needs to be moved.
3. Aluminum foil isolation: Use the characteristics of aluminum foil to add aluminum foil to the periphery of the wire as a shield, and match a ground wire for grounding, which has a good shielding effect. This type of wire is mostly used in engineering installations or stage multi-core wires.
4. Conductive PVC/PE: Use the soft material conductive PVC/PE to wrap the outside of the wire. It has the characteristics of full coverage and not easy to break. It needs to be wound or braided. It is generally used on wires that are easy to be thrown and stepped on. Because of its characteristics between conductors and non-conductors, it can cause the space between the lines to change instantly when the ground is stepped on, and then the situation of distributed capacitance discharge is alleviated.
5. Composite isolation (double isolation): Double shielding is to make up for the advantages and disadvantages of the above multiple shielding, the most common is aluminum foil + braid, which is mainly used for wires that require extremely high shielding. In addition, the UL2919 wire for VGA signal transmission also uses this Class technology.

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