Type and Introduction of Audio Interface

- Jul 30, 2018-

1. RCA Connector

The RCA connector is often referred to as the Lotus Head. The use of RCA cables to transmit analog signals is currently the most common audio connection. Each RCA cable is responsible for transmitting the audio signal of one channel, so stereo signals require a pair of cables. For multi-channel systems, the same number of cables is used depending on the actual number of channels. Stereo RCA audio interface, generally the right channel is marked in red, and the left channel is marked in blue or white.


S/PDIF (Sony/Philips Digital Interface, Sony and Philips Digital Interface) is a digital audio output interface jointly developed by SONY and PHILIPS. This interface is widely used in CD players, sound cards and home appliances to improve the sound quality of CDs and give us a more pure auditory effect. This interface transmits digital signals, so it does not interfere with analog signals and degrades audio quality. It should be noted that the S/PDIF interface is a standard, and both the coaxial digital interface and the optical interface belong to the S/PDIF interface.

3. Digital Coaxial

Digital Coaxial is an interface that outputs digital audio using the S/PDIF interface. The coaxial cable has two concentric conductors, and the conductor and the shield share the same axis. The coaxial cable is a copper wire conductor isolated by an insulating material with an impedance of 75 ohms. On the outside of the inner insulating material is another layer of ring conductor and its insulator. The entire cable is sheathed of polyvinyl chloride or Teflon material. Wrap it up. The advantage of the coaxial cable is that the impedance is stable and the transmission bandwidth is high, which ensures the quality of the audio. Although the standard connector of the coaxial digital cable is a BNC connector, the coaxial digital wire on the market mostly uses an RCA connector.

4. Optical Fiber

Optical transmits digital signals in the form of light pulses, which are made of glass or plexiglass. The fiber also uses the S/PDIF interface output, which has high bandwidth and low signal attenuation. It is often used to connect DVD players and AV amplifiers, and supports PCM digital audio signals, Dolby and DTS audio signals.

5. XLR Interface

The way the RCA analog audio cable transmits sound directly is different. The Balanced Analog Audio interface uses two channels to transmit signals with the same signal and opposite phases. The receiving device subtracts the two sets of signals, and the interference signal is cancelled out, thereby obtaining a high quality analog signal. Balanced analog audio typically uses an XLR interface and a large three-pin interface. The XLR, commonly known as the card head, consists of a three-pin plug and a locking device. Thanks to the locking device, the XLR connection is quite secure. The large three-core interface uses a 6.35 mm diameter plug, which has the advantage of being wear resistant and suitable for repeated insertion and removal. Balanced analog audio connections are found primarily in advanced analog audio equipment or professional audio equipment.



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