Too many audio interfaces do not know? Take you for a variety of audio interfaces in 2 minutes


When installing professional audio equipment, you will inevitably become dizzy when facing various types of equipment audio interfaces. Next, I will introduce several common audio interfaces. I hope to provide some help when you install your device or choose the audio cable.


audio port

Audio input output interface: Enter the audio signal of computers, video recorders, etc., and play through its own speakers. You can also connect the amplifier and external speakers through the audio output interface. Simply put, the audio interface is a device that connects microphones and other sound sources and computers, which plays a bridge connection between simulation and digital signals. The audio interface is usually used in conjunction with the front microphone, line input and other series of input devices.

3.5mm stereo interface


The most common analog interface -3.5mm stereo interface (small three core interface)

The 3.5mm stereo interface is also called the small three core interface. This is the most important sound card interface we are currently seen. Most of the consumer sound cards (including board sound cards) are using this type of interface.

The 3.5mm interface provides a stereo input and output function. Therefore, generally speaking, the 5.1 sound card (6 -channel) or speakers requires 3 3.5mm stereo interfaces to connect to the analog speaker (3 × 2 channels = 6. 6 Channel); 7.1 sound card or speaker requires 4 3.5mm stereo interfaces (4 × 2 channels = 8 channels), and so on.

In order to meet the needs of different device, similar interfaces can currently see three size specifications, including 2.5mm, 3.5mm, and 6.22mm interfaces, respectively. The 2.5mm interface is more common in mobile phone, because the interface can be done very small; the 3.5mm interface is more common in PC products and household devices, and it is also the most common interface type we see. Improved contact with contact surface and durable design, commonly on professional audio equipment such as monitoring.

This audio cable interface is widely used, mostly used for computer and portable audio sources, such as notebooks, mobile phones, MP3, DVDs, TV, radios, computers, CDs and amplifiers, and transmit their audio signals and their audio signals and their audio signals and To achieve recording between equipment and equipment, it can also be applied to the transmission of vehicle audio signals.

6.5mm audio interface


This audio cable is suitable for signal connections with 6.5mm audio devices, such as power amplifiers, audio, guitar, tuning table, etc.


RCA simulation audio interface

The RCA connector is often called the lotus head. The use of RCA cable transmission simulation signals is currently the most common audio connection method. Each RCA cable is responsible for transmitting an audio signal of a channel, so the stereo signal needs to use a pair of cables. For the multi -channel system, the same number of cables must be matched according to the actual number of channels. Stereo RCA audio interface,

The right sound is generally marked with red, and the left sound is marked with blue or white.

Lotus heads are often used to connect to devices with RCA composite video signal interfaces, such as DVDs, set -top boxes, and other connections with TV; can also transmit audio signals separately, such as audio devices such as DVD machines to the amplifier.

XLR interface

XLR is commonly known as the Caval head, which consists of a three -shot plug and a lock device. Because the locking device is used, the XLR connection is quite reliable. XLR interfaces can usually be seen on microphone, electric guitar and other devices, but it is not necessarily a balanced interface, because the implementation of the transmission of the balance interface is relatively complicated, and the requirements for the circuit are relatively high. Audio, video and video system engineering.

Optical (Optical)

Optical (Optical) transmits digital signals in the form of light pulses, and its material is mainly glass or organic glass. The fiber also uses the S/PDIF interface output. It is a high bandwidth and a small signal attenuation. It is often used to connect to DVD players and AV amplifiers. It supports PCM digital audio signals, Dolby and DTS audio signals.

Pay attention to 3 points when using optical fiber audio cables:

1. Do not bend the fiber line to the angle of less than 50 degrees to avoid damage to the fiber core;

2. Before use, remove the dust plugs on the fiber plug and keep the fiber plug clean;

3. Fiber plugs are directed. When used, please make sure that the plug and socket are consistent and then insert into the socket.

Interface classification


There are many types of interfaces between computers and audio devices, but the roots are divided into the type of transmitted signal, which is nothing more than two categories: audio signal interface and synchronous signal interface.


1. Audio signal interface

(1) The type of transmission signal can be divided into analog interface and digital interface.

(A) Simulation interface

The simulation interface occupies a large proportion in the audio field. Common simulation input, output interfaces such as: large/small three core plugs, RCA singing models (lotus type) plugs, XLR cartoon -type plugs, etc., because we usually use such interfaces more and more familiar. No longer say more.

(B) Digital interface

Professional digital audio systems and certain civilian systems have digital interfaces that meet certain standard protocols. Using it can transmit digital audio data of multiple channels in two devices without generating sound losses. As long as the error code can be completely corrected, no matter how many generations of digital replication, it will not affect the sound quality of the last generation, so that the real digital domain is not damaged.


(2) According to the wiring method, it can be divided into equilibrium class interfaces and unbalanced class interfaces.

(A) Balanced interface


Most of the professional audio and radio equipment have a balanced input/output circuit interface. The input and output terminals are generally XLR Caval -style sockets, and there are three terminals on the socket:+, -, land. The significance of+( -) refers to the+signal of the output signal and the+signal of the input terminal (or reverse). The input/output device of the balanced method is strong, because the noise in the cable or device generally appears at the same time on the positive and negative input end. Modular noise. However, the subsequent balance input circuit only transmits the difference between the signal of the positive and negative ends and can inhibit co -model noise.

(b) Infaculture class interface


The interface is often used for civil audio equipment. The input/output end is the heat end of the rack, and the connector is generally the RCA singing model. The anti -noise ability of the unbalanced connection method is weak. This connection method is generally used for short -term connections with a short -term connection of about 1M, or the noise is small, or the connection between the low -resistance and high output signal, such as the amplifier and the speaker.

2. Synchronous signal interface


Unlike analog audio signals, digital audio signals have a strict time structure. Because a sampling signal must further constitute frames and blocks with a certain length of time with other samples. If the digital audio device intends to communicate with each other, or the digital signal must be combined in some way, then they need to synchronize with the shared reference signal so that the sampling frequency of the device is completely consistent, and the sampling frequency of each other will not produce each other. Drift.

Therefore, digital audio workstations designed for professional applications often provide a variety of synchronous input interfaces. At the synchronous starting point, the record and replacement should be locked to the SMPTE/EBU or MIDI timing code (MTC) source, or the sampling rate clock, video synchronization or digital audio synchronization standards are locked on the external sampling rate.

In the internal synchronization method, the system is locked on its own crystal oscillator. If it conforms to AES’s application occasion (AES-1984), then there should be accuracy of ± 10ppm in professional devices (the accuracy of civil equipment should be required It is much lower than this). In the outer synchronization method, the system is locked on one of its synchronous inputs.

The typical synchronous input is a word clock (WCLK), which is usually a level signal (0 ~ 5V) of the sample square wave TTL. Generally, the BNC interface terminal is used, and the SONY interface (SDIF) is generally used on the device. In all cases, a machine or source must be recognized as “host”, which is used as a synchronous reference for the entire system, and other machines are “SLAVE”.

(Source: Network)