Interpretation of the difference between balanced and unbalanced CD playback
The balanced transmission method is only for the purpose of being able to transmit signals over a long distance in the professional field, and has a standard interface for uniform input and output impedance. The three wires transmit a channel of positive and negative signals + ground, which is almost the standard on professional recording equipment. Match. Later, it seems that Japanese manufacturers have extended this interface to the civilian field. The essence of balanced transmission is push-pull amplification, which can resist common mode interference. The essence of unbalanced transmission is single-ended amplification, which requires ground wire to participate in signal transmission.
Most balanced headphones are wired as L + L- R + R- four wires. The difference from the LR GND of ordinary earphones is that each earphone is driven by the BTL bridge mode inside the player, and is not driven by the OTL / OCL mode.
I have seen the balanced interface of the headset with a four-core Canon head, and I have never seen a four-core 3.5 and 2.5 interface. From the sense of hearing, after amplifying well-designed balanced transmission analog signals, the sound dynamics, speed, sound field, and signal-to-noise ratio will be greatly improved. In contrast to unbalanced sound, the sound is soft and the sound field is relatively small. However, the sound of the crudely manufactured balanced interface is sharp and harsh, and it is completely inferior to output alone. Ordinary players are meaningless with a balanced output interface, especially portable playback devices, unless they are portable recorders for professional use.
Most people who have played audio editing software have done one thing: silenced accompaniment. Yes, if you can understand this principle, you have basically understood most of it. One of the left and right channels of the stereo audio is inverted and superimposed, so that the two originally identical waveforms become one upward and one downward.
In true stereo original vocal audio, the recording method usually used is that the sound image of the instrument is on the left and right sides, and the vocals are centered. After inverting and superimposing, the centered vocal waveform is exactly the opposite, so the peak to the peak, the valley to the valley, the two The offsets are gone (absolutely ideal, it is gone, the actual recording will be a little bit off, the red part is the rest of the centered vocal, it is already very small).
On the left or right instruments, because they do not have exactly opposite waveforms after being reversed, they are not greatly affected, but some will disappear, such as percussion that is relatively centered and has little reverberation. Therefore, the silencer accompaniment is actually mono, and the sound quality is poor.
The balanced signal of the XLR or TRS interface is based on this principle. One of the three cores is a positive phase signal, one is a reverse phase signal, and the other is a shared ground. When the signal reaches the receiving device, the receiving device will reverse the phase The signals are inverted into normal phase signals and superimposed together, so that the interfering signals of the half-way wires will cancel each other out, leaving a clean original signal. Therefore, balanced signals can be transmitted far away from interference. Although the distance also has a limit, it is much better than the two-core unbalanced signal that uses only positive and negative poles! Therefore, professional audio equipment is generally a balanced interface.
This article describes the working principle of a single-channel audio signal. A device with a balanced interface will first divide a signal into two parts, and reverse one of them, and transmit it in the same set of three-core cables as the normal phase signal. Therefore, the interference waveforms received by the two signals are basically the same, and the receiver will just cancel out after inverting and superimposing again. The same is true for stereo or surround sound transmission, just one set of three-core cables per channel.
In addition, two-channel is not equal to stereo, stereo must be two-channel, multi-channel is not equal to surround sound, surround sound must be multi-channel, please understand if personal understanding is wrong.
Shenzhen Sunwind Energy Tech Co.,Ltd , https://www.sunwindbatterylm.com