Generally speaking, our most common is the 3.5mm audio plug, which is almost the standard plug specification for most electronic products. The mobile phones and players we use in life are basically 3.5mm plugs. Of course, 3.5mm also belongs to the very old Wide range of headphone plugs. In addition, what other headphone plugs are there, and which audio products are they used for?
Let's explain TRS first:
TRS is a connector commonly used to connect audio equipment and transmit signals. Its three letters represent Tip (tip), Ring (ring) and Sleeve (sleeve). For example, our common 3.5mm headphone plug, also known as "3.5mm TRS". Because it is often used to plug in mobile phones, it is also called Phone Jack. TS, TRS and TRRS are collectively referred to as TRS, and can be referred to as TS (no ring, that is, the tip and the sleeve each provide one contact point), TRS (one ring, three contact points) according to the number of rings (R) of the specific plug/socket. ), TRRS (two rings, four touch points), etc.
3.5mm TRS: 3-stage, 3.5mm TRS is the most common headphone plug, from top to bottom, it is left channel, right channel and ground, compatible with most mobile phones and DAPs, and belongs to portable audio equipment. commonly used. 3.5mm TRRS: For headphones with in-line control, you will find that the plug is a 4-segment TRRS. In addition to the left channel, right channel, and ground, there is also a segment that can transmit radio microphone signals.
3.5mm TRRS: 4-segment plug, can transmit left channel, right channel, ground and radio microphone signals. Unlike 3.5mm TRS, it can not only make calls, but also control music playback by transmitting signals.
The audio interface can be divided into balanced output and unbalanced output. Generally, the specification of unbalanced output is 3.5mm, while the balanced output is generally found in high-end portable audio equipment. At present, it does not have a unified specification. have their own standards.
The difference between them is that the unbalanced output (also called single-ended output) is divided into three channels: left channel, right channel and ground wire, while the balanced output is divided into left channel positive, left channel negative, right channel positive and The right channel has four negative poles. For unbalanced output, the signals of the left and right channels will flow to a ground wire, causing the signals to interfere with each other and the sound separation is not high enough. The left and right positive and negative channels of the balanced output have independent ground wires and do not need to be shared, so they can achieve a very good degree of separation.
2.5mm TRRS: 2.5mm generally only appears in the balanced output of high-end portable audio equipment. Since the 2.5mm balanced plug can increase the thrust on the one hand, the playback sound field is usually wider than the 3.5mm plug. Some DAPs have balanced output The jack, the amplifier circuit can be processed independently on the left and right, and the gain output is very sufficient, which not only makes the headphones easier to push, but also reduces the noise affected by the current, making the music more clear and pleasant. The 2.5mm TRRS balanced plug is a 4-stage structure, the positive and negative signals of the left and right channels are transmitted separately and have a ground wire.
4.4mm: 5-segment plug, Japan Electronics and Information Technology Industries Association (JEITA) announced the headphone definition standard "RC-8141C" in March 2016, and chose 4.4mm 5-segment as the balanced headphone plug standard, except for the left and right In addition to the positive and negative poles of the channel, the grounding is also independent. 4.4mm balanced plugs and sockets are not widely used now, mainly for Sony's audio products.
4-pin XLR: It is a balanced plug, the positive and negative of the left and right channels are completely separated, but the ground is shared, which can achieve balanced transmission. This plug is different from the terminals collectively referred to as "TRS" above, and its shape is much rounder and thicker. XLR connectors are generally found in professional audio, video and stage lighting equipment. Look carefully at how many pins are standing on the plug, depending on the number of pins used in different places. "4-pin XLR" is divided into left channel positive, left channel negative, right channel positive, right channel negative, the ground wire is common, but it can also achieve balanced transmission. We have more contact with 4-pin plugs, and most of them are used in audio amplifiers and headphone amplifiers.
6.3mm: 3-segment plug, left channel, right channel and ground. Due to the large area occupied, under normal circumstances, it is only used on home audio equipment, which is commonly used in two-channel amplifiers, large-ear cows, headphone amplifiers, and professional audio equipment.
USB Type-C: The Lightning interface is an exclusive connector specification for Apple, while USB Type-C belongs to some Android phones. They partially follow Apple’s approach and cancel the traditional 3.5mm headphone jack. The way of transmission output audio signal. Many LeEco products use USB Type-C.Wired Universal Earphone\The following models:T110
Lightning: It is rumored that the 3.5mm headphone jack has been removed from the iPhone 7. There are quite a few Lightning earphones on the market. As the name suggests, they are designed for iOS devices and lack flexibility to some extent. The output of the traditional 3.5mm headphone jack is an analog signal, which needs to be decoded by the built-in DAC of the mobile phone and converted into a signal before being transmitted to the headphone. However, the headset with Lightning interface can put the DAC chip in the headset, and the headset manufacturer can choose the DAC decoder chip to ensure that the headset can exert its strength.
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