What are lightning and USB Type-C headphones? What's the difference between them and traditional headphones?

When it comes to the next generation iPhone, many people should see that Apple intends to cancel the 3.5mm headphone jack and connect headphones with Lightning instead. Yesterday, China brand LeTV also cancelled the 3.5mm headphone jack in the newly released mobile phone and provided USB Type-C headphones. What's the difference between these two headphones and the current 3.5 mm headphones? What's the point?

Understandably, because mobile phone manufacturers want to make the mobile phone thinner and simplify the terminals on the device, they simply re-integrate the only terminal on the mobile phone, leaving only an ordinary digital interface on the appearance of the mobile phone, which is also the development of mobile phone design after the extreme pursuit of thinness.

In the traditional structure of mobile phone sound, digital files are first converted into analog signals by the digital-to-analog converter (DAC) in the mobile phone, then amplified by the amplifier chip, and then output to the 3.5mm terminal, and the converted analog signals are transmitted to the earphone unit to make sound.

There are several ways to make mobile phones at present. One is to directly output analog sound to the power amplifier chip through the processor integrated digital-to-analog conversion architecture, the other is to output it to the power amplifier chip through an independent digital-to-analog conversion chip, and the other is to output the integrated digital-to-analog conversion and amplification chip. But no matter which architecture, it needs the process of digital-to-analog conversion and then amplification.

Lightning headphones and USB Type-C interface are connected digitally, and they do not have the function of analog output (although Apple's early 30pin can be converted into analog output, Lightning has cancelled analog output), but the sound emitted by headphones is analog. How to drive a monomer that sounds in an analog way? Simply put, it is to replace the original digital-to-analog conversion chip in the mobile phone with an earphone.

Simply put, the program that drives the earphone remains unchanged, only the position of the structure is changed. The original digital-analog chip and the amplified chip are hidden in the design of digital headphones. In short, compared with the original 3.5mm headphones, the cost of digital headphones will be higher, especially the Lightning and USB Type-C interfaces, which can be inserted in both directions.

Because Lightning and USB Type-C consider the convenience of use and higher data and power supply, the contacts become double-sided. At the same time, Lightning and USB Type-C need to be used on both sides. Compared with the single-sided contact and directivity of microUSB, it needs additional communication and conversion chips. After the device is plugged in, you need to communicate with the mobile phone, confirm that the output signal points are consistent, and finally integrate the signals, so that both sides can use it, only the terminal.

In addition, the earphone terminal needs a plurality of analog-to-digital conversion chips and amplification structures, and because the weight of the earphone cannot be increased too much, the internal power supply of the mobile phone must be used for output, and no additional battery design will be added, so the selected digital-to-analog conversion chips and amplification chips need to meet the requirements of low-voltage startup and low-current operation, so as to avoid the earphone from working normally due to insufficient power supply at the mobile phone terminal.

In addition, whether it is Lightning or USB Type-C, there is one more process to convert digital audio signals into Lightning and USB signals compared with the earphone driving structure built in the mobile phone, so the digital earphone needs one more decoding chip to convert the received signals into SPDIF, otherwise most digital-to-analog conversion chips cannot directly identify USB and Lightning signals.

But in fact, to put it bluntly, both Lightning headphones and USB Type-C headphones have the same meaning as the DAC integrated amplifier for mobile phones that can be bought in the market. The only difference is that these digital headphones directly integrate headphones with digital power amplifier, and have strict requirements on power and size.

Compared with Android, the MFI specification of iOS has its advantages and limitations. Lightning headset through MFI means that you can plug and play as long as you connect iPhone and iPad, and Apple originally pre-installed USB sound driver in iOS system, unless it is an early 30 PIN device, it will not encounter compatibility problems; However, MFI has strict requirements on the power consumption of equipment and the format of digital signal receiving chip. For example, the digital receiving chip only allows formats of up to 24 bit and 48 kHz, which also limits the performance of some headphones and high-standard audio files.

At present, although the Android camp began to add universal drivers for USB audio at the bottom of the system after Android 5.0, because Android still allows manufacturers to make some adjustments to a certain extent, some entry-level models have removed USB drivers in order to save system storage space. Secondly, some models have modified their drivers because of adding more complicated USB connection functions, which leads to unstable connection of USB audio devices from time to time.

Is it an inevitable trend to cancel the headphone jack? The author is actually skeptical, because the complexity of digital headphones is higher than that of traditional headphones, and the wear rate is higher. After all, the durability of the wire is equivalent to Lightning and USB 3. 1 wire, and once the enlarged end or the earphone end is damaged, it is equivalent to the failure of the earphone. However, in the case that manufacturers are eager for consumers to wear consumables quickly, perhaps canceling earphone holes is more like a conspiracy theory of making money in disguise.

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