Using a USB to Aux Cables in Car Radio
Generally speaking, car audio systems often lag behind independent audio equipment and other electronic products. So you might find a 3.5mm auxiliary jack in your car radio instead of a USB port. If you know the USB to AUX cables, you may be wondering if you can use it to connect your mobile phone or USB flash drive to your car radio. The answer may be no, but the actual situation is much more complicated than this.
Do USB to Aux Cables Exist?
The answer is YES. However, they cannot be used as a conduit for digital music files to your car radio.
If you plug the USB flash drive into the USB to Aux Cables and connect the cable to the head unit, the head unit will not recognize it. In most cases, this is also the case if you plug the USB to Aux Cables into mobile phone and connect it to the head unit.
Some MP3 players and mobile phones are designed to output audio signals through a USB port. For example, the original HTC Dream used a micro USB port to achieve power and audio output, but this is not always the case.
Using USB vs. Auxiliary in Car Radio
If you put the music on a USB flash drive, mobile phone or any other storage medium, it will be stored as a digital file. Files are usually compressed into MP3, WMA, FLAC or other formats, unless you buy high-resolution digital music.
You need a program, APP or firmware to listen to these files, be able to read the data, and convert it into an analog signal for headphones or speakers. Whether it's the software on the computer, the phone, the MP3 player, or the head unit of your car, the process is basically the same.
When you use a USB flash drive, it is a passive storage medium to save song data, but it cannot do anything with these data. When you plug the drive into a USB-connected compatible head unit, the head unit read it just like a computer. It reads data from the drive and can play songs as it has the correct firmware or software.
Nothing happens when you connect the USB flash drive to USB to Aux Cables and plug the cable into the aux port of the head unit. The thumb drive can neither output audio signals, nor can the auxiliary input on the head unit read the digital information saved on the drive.
Can You Plug MP3 Player Into Car Head Unit?
The same principle applies to mobile phones and MP3 players that do not output sound through the USB port. The USB connection can transfer digital data back and forth and can also be used to charge the device, but it may not be used to output audio signals.
If the phone does not include a headphone jack, which will be the only case you want or need to output audio from the phone's USB connection to an auxiliary input head unit. Some mobile phones omit the headphone jack in order to support sound output through the USB connection.
Uses for USB to Aux Cables
Some devices support USB-to-aux cables, but they are far from universal on all devices. Some devices are designed to receive power through a 3.5 mm TRS connection. In this case, the USB-to-aux cable can usually be used for power supply.
You can use a USB-to-aux cable to connect USB headphones to the 3.5mm headphone jack on your computer sometimes. This is usually only possible if the headset does not need to be powered by USB except for the audio signal.
This applies to some headphones designed to receive analog audio signals. However, it does not apply to other headsets that require a computer's digital output or need to be powered via a USB connection.