Bluetooth headphones are all the rage right now, having spent the better part of a decade as a niche product aimed at tech enthusiasts. You can now find an incredible variety of Bluetooth headphones on electronic store shelves, and even more online. But as with almost all product categories, not all sets of wireless headphones are created equal.
We'll talk about three Bluetooth technologies that relate to how accurate your Bluetooth headset sounds and what you're looking for in a new pair. A2DP is the main Bluetooth streaming protocol, aptX is an advanced codec specifically designed for Bluetooth, and Apple's W1 chip system is proprietary and only works with Apple hardware.
How to enable hands free on your phone?
It looks something like this:
- Select adding a new Bluetooth device in the multimedia system
- Turn on
Bluetooth on your smartphone and select your car from the list of found ones - Enter the PIN code (usually “0000”) which is indicated on the screen of the car’s multimedia system
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A2DP: default
A2DP stands for Advanced Audio Distribution Profile, which means - well, it doesn't mean much in the context of something that already broadcasts audio. But, as one of the oldest parts of the unified Bluetooth specification, A2DP is more or less the default for Bluetooth audio streaming. Any Bluetooth audio product you buy—headphones, speakers, cell phones, laptops—will at least support A2DP, regardless of whether it can handle aptX as well.
My trusty, rusty Motorola s305 Bluetooth headphones from 2009 only support A2DP.
The A2DP standard operates in stereo mode and supports most standard audio compression codecs. The recommended sub-band coding (SBC) codec supports up to 345 kilobits per second at 48 kilohertz. That's about one-third the quality of a standard audio CD—roughly the equivalent of a high-quality MP3 recording. Due to the high "lossy" compression in the SBC codec, the reality of audio quality is significantly lower, somewhere in the 256 kbps range.
The system also supports other popular audio encoding and compression methods, such as MP3 itself. If the audio source is already compressed in a format such as MP3, AAC or ATRAC, it does not need to be transcoded to SBC in order to stream from the source device. With A2DP's maximum audio throughput of 728 kbps, it's at least possible to start getting closer to what we'd call "high-quality audio" using just the base standard. (CD audio quality, uncompressed, is approximately 1400 kbps.)
Unfortunately, very few equipment manufacturers seem to actually use this capability, and most devices that only support A2DP transcode the audio to SBC and decode at the receiving end. This makes the whole process more complex, resulting in poorer sound quality.
aptX: update
Mobile chip maker Qualcomm acquired CSR and aptX technology in 2015.
It licenses the codec to many telephone and audio companies. AptX is also a compression standard like SBC or MP3. But it's overall better and designed to handle the limited bandwidth and low power available to Bluetooth devices. CSR, the developer behind aptX, says it uses a proprietary compression method that preserves a larger range of audio frequencies while simultaneously "compressing" it to fit into the limited data channel that A2DP offers.
In layman's terms, think of the A2DP profile as a McDonald's two-quarter pound burger, and aptX as the "special sauce" that makes that Big Mac burger.
[Editor's note: Michael, your metaphors need work.]
The company claims that this advanced compression results in CD-like audio quality, and while it may be stretching it a bit, a full aptX system sounds significantly better than most A2DP-only systems. The codec is also faster to encode and decode, resulting in a reduced gap between the screen and speakers when watching videos with Bluetooth audio turned on. AptX HD is an even higher quality standard, with 24-bit/48kHz audio and slightly higher bit-rate streaming.
Unfortunately, aptX requires the codec to be supported by both the broadcast device and the receiver. If your headphones or speakers don't support aptX, they will default back to A2DP only, resulting in a lower level of Bluetooth audio quality that you may already be disappointed with.
Audio/Video Remote Control Profile (AVRCP)
This profile is responsible for the functionality of remote control of Bluetooth devices. You'll find this profile on devices such as TVs, headphones, smart speakers, sound bars, smartphones, and other stereo equipment. ACRCP provides an interface that allows your Bluetooth device to pause music, increase and decrease the volume, skip to the next and previous file in your playlist, and more.
AVRCP plays a vital role in the control device (such as a smartphone) and the target device (Bluetooth headset, speaker, etc.).
When you press a button (play, pause, then, etc.) on a control device, the command is detected by the controller using AVRCP. The profile subsequently converts the command into an A/V control signal, which it transmits to the target device.
Advanced Audio Distribution Profile (A2DP)
Briefly known as A2DP, this profile is responsible for transmitting high-quality stereo audio from the source (SRC) to the destination (SNK). The source (SRC) is basically a device that produces digital audio, and the sink (SNK) is the receiving device in a piconet, a network of devices connected using Bluetooth technology.
If you use Bluetooth headphones, headphones, car stereo, your device uses this profile to deliver high-quality audio.
Features of Advanced Audio Distribution Profile
Often the profile has AVRCP support. What is required to control a transmitting device over a short distance.
bandwidth is not so large as to pass a 2-channel signal of good quality without compression, and therefore in the A2DP profile it is possible to use different codecs that provide compression of the digital stream. Usually this is the SBC codec, less often - MP3, AAC and others. They must provide support for both devices - headphones and a smartphone.
It should be noted that the signal quality when using the SBC codec is worse than MP3 with conventional compression options. When the receiving and transmitting devices establish communication, the codec used, encoding settings: sampling frequency, bitrate, etc. are agreed upon
Account - what is it and why is it needed?
Apple's AirPods and W1 chip: different
What about iPhone? Does it support aptX, and do those fancy AirPod wireless headphones use it? No. While AirPods do use Bluetooth (not AirPlay, which is more of a Chromecast-type Wi-Fi audio protocol), they use the proprietary W1 Bluetooth chip, which is only fully supported by Apple devices running iOS 10.2 or Sierra 10.12 (or later). This special connection allows for higher quality listening than standard A2DP (and almost instantaneous automatic connection), but it is not compatible with aptX, and connecting your iPhone to an aptX-enabled headset or speaker will still use low-quality A2DP.
There are other headphones compatible with the patented Bluetooth standard enhanced by the W1: Beats. (Apple acquired the Beats brand back in 2014.) And Beats Bluetooth headphones that support AirPods and W1 can be connected to regular non-iPhone audio sources. But the new Beats products don't use aptX either, and since Apple isn't interested in licensing its W1 technology the way Qualcomm does with aptX, AirPods or Beats headphones are basically your only choice for high-quality wireless audio on iOS.
Note. You can use AirPods or Beats with non-Apple devices or Apple devices running older versions of iOS or Sierra. These devices simply won't be able to take full advantage of the W1 chip. They will connect fine via regular Bluetooth and will use A2DP by default.
Bluetooth version
In modern devices you can most often find support for Bluetooth 3.0 or 4.0, in some top smartphones and other gadgets - 4.1. In this case, it may well turn out that the purchased headset supports connection only via protocol version 2.1. The adapters are backwards compatible, but when connected, the slowest protocol of the two works.
The differences between protocol versions for the average user are minimal due to backward compatibility. The main thing that catches your eye is that with each new version the power consumption of devices is reduced, and starting from 3.0 a second module has been added for high-speed data transfer at a speed of 24 Mbit/s.
Version 2.1 + EDR transmits data at a speed of no more than 2.1 Mbit/s. This is enough to play a low bitrate audio stream. To play audio and video streams, it is recommended to use Bluetooth version no lower than 3.0.
It is necessary to take into account that in order to fully use the device as a player, it is highly desirable to have Bluetooth version 4.0 or higher, or better yet, with reduced power consumption.
You can identify such an adapter thanks to the following categories.
How do you know you're getting aptX?
First, check your current device, which is probably your phone. Most new phones sold over the past few years include this feature, especially those equipped with Qualcomm Snapdragon processors. High-end phones from Samsung, LG, HTC, Sony, Huawei and OnePlus support Bluetooth streaming via aptX. Apple's iPhone is a notable exception.
Most Android phones released since 2014 support aptX Bluetooth.
Next, make sure your receiving equipment—speaker, car stereo, or headphones—also supports aptX. This is less common and you'll need to specifically check the spec sheet to see if aptX is listed. This used to be limited to only the most expensive models, but these have come down in price recently and you can usually find aptX support for a wide variety of models. The aptX codec can handle everything from a pair of Sennheiser noise-cancelling headphones and in-ear headphones under $400 to inexpensive Aukey headphones for $26. Look specifically for aptX HD support for even better audio.
Left: Sennheiser HD1 Wireless, $340. Right: Aukey Latitude, $26. Both support aptX Bluetooth. Well-groomed!
Unfortunately, it can be difficult to determine whether the actual audio playing on your device supports aptX streaming. In particular, phone manufacturers do a poor job of informing the user about the codec or bitrate that is actually used to transmit audio. Once you've made sure your player and audio device are compatible, you'll usually have to (ahem) play it by ear.
Image source: Sony, Amazon, Samsung, Apple
