A must-have brief on Bluetooth, from the basics to daily practice in audio land, was posted on HiFi.nl this summer. That raised a number of questions for readers, which, in short, are almost the same: “Great, that wireless connection, but what is left of the quality of the source file when you send audio over Bluetooth?”
We know that since the introduction of the current standard in the field of wireless connection, things have evolved considerably. While Bluetooth was never primarily intended to send or receive audio signals, but rather to allow hardware like the mouse and keyboard to communicate with each other, quite a few steps have been taken to exploit and enhance those capabilities. Consider Bluetooth version 4.0 and the arrival of the now-familiar aptX codec. However, the transfer is not (yet) loss-free. Is the quality of the source file sufficiently preserved with a wireless connection via Bluetooth? In other words, does it make sense to play FLAC instead of MP3, for example if you use Bluetooth to send the music to your speaker?
Codecs
The wired versus wireless discussion will likely always persist. After all, there are numerous hi-fi manufacturers that specialize in audio cables and tell a very good story about it (and besides, of course, there’s the good digital cable twist). When talking specifically about wireless audio over Bluetooth, there is always the element of compression. Due to the limited bandwidth of the connection, by definition there will be data compression and therefore loss of quality. (Not to mention, Bluetooth operates within the 2.4Ghz frequency that many other equipment in the house are also ‘connected’ to.)
aptX
The algorithm used also depends on the codecs supported by both the sender and the receiver. The only one that always works is low complexity subband encoding, or SBC. SBC is still used if, for example, the smartphone supports aptX, but the headphones do not; is the backup option. aptX, which has already done a lot to limit compromise, is certainly not the official standard and is still quite rare, regardless of the fact that there are so many different variants of su. What aptX also does exactly to ensure the ‘lossless CD quality’ of the connection is known only to the creator CSR and owner Qualcomm (you know, the American telecom giant), and their interpretation is, at best of the cases, vague. to name. In any case, the transport of audio data is still dependent on the bandwidth of the connection, which does not have the lossless qualities of transmission over optical cables, for example. The essence: With Bluetooth audio streaming, the audio stream is encoded with a lossy algorithm. After all, Bluetooth has insufficient bandwidth for lossless, let alone high resolution.
“It is always recommended to work with lossless FLAC or ALAC files”
Now what?
Well then there is loss of audio quality. And it’s no secret that hi-fi enthusiasts aren’t fans of compression. However, is the commitment so present that there is as much to horrify as with MP3? No, because thanks to innovations in the quality and bandwidth of a Bluetooth connection, much is being done to minimize the audible effect of compression, as this study shows between SBC, the younger aptX, and 320 mp3 Kbps. So the question is whether it can still be heard in an a / b test with, for example, optical cabling as an alternative. However, the main question is whether an a / b test with different source files via Bluetooth has any effect. The answer is really simple: do you prefer the loss of a good file or a less good file? After all: the better the source, given the (for the moment) inevitable but increasingly marginal loss of quality via Bluetooth, the better the end result. So it is always wise to work with lossless FLAC or ALAC files, because no matter what happens behind the scenes with Bluetooth streaming, you certainly won’t have to deal with double lossy compression, which is always a downside.
Finally, you have to put the Bluetooth app in perspective. After all, for many seasoned audiophiles, the above won’t be a discussion at all, for the simple reason that the listening room isn’t set up for an audio connection via Bluetooth (“Wired! Wired! “). Therefore, the use depends on the circumstances.
