Making Stereo Wireless Over Bluetooth : Proper Selection of Devices

Today, it is becoming common to see a USB pen drive like thing plugged to some power source and any type of audio system or speaker including normal earphone or headphone (we discussed how earphone and headphone differs) and audio is streamed from mobile device like Android smartphone. Such China made units cost hardly $2 per unit. Making Stereo Wireless With Bluetooth or Wi-Fi Probably One of the Most High Demand Thing Now. But How These Aftermarket Tweaks Affect Sound Quality. Many want to know minimum technical matters behind these things before jumping to buy one.

Making Stereo Wireless With Bluetooth

Bluetooth still probably do some reduction of sound quality. It may be almost unnoticeable deterioration, but it does. There are several ongoing research & development to counteract that loss of quality. AirPlay, DLNA, Play-Fi, Sonos are Wi-Fi technologies. Chromecast is a specialized line of dongles developed by Google. Chromecast more popular for mirroring screen of some Android devices to watch on screens with HDMI port, like television or computer monitor. There is Chromecast Audio with 3.5mm audio port and also Chromecast with audio port and HDMI port. Google actually has lot of stuffs now :

But unlike Sony, Panasonic like mainstream consumer product manufacturers, latest stuffs manufactured by Google not everywhere easily available. Some companies have cheaper clones of Chromecast. Wifi audio receiver dongles not so cheap, small, convenient unlike the Bluetooth audio receiver dongles. Also not all mobile devices has Wi-Fi. Bluetooth and Wi-Fi has technical closeness. These matters force us to select Bluetooth audio receiver dongles when the matter is just playing sound/music.

Bluetooth’s this way of usage originally was not for Hi-Fi audio streaming, but for wireless phone headsets. It designed with a narrow bandwidth which forces data compression to any audio signal. Because for for phone conversations, we do not need so high quality. So when Bluetooth is playing digital audio files, we need to know what device specifications and file types may avoid the possible deterioration. Different codecs send audio data using slightly different data formats. They use different standards to perform handshakes between compatible devices. They can also introduce their own compression technologies in order to balance sound quality against package size.

Most of these devices support SBC (Low Complexity Subband Coding). Some devices support optional codecs. Qualcomm and Sony both has own proprietary codecs – AptX and LDAC. Those codecs can be found in the Bluetooth Advanced Audio Distribution Profile (A2DP) specification. The list includes MPEG 1 & 2 Audio (MP2 and MP3), MPEG 3 & 4 (AAC), ATRAC, and aptX. MP3 is actually MPEG-1 Layer 3. MP3 will not play so nice over Bluetooth streaming. Official Bluetooth site gives lot of information :

Both the Bluetooth devices (source and receiver units) must support the aptX and Sony’s LDAC codec in order to benefit. You can read about AptX codec :

Now, FLAC commonly used to rip CD as lossless. For using aptX HD, you need hardware like CSR8675 Bluetooth audio SOC (system on chip). It handle end-to-end 24-bit audio, provides greater digital-signal processing. Which mobiles has CSR8675 Bluetooth audio chipset? Sarcastically, Apple is out. Wi-Fi also has complexity. But, basically Wi-Fi is lesser complex and improved to handle more data.

This is total matter explained for Sony’s LDAC. AptX will be similar :

Conclusion

Do you expect AptX support for $2 China Made Bluetooth music streaming dongle? Recently we discussed about an Android from Vivo. That Vivo’s model supports AptX :

With it, you need Bluetooth streaming music dongle like thing which supports AptX HD. As example, this receiver supports AptX HD :

You probably understood why we named the article – Making Stereo Wireless Over Bluetooth : Proper Selection of Devices. Now you need to go towards audiophile forums and ask them whether your Sony audio system’s ADC actually supports that high quality.