Bluetooth audio coding technology Q&A and buying advice

With the continuous progress of transmission technology, Bluetooth music playback from the role of walk-on gradually onto the front desk, its sound quality is slowly accepted by picky audiophilists, and has become an option in the audio system sound source, many audio products priced at tens of thousands of dollars, but also integrated Bluetooth music playback function. However, how to choose the right HIFI Bluetooth audio device, the average user is completely confused about those letter protocols. Today is a brief description of the Bluetooth options for HIFI. Most of our Bluetooth devices support the industry’s trusted transmission protocols such as AptX-HD or LDAC, and the manufacturer’s careful tuning has the ability to make Bluetooth music Hi-Fi.

Bluetooth audio coding technology Q&A
> What are Bluetooth audio coding technologies?
At present, there are roughly SBC, AAC, aptX, aptX LL, APTX-HD, APTX-Adapitve, LDAC and LHDC. SBC is the most common encoding and must be supported by all Bluetooth devices. AAC is a high compression ratio of audio encoding, AAC in Bluetooth commonly used bit rate is 256Kbps, AAC encoding’s biggest supporter is Apple. aptX is a code developed by Qualcomm that can transmit audio that is close to CD quality. The aptX LL can be considered a low-latency version of the aptX, allowing the sound transmitted by Bluetooth to be highly synchronized with the image you see. Aptx-hd is a better encoding than aptX and can transmit lossless or even high-definition audio. Aptx-adapitve is a combination of aptx HD lossless sound quality and aptX LL low delay protocols. It is automatically switched by the device to provide the best synchronization with the highest possible transmission rate and the lowest delay. LDAC is an encoding developed by SONY that, like aptX-HD, can transmit lossless or even high-definition audio. The LHDC is similar to SONY’s LDAC, both certified to Hi-Res Audio Wireless Bluetooth high sound quality standard by the Japan Audio Association.
Among these codes, APTX-HD, LDAC and LHDC codes are the best in sound quality, followed by APTX-Adapitve, aptX LL and aptX, followed by SBC and AAC. In other words, the sound quality of APTX-HD, LDAC and LHDC is the best, APTX-Adapitve, aptX LL and aptX are slightly better, and SBC and AAC are very average. But the delay aptX LL is the smallest, the lowest 40MS.

Support aptX-HD, LDAC, LHDC encoding Bluetooth devices must be good sound?
In general, support for the above coding is one of the conditions of good sound. Secondly, it depends on the manufacturer’s design, hardware configuration and tuning.
> Can I use mobile phones and Bluetooth devices to play HD music?
aptX-Adapitve, aptX-HD, LDAC, and LHDC encoding are the basis for transmitting high-definition music. Theoretically, mobile phones that support aptX-Adapitve, aptX-HD, LDAC, and LHDC encoding can be used to play high-definition music with related Bluetooth devices. But in fact, most mobile phones are limited by the system, even if the above encoding is supported, it can not fully present high-definition music, that is, it can be played, but the transmission is not really high-definition music, but it is still possible to lossless, the LDAC encoding limited by the system can even transmit 24bit/96kHz, so whether it is high-definition, it does not need to be too tangled. Otherwise I suggest playing with wired digital sound cards. For Apple phones that do not support the above coding, to achieve Bluetooth HD music playback, you need to buy a Bluetooth transmitter that supports the above protocol to match.
Bluetooth receiving device purchase recommendations
> First determine which Bluetooth encoding your mobile device supports
Once a friend bought a Bluetooth receiver that supports aptX-HD and LDAC coding, the result is that his mobile phone does not support aptX-HD and LDAC coding, and can only play music with SBC coding, completely unable to experience the fun of lossless music. Therefore, make sure that before purchasing the relevant Bluetooth audio receiving device, determine whether your phone or tablet supports the relevant encoding, unless you feel that the sound quality of the SBC encoding is acceptable or directly upgrade the Bluetooth transmitter of the relevant encoding.
> Second, look at the encoding supported by Bluetooth audio receiving devices
There is no doubt that among all the current encodings, aptX-Adapitve, aptX-HD, LDAC, and LHDC are better, but aptX-HD and LDAC are more popular encodings, and the best Bluetooth receiving devices can support both encodings (or one of them). As long as the phone or tablet is not too backward, it also supports both encodings. LHDC, on the other hand, is relatively unpopular and is not recommended as a priority. Therefore, Bluetooth receiving devices that support aptX-Adapitve, aptX-HD, and LDAC encoding are recommended.
> It is necessary to choose products with independent decoding
At present, many Bluetooth Hi-Fi audio receiving devices use Qualcomm’s CSR8675 and QCC5125 flagship Bluetooth chips, which integrate audio decoding functions (like computer display), and can output analog signals without the addition of a decoder, but in any case, the internal integrated decoding is not as good as the independent decoding. In order to improve sound performance, many manufacturers have reservations about using the CSR8675, in addition to changing parameters through Settings, is to jump off the internal decoder and replace it with a separate decoder. A Yin has many years of experience in the production and sales of wireless Bluetooth devices, mainly focusing on Qualcomm chips, and the adjustment of Bluetooth transmitter receivers in Qualcomm solutions is a very high level.
> Preferably with digital output
Many Bluetooth Hi-Fi audio receiving devices are relatively small in appearance, can not be perfect, the power supply and configuration are lacking, the quality of analog output may be insufficient, so the manufacturers of HIFI requirements will set digital output to the equipment, to facilitate the user through the external decoder to improve sound performance, so when buying, the preferred product with digital output is best.
> Finally, try and listen
Of course, the test is the connection performance, such as connection speed and connection distance, whether the playback process often appears stuck or disconnected without reason, if everything is normal, you can carefully audition.
For those who have not listened to aptX-Adapitve, aptX-HD, and LDAC coding, it is estimated that they will have a new feeling when they listen for the first time. In general, the Bluetooth receiving device that supports the above coding has greatly improved the fluency and texture of the sound. If you hear a smooth, natural, and glossy sound, then it means that the product has a certain quality and is worth having.
Demanding friends, if possible, can also be further compared with other audio sources, such as CD players and digital players. However, it should be noted that the better the performance, the higher the configuration of Bluetooth music devices, the price will of course rise, whether it is worth starting, but also depends on the demand and affordability.