DSP Amps
Subwoofer Box
September 24, 2022




No category has been more confusing, or more disappointing, to in-car audiophiles than “high-resolution Bluetooth receivers”. Different handsets and different digital media players often deliver different sound-quality results, and it can be difficult to predict those results before the installation. Now, with the Audison B-CON audiophile Bluetooth receiver, you can guarantee performance. Audison B-CON is the first (and the only, at the time of this writing) Bluetooth 5.0® player designed for automotive use that has obtained the “Hi-Res audio wireless” certification from the Japan Audio Society.





  Audiophile performance over Bluetooth is, first and foremost, about the codec - the digital encoding format that both the sending device and receiving device use to transfer the data. Part of the “pairing” process is the two devices agreeing on which codec they will use. We can only select a codec that both devices - the sender and the receiver - both support.  



All Bluetooth devices support a codec called SBC. It’s the baseline codec in the Bluetooth specification. It’s not a lossless codec. It’s decent, but it’s not great, and under some conditions, it sounds pretty poor. But the Bluetooth specification lets you use a better codec than SBC - as long as it’s supported by both devices. Some of these other codecs promise to deliver “high resolution” support, but in reality, the connections made using those codecs may often not be established at the highest quality level - the user may not get what they’re expecting. It’s usually impossible to see - this happens invisibly at the Bluetooth wireless level.  




LDAC is now available in many Android phone handsets, as well as many audiophile digital-media players. Like most codecs, the LDAC data connection can be implemented at various levels of quality, but at the highest level, it’s a lossless codec. Our stringent lab testing shows that over the highest-quality LDAC connection, the analog frequency response reaches 40kHz - and this is the mode that earned the B-CON the “High Resolution” certification from the JAS.  



B-CON is compatible with all audio formats and reaches maximum performance with uncompressed BT streaming (max 96kHz / 24bit, only with Android LDAC devices), both playing local files and with Apps that provide Hi-Res streaming (Tidal, Qobuz…). With B-CON, you know the level of quality the connection has achieved!




The LED indicators on the top of the device confirm the data rate for you - 48k, or 96k.    





  B-CON also uses AAC, which is the highest-performance codec supported by iOS. (Many assume AAC is “Apple Lossless”, but Apple Lossless isn’t suitable for use with Bluetooth and no one uses it. AAC stands for Advanced Audio Codec, and it’s not a proprietary Apple thing - it’s used widely in the tech world). Even though AAC isn’t lossless, and doesn’t permit high-resolution performance above 20k, it still performs audibly better than SBC (the default Bluetooth audio codec), and that means that B-CON gives you the best sound possible from iOS devices over Bluetooth. As you can see in the figure below, the bandwidth obtained by playing a “White Noise 96 kHz / 24 bit at -3dB” audio file with LDAC codec from an Android device is 20 ÷ 48 kHz. With Apple IOS devices, bandwidth is limited to 20 ÷ 20 kHz. This limitation does not depend on the B-CON but on the type of Bluetooth codec used in the Apple device (AAC).    





  The B-CON has RCA analog and Toslink SPDIF optical outputs (the digital output is 96kHz / 24bit). The analog outputs are High-Resolution certified, with a signal-noise ratio of 100dBA. Please check the B-CON product page to download the manual and tech. sheet to discover all the connection possibilities.    



The B-CON also has a Toslink SPDIF input, and an internal digital switcher with some innovative logic. If you have a Toslink source - such as the output of an external preamp - and you add the B-CON, connect the B-CON Toslink out to the bit device’s Toslink input, and the preamp’s Toslink output to the input of the B-CON. Then re-connect your Bluetooth devices. Now, when listening to streaming audio from your handset, it will come through the B-CON. When you get a phone call, the B-CON will switch to passthrough mode and allow the OEM Bluetooth hands-free device to handle call audio. It works seamlessly.  


 In keeping with Audison tradition, during the design phase, particular attention was paid to volume management, a fundamental aspect for the search for the highest audio quality. Most Bluetooth devices apply the volume controls to the audio stream, but this compromises the potential dynamic range significantly - often below the expected performance from digital audio!



The study by the Audison R&D team focused on the audiophile use of the “Absolute Volume” function. In the B-CON this manages the Master Volume of the DSP while keeping the digital stream at full potential dynamic range - avoiding the loss of resolution that occurs when applying the handset’s volume commands to the audio stream. This requires an ADC port, present on bit Virtuoso and Forza bit DSP amps line.


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