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Bluetooth vs Purepath

Pawel Piwowarski87949
Intellectual 805 points


I have recently come across a Microchip announcement of their Bluetooth audio solution capable of 16/24 bit up to 192 kHz audio bandwidth.  Up till now I have thought BT A2DP has a maximum bandwidth of 768kbps so Purepath is about the only "open" technology for CD-quality streaming. But there might have been some new BT developments and it can handle HQ audio transmission. Documentation available at Microchip is not very detailed and somehow I feel it might not "work as advertised". TI also has BT chips so I would appreciate some explanation what differences there are between the two technologies and what are Purepath's advantages over a HQ audio BT technology.
That would help me stay firm with Purepath my developments.

Regards, Pawel

  • 0
    Prodigy 30 points

    Bandwidth is not the only concern but latency is as well. 100ms delay (500mS for most BT links) is in many cases unacceptable, like watching TV with a wireless HP or wireless mics and monitoring. Latency is unavoidable with a digital audio link but need to be kept as minimal as possible and compression will not do any good to that.  Also have a look here http://wisaassociation.org/Compliance/Key-Attributes.aspx PP can have a minimal latency  of 10 ms at the cost of link reliability but I have good results on short distances (< 5m)..


    I am on my side wonder why major chip vendors like TI do not jump (up to now) on the wisa bandwagon while major audio brands do. Thre is much to come next future.

  • 0
    TI__Mastermind 21125 points

    Hi Pawel, 

    Have not seen this myself and wonder how they will accomplish this on a RF datarate (Bluetooth 2.0 EDR) of 3 Mbit/s. 
    If you look at this reference guide for the kit it seems that the kit has a high quality DAC and USB interface that can do 16/24 bit and 32-192 kHz sampling rates. Also chapter 2.1.3 indicates that the Bluetooth link is nothing but a standard 44.1kHz A2DP link. 
    http://ww1.microchip.com/downloads/en/DeviceDoc/70005140A.pdf

    Regards, 
    Kjetil

  • 0 in reply to Pjotr
    TI__Mastermind 21125 points

    Hi Pjotr, 

    You do bring up some good points on BT and latency. 

    With regards to WISA and TI I really can not comment. The PurePath Wireless solution and the CC85xx was developed by the TI low power RF team for being a low power / CD quality wireless audio device. The WISA and the technology behind is definitely not low power (more in common with WiFi) and although off course good for many applications like home audio with mains powered nodes it is significantly different from what we set out to do with PurePath Wireless. 

    That being said, TI is big in the Wireless space and do have the technology and capability to do something like WISA, but it would not be the PurePath Wireless team that did this. 

    Regards, 
    Kjetil

  • 0 in reply to Kjetil
    Prodigy 20 points

    Yes forgive me,  as per chapter 2.1.3 looks like they're only able to send an analog signal to amplifier via BT and not a digital signal to THE External DAC.   

    (I am also trying to stream 32 bit Resolution)