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Mini-Bluetooth Power-Amp Mono Mode

Daniel Ejsersen
Prodigy 80 points

Hi,

I got this unit in a finished consumer product where the input interface is Bluetooth, USB sound card or AUX. How do I enable mono mode with Bluetooth or an aux plug? I love the compactness of this unit, it is so good! Now I just had a little too much distortion in the higher volumes so thought I would try mono mode. (I know I can't expect loud and crystal clear audio with such a small unit).

Best regards

  • 0
    TI__Guru 71516 points

    Hello Daniel, 

    You will have to go to the manufacturer of this module and obtain an operating manual.  The thread you first posted this question on is for the TPA3116, and there is no way of knowing if the audio amp module you have even uses the TPA3116.  I would guess there is a command sequence you would need to send to change the mode.

    I hope you are successful in obtaining a manual and perhaps a schematic as well.

    ~Leonard   

  • 0 in reply to LeonardEllis
    Prodigy 80 points

    Hi Leonard,

    Thanks for the response.

    It is this one: 

    "Specifications:

    • Bluetooth distance: 10 meters
    • Bluetooth standard protocol: Bluetooth 4.0 + EDR
    • Rated power: 50W × 2
    • Input Interface: Bluetooth, USB sound card, AUX
    • Voice prompts: English Girl
    • Operating mode: button
    • Amplifier chip: American TI Texas Instruments TPA3116 ×2
    • Power input: DC9V-24V / 3A or above
    • Dimensions (Excluding protrusions): (W)80 × (D)53 × (H)22mm (3.15 × 2.09 × 0.87 inches)
    • Net Weight: 105 grams (0.231 pounds)"

    It came with no schematics or manuals about it, it is from ebay obviously ;-) But it says 2x TI TPA3116 and I don't think they would lie about that. 

    What I was hoping for was exactly that, some kind of signal to send through the input signal, with usb sound, bluetooth or aux. Without having to remove the left  channel every time i needed mono bridge :-)

    And by the way, I love your manuals, very useful!

  • 0 in reply to Daniel Ejsersen
    TI__Guru 71516 points

    Hi Daniel,

    Thanks for the additional information.  With all the features this device has, I'm fairly certain there is some intelligence (such as DSP or Microcontroller) in the design, and this is what would control the audio configuration. 

    The Douk Audio website and the ebay page you referenced both said an "English Manual" was included, so if you did not receive this, perhaps click the CONTACT link on Douk Audio ( www.doukaudio.com/Category/index/id/215.html ) and ask for one.  We have no way of knowing how Douk has designed for control of the TPA3116, so it would be best to try and get this information from them.  They may even have a suggestion on how to correct the condition you are seeing.   

    Good luck!

    ~Leonard    

  • 0 in reply to LeonardEllis
    Prodigy 80 points
    Hi Leonardo di Cabriolet,

    Yes there is a 'manual' included, it is also to be seen on the ebay web page, you can see it under specifications. They call it "Directions for use" It is about 20 lines :-)

    I have contacted them, but since you were the manufacturer of the chip and they were just the installers of the chip, like I don't ask the painter or floorman what ingredients is inside the lacquer or inside the paint, not their table.
    I know they can have applied it in a certain way, but I'd still like to know what commands to send if both line in's are connected (which they are in almost all circumstances, almost nobody opens their amplifiers up just to change that) to trigger the mono bridge mode.

    That's just it
  • 0 in reply to Daniel Ejsersen
    TI__Expert 6985 points
    Hello Daniel! I answered your other thread thinking it was a system design question, but now I fully understand your situation. If in fact the amp inside is the TPA3116, than this is a simple analog input Class-D amp with no processing. It simply operates with an analog input signal (left and right) from some type of audio processor / DAC combination feeding into it. The only other inputs to the amp itself are really only gain, mute and fault connections. The outputs from the amp would then be fixed / hardwired. The only other thought I would have is that the system's processor may have the ability to switch off one channel to make the system mono, but that would a system issue by the manufacturer. Thanks, Jeff
  • 0 in reply to Daniel Ejsersen
    TI__Guru 71516 points

    Hi Daniel,

      As Jeff described, the TPA3116 is basically an analog amp/driver.  As such, it really does not have any features you can control by sending a command.  You could have external circuitry that does things like change the gain, but that would have had to be designed into the product from the beginning. 

    From your original question: " How do I enable mono mode " see page 24 of the datasheet, it shows how to operate in MONO mode.  But this again would take some external analog switching circuitry that would have had to be designed-in from the beginning, and controlled by whatever uC they have in this product.   Unfortunately, the short answer to your question is that you cannot command this product to MONO mode.

      You may want to express the need for this feature to Douk, and perhaps they can design an amp that has this.

    Thanks for your inquiry,

    ~Leonard 

  • 0 in reply to Jeff Kohnle
    Prodigy 80 points
    Hi Jeff!

    Thanks a bunch for your reply, was what I needed to hear :-)

    I'll try this: "may have the ability to switch off one channel to make the system mono, but that would a system issue by the manufacturer."

    That's interesting.

    Hm just realized they said they used 2 chips, 1 for each channel? Would mono mode even make a difference?
  • 0 in reply to LeonardEllis
    Prodigy 80 points
    Yes that's why I contacted you, found it on page 24 :-) "Unfortunately, the short answer to your question is that you cannot command this product to MONO mode." This was also what I needed to hear, thanks :-)

    Good day.
  • 0 in reply to Daniel Ejsersen
    TI__Expert 6985 points

    If they are using two TPA3116's, then they are likely operating each in parallel (PBTL) to drive each speaker... meaning that both L&R outputs are put in parallel to essential operate in a higher power mono state.  We would need a schematic from the designer to really know what they are doing within their circuit.  Thanks, Jeff

  • 0 in reply to Jeff Kohnle
    Prodigy 80 points

    Hi Jeff,

    I tried to get them to send me the schematics several times, but they keep refusing. 

    Then I'll take a look inside myself and see what's going on.

    Thanks for your support.

    Best regards

  • 0 in reply to Daniel Ejsersen
    TI__Expert 6985 points
    You are very welcome!