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TAS5754/TAS5756 problem with dynamic bass enhance and master volume

Jonathan.MB
Prodigy 40 points
Other Parts Discussed in Thread: PCM5242, TAS5754M

In my current setup I have a TAS5754 receiving I2S audio (always full volume) from a BT module.

I'd like to configure the DBE so that when I set the volume of the TAS5754 to a low  level, an increase in bass frequencies is applied. When I set the volume of the TAS5754 to max, no increase should be applied to not overload the speakers.

If I am correct, however, the volume is only changed directly at the output, after the dynamic bass enhance. Thus, the Energy Estimator is always detecting a high volume, regardless of volume, and is therefore always using the high level EQ.

Is there any way to change the volume before any level-dependant effects are applied?

Thanks in advance,

Jonathan

  • 0
    TI__Guru 52115 points

    Hi Jonathan,

    Did you take a look at this app note "Using the TAS5754/6M and PCM5242 HybridFlow Processor"？ Here is a link to it.

    On Page 72, you will find some tips about how to tune the DBE.

    Andy

  • 0 in reply to Andy Liu (BMS)
    Prodigy 40 points

    Hi Andy,

    first, thanks for the quick reply.

    Sadly, the manual doesn't really solve my problem. If I set the output volume of the TAS5754 to a fixed value and change the volume of the audio signal before it enters the TAS5754, I can get the DBE to have the desired effect. (Bass enhancement when music is played at a low volume, no bass enhancement at high volume).

    In our product, however, there will be no way to change the volume of the signal before it enters the TAS5754.
    And if I change the volume on the TAS5754 and not before it, the DBE has no effect at all (it is always using the high level eq).
    Is ther any way to change the volume of the signal on the tas5754 before it enters the DBE?

    Thanks,
    Jonathan

  • 0 in reply to Jonathan.MB
    TI__Guru 52115 points

    Hi Jonathan,

    Which flow are you using now? New process flows (HF8/9/10) are available in the latest PPC2 software. They have the volume control (See the "Volume In" option in the GUI) before the DRC. Since you mentioned DBE, I guess HF8/9/10 probably cannot fit into your project.

    Another workaround is to make use of the Biquads. However, BQs for volume control in TAS5754M should be used for attenuation, not boost. The max BQ volume will be 0dB.

    Rerfer to this thread for more details on how to configure a BQ for volume control.
    e2e.ti.com/.../402370

    Andy

  • 0 in reply to Andy Liu (BMS)
    Prodigy 40 points
    Hi Andy,

    I'm currently using HF1.

    I see now that I'm apparently using an outdated version of PPC. I have requested the new software.

    Using BQ might be an option. Sadly I can't access the link you sent me, I just get "Permission Denied". Could you grant me access to the forum and maybe speed up the software request process?

    Thanks for the helpful answers,
    Jonathan
  • 0 in reply to Jonathan.MB
    TI__Guru 52115 points

    Hi Jonathan,

    I have just copied the answer from that thread for you.

    If you have free BQ, you can use it for volume control. Set to all pass it's the 0dB full scale setting. Use the BQ to decrease and increase volume. Below are two examples of 0dB and -6dB volume control level using BQ. Set BQ to custom then click on the coeff button.

    Andy

  • 0 in reply to Andy Liu (BMS)
    Prodigy 40 points

    Hi Andy,

    thanks very much for your suggestion, this seems to have solved our problem!

    Kind regards,

    Jonathan