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Speaker playback regular noise

Ares Tsai
Prodigy 125 points
Other Parts Discussed in Thread: TAS2557, TAS2557EVM

Hi TI,

I used the TAS2557 for our Speaker. When I playback 44.1kHz sample rate sine tone(also ocuur in music), speaker will have an audiable noise.(Pls refer to the attachment file.)

But 32kHz & 48kHz sample rate are OK. What happened?

  • 0
    TI__Guru** 112245 points
    Hi Ares,

    I would like to ask some questions to know the background of this:
    - What is your device configuration? Did you generated your cfg's from PPC3?
    - Are you using TAS2557EVM or custom board? If using the EVM, are you using external digital source?
    I ask this last question because the EVM is configured for 48kHz playback.
    - What are your overall clock frequencies? (MCLK, BCLK and WCLK)

    Best regards,
    -Ivan Salazar
    Applications Engineer - Low Power Audio & Actuators
  • 0 in reply to Ivan Salazar
    Prodigy 125 points

    Hi Ivan,
     - What is your device configuration?Could you say something more configuration detail like what? thanks.   

    Did you generated your cfg's from PPC3?-->yes


    - Are you using TAS2557EVM or custom board? -->custom board   (If using the EVM, are you using external digital source?I ask this last question because the EVM is configured for 48kHz playback.)


     - What are your overall clock frequencies? (MCLK, BCLK and WCLK)-->BCLK= 2.822MHz / 3072MHz and WCLK= 44.1Hz / 48kHz

  • 0 in reply to Ares Tsai
    TI__Guru** 112245 points
    Ares,

    Could you share the cfg you obtained from PPC3? I'd like to test this on my side.
    You're not using MCLK? Have you configured the device to use BCLK as source clock for internal dividers?

    Best regards,
    -Ivan Salazar
    Applications Engineer - Low Power Audio & Actuators
  • 0 in reply to Ivan Salazar
    Prodigy 125 points

    Have you configured the device to use BCLK as source clock for internal dividers?-->Yes

    cfg is in attached.https://e2e.ti.com/cfs-file/__key/communityserver-discussions-components-files/6/TAS2557.7z

  • 0 in reply to Ares Tsai
    TI__Guru** 112245 points

    Ares,

    Can you send a capture of your WCLK and BCLK signals?
    I tried your scripts but I'm not getting the same noise. Although audio amplitude is oscillating at low signal values; are you configuring some of the device features based on your speaker?
    I generated a script based on default values for Fs = 44.1kHz and BCLK as master (attached) and it works just fine.

    Best regards,
    -Ivan Salazar
    Applications Engineer - Low Power Audio & Actuators

    combined_configuration_0_TuningMode_44.1KHz.cfg

  • 0 in reply to Ivan Salazar
    Prodigy 125 points

    Hi Ivan,

    Could you provide bin file for me, cause we can not use cfg file. Thanks

  • 0 in reply to Ares Tsai
    TI__Guru** 112245 points

    Ares,

    Attached is the full dump from PPC3.
    Also let me check if that slow slope on last DIN bit from your scope capture could cause issues. Have you used it this way before? Our EVMs have sharp transitions for digital signals, including DIN.

    Best regards,
    -Ivan Salazar
    Applications Engineer - Low Power Audio & Actuators

    default.zip

  • 0 in reply to Ares Tsai
    Prodigy 125 points

    Hi Ivan,

    I also have another issue in this PPC3, my speaker rated power can not go up by add input gain.

    I was wonder if it is register 0x22 setting problem or something else, could you help me check it out

    thanks a ton

  • 0 in reply to Ares Tsai
    TI__Guru** 112245 points
    Hi Ares,

    Is the periodic noise issue is solved now?
    Regarding the output power, perhaps you could try to use the device in ROM mode. This is just to verify if smart-amp mode is automatically reducing output power, this happens sometimes when a tone is played instead of real audio tracks.

    Best regards,
    -Ivan Salazar
    Applications Engineer - Low Power Audio & Actuators
  • 0 in reply to Ivan Salazar
    Prodigy 125 points

    Hi Ivan,

    I'm working on it.

    By the way, the output power is really automatically reduced.

    How to solve this problem, cause we want to use smart amp mode and protection.

  • 0 in reply to Ares Tsai
    TI__Guru** 112245 points
    Ares,

    You could try with an actual audio track or playing a song to check if output amplitude is still being affected; I assume you're currently using a single tone for testing.

    Best regards,
    -Ivan Salazar
    Applications Engineer - Low Power Audio & Actuators
  • 0 in reply to Ivan Salazar
    Prodigy 125 points
    Hi Ivan,
    How about white noise & sweep?
    And I need to know what the reason.
    thanks a lot

    Ares
  • 0 in reply to Ares Tsai
    TI__Guru** 112245 points
    Ares,

    White noise would also be good for testing.
    Speaker protection algorithm is adjusting the amplitude of the output signal so that speaker is not damaged due to overload or over-excursion. This can be seen as an AGC, if a periodic signal is being played, the automatic control is being gradually adjusted as the signal level changes over time.

    Best regards,
    -Ivan Salazar
    Applications Engineer - Low Power Audio & Actuators
  • 0 in reply to Ivan Salazar
    TI__Guru** 112245 points
    Ares,

    One additional comment:
    Have you characterized the speaker you're using before your test? If not it would be good to try. Sometimes if speaker is not calibrated the speaker protection algorithm might not work the best as the speaker characteristics are not correct.

    Best regards,
    -Ivan Salazar
    Applications Engineer - Low Power Audio & Actuators