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TAS5822M: Loss of sound in DRC power limit mode

Part Number: TAS5822M

Dears:

    When using DRC to limit power, the amplifier loses sound effects, what's the reason?

  • hi

    thank you for your question.

    What do you mean loss sound effects?

    the EQ effect or any frequency been limited?

    DRC is used to limit the output power when large input signal exceed the threshold be configured.

    thanks.

    Jesse

  • Hi Jesse:

        "loss sound effects" it is means we can not set jazz, pop, rock, etc. sound, only set normal sound.

       

  • Hi

    DRC is used to limit the large input signal.

    For example:

    when you playing music, if the sound or some duration in the sound is very large, then the DRC will limit those signal according to the threshold.

    the threshold is set by customer according to the spec like PVDD, rate power of speaker, volume they set in the DSP and so on.

    DRC will not limit any specific sound effect like jazz, rock or anything else.

    so when hearing a music and if feel some sound effect disappear, it maybe caused for those sound effect has very large amplitude so that they are suppressed by DRC.

    thanks.

    Jesse

  • Hi Jesse:

       Visit customer today, the actual problem is below:

       Customer set DRC to limit output power, but it is didn't work. For example. The maximum power of the power supply is 60W, customer set the threshold 30W, the output is still exceed 30W. also threshold have been set to 25W,20W, etc, output power still exceed threshold. 

    the registration map as below, could you help to check whether there is any error in the configuration, thanks you!

    DRC_3.txt
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    typedef unsigned char cfg_u8;
    typedef union {
    struct {
    cfg_u8 offset;
    cfg_u8 value;
    };
    struct {
    cfg_u8 command;
    cfg_u8 param;
    };
    } cfg_reg;
    #define CFG_META_SWITCH (255)
    #define CFG_META_DELAY (254)
    #define CFG_META_BURST (253)
    /* Example C code */
    /*
    // Externally implemented function that can write n-bytes to the device
    XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX

  • Hi

    can you share me what kind of configure you set in the DRC. or if possible, you can give me your ppc3 file.

    then i can input your setting to PPC3.

    i can dump the code with ppc3 and compare the dumped code with customer's code.

    thanks.

    jesse

  • Hi Jesse:

        The original file exported from PPC3 as attachment, could you help to input it to ppc3, and compare your set, thanks a lot!

         //Please ignore the last reply file//

         5822.h

  • Hi

    PPC3 cannot import .h file, it can only import ppc3 file.

    -> The maximum power of the power supply is 60W, customer set the threshold 30W, the output is still exceed 30W. also threshold have been set to 25W,20W, etc, output power still exceed threshold. 

    "Exceed threshold", how it exceed the threshold? it doesn't even work? or it just exceed during a very short time?

    if it just exceed during very short time, it should be normal, because DRC need time (within several ms) to response, then start suppressing.

    Please clear below several things with customer.

    1. what is the configuration of the customer? PVDD, load resistance, speaker rated power?

    2. the ppc3 configuration file is necessary.

    3. please describe how they verifying DRC not work? like what kind of signal they use? how they measure the power? both output voltage and current been measured? how they calculated how much db should be suppressed in the DRC, have they disabled all other module when verifying DRC? it would be better if having waveform starting from DRC on to DRC off.

    4. have they verify the setting with our TI EVM board? 

    5. when they flashing the registers setting in DRC, have they verified that whether the registers been flashed really right or not? especially if customer using their own board.

    thanks.

    jesse

  • Hi Jesse:

       PPC3 File can not insert, i will Email to you. 

       PVDD 24V, Load resistance is 8Ω,speaker power is 30W, DRC threshold is 30W.

       Power supply have been limited 60W, it will turn off if load power exceed 60W.

       So customer test it on one speaker, when it exceed 30W, about 35W, it will hold on this power, not have been limited.

        At the same time, we suggest customer test on two speaker and set threshold be lower such as 25W, 20W and so on.

        

  • Hi Jesse:

        We have found the issue, customer manually adjusted the DAC GAIN through software, so the total gain exceed the threshold. DRC is active when turned off DAC gain.

  • Hi Jesse:

       We found a new issue, if we can not set the volume by DAC gain. How to set the volume without affecting DRC? We are trying set DSP Volume, there is no register configuration description.

  • Hi Jesse:

       We found a new issue, if we can not set the volume by DAC gain. How to set the volume without affecting DRC? We are trying set DSP Volume, there is no register configuration description.

  • Hi Jesse:

       We found a new issue, if we can not set the volume by DAC gain. How to set the volume without affecting DRC? We are trying set DSP Volume, there is no register configuration description.

  • Hi 

       Because the total number of registers is too many to put all of them into datasheet, we put the tuning related registers into Process Flows user manual, including the Volume. Please refer to below document. 

    https://www.ti.com/lit/an/slaa786a/slaa786a.pdf?ts=1662946996171&ref_url=https%253A%252F%252Fwww.ti.com%252Fproduct%252FTAS5825M%253FkeyMatch%253D%2526tisearch%253Dsearch-everything%2526usecase%253Dpartmatches