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TAS5782M: BQ Settings

Sadanori Kato
Guru 36540 points
Part Number: TAS5782M


Hi

Could you please tell me the following BQ settings ?

Q1.
Is my understanding correct that the output signal is only clipped if setting 3dB to BQ gain and inputting 0dBFS as the input signal ?
So, please let me know if you have any concerns.

Q2.
Are there any concerns if setting 20dB to 1st BQ gain ?

Best regards,
Kato

  • 0
    TI__Mastermind 24835 points
    Hi Kato-san,
    We are looking into your questions, and Alix will answer you later. Thanks for your patience!
    Best regards,
    Shawn Zheng
  • 0 in reply to Shawn Zheng
    Guru 36540 points

    Hi Shawn-san,

    Thank you for your prompt reply.

    I am looking forward to getting the information from Alix-san.

    Best regards,
    Kato

  • 0
    TI__Genius 9995 points

    Hi Kato-san,

    As to your questions:

    1. I am not sure about your question, can you clarify more clearly about you aims, you solutions and your questions?
      1. Output signal clipper: digital part or analog part? In digital domain, if input signal * Digital gain (input mixer/EQ/Volume) exceeds 0dBFS, it will cause digital clipper; If anlog output exceeds PVDD, it will cause output clipping.
      2. Set 3 dB to EQ with 0dBFS input signal? Do you want to calculate maximum level to avoid clipper? 0dBFS with 3dB gain can cause digital clipper
      3. What is your aims? Can you clariy more details about your application?
    2. We recommend to set less than 20dB gain for 1st BQ gain. As you known, we have to leave some headroom for digital processing. If you set too larger gain for 1st EQ, the headroom for other EQ is not enough. Why do you want to set a so large gain?

    Regards,

    Alix Wan.

  • 0 in reply to Alix Wan
    Guru 36540 points

    Hi Alix-san,

    Thank you for your support.

    Our customer is concerned about malfunctions due to overflow of internal arithmetic processing, so is there such a concern ?

    Best regards,
    Kato

  • 0 in reply to Sadanori Kato
    TI__Genius 9995 points

    Hi Kato-san,

    In fact, 3 principles are needed to follow to avoid overflow:

    1. Output of digital part of TAS5782 cannot exceeds 0dB;
    2. Total gain of blocks in the path of process flow cannot exceeds 24dB. (24 dB is the headroom of the gain);
    3. Gain of every processing block is determined by their data format (data format can be found in application note of "TAS5782 process flows".)

    For example, assump only 3 blocks in processing path: Input mixer, EQ, DRC. Their gain is G1, G2 and G3; Level of input signal is Xin. 

    • Xin*G1*G2*G3<=0dB;
    • G1*G2*G3<=24dB;
    • Input mixer of TAS5782 is 9.23 format, hence G1=20*log(2^8)~=48dB, maximum value of G1=48dB. In similiar, G2 (5.27)<= 0dB; G3 (5.27)<=24dB;

    Regards,

    Alix Wan.

  • 0 in reply to Alix Wan
    Guru 36540 points

    Hi Alix-san,

    Thank you for the explanation.

    I understood and will inform the information to our customer.

    Best regards,
    Kato