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PUREPATHCONSOLE: Low Shelf Filter and Bass Shelf Filter Difference?

Jay Yoo
Intellectual 2651 points

Part Number: PUREPATHCONSOLE

Hi Team,

I have questions about Low Shelf and Bass Shelf Filter.

  1. What's difference between Low Shelf and Bass Shelf? Are they only different in Q settings?
  2. What's the order of Bass Shelf Filter? 

Would you share a relevant materials if you had?

Thank you always,

Jay

  • 0
    TI__Guru 50250 points

    Hi Jay,

    A bass shelf is a high pass filter that rolls off ideally infinitely from the cut off frequency. A low shelf rolls off from a cutoff frequency but returns eventually to a constant magnitude. See the picture below for an example:

    The Q factor controls how steep the transition band is. Because the bass shelf continues ideally to 0 Hz, there is no Q factor.

    The order of the filters will likely be in the documentation/user guide of whatever part you're using. 

    Regards,

    Jeff

  • 0 in reply to Jeff McPherson
    TI__Intellectual 2651 points

    Hi Jeff,

    Thanks for your reply. However I tried to search every documentation and couldn't find any filter information .

    But from what I found on PPC3, It seems that Bass and Low Shelving filters are 2nd order filters which has two poles respectively. Am I correct?

    Jeff McPherson said:
    A bass shelf is a high pass filter that rolls off ideally infinitely from the cut off frequency.

    And for Bass shelf filter, you said it rolls off ideally infinitely like high pass filter. But it seems more acting like a Low shelf not high pass. Could you share more detailed information if you don't mind?

    Thanks,

    Jay

  • +1 in reply to Jay Yoo
    TI__Guru 50250 points

    Hi Jay,

    Thanks for clarifying what you're seeing. It's likely then that the difference is only a naming convention for the script that is running in the background. They are certainly second order, and are most likely biquad filters. The bass shelf likely lacks the Q parameter since the bass shelf is typically at the very bottom of the frequency response and used more like a cutoff than a shelf. 

    Best Regards,

    Jeff

  • 0 in reply to Jeff McPherson
    TI__Intellectual 2651 points

    Hi Jeff,

    Thanks for your confirmation!

    Regards,

    Jay