Forum Rule: Always post complete source code & details to reproduce any issue!
Results 1 to 5 of 5

Thread: Baxandall Tone control

  1. #1
    Junior Member
    Join Date
    Mar 2017
    Posts
    9

    Baxandall Tone control

    Hi, Has anyone implemented an equivalent of a simple two stage Baxandall tone control in code for the Teensy and the Audio board? I've searched on Baxandall to no avail and read the information on the audio system design tool but I still haven't got a clue. Too few joined up grey cells I guess.

    Thanks.

  2. #2
    Senior Member+ Theremingenieur's Avatar
    Join Date
    Feb 2014
    Location
    Colmar, France
    Posts
    1,788
    Understanding the principle of operation of the baxandall tone control which consists of combining two shelve filters (see http://makearadio.com/tech/tone.htm) will allow you to do the necessary transforms to calculate the corresponding coefficients for the biquad Filter object which already exists in the audio library.

  3. #3
    Senior Member PaulStoffregen's Avatar
    Join Date
    Nov 2012
    Posts
    18,153
    You could use 3 filters and a mixer, like this.

    Click image for larger version. 

Name:	sc.png 
Views:	2 
Size:	14.8 KB 
ID:	14718

    3 biquad filters are probably the most flexible way. The biquad filter as a convenient functions to set high and low shelf responses. (right side panel - scroll down to setLowShelf & setHighShelf)

    https://www.pjrc.com/teensy/gui/?info=AudioFilterBiquad

    Then to adjust the relative tone, just change the gain settings of the 3 mixer channels.

  4. #4
    Junior Member
    Join Date
    Mar 2017
    Posts
    9

    Thank you both

    Thank you both. I'll experiment with the biquad filters setLowShelf and setHighShelf. I'm afraid I still don't see why you're using three biquad filters Paul.




    Quote Originally Posted by PaulStoffregen View Post
    You could use 3 filters and a mixer, like this.

    Click image for larger version. 

Name:	sc.png 
Views:	2 
Size:	14.8 KB 
ID:	14718

    3 biquad filters are probably the most flexible way. The biquad filter as a convenient functions to set high and low shelf responses. (right side panel - scroll down to setLowShelf & setHighShelf)

    https://www.pjrc.com/teensy/gui/?info=AudioFilterBiquad

    Then to adjust the relative tone, just change the gain settings of the 3 mixer channels.

  5. #5
    Senior Member PaulStoffregen's Avatar
    Join Date
    Nov 2012
    Posts
    18,153
    Some of the Baxandall schematics have 2 tone controls, others have 3.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •