

      #define HARMONICS 11
      #define STAGES 2

      static float cd_lut[STAGES][HARMONICS];

      /* Calculate Chebychev coefficents from partial magnitudes, adapted from
       * example in Num. Rec. */
      void chebpc(float c[], float d[])
      {
          int k, j;
          float sv, dd[HARMONICS];
      
          for (j = 0; j < HARMONICS; j++) {
              d[j] = dd[j] = 0.0;
          }
      
          d[0] = c[HARMONICS - 1];
      
          for (j = HARMONICS - 2; j >= 1; j--) {
              for (k = HARMONICS - j; k >= 1; k--) {
                  sv = d[k];
                  d[k] = 2.0 * d[k - 1] - dd[k];
                  dd[k] = sv;
              }
              sv = d[0];
              d[0] = -dd[0] + c[j];
              dd[0] = sv;
          }
      
          for (j = HARMONICS - 1; j >= 1; j--) {
              d[j] = d[j - 1] - dd[j];
          }
          d[0] = -dd[0] + 0.5 * c[0];
      }

    ]]>

Chebyshev distortion

This is an interesting distortion effect that is seeded from incoming signal envelope. As the level of the signal rises more and more harmonics will for added to the output signal.

The distortion control sets the sensitivity of the input.

The effect eveolved from some experiments between Tim Goetze and myself, apptempting to emulate valve based guitar amp distortion. This was one of the failures, but it still makes an interesting noise.

env) { env = env * 0.9f + a * 0.1f; } else { env = env * 0.97f + a * 0.03f; } if (count-- == 0) { for (i=0; iitm1 = itm1; plugin_data->otm1 = otm1; plugin_data->env = env; plugin_data->count = count; ]]> Distortion Input Output