# Simple Tilt equalizer¶

notes
```There are a few ways to implement this. (crossover, shelves, morphing shelves [hs->lp,
ls->hp] ...etc)
This particular one tries to mimic the behavior of the "Niveau" filter from the "Elysia:
mPressor" compressor.

[The 'Tilt' filter]:
It uses a center frequency (F0) and then boosts one of the ranges above or below F0, while
doing the opposite with the other range.

In the case of the "mPressor" - more extreme settings turn the filter into first order
low-pass or high-pass. This is achieved with the gain factor for one band going close to
-1. (ex: +6db -> lp; -6db -> hp)

Lubomir I. Ivanov
```
code
 ``` 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41``` ```//======================= // tilt eq settings // // srate -> sample rate // f0 -> 20-20khz // gain -> -6 / +6 db //======================= amp = 6/log(2); denorm = 10^-30; pi = 22/7; sr3 = 3*srate; // conditition: // gfactor is the proportional gain // gfactor = 5; if (gain > 0) { g1 = -gfactor*gain; g2 = gain; } else { g1 = -gain; g2 = gfactor*gain; }; //two separate gains lgain = exp(g1/amp)-1; hgain = exp(g2/amp)-1; //filter omega = 2*pi*f0; n = 1/(sr3 + omega); a0 = 2*omega*n; b1 = (sr3 - omega)*n; //================================== // sample loop // in -> input sample // out -> output sample //================================== lp_out = a0*in + b1*lp_out; out = in + lgain*lp_out + hgain*(in - lp_out); ```

```correction:
```Where is the denorm value meant to be used in the code? The code works regardless by noise is created when the gain control being used, it may be a result of the denorm value not being used?