Hello,

I am trying to implement a Linkwitz-Riley 4th order low pass filter using the juce dsp IIR filter.

I found some code at musicdsp.org and i am trying to plugin the coefficients it to the juce IIR filter, but the dsp::IIR::Coefficients class takes in max 8 coefficients, but i need 9…can someone point me in the right direction?

here is my code so far:

```
auto wc = 2.0 * MathConstants<float>::pi*frequency;
auto wc2 = wc * wc;
auto wc3 = wc2 * wc;
auto wc4 = wc2 * wc2;
auto k = wc / tan(MathConstants<float>::pi*frequency / sampleRate);
auto k2 = k * k;
auto k3 = k2 * k;
auto k4 = k2 * k2;
auto sqrt2 = sqrt(2);
auto sq_tmp1 = sqrt2 * wc3*k;
auto sq_tmp2 = sqrt2 * wc*k3;
auto a_tmp = 4 * wc2*k2 + 2 * sq_tmp1 + k4 + 2 * sq_tmp2 + wc4;
auto b1 = (4 * (wc4 + sq_tmp1 - k4 - sq_tmp2)) / a_tmp;
auto b2 = (6 * wc4 - 8 * wc2*k2 + 6 * k4) / a_tmp;
auto b3 = (4 * (wc4 - sq_tmp1 + sq_tmp2 - k4)) / a_tmp;
auto b4 = (k4 - 2 * sq_tmp1 + wc4 - 2 * sq_tmp2 + 4 * wc2*k2) / a_tmp;
auto a0 = wc4 / a_tmp;
auto a1 = 4 * wc4 / a_tmp;
auto a2 = 6 * wc4 / a_tmp;
auto a3 = a1;
auto a4 = a0;
```