diff --git a/inc/Filter.h b/inc/Filter.h
index 7961881..7127945 100644
--- a/inc/Filter.h
+++ b/inc/Filter.h
@@ -2,21 +2,16 @@
 #include "Effect.h"
 
 class Filter : public Effect {
-
   protected:
-    struct Normals {
-        float V;
-        float K;
-    };
-
     float m_freq;  // cutoff frequency
     float m_q;     // filter quantity (resonance)
     float m_order; // filter order (peakGain)
     /* todo: filter adsr */
-    float m_norm;
+    float m_norm, m_v, m_k;
     float m_a0, m_a1, m_a2, m_b1, m_b2;
     float m_z1, m_z2;
-    Normals calculate_normals();
+
+    void calculate_normals();
     virtual void calculate_coefficients(){};
 
   public:
diff --git a/src/BandPassFilter.cpp b/src/BandPassFilter.cpp
index c6d51a8..7b2a39c 100644
--- a/src/BandPassFilter.cpp
+++ b/src/BandPassFilter.cpp
@@ -13,11 +13,11 @@ BandPassFilter::BandPassFilter(float freq, float res, float q) {}
 BandPassFilter::~BandPassFilter() {}
 
 void BandPassFilter::calculate_coefficients() {
-    Filter::Normals base = calculate_normals();
-    m_norm = 1 / (1 + base.K / m_q + base.K * base.K);
-    m_a0 = base.K / m_q * m_norm;
+    calculate_normals();
+    m_norm = 1 / (1 + m_k / m_q + m_k * m_k);
+    m_a0 = m_k / m_q * m_norm;
     m_a1 = 0;
     m_a2 = -m_a0;
-    m_b1 = 2 * (base.K * base.K - 1) * m_norm;
-    m_b2 = (1 - base.K / m_q + base.K * base.K) * m_norm;
+    m_b1 = 2 * (m_k * m_k - 1) * m_norm;
+    m_b2 = (1 - m_k / m_q + m_k * m_k) * m_norm;
 }
\ No newline at end of file
diff --git a/src/Filter.cpp b/src/Filter.cpp
index 181f72e..77962e7 100644
--- a/src/Filter.cpp
+++ b/src/Filter.cpp
@@ -5,12 +5,9 @@ Filter::Filter(/* args */) {}
 
 Filter::~Filter() {}
 
-Filter::Normals Filter::calculate_normals() {
-    Filter::Normals res;
-    res.V = powf(10, fabs(m_order) / 20.0);
-    res.K = tanf(M_PI * m_freq);
-
-    return res;
+void Filter::calculate_normals() {
+    m_v = powf(10, fabs(m_order) / 20.0);
+    m_k = tanf(M_PI * m_freq);
 }
 
 void Filter::Trigger() {}
diff --git a/src/HighPassFilter.cpp b/src/HighPassFilter.cpp
index b44573e..b210f8c 100644
--- a/src/HighPassFilter.cpp
+++ b/src/HighPassFilter.cpp
@@ -13,11 +13,11 @@ HighPassFilter::HighPassFilter(float freq, float res, float q) {}
 HighPassFilter::~HighPassFilter() {}
 
 void HighPassFilter::calculate_coefficients() {
-    Filter::Normals base = calculate_normals();
-    m_norm = 1 / (1 + base.K / m_q + base.K * base.K);
+    calculate_normals();
+    m_norm = 1 / (1 + m_k / m_q + m_k * m_k);
     m_a0 = 1 * m_norm;
     m_a1 = -2 * m_a0;
     m_a2 = m_a0;
-    m_b1 = 2 * (base.K * base.K - 1) * m_norm;
-    m_b2 = (1 - base.K / m_q + base.K * base.K) * m_norm;
+    m_b1 = 2 * (m_k * m_k - 1) * m_norm;
+    m_b2 = (1 - m_k / m_q + m_k * m_k) * m_norm;
 }
\ No newline at end of file
diff --git a/src/LowPassFilter.cpp b/src/LowPassFilter.cpp
index 9d43e56..2b42168 100644
--- a/src/LowPassFilter.cpp
+++ b/src/LowPassFilter.cpp
@@ -23,11 +23,11 @@ LowPassFilter::LowPassFilter(Filter* filter) {
 LowPassFilter::~LowPassFilter() {}
 
 void LowPassFilter::calculate_coefficients() {
-    Filter::Normals base = calculate_normals();
-    m_norm = 1 / (1 + base.K / m_q + base.K * base.K);
-    m_a0 = base.K * base.K * m_norm;
+    calculate_normals();
+    m_norm = 1 / (1 + m_k / m_q + m_k * m_k);
+    m_a0 = m_k * m_k * m_norm;
     m_a1 = 2 * m_a0;
     m_a2 = m_a0;
-    m_b1 = 2 * (base.K * base.K - 1) * m_norm;
-    m_b2 = (1 - base.K / m_q + base.K * base.K) * m_norm;
+    m_b1 = 2 * (m_k * m_k - 1) * m_norm;
+    m_b2 = (1 - m_k / m_q + m_k * m_k) * m_norm;
 }
\ No newline at end of file