diff --git a/plugin/DistrhoPluginInfo.h b/plugin/DistrhoPluginInfo.h
index 6370ea0..85daadc 100644
--- a/plugin/DistrhoPluginInfo.h
+++ b/plugin/DistrhoPluginInfo.h
@@ -63,7 +63,7 @@
         pSustain,
         pRelease,
 
-        pChorus,
+        pChorusMode,
 
         parameterCount
     };
diff --git a/plugin/chorus.cpp b/plugin/chorus.cpp
index d6a8431..1a16739 100644
--- a/plugin/chorus.cpp
+++ b/plugin/chorus.cpp
@@ -21,6 +21,7 @@
 #include <math.h>
 #include <string.h>
 
+#include <stdio.h>
 Chorus::Chorus() {
     lpfOut1 = new float[bufferSize];
     lpfOut2 = new float[bufferSize];
@@ -102,6 +103,7 @@ void Chorus::run(float* input, float** outputs, uint32_t frames) {
         delayptr++;
         delayptr &= 0x3ff;
     }
+        //printf("dly1 = %f\n", dly1);
 
     postFilter1l->runSVF(lpfOut1, lpfOut1, frames);
     postFilter2l->runSVF(lpfOut1, lpfOut1, frames);
@@ -152,11 +154,11 @@ void Chorus::setChorus(uint8_t mode) {
             break;
         case 0x40:
             gain = 1.2;
-            lfoSpeed = 6.283 * 0.5 / sampleRate;
+            lfoSpeed = 6.283 * 0.3 / sampleRate;
             break;
         case 0x00:
             gain = 1.2;
-            lfoSpeed = 6.283 * 0.9 / sampleRate;
+            lfoSpeed = 6.283 * 0.5 / sampleRate;
             break;
     }
 }
diff --git a/plugin/module.cpp b/plugin/module.cpp
index 99b5d51..aff551c 100644
--- a/plugin/module.cpp
+++ b/plugin/module.cpp
@@ -74,7 +74,7 @@ void Module::run(Voice* voices, uint32_t blockSize) {
     sub = patchRam.sub / 127.0f;
     lfoPhase += lfoRateTable[patchRam.lfoRate];
 
-    res = patchRam.vcfReso / 127.0 * 5;
+    res = patchRam.vcfReso / 127.0;
     noise = patchRam.noise / 127.0;
 
     // FIXME the exp in these is expensive, don't call it all the time
diff --git a/plugin/module.hpp b/plugin/module.hpp
index a28902f..642dffd 100644
--- a/plugin/module.hpp
+++ b/plugin/module.hpp
@@ -48,26 +48,74 @@ class Module {
 
     float saw = 0, square = 0, sub = 0, noise = 0;
 
+    /*
+    #if 0
+        struct {
+            uint8_t lfoRate = 0x58;
+            uint8_t lfoDelay = 0x00;
+            uint8_t vcoLfo = 0x00;
+            uint8_t pwmLfo = 0x3b;
+            uint8_t noise = 0x00;
+            uint8_t vcfFreq = 0x25;  // 1c;  // 0x3f80
+            uint8_t vcfReso = 0x6a;
+            uint8_t vcfEnv = 0x25;  // 4e;
+            uint8_t vcfLfo = 0x00;
+            uint8_t vcfKey = 0x00;  // 47;
+            uint8_t vca = 0x35;
+            uint8_t env_a = 0x00;
+            uint8_t env_d = 0x3c;
+            uint8_t env_s = 0x00;  // 0x3f80
+            uint8_t env_r = 0x3c;
+            uint8_t sub = 0x7f;
+            uint8_t switch1 = 0x4a;
+            uint8_t switch2 = 0x18;
+        } patchRam;
+
+    #else
+        struct {
+            uint8_t lfoRate = 0x40;
+            uint8_t lfoDelay = 0x00;
+            uint8_t vcoLfo = 0x00;
+            uint8_t pwmLfo = 0x00;
+            uint8_t noise = 0x01;
+            uint8_t vcfFreq = 0x31;
+            uint8_t vcfReso = 0x7f;
+            uint8_t vcfEnv = 0x00;
+            uint8_t vcfLfo = 0x00;
+            uint8_t vcfKey = 0x7f;
+            uint8_t vca = 0x40;
+            uint8_t env_a = 0x00;
+            uint8_t env_d = 0x00;
+            uint8_t env_s = 0x00;  // 0x3f80
+            uint8_t env_r = 0x00;
+            uint8_t sub = 0x00;
+            uint8_t switch1 = 0x22;
+            uint8_t switch2 = 0x1d;
+        } patchRam;
+    #endif
+    */
+
     struct {
-                uint8_t lfoRate = 0x58;
+        uint8_t lfoRate = 0x58;
         uint8_t lfoDelay = 0x00;
         uint8_t vcoLfo = 0x00;
-        uint8_t pwmLfo = 0x3b;
+        uint8_t pwmLfo = 0x00;
         uint8_t noise = 0x00;
-        uint8_t vcfFreq = 0x25;  // 1c;  // 0x3f80
-        uint8_t vcfReso = 0x6a;
-        uint8_t vcfEnv = 0x25;  // 4e;
+        uint8_t vcfFreq = 0x00;  // 1c;  // 0x3f80
+        uint8_t vcfReso = 0x7f;
+        uint8_t vcfEnv = 0x7f;  // 4e;
         uint8_t vcfLfo = 0x00;
         uint8_t vcfKey = 0x00;  // 47;
-        uint8_t vca = 0x35;
+        uint8_t vca = 0x20;
         uint8_t env_a = 0x00;
-        uint8_t env_d = 0x3c;
+        uint8_t env_d = 0x5c;
         uint8_t env_s = 0x00;  // 0x3f80
         uint8_t env_r = 0x3c;
         uint8_t sub = 0x7f;
-        uint8_t switch1 = 0x4a;
-        uint8_t switch2 = 0x18;
+        uint8_t switch1 = 0x3a;
+        uint8_t switch2 = 0x19;
     } patchRam;
+
     Chorus* chorus;
 
     float vcaTC;
@@ -104,14 +152,16 @@ class Voice {
 
     uint8_t envPhase = 0;
     int16_t env = 0;  // output amplitude
-    int16_t vcfCut;
+    uint16_t vcfCut;
     int16_t vcaEnv;
     float vcaRC = 0, vcfRC = 0;
 
     uint8_t note = 0;
 
     // filter
-    float b1 = 0, b2 = 0, b3 = 0, b4 = 0;
+    float y0 = 0, y1 = 0, y2 = 0, y3 = 0;
+    double s[4] = {0, 0, 0, 0};
+    float zi = 0;
 };
 
 #endif
diff --git a/plugin/parameters.cpp b/plugin/parameters.cpp
index 89160cf..e0460a4 100644
--- a/plugin/parameters.cpp
+++ b/plugin/parameters.cpp
@@ -23,7 +23,7 @@ void Peacock::initParameter(uint32_t index, Parameter& parameter) {
         case pLFORate:
             parameter.hints = kParameterIsAutomatable;
             parameter.name = "LFO Rate";
-            parameter.symbol = "ch_lforate";
+            parameter.symbol = "pfau_lforate";
             parameter.ranges.min = 0.0f;
             parameter.ranges.max = 127.0f;
             parameter.ranges.def = 48.0f;
@@ -33,7 +33,7 @@ void Peacock::initParameter(uint32_t index, Parameter& parameter) {
         case pLFODelay:
             parameter.hints = kParameterIsAutomatable;
             parameter.name = "LFO Delay";
-            parameter.symbol = "ch_lfodelay";
+            parameter.symbol = "pfau_lfodelay";
             parameter.ranges.min = 0.0f;
             parameter.ranges.max = 127.0f;
             parameter.ranges.def = 0.0f;
@@ -43,7 +43,7 @@ void Peacock::initParameter(uint32_t index, Parameter& parameter) {
         case pVCORange:
             parameter.hints = kParameterIsAutomatable | kParameterIsInteger;
             parameter.name = "Range";
-            parameter.symbol = "ch_vcorange";
+            parameter.symbol = "pfau_vcorange";
             parameter.ranges.min = 0.0f;
             parameter.ranges.max = 2.0f;
             parameter.ranges.def = 1.0f;
@@ -65,7 +65,7 @@ void Peacock::initParameter(uint32_t index, Parameter& parameter) {
         case pLFODepth:
             parameter.hints = kParameterIsAutomatable;
             parameter.name = "LFO";
-            parameter.symbol = "ch_lfo";
+            parameter.symbol = "pfau_lfo";
             parameter.ranges.min = 0.0f;
             parameter.ranges.max = 127.0f;
             parameter.ranges.def = 10.0f;
@@ -75,7 +75,7 @@ void Peacock::initParameter(uint32_t index, Parameter& parameter) {
         case pPWMDepth:
             parameter.hints = kParameterIsAutomatable;
             parameter.name = "PWM";
-            parameter.symbol = "ch_pwm";
+            parameter.symbol = "pfau_pwm";
             parameter.ranges.min = 0.0f;
             parameter.ranges.max = 127.0f;
             parameter.ranges.def = 48.0f;
@@ -85,7 +85,7 @@ void Peacock::initParameter(uint32_t index, Parameter& parameter) {
         case pPWMMode:
             parameter.hints = kParameterIsAutomatable | kParameterIsBoolean;
             parameter.name = "PWM Mode";
-            parameter.symbol = "ch_pwmmode";
+            parameter.symbol = "pfau_pwmmode";
             parameter.ranges.min = 0.0f;
             parameter.ranges.max = 1.0f;
             parameter.ranges.def = 1.0f;
@@ -106,7 +106,7 @@ void Peacock::initParameter(uint32_t index, Parameter& parameter) {
         case pSaw:
             parameter.hints = kParameterIsAutomatable | kParameterIsBoolean;
             parameter.name = "Saw";
-            parameter.symbol = "ch_saw";
+            parameter.symbol = "pfau_saw";
             parameter.ranges.min = 0.0f;
             parameter.ranges.max = 1.0f;
             parameter.ranges.def = 1.0f;
@@ -116,7 +116,7 @@ void Peacock::initParameter(uint32_t index, Parameter& parameter) {
         case pSqr:
             parameter.hints = kParameterIsAutomatable | kParameterIsBoolean;
             parameter.name = "Square";
-            parameter.symbol = "ch_sqr";
+            parameter.symbol = "pfau_sqr";
             parameter.ranges.min = 0.0f;
             parameter.ranges.max = 1.0f;
             parameter.ranges.def = 1.0f;
@@ -126,7 +126,7 @@ void Peacock::initParameter(uint32_t index, Parameter& parameter) {
         case pSubLevel:
             parameter.hints = kParameterIsAutomatable;
             parameter.name = "Sub Osc";
-            parameter.symbol = "ch_sub";
+            parameter.symbol = "pfau_sub";
             parameter.ranges.min = 0.0f;
             parameter.ranges.max = 127.0f;
             parameter.ranges.def = 0.0f;
@@ -136,7 +136,7 @@ void Peacock::initParameter(uint32_t index, Parameter& parameter) {
         case pNoiseLevel:
             parameter.hints = kParameterIsAutomatable;
             parameter.name = "Noise";
-            parameter.symbol = "ch_noise";
+            parameter.symbol = "pfau_noise";
             parameter.ranges.min = 0.0f;
             parameter.ranges.max = 127.0f;
             parameter.ranges.def = 0.0f;
@@ -146,7 +146,7 @@ void Peacock::initParameter(uint32_t index, Parameter& parameter) {
         case pHPF:
             parameter.hints = kParameterIsAutomatable | kParameterIsInteger;
             parameter.name = "HPF";
-            parameter.symbol = "ch_hpf";
+            parameter.symbol = "pfau_hpf";
             parameter.ranges.min = 0.0f;
             parameter.ranges.max = 3.9f;
             parameter.ranges.def = 0.0f;
@@ -156,7 +156,7 @@ void Peacock::initParameter(uint32_t index, Parameter& parameter) {
         case pCutoff:
             parameter.hints = kParameterIsAutomatable;
             parameter.name = "Freq";
-            parameter.symbol = "ch_freq";
+            parameter.symbol = "pfau_freq";
             parameter.ranges.min = 0.0f;
             parameter.ranges.max = 127.0f;
             parameter.ranges.def = 60.0f;
@@ -165,7 +165,7 @@ void Peacock::initParameter(uint32_t index, Parameter& parameter) {
         case pRes:
             parameter.hints = kParameterIsAutomatable;
             parameter.name = "Res";
-            parameter.symbol = "ch_reso";
+            parameter.symbol = "pfau_reso";
             parameter.ranges.min = 0.0f;
             parameter.ranges.max = 127.0f;
             parameter.ranges.def = 0.0f;
@@ -174,7 +174,7 @@ void Peacock::initParameter(uint32_t index, Parameter& parameter) {
         case pVCFPol:
             parameter.hints = kParameterIsAutomatable | kParameterIsInteger;
             parameter.name = "Polarity";
-            parameter.symbol = "ch_vcfmode";
+            parameter.symbol = "pfau_vcfmode";
             parameter.ranges.min = 0.0f;
             parameter.ranges.max = 1.0f;
             parameter.ranges.def = 0.0f;
@@ -194,7 +194,7 @@ void Peacock::initParameter(uint32_t index, Parameter& parameter) {
         case pEnv:
             parameter.hints = kParameterIsAutomatable;
             parameter.name = "Env";
-            parameter.symbol = "ch_vcfenv";
+            parameter.symbol = "pfau_vcfenv";
             parameter.ranges.min = 0.0f;
             parameter.ranges.max = 127.0f;
             parameter.ranges.def = 46.0f;
@@ -203,7 +203,7 @@ void Peacock::initParameter(uint32_t index, Parameter& parameter) {
         case pLfo:
             parameter.hints = kParameterIsAutomatable;
             parameter.name = "LFO";
-            parameter.symbol = "ch_vcflfo";
+            parameter.symbol = "pfau_vcflfo";
             parameter.ranges.min = 0.0f;
             parameter.ranges.max = 127.0f;
             parameter.ranges.def = 0.0f;
@@ -212,7 +212,7 @@ void Peacock::initParameter(uint32_t index, Parameter& parameter) {
         case pKyb:
             parameter.hints = kParameterIsAutomatable;
             parameter.name = "Kybd";
-            parameter.symbol = "ch_vcfkey";
+            parameter.symbol = "pfau_vcfkey";
             parameter.ranges.min = 0.0f;
             parameter.ranges.max = 127.0f;
             parameter.ranges.def = 71.0f;
@@ -222,7 +222,7 @@ void Peacock::initParameter(uint32_t index, Parameter& parameter) {
         case pAttack:
             parameter.hints = kParameterIsAutomatable;
             parameter.name = "Attack";
-            parameter.symbol = "ch_attack";
+            parameter.symbol = "pfau_attack";
             parameter.ranges.min = 0.0f;
             parameter.ranges.max = 127.0f;
             parameter.ranges.def = 27.0f;
@@ -232,7 +232,7 @@ void Peacock::initParameter(uint32_t index, Parameter& parameter) {
         case pDecay:
             parameter.hints = kParameterIsAutomatable;
             parameter.name = "Decay";
-            parameter.symbol = "ch_decay";
+            parameter.symbol = "pfau_decay";
             parameter.ranges.min = 0.0f;
             parameter.ranges.max = 127.0f;
             parameter.ranges.def = 57.0f;
@@ -242,7 +242,7 @@ void Peacock::initParameter(uint32_t index, Parameter& parameter) {
         case pSustain:
             parameter.hints = kParameterIsAutomatable;
             parameter.name = "Sustain";
-            parameter.symbol = "ch_sustain";
+            parameter.symbol = "pfau_sustain";
             parameter.ranges.min = 0.0f;
             parameter.ranges.max = 127.0f;
             parameter.ranges.def = 57.0f;
@@ -252,7 +252,7 @@ void Peacock::initParameter(uint32_t index, Parameter& parameter) {
         case pRelease:
             parameter.hints = kParameterIsAutomatable;
             parameter.name = "Release";
-            parameter.symbol = "ch_release";
+            parameter.symbol = "pfau_release";
             parameter.ranges.min = 0.0f;
             parameter.ranges.max = 127.0f;
             parameter.ranges.def = 48.0f;
@@ -262,7 +262,7 @@ void Peacock::initParameter(uint32_t index, Parameter& parameter) {
         case pEnvGate:
             parameter.hints = kParameterIsAutomatable | kParameterIsInteger;  // | kParameterIsBoolean;
             parameter.name = "Env-Gate";
-            parameter.symbol = "ch_envgate";
+            parameter.symbol = "pfau_envgate";
             parameter.ranges.min = 0.0f;
             parameter.ranges.max = 1.0f;
             parameter.ranges.def = 0.0f;
@@ -282,39 +282,38 @@ void Peacock::initParameter(uint32_t index, Parameter& parameter) {
         case pVCALevel:
             parameter.hints = kParameterIsAutomatable;
             parameter.name = "VCA Level";
-            parameter.symbol = "ch_vcalevel";
+            parameter.symbol = "pfau_vcalevel";
             parameter.ranges.min = 0.0f;
             parameter.ranges.max = 127.0f;
             parameter.ranges.def = 40.0f;
             parameter.midiCC = 26;
             break;
 
-        case pChorus:
+        case pChorusMode:
             parameter.hints = kParameterIsAutomatable | kParameterIsInteger;
             parameter.name = "Chorus";
-            parameter.symbol = "ch_chorus";
+            parameter.symbol = "pfau_chorus";
             parameter.ranges.min = 0.0f;
             parameter.ranges.max = 2.0f;
-            parameter.ranges.def = 1.0f;
+            parameter.ranges.def = 0.0f;
             parameter.midiCC = 93;
             parameter.enumValues.count = 3;
             parameter.enumValues.restrictedMode = true;
             {
                 ParameterEnumerationValue* const enumValues = new ParameterEnumerationValue[3];
                 enumValues[0].value = 0.0f;
-                enumValues[0].label = "Off'";
+                enumValues[0].label = "Off";
                 enumValues[1].value = 1.0f;
                 enumValues[1].label = "Slow";
                 enumValues[2].value = 2.0f;
                 enumValues[2].label = "Fast";
                 parameter.enumValues.values = enumValues;
             }
-            break;
             /*
                     case pModWheel:
                         parameter.hints = kParameterIsAutomatable | kParameterIsHidden;
                         parameter.name = "Mod wheel";
-                        parameter.symbol = "ch_modwheel";
+                        parameter.symbol = "pfau_modwheel";
                         parameter.ranges.min = 0.0f;
                         parameter.ranges.max = 127.0f;
                         parameter.ranges.def = 0.0f;
@@ -400,7 +399,7 @@ void Peacock::setParameterValue(uint32_t index, float value) {
             m->patchRam.switch1 |= (value >= 0.5) << 4;
             break;
 
-        case pChorus:
+        case pChorusMode:
             m->patchRam.switch1 &= 0x9f;
             switch ((int)value) {
                 case 0:
@@ -526,8 +525,7 @@ float Peacock::getParameterValue(uint32_t index) const {
         case pVCALevel:
             return m->patchRam.vca;
             break;
-        case pChorus:
-
+        case pChorusMode:
             switch (m->patchRam.switch1 & 0x60) {
                 case 0x60:
                     return 0;
diff --git a/plugin/ui.cpp b/plugin/ui.cpp
index 3017866..cc49be4 100644
--- a/plugin/ui.cpp
+++ b/plugin/ui.cpp
@@ -269,7 +269,7 @@ void DistrhoUIPeacock::parameterChanged(uint32_t index, float value) {
             sw1 |= (value > 0.5) << 4;
             break;
 
-        case pChorus:
+        case pChorusMode:
             sw1 &= 0x9f;
             // 60, 40, 00
             switch ((int)value) {
@@ -326,15 +326,15 @@ void DistrhoUIPeacock::imageButtonClicked(ImageButton* imgBtn, int) {
             break;
         case btnCh0:
             sw1 = (sw1 & 0x9f) | 0x20;
-            setParameterValue(pChorus, 0);
+            setParameterValue(pChorusMode, 0);
             break;
         case btnCh1:
             sw1 = (sw1 & 0x9f) | 0x40;
-            setParameterValue(pChorus, 1);
+            setParameterValue(pChorusMode, 1);
             break;
         case btnCh2:
             sw1 = (sw1 & 0x9f);
-            setParameterValue(pChorus, 2);
+            setParameterValue(pChorusMode, 2);
             break;
 
         default:
diff --git a/plugin/voice.cpp b/plugin/voice.cpp
index ec81b15..9b268c2 100644
--- a/plugin/voice.cpp
+++ b/plugin/voice.cpp
@@ -41,7 +41,7 @@ Voice::Voice() {
 
 void Voice::on(uint8_t midiNote) {
     while (midiNote < 24) midiNote += 12;
-    while (midiNote > 108) midiNote -=12;
+    while (midiNote > 108) midiNote -= 12;
     note = midiNote - 24;
     envPhase = 1;
 }
@@ -50,15 +50,26 @@ void Voice::off() {
     envPhase = 0;
 }
 
+// tanh(x)/x approximation, flatline at very high inputs
+// so might not be safe for very large feedback gains
+// [limit is 1/15 so very large means ~15 or +23dB]
+
+double tanhXdX(double x) {
+    float s = 0.0333, d = 30.0;
+    return 1.0f - s * (d + 1.0f) * x * x / (d + x * x);
+
+}
+
 void Voice::run(Module* m, float* buffer, uint32_t samples) {
     // carry out per-voice calculations for each block of samples
     float out, t, fb;
 
-    // FIXME incorrect
     // calculate cutoff frequency
-    float cut = 248.0f * (powf(2, (vcfCut - 0x1880) / 1143.0f));
-    cut = 0.25 * 6.2832 * cut / 48000.0f;  // FIXME hardcoded values
-    cut = cut / (1 + cut);                 // correct tuning warp
+    float cut = 261.0f * (powf(2, (vcfCut - 0x1880) / 1143.0f));
+    cut = M_PI * cut / sampleRate;
+    cut = cut / (1 + cut);  // correct tuning warp
+    // if (cut > 0.7) cut = 0.7;
+    double r = 5 * m->res;
 
     float amp = vcaEnv / 4096.0f;
 
@@ -95,32 +106,105 @@ void Voice::run(Module* m, float* buffer, uint32_t samples) {
         // FIXME DC offset removal
         delay += m->saw * (1 - (2 * theta));
         delay += m->square * ((pulseStage ? -1.f : 1.f) - m->pwmBuf[i] + 0.5);
-        delay += m->subBuf[i] * subosc ;
-        
+        delay += m->subBuf[i] * subosc;
+
         out += m->noise * (0.8 - 1.6 * (rand() & 0xffff) / 65536.0);
-        out *= 0.5;
+        // out *= 0.1;
 
         // same time constant for both VCF and VCF RC circuits
         vcfRC = (cut - vcfRC) * m->vcaTC + vcfRC;
 
-        for (uint8_t ovs = 0; ovs < 4; ovs++) {
-            fb = b4;
+#if 1
+
+        //// LICENSE TERMS: Copyright 2012 Teemu Voipio
+        //
+        // You can use this however you like for pretty much any purpose,
+        // as long as you don't claim you wrote it. There is no warranty.
+        //
+        // Distribution of substantial portions of this code in source form
+        // must include this copyright notice and list of conditions.
+        //
+
+        // input delay and state for member variables
+
+        // cutoff as normalized frequency (eg 0.5 = Nyquist)
+        // resonance from 0 to 1, self-oscillates at settings over 0.9
+        // void transistorLadder(
+        //    double cutoff, double resonance,
+        //    double * in, double * out, unsigned nsamples)
+        //{
+        // tuning and feedback
+
+        //------------------------------------------------------------------------------ sample loop
+        // for(unsigned n = 0; n < nsamples; ++n)
+        //{
+
+        out *= 0.025;
+        // input with half delay, for non-linearities
+        double ih = 0.5 * (out + zi);
+        zi = out;
+
+        // double ih = out;
+
+        // evaluate the non-linear gains
+        double t0 = tanhXdX((ih * (r + 1)) - r * s[3]);
+
+        double t1 = tanhXdX(s[0]);
+        double t2 = tanhXdX(s[1]);
+        double t3 = tanhXdX(s[2]);
+        double t4 = tanhXdX(s[3]);
+
+        double f = vcfRC;
+
+        // g# the denominators for solutions of individual stages
+        double g0 = 1 / (1 + f * t1), g1 = 1 / (1 + f * t2);
+        double g2 = 1 / (1 + f * t3), g3 = 1 / (1 + f * t4);
+
+        // f# are just factored out of the feedback solution
+        double f3 = f * t3 * g3, f2 = f * t2 * g2 * f3, f1 = f * t1 * g1 * f2, f0 = f * t0 * g0 * f1;
+
+        // solve feedback
+        double y3 = (g3 * s[3] + f3 * g2 * s[2] + f2 * g1 * s[1] + f1 * g0 * s[0] + f0 * out) / (1 + r * f0);
+
+        // then solve the remaining outputs (with the non-linear gains here)
+        double xx = t0 * ((out * (r + 1)) - r * y3);
+        double y0 = t1 * g0 * (s[0] + f * xx);
+        double y1 = t2 * g1 * (s[1] + f * y0);
+        double y2 = t3 * g2 * (s[2] + f * y1);
+
+        // update state
+        s[0] += 2 * f * (xx - y0);
+        s[1] += 2 * f * (y0 - y1);
+        s[2] += 2 * f * (y1 - y2);
+        s[3] += 2 * f * (y2 - t4 * y3);
+
+        // out[n] = y3;
+        // }
+        // out *= 0.1;
+
+        out = y3;
+
+#else
+
+        out *= 0.5;
+        for (uint8_t ovs = 0; ovs < 2; ovs++) {
+            fb = y3;
             // hard clip
-            fb = ((out * 0.5) - fb) * m->res;
+            fb = ((out * 0.5) - fb) * r;
             if (fb > 4) fb = 4;
             if (fb < -4) fb = -4;
             // fb = 1.5 * fb - 0.5 * fb * fb * fb;
             //
 
-            b1 = ((out + fb - b1) * vcfRC) + b1;
-            b2 = ((b1 - b2) * vcfRC) + b2;
-            b3 = ((b2 - b3) * vcfRC) + b3;
-            b4 = ((b3 - b4) * vcfRC) + b4;
+            y0 = ((out + fb - y0) * vcfRC) + y0;
+            y1 = ((y0 - y1) * vcfRC) + y1;
+            y2 = ((y1 - y2) * vcfRC) + y2;
+            y3 = ((y2 - y3) * vcfRC) + y3;
         }
-
+#endif
         vcaRC = (amp - vcaRC) * m->vcaTC + vcaRC;
-        buffer[i] += 0.09367 * m->vcaBuf[i] * vcaRC * b4;
-        
+        buffer[i] += m->vcaBuf[i] * vcaRC * out;
+
         lastpw = m->pwmBuf[i];
     }
     // buffer[0] += 1;