diff --git a/filter/ybandpass.h b/filter/ybandpass.h
index 9cb048f..27801fa 100644
--- a/filter/ybandpass.h
+++ b/filter/ybandpass.h
@@ -73,10 +73,10 @@ public:
     }
     void processblock(t_sample** inputs, t_sample** outputs, int blockSize)
     {
-        double* in1 = inputs[0];
-        double* in2 = inputs[1];
-        double* out1 = outputs[0];
-        double* out2 = outputs[1];
+        t_sample* in1 = inputs[0];
+        t_sample* in2 = inputs[1];
+        t_sample* out1 = outputs[0];
+        t_sample* out2 = outputs[1];
 
         int inFramesToProcess = blockSize;
         double overallscale = 1.0;
diff --git a/filter/yhighpass.h b/filter/yhighpass.h
index 1abb1e6..a5387c7 100644
--- a/filter/yhighpass.h
+++ b/filter/yhighpass.h
@@ -73,10 +73,10 @@ public:
     }
     void processblock(t_sample** inputs, t_sample** outputs, int blockSize)
     {
-        double* in1 = inputs[0];
-        double* in2 = inputs[1];
-        double* out1 = outputs[0];
-        double* out2 = outputs[1];
+        t_sample* in1 = inputs[0];
+        t_sample* in2 = inputs[1];
+        t_sample* out1 = outputs[0];
+        t_sample* out2 = outputs[1];
 
         int inFramesToProcess = blockSize;
         double overallscale = 1.0;
diff --git a/filter/ynotch.h b/filter/ynotch.h
index 23db0de..74584d3 100644
--- a/filter/ynotch.h
+++ b/filter/ynotch.h
@@ -73,10 +73,10 @@ public:
     }
     void processblock(t_sample** inputs, t_sample** outputs, int blockSize)
     {
-        double* in1 = inputs[0];
-        double* in2 = inputs[1];
-        double* out1 = outputs[0];
-        double* out2 = outputs[1];
+        t_sample* in1 = inputs[0];
+        t_sample* in2 = inputs[1];
+        t_sample* out1 = outputs[0];
+        t_sample* out2 = outputs[1];
 
         int inFramesToProcess = blockSize;
         double overallscale = 1.0;
diff --git a/filter/ysvf.h b/filter/ysvf.h
index a4a18bd..01bbd1f 100644
--- a/filter/ysvf.h
+++ b/filter/ysvf.h
@@ -16,7 +16,7 @@ enum filter_types {
 template <typename t_sample>
 class ysvf {
 public:
-    ysvf(double _samplerate)
+    ysvf(double _samplerate = 44100)
         : lowpass { _samplerate }
         , highpass { _samplerate }
         , bandpass { _samplerate }
@@ -96,10 +96,10 @@ public:
 
 private:
     filter_types filter_type;
-    ylowpass lowpass;
-    yhighpass highpass;
-    ybandpass bandpass;
-    ynotch notch;
+    ylowpass<t_sample> lowpass;
+    yhighpass<t_sample> highpass;
+    ybandpass<t_sample> bandpass;
+    ynotch<t_sample> notch;
 
     double clamp(double& value, double min, double max) {
         if (value < min) {
diff --git a/synth/tx_envelope.h b/synth/tx_envelope.h
index 6cf2fe6..e50f09e 100644
--- a/synth/tx_envelope.h
+++ b/synth/tx_envelope.h
@@ -17,55 +17,46 @@ enum env_state {
 
 class tx_envelope {
 public:
-    env_state state;
-    float attack1_rate;
-    float attack1_level;
-    float attack2_rate;
-    float hold_rate;
-    float decay1_rate;
-    float decay1_level;
-    float decay2_rate;
-    float sustain_level;
-    float release1_rate;
-    float release1_level;
-    float release2_rate;
+    env_state state = idle;
+    float attack1_rate = 0;
+    float attack1_level = 0;
+    float attack2_rate = 0;
+    float hold_rate = 0;
+    float decay1_rate = 0;
+    float decay1_level = 0;
+    float decay2_rate = 0;
+    float sustain_level = 0;
+    float release1_rate = 0;
+    float release1_level = 0;
+    float release2_rate = 0;
 
-    tx_envelope()
-        : samplerate { 44100. }
-        , attack1_rate { 0 }
-        , attack1_level { 0 }
-        , attack2_rate { 0 }
-        , hold_rate { 0 }
-        , decay1_rate { 0 }
-        , decay1_level { 0 }
-        , decay2_rate { 0 }
-        , sustain_level { 0 }
-        , release1_rate { 0 }
-        , release1_level { 0 }
-        , release2_rate { 0 }
-        , level { 0.f }
-        , phase { 0 }
-        , state { idle }
-        , start_level { 0.f }
-        , h1 { 0. }
-        , h2 { 0. }
-        , h3 { 0. }
+    tx_envelope(bool _retrigger = false)
+        : retrigger { _retrigger }
     {
     }
 
     float process_sample(bool gate, bool trigger) {
 
-        int attack_mid_x1 = ms_to_samples(attack1_rate);
-        int attack_mid_x2 = ms_to_samples(attack2_rate);
-        int hold_samp = ms_to_samples(hold_rate);
-        int decay_mid_x1 = ms_to_samples(decay1_rate);
-        int decay_mid_x2 = ms_to_samples(decay2_rate);
-        int release_mid_x1 = ms_to_samples(release1_rate);
-        int release_mid_x2 = ms_to_samples(release2_rate);
+        return process_sample<float>(gate, trigger, 0, 0);
+    }
+
+    template <typename t_sample>
+    float process_sample(bool gate, bool trigger, t_sample _attack_mod, t_sample _decay_mod) {
+
+        size_t attack_mid_x1 = ms_to_samples(attack1_rate + (float)_attack_mod);
+        size_t attack_mid_x2 = ms_to_samples(attack2_rate + (float)_attack_mod);
+        size_t hold_samp = ms_to_samples(hold_rate);
+        size_t decay_mid_x1 = ms_to_samples(decay1_rate + (float)_decay_mod);
+        size_t decay_mid_x2 = ms_to_samples(decay2_rate + (float)_decay_mod);
+        size_t release_mid_x1 = ms_to_samples(release1_rate + (float)_decay_mod);
+        size_t release_mid_x2 = ms_to_samples(release2_rate + (float)_decay_mod);
 
         // if note on is triggered, transition to attack phase
         if (trigger) {
-            start_level = level;
+            if (retrigger) 
+                start_level = 0.f;
+            else
+                start_level = level;
             phase = 0;
             state = attack1;
         }
@@ -73,7 +64,7 @@ public:
         if (state == attack1) {
             // while in attack phase
             if (phase < attack_mid_x1) {
-                level = lerp(0, start_level, attack_mid_x1, attack1_level, phase);
+                level = lerp(0, start_level, (float)attack_mid_x1, attack1_level, (float)phase);
                 phase += 1;
             }
             // reset phase if parameter was changed
@@ -90,7 +81,7 @@ public:
         if (state == attack2) {
             // while in attack phase
             if (phase < attack_mid_x2) {
-                level = lerp(0, attack1_level, attack_mid_x2, 1, phase);
+                level = lerp(0, attack1_level, (float)attack_mid_x2, 1, (float)phase);
                 phase += 1;
             }
             // reset phase if parameter was changed
@@ -121,7 +112,7 @@ public:
         if (state == decay1) {
             // while in decay phase
             if (phase < decay_mid_x1) {
-                level = lerp(0, 1, decay_mid_x1, decay1_level, phase);
+                level = lerp(0, 1, (float)decay_mid_x1, decay1_level, (float)phase);
                 phase += 1;
             }
             // reset phase if parameter was changed
@@ -138,7 +129,7 @@ public:
         if (state == decay2) {
             // while in decay phase
             if (phase < decay_mid_x2) {
-                level = lerp(0, decay1_level, decay_mid_x2, sustain_level, phase);
+                level = lerp(0, decay1_level, (float)decay_mid_x2, sustain_level, (float)phase);
                 phase += 1;
             }
             // reset phase if parameter was changed
@@ -161,7 +152,7 @@ public:
         if (state == release1) {
             // while in release phase
             if (phase < release_mid_x1) {
-                level = lerp(0, sustain_level, release_mid_x1, release1_level, phase);
+                level = lerp(0, sustain_level, (float)release_mid_x1, release1_level, (float)phase);
                 phase += 1;
             }
             // reset phase if parameter was changed
@@ -178,7 +169,7 @@ public:
         if (state == release2) {
             // while in release phase
             if (phase < release_mid_x2) {
-                level = lerp(0, release1_level, release_mid_x2, 0, phase);
+                level = lerp(0, release1_level, (float)release_mid_x2, 0, (float)phase);
                 phase += 1;
             }
             // reset phase if parameter was changed
@@ -202,37 +193,41 @@ public:
         this->samplerate = sampleRate;
     }
 
-    // returns the x/y coordinates of the envelope points as a list for graphical representation.
-    std::array<float, 18> calc_coordinates() {
+    // converts the x/y coordinates of the envelope points as a list for graphical representation.
+    std::array<float, 18> calc_coordinates(float _max_attack, float _max_decay, float _max_release) {
+
+        auto scale = [](float _value, float _max) {
+            return powf(_value / _max, 0.25) * _max;
+        };
 
         float a_x = 0;
         float a_y = 0;
 
-        float b_x = attack1_rate;
+        float b_x = scale(attack1_rate, _max_attack / 2);
         float b_y = attack1_level;
 
-        float c_x = b_x + attack2_rate;
+        float c_x = b_x + scale(attack2_rate, _max_attack / 2);
         float c_y = 1;
 
         float d_x = c_x + hold_rate;
         float d_y = 1;
         
-        float e_x = d_x + decay1_rate;
+        float e_x = d_x + scale(decay1_rate, _max_decay / 2);
         float e_y = decay1_level;
 
-        float f_x = e_x + decay2_rate;
+        float f_x = e_x + scale(decay2_rate, _max_decay / 2);
         float f_y = sustain_level;
 
-        float g_x = f_x + 125;
+        float g_x = _max_attack + _max_decay;
         float g_y = sustain_level;
 
-        float h_x = g_x + release1_rate;
+        float h_x = g_x + scale(release1_rate, _max_decay / 2);
         float h_y = release1_level;
 
-        float i_x = h_x + release2_rate;
+        float i_x = h_x + scale(release2_rate, _max_decay / 2);
         float i_y = 0;
 
-        float total = i_x;
+        float total = _max_attack + _max_decay + _max_release;
 
         return {
             a_x,
@@ -257,13 +252,14 @@ public:
     }
     
 private:
-    double samplerate;
-    int phase;
-    float level;
-    float start_level;
-    float h1;
-    float h2;
-    float h3;
+    double samplerate = 44100.;
+    size_t phase = 0;
+    float level = 0.f;
+    float start_level = 0.f;
+    float h1 = 0.f;
+    float h2 = 0.f;
+    float h3 = 0.f;
+    bool retrigger;
 
     float lerp(float x1, float y1, float x2, float y2, float x) { return y1 + (((x - x1) * (y2 - y1)) / (x2 - x1)); }
 
@@ -275,6 +271,8 @@ private:
         return (h1 + h2 + h3) / 3.f;
     }
 
-    float ms_to_samples(float ms) { return ms * samplerate / 1000.f; }
+    size_t ms_to_samples(float ms) { 
+        return static_cast<size_t>(ms * samplerate / 1000.f);
+    }
 };
 }
\ No newline at end of file
diff --git a/synth/voice_allocator.h b/synth/voice_allocator.h
index 0f85716..16f58ab 100644
--- a/synth/voice_allocator.h
+++ b/synth/voice_allocator.h
@@ -11,7 +11,7 @@ public:
     std::vector<t_voice> voices;
 
     voice_allocator()
-        : voices(8, t_voice())
+        : voices(4, t_voice())
     {
         // checks whether template derives from ivoice
         typedef t_voice assert_at_compile_time[is_convertible<t_voice>::value ? 1 : -1];
@@ -92,6 +92,7 @@ public:
 
 private:
     std::vector<midi_event> input_queue;
+    int index_to_steal = 0;
 
     t_voice* get_free_voice(float frequency)
     {
@@ -118,7 +119,13 @@ private:
         }
 
         if (free_voice == nullptr) {
-            free_voice = &voices.at(0);
+            free_voice = &voices.at(index_to_steal);
+            
+            if (index_to_steal < voices.size() - 1) {
+                index_to_steal++;
+            } else {
+                index_to_steal = 0;
+            }
         }
 
         return free_voice;
@@ -153,4 +160,4 @@ private:
         }
     }
 };
-}
\ No newline at end of file
+}
diff --git a/util/demo_noise.h b/util/demo_noise.h
new file mode 100644
index 0000000..d51ae47
--- /dev/null
+++ b/util/demo_noise.h
@@ -0,0 +1,38 @@
+#pragma once
+#define _USE_MATH_DEFINES
+#include <math.h>
+#include <cstdlib>
+
+namespace trnr {
+template <typename t_sample>
+class demo_noise {
+public:
+    void set_samplerate(double _samplerate) {
+        samplerate = _samplerate;
+    }
+
+    void process_block(t_sample** samples, long sample_frames) {
+
+        for (int s = 0; s < sample_frames; s++) {
+            demo_counter++;
+
+            if (demo_counter == samplerate * 20) {
+                demo_counter = 0;
+            }
+            if (demo_counter > samplerate * 17) {
+                t_sample r1 = static_cast<t_sample>(rand()) / static_cast<t_sample>(RAND_MAX);
+                t_sample r2 = static_cast<t_sample>(rand()) / static_cast<t_sample>(RAND_MAX);
+
+                t_sample noise = static_cast<t_sample>(sqrt(-2.0 * log(r1)) * cos(2.0 * M_PI * r2));
+
+                samples[0][s] = noise / 10.0;
+                samples[1][s] = noise / 10.0;
+            }
+        }
+    }
+
+private:
+    double samplerate = 44100;
+    int demo_counter = 0;
+};
+}
\ No newline at end of file
diff --git a/util/retro_buf.h b/util/retro_buf.h
new file mode 100644
index 0000000..fa0d719
--- /dev/null
+++ b/util/retro_buf.h
@@ -0,0 +1,156 @@
+#pragma once
+
+#include "../filter/chebyshev.h"
+#include "../companding/ulaw.h"
+#include <iostream>
+
+namespace trnr {
+
+struct retro_buf_modulation {
+    double midi_note;
+    double pitch_mod;
+    double samplerate; // the (re)samplerate
+    double bitrate;
+    size_t start; // sets the start point from which to play
+    size_t end; // sets the end point
+    bool looping; // sets whether the sample should loop
+    bool reset; // resets the phase
+    int jitter; // jitter amount
+    double deviation;
+};
+
+// base class for accessing a sample buffer with adjustable samplerate, bitrate and other options.
+class retro_buf {
+public:
+    void set_host_samplerate(double _samplerate) {
+        m_host_samplerate = _samplerate;
+        m_imaging_filter_l.set_samplerate(_samplerate);
+        m_imaging_filter_r.set_samplerate(_samplerate);
+    }
+
+    void set_buf_samplerate(double _samplerate) {
+        m_buf_samplerate = _samplerate;
+    }
+
+    void set_buffer_size(size_t _buffer_size) {
+        m_buffer_size = _buffer_size;
+    }
+
+    void set_channel_count(size_t _channel_count) {
+        m_channel_count = _channel_count;
+    }
+
+    void start_playback() {
+        if (m_modulation.reset || (!m_modulation.reset && m_playback_pos == -1)) {
+            m_playback_pos = (double)m_modulation.start;
+        }
+    }
+
+    // @return is active
+    bool process_block(double** _outputs, size_t _block_size, retro_buf_modulation _mod) {
+
+        m_modulation = _mod;
+
+        for (int i = 0; i < _block_size; ++i) {
+            double output_l = 0;
+            double output_r = 0;
+            
+            // if within bounds
+            if (m_playback_pos > -1 && m_playback_pos <= _mod.end)  {
+                
+                // quantize index
+                double samplerate_divisor = m_host_samplerate / _mod.samplerate;
+                size_t quantized_index = static_cast<size_t>(static_cast<size_t>(m_playback_pos / samplerate_divisor) * samplerate_divisor);
+
+                // get sample for each channel
+                output_l = get_sample((size_t)wrap(quantized_index + jitterize(_mod.jitter), m_buffer_size), 0);
+                if (m_channel_count > 0) {
+                    output_r = get_sample((size_t)wrap(quantized_index + jitterize(_mod.jitter), m_buffer_size), 1);
+                } else {
+                    output_r = output_l;
+                }
+                
+                // advance position
+                double note_ratio = midi_to_ratio(_mod.midi_note + _mod.pitch_mod);
+                m_playback_pos += note_ratio * (m_buf_samplerate / m_host_samplerate);
+            
+                reduce_bitrate(output_l, output_r, _mod.bitrate);
+
+                // calculate imaging filter frequency + deviation
+                double filter_frequency = ((_mod.samplerate / 2) * note_ratio) * ((_mod.deviation * 9) + 1);
+
+                m_imaging_filter_l.process_sample(output_l, filter_frequency);
+                m_imaging_filter_r.process_sample(output_r, filter_frequency);
+            }
+            // else if loop
+            else if(_mod.looping) {
+                // loop
+                m_playback_pos = (double)_mod.start;
+            }
+            // else
+            else {
+                // stop
+                m_playback_pos = -1;
+            }
+
+            _outputs[0][i] = output_l;
+            _outputs[1][i] = output_r;
+        }
+
+        return m_playback_pos > -1;
+    }
+
+    virtual float get_sample(size_t _index, size_t _channel) = 0;
+
+private:
+    size_t m_channel_count = 0;
+    size_t m_buffer_size = 0;
+    double m_buf_samplerate = 44100.0;
+    double m_host_samplerate = 44100.0;
+    double m_playback_pos = -1;
+
+    chebyshev m_imaging_filter_l;
+    chebyshev m_imaging_filter_r;
+    ulaw m_compander;
+    retro_buf_modulation m_modulation;
+
+    float midi_to_ratio(double midi_note) {
+        return powf(powf(2, (float)midi_note - 60.f), 1.f / 12.f);
+    }
+    
+    template <typename T>
+    T clamp(T& value, T min, T max) {
+        if (value < min) {
+            value = min;
+        } else if (value > max) {
+            value = max;
+        }
+        return value;
+    }
+
+    double wrap(double value, double max) {
+        while (value > max) {
+            value =- max;
+        }
+        return value;
+    }
+
+    int jitterize(int jitter) {
+        if (jitter > 0) {
+            return static_cast<int>(rand() % jitter);
+        } else {
+            return 0;
+        }
+    }
+
+    void reduce_bitrate(double& value1, double& value2, double bit) {
+        m_compander.encode_samples(value1, value2);
+
+        float resolution = powf(2, bit);
+        value1 = round(value1 * resolution) / resolution;
+        value2 = round(value2 * resolution) / resolution;
+
+        m_compander.decode_samples(value1, value2);
+    }
+};
+}
\ No newline at end of file