diff --git a/.gitmodules b/.gitmodules
index 458bc28..6e25929 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -1,4 +1,3 @@
 [submodule "lib/DPF"]
-	ignore = all
 	path = lib/DPF
 	url = https://github.com/DISTRHO/DPF.git
\ No newline at end of file
diff --git a/lib/DPF b/lib/DPF
index 86a621b..23692d0 160000
--- a/lib/DPF
+++ b/lib/DPF
@@ -1 +1 @@
-Subproject commit 86a621bfd86922a49ce593fec2a618a1e0cc6ef3
+Subproject commit 23692d024e57c617bd0692beb1835d48f98eb914
diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index cc47410..df15ee5 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -2,4 +2,5 @@ cmake_minimum_required(VERSION 3.10)
 add_subdirectory(yaw-tab)
 add_subdirectory(yaw-shepard)
 add_subdirectory(yaw-vowel)
-add_subdirectory(yaw-totune)
\ No newline at end of file
+add_subdirectory(yaw-totune)
+add_subdirectory(yaw-shep)
\ No newline at end of file
diff --git a/src/yaw-shep/CMakeLists.txt b/src/yaw-shep/CMakeLists.txt
new file mode 100644
index 0000000..bf07c21
--- /dev/null
+++ b/src/yaw-shep/CMakeLists.txt
@@ -0,0 +1,11 @@
+dpf_add_plugin(yaw-shep
+  TARGETS vst2 vst3
+  FILES_DSP
+      dsp.cpp
+      synth.cpp
+  FILES_UI
+      ui.cpp)
+
+target_include_directories(yaw-shep PUBLIC
+    "."
+    "../../lib/scale")
\ No newline at end of file
diff --git a/src/yaw-shep/DistrhoPluginInfo.h b/src/yaw-shep/DistrhoPluginInfo.h
new file mode 100644
index 0000000..1169f41
--- /dev/null
+++ b/src/yaw-shep/DistrhoPluginInfo.h
@@ -0,0 +1,26 @@
+#ifndef DISTRHO_PLUGIN_INFO_H_INCLUDED
+#define DISTRHO_PLUGIN_INFO_H_INCLUDED
+
+#define DISTRHO_PLUGIN_BRAND "yaw-audio"
+#define DISTRHO_PLUGIN_NAME  "yaw-shep"
+#define DISTRHO_PLUGIN_URI   "https://yaw.man/plugins/yaw-shep"
+
+
+#define DISTRHO_PLUGIN_IS_RT_SAFE   1
+#define DISTRHO_PLUGIN_NUM_INPUTS   0
+#define DISTRHO_PLUGIN_NUM_OUTPUTS  1
+#define DISTRHO_PLUGIN_WANT_MIDI_INPUT  1
+#define DISTRHO_PLUGIN_WANT_MIDI_OUTPUT 0
+
+#define DISTRHO_PLUGIN_HAS_UI       1
+#define DISTRHO_UI_USE_NANOVG       1
+
+enum Parameters {
+    kMouseX = 0,
+    kMouseY,
+    kVolume,
+    kHz,
+    kParameterCount,
+};
+
+#endif // DISTRHO_PLUGIN_INFO_H_INCLUDED
diff --git a/src/yaw-shep/dsp.cpp b/src/yaw-shep/dsp.cpp
new file mode 100644
index 0000000..e9a384d
--- /dev/null
+++ b/src/yaw-shep/dsp.cpp
@@ -0,0 +1,143 @@
+#include "DistrhoPlugin.hpp"
+#include "synth.h"
+
+START_NAMESPACE_DISTRHO
+
+class ShepPlug : public Plugin
+{
+public:
+	ShepPlug()
+		: Plugin(kParameterCount, 0, 0),
+		sampleRate(getSampleRate()),
+		synth(sampleRate),
+		fParameters { 0 }
+	{
+	}
+
+protected:
+	const char* getLabel() const override { return "yaw-shep"; }
+	const char* getDescription() const override { return "Generalized Shepard tone, mouse UI"; }
+	const char* getMaker() const override { return "yaw-audio"; }
+	const char* getHomePage() const override { return "https://yaw.man/plugins/yaw-shep"; }
+	const char* getLicense() const override { return "Fuck You Pay Me"; }
+	uint32_t    getVersion() const override { return d_version(1, 0, 0); }
+	int64_t     getUniqueId() const override { return d_cconst('y', 's', 'p', 'm'); }
+
+
+	void initParameter(uint32_t index, Parameter& parameter) override
+	{
+		parameter.hints = kParameterIsAutomable;
+		parameter.ranges.def = 0.0f;
+		parameter.ranges.min = 0.0f;
+		parameter.ranges.max = 1.0f;
+
+		switch (index)
+		{
+		case kHz:
+			parameter.name = "hz";
+			parameter.symbol = "hz";
+			parameter.hints = kParameterIsOutput;
+			parameter.ranges.def = 55.0f;
+			parameter.ranges.min = 55.0f;
+			parameter.ranges.max = 880.0f;
+		case kMouseX:
+			parameter.name = "x";
+			parameter.symbol = "x";
+			break;
+		case kMouseY:
+			parameter.name = "y";
+			parameter.symbol = "y";
+			break;
+		case kVolume:
+			parameter.name = "Volume";
+			parameter.symbol = "vol";
+			break;
+		}
+	}
+
+	void sampleRateChanged(double newRate) override
+	{
+		synth.setSampleRate(sampleRate, newRate);
+		sampleRate = newRate;
+	}
+
+	float getParameterValue(uint32_t index) const override
+	{
+		return fParameters[index];
+	}
+
+	void setParameterValue(uint32_t idx, float val) override
+	{
+		fParameters[idx] = val;
+		switch (idx) {
+		case kMouseX:
+			synth.setPhaseVelocity(val);
+			break;
+		case kMouseY:
+			synth.setTone(val);
+			break;
+		case kVolume:
+			synth.setVolume(val);
+			break;
+		}
+	}
+
+	void run(const float** inputs, float** outputs, uint32_t frames,
+             const MidiEvent* midiEvents, uint32_t midiEventCount) override
+	{
+
+		for (uint32_t i = 0; i < midiEventCount; ++i)
+        {
+            if (midiEvents[i].size <= 3)
+            {
+                uint8_t status = midiEvents[i].data[0];
+                uint8_t data = midiEvents[i].data[1] & 127;
+                uint8_t velocity = midiEvents[i].data[2] & 127;
+
+				float vol = velocity / 127.0f;
+
+                switch (status & 0xf0)
+                {
+				//Controller change.
+				case 0xb0:
+					//Channel Volume.
+					if( data == 7 ) setParameterValue(kVolume, vol);
+					//Breath Control.
+					if( data == 2 ) setParameterValue(kVolume, vol);
+					break;
+				//Aftertouch.
+				case 0xd0:
+					setParameterValue(kVolume, vol);
+					break;
+				//Note On.
+                case 0x90:
+					synth.setNote(data);
+                    /* fall through */
+				//Note Off.
+                case 0x80:
+					setParameterValue(kVolume, vol);
+                    break;
+
+                }
+            }
+        }
+		
+		synth.process(*outputs, frames);
+		fParameters[kHz] = synth.hzFund;
+	}
+
+private:
+	float fParameters[kParameterCount];
+	double sampleRate;
+	bool parity = false;
+
+	Synth synth;
+	DISTRHO_DECLARE_NON_COPYABLE_WITH_LEAK_DETECTOR(ShepPlug)
+};
+
+Plugin* createPlugin()
+{
+	return new ShepPlug();
+}
+
+END_NAMESPACE_DISTRHO
diff --git a/src/yaw-shep/synth.cpp b/src/yaw-shep/synth.cpp
new file mode 100644
index 0000000..21dfe77
--- /dev/null
+++ b/src/yaw-shep/synth.cpp
@@ -0,0 +1,119 @@
+#include "synth.h"
+
+Synth::Synth(double sampleRate){
+    setSampleRate(48000.0, sampleRate);
+}
+
+void Synth::resetPhase(){
+    spectrumPhase = 0.0;
+}
+
+#define frac(x) ((x) - ((long)x))
+constexpr double MIN_VOLUME = 0.00001;
+
+static constexpr double amin = 50;
+static constexpr double apiq = 500;
+static constexpr double amax = 10000;
+//Volume of voice as a function of sample rate independent frequency.
+static constexpr inline float getAmplitude( double hz )
+{
+  if( hz < amin )       return 0.0;
+  if( hz < apiq )      {
+        double a = (hz - amin) / (apiq - amin);
+        return a * a;}
+  if( hz < amax )     {
+        double a  = 1.0 - (hz - apiq) / (amax - apiq);
+        return a * a;
+  }
+  return 0.0;
+}
+
+//Interpolation function on unit interval with good regularity as a function on S^1.
+static constexpr inline float smooth( double x )
+{
+    return x * x * x;//(3.0 * x - 2.0);
+}
+
+//Sanity checks: voices should become silent outside audible frequencies.
+static_assert( MIN_VOLUME > getAmplitude(10.0) );
+static_assert( MIN_VOLUME > getAmplitude(20000.0));
+
+//New fundamental is twice as high as old fundamental.
+//Even overtones become plain overtones.
+void Synth::shiftUp()
+{
+    tablePhase *= 2.0;
+    spectrumPhase += 1.0;
+}
+
+//New fundamental is half as high as old fundamental.
+//Overtones become even overtones.
+void Synth::shiftDown()
+{
+    tablePhase /= 2.0;
+    spectrumPhase -= 1.0;
+}
+
+void Synth::process(float* output, const uint32_t frames)
+{
+    //Render.
+    for(uint32_t i = 0; i < frames; i++){
+
+        //Set pitch.
+        hzFund = exp2(spectrumPhase) * fMin;
+        
+        tablePhase += hzFund * sampleInterval;
+        tablePhase = frac(tablePhase);
+
+        bool isOddHarmonic = true;
+        
+        for(uint voice = 0; voice < NUM_VOICES; ++voice){
+
+            double voicePhase = 2.0 * M_PI * tablePhase * (voice + 1.0);
+            //Anti-aliasing: don't bother rendering anything over the Nyquist rate.
+            if( hzFund * (voice + 1.0) > hzNyq ) break;
+
+            output[i] += (!isOddHarmonic + isOddHarmonic * smooth(spectrumPhase))   //Fade in odd harmonics.
+            * getAmplitude(hzFund * (voice + 1.0))                                  //Frequency response.
+            * sinf(static_cast<float>(voicePhase));                                 //Additives.
+
+            isOddHarmonic = !isOddHarmonic;
+        }
+
+        output[i] *= fMin * volume / static_cast<float>(8 * NUM_VOICES);
+
+        //Wrapping.
+        spectrumPhase += spectrumPhaseVelocity * sampleInterval;
+        if( spectrumPhase > 1.0) shiftDown();
+        if( spectrumPhase < 0.0)   shiftUp();
+    }
+
+}
+
+void Synth::setSampleRate(double oldRate, double newRate){
+    sampleInterval = 1.0 / newRate;
+    hzNyq = newRate / 2;
+}
+
+//Takes value from 0 to 1 representing rate of wrapping pitch increase.
+//0 : lower one octave per second
+//1 : raise one octave per second
+void Synth::setPhaseVelocity(double in){
+    spectrumPhaseVelocity = 2.0 * (in - 0.5);
+}
+
+//Vary pitch of fundamental in a non-wrapping kinda way.
+//Current range is six octaves, current bottom is 13.75 Hz (A0)
+void Synth::setTone(double in){
+    falloff = in;
+}
+
+
+void Synth::setVolume(double in){
+    volume = in;
+}
+
+void Synth::setNote(uint8_t step){
+    fMin = 440.0 * exp2((step - 69.0) / 12.0);
+    Synth::resetPhase();
+}
\ No newline at end of file
diff --git a/src/yaw-shep/synth.h b/src/yaw-shep/synth.h
new file mode 100644
index 0000000..2259639
--- /dev/null
+++ b/src/yaw-shep/synth.h
@@ -0,0 +1,45 @@
+#include "DistrhoPlugin.hpp"
+#include <array>
+
+constexpr unsigned int NUM_VOICES = 512;
+constexpr unsigned int VOICE_MASK = NUM_VOICES - 1;
+
+class Synth
+{
+public:
+    explicit Synth(double sampleRate);
+    void process(float *output, uint32_t frames);
+    void setPhaseVelocity(double in);
+    void setTone(double in);
+    void setSampleRate(double oldRate, double newRate);
+    void setVolume(double in);
+    void setNote(uint8_t step);
+
+    //For recordable performances.
+    //For now it requires a button push, but perhaps
+    //we should require time position and have the phase reset automatically
+    //on song start?
+    void resetPhase();
+
+
+    //Current fundamental frequency of blit.
+    double hzFund = fMin;
+
+private:
+    void shiftUp();
+    void shiftDown();
+    //Phase of wavetable.
+    double tablePhase = 0.0;
+    float volume = 0.0f;
+    //Parameter in unit circle controlling pitch (varies by one octave).
+    double spectrumPhase = 1.0f;
+    //Revolutions per second of spectrum phase.
+    double spectrumPhaseVelocity = 0.0;
+    //Lowest fundamental frequency of blit.
+    double fMin = 55.0;
+
+    double falloff = 1.0;
+
+    double hzNyq = 24000.0;
+    double sampleInterval = 1.0 / 48000.0;
+};
\ No newline at end of file
diff --git a/src/yaw-shep/ui.cpp b/src/yaw-shep/ui.cpp
new file mode 100644
index 0000000..7a7dfc0
--- /dev/null
+++ b/src/yaw-shep/ui.cpp
@@ -0,0 +1,143 @@
+#include "ui.h"
+#include <format>
+#include <algorithm>
+
+START_NAMESPACE_DISTRHO
+
+static constexpr uint kInitialWidth = 800;
+static constexpr uint kInitialHeight = 600;
+
+MouseUI::MouseUI()
+	: UI(kInitialWidth, kInitialHeight)
+{
+
+#ifdef DGL_NO_SHARED_RESOURCES
+	createFontFromFile("sans", "/usr/share/fonts/truetype/ttf-dejavu/DejaVuSans.ttf");
+#else
+	loadSharedResources();
+#endif
+}
+
+
+void MouseUI::parameterChanged(uint32_t index, float value)
+{
+
+	if (index < kParameterCount)
+	{
+		switch (index)
+		{
+		case (kHz):
+			hz = value; break;
+		case (kMouseX):
+			x = value; break;
+		case (kMouseY):
+			y = value; break;
+		case (kVolume):
+			vol = value; break;
+		}
+		return;
+	}
+
+}
+
+void MouseUI::uiIdle()
+{
+}
+
+bool MouseUI::onMouse(const MouseEvent &ev)
+{
+	record = ev.press;
+	repaint();
+	return false; // Allow event to propagate.
+}
+
+bool MouseUI::onMotion(const MotionEvent &ev)
+{
+	if(!record) return false;
+	
+	x = std::clamp(ev.pos.getX() / (1.0 * getWidth()), 0.0, 1.0);
+	y = std::clamp(ev.pos.getY() / (1.0 * getHeight()), 0.0, 1.0);
+	setParameterValue(kMouseX, x);
+	setParameterValue(kMouseY, y);
+	repaint();
+
+	return false;
+}
+
+void MouseUI::onResize(const ResizeEvent &ev)
+{
+	return UI::onResize(ev);
+}
+
+void MouseUI::onNanoDisplay()
+{
+	fontSize(15.0f);
+	textLineHeight(1.f);
+
+	// Numerical feedback.
+	beginPath();
+	fillColor(200, 200, 200);
+	textBox(0.f, 15.f, 250.f,
+			std::format("Frequency: {:.3f}\nNearest: {:.3f}\n",
+						hz, scale.getNearestNoteNumber(hz))
+				.c_str(),
+			nullptr);
+	closePath();
+
+	beginPath();
+	fillColor(200, 200, 200);
+	textBox(0.f, 45.f, 250.f,
+			std::format("x: {:.3f}\ny: {:.3f}\n",
+						x * getWidth(), y * getHeight())
+				.c_str(),
+			nullptr);
+	closePath();
+
+
+	// Pen position and pressure.
+	drawCircle(x, y, 0.f, 0.5f);
+}
+
+void MouseUI::drawCircle(float x, float y, float z = 0.f, float p = 1.f)
+{
+
+	static constexpr float circleRadius = 25.f;
+	x *= getWidth();
+	y *= getHeight();
+	z = 1.f - z;
+
+	beginPath();
+	strokeColor(1.f, 1.f, 1.f, 0.5f);
+	moveTo(x - z * circleRadius, y);
+	lineTo(x + z * circleRadius, y);
+	stroke();
+	closePath();
+
+	beginPath();
+	strokeColor(1.f, 1.f, 1.f, 0.5f);
+	moveTo(x, y - z * circleRadius);
+	lineTo(x, y + z * circleRadius);
+	stroke();
+	closePath();
+
+	beginPath();
+	fillColor(1.f, 1.f, 1.f, p);
+	strokeColor(255, 255, 255, 255);
+	circle(x, y, circleRadius);
+	fill();
+	stroke();
+	closePath();
+
+	beginPath();
+	strokeColor(1.f, 1.f, 1.f, z);
+	circle(x, y, z * circleRadius);
+	stroke();
+	closePath();
+}
+
+UI *createUI()
+{
+	return new MouseUI();
+}
+
+END_NAMESPACE_DISTRHO
diff --git a/src/yaw-shep/ui.h b/src/yaw-shep/ui.h
new file mode 100644
index 0000000..a2e24b8
--- /dev/null
+++ b/src/yaw-shep/ui.h
@@ -0,0 +1,37 @@
+#include "DistrhoUI.hpp"
+#include "scale.h"
+#ifdef DEBUG
+#include <format>
+#include <optional>
+#endif
+
+START_NAMESPACE_DISTRHO
+
+class MouseUI : public UI
+{
+public:
+    explicit MouseUI();
+
+    //void buttonClicked(SubWidget *const widget, int) override;
+    void parameterChanged(uint32_t index, float value) override;
+
+    void uiIdle() override;
+    bool onMouse(const MouseEvent &ev) override;
+    bool onMotion(const MotionEvent &ev) override;
+    void onResize(const ResizeEvent &ev) override;
+    void onNanoDisplay() override;
+
+private:
+    void drawCircle(float x, float y, float z, float p);
+
+    bool record = false;
+    float x = 0.f;
+    float y = 0.f;
+    float vol = 0.f;
+    float hz = 55.f;
+    Scale scale{440.0};
+
+    DISTRHO_DECLARE_NON_COPYABLE_WITH_LEAK_DETECTOR(MouseUI)
+};
+
+END_NAMESPACE_DISTRHO
\ No newline at end of file