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diff --git a/src/main/java/com/jsyn/unitgen/MixerStereo.java b/src/main/java/com/jsyn/unitgen/MixerStereo.java
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+/*
+ * Copyright 2014 Phil Burk, Mobileer Inc
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.jsyn.unitgen;
+
+import com.jsyn.ports.UnitInputPort;
+
+/**
+ * Mixer with monophonic inputs and two channels of output. Each signal can be panned left or right
+ * using an equal power curve. The "left" signal will be on output part zero. The "right" signal
+ * will be on output part one.
+ * 
+ * @author Phil Burk (C) 2014 Mobileer Inc
+ * @see MixerMono
+ * @see MixerStereoRamped
+ */
+public class MixerStereo extends MixerMono {
+    /**
+     * Set to -1.0 for all left channel, 0.0 for center, or +1.0 for all right. Or anywhere in
+     * between.
+     */
+    public UnitInputPort pan;
+    protected PanTracker[] panTrackers;
+
+    static class PanTracker {
+        double previousPan = Double.MAX_VALUE; // so we update immediately
+        double leftGain;
+        double rightGain;
+
+        public void update(double pan) {
+            if (pan != previousPan) {
+                // fastSine range is -1.0 to +1.0 for full cycle.
+                // We want a quarter cycle. So map -1.0 to +1.0 into 0.0 to 0.5
+                double phase = pan * 0.25 + 0.25;
+                leftGain = SineOscillator.fastSin(0.5 - phase);
+                rightGain = SineOscillator.fastSin(phase);
+                previousPan = pan;
+            }
+        }
+    }
+
+    public MixerStereo(int numInputs) {
+        super(numInputs);
+        addPort(pan = new UnitInputPort(numInputs, "Pan"));
+        pan.setup(-1.0, 0.0, 1.0);
+        panTrackers = new PanTracker[numInputs];
+        for (int i = 0; i < numInputs; i++) {
+            panTrackers[i] = new PanTracker();
+        }
+    }
+
+    @Override
+    public int getNumOutputs() {
+        return 2;
+    }
+
+    @Override
+    public void generate(int start, int limit) {
+        double[] amplitudes = amplitude.getValues(0);
+        double[] outputs0 = output.getValues(0);
+        double[] outputs1 = output.getValues(1);
+        for (int i = start; i < limit; i++) {
+            double sum0 = 0.0;
+            double sum1 = 0.0;
+            for (int n = 0; n < input.getNumParts(); n++) {
+                double[] inputs = input.getValues(n);
+                double[] gains = gain.getValues(n);
+                double[] pans = pan.getValues(n);
+                PanTracker panTracker = panTrackers[n];
+                panTracker.update(pans[i]);
+                double scaledInput = inputs[i] * gains[i];
+                sum0 += scaledInput * panTracker.leftGain;
+                sum1 += scaledInput * panTracker.rightGain;
+            }
+            double amp = amplitudes[i];
+            outputs0[i] = sum0 * amp;
+            outputs1[i] = sum1 * amp;
+        }
+    }
+
+}