Chorus works :-) but linear interpolation is not the best... will try

splines...

MicroMDAEPiano.ino

@@ -56,15 +56,15 @@ AudioAmplifier           volume_r;
 AudioAmplifier           volume_l;
 AudioModulatedEffectChorus   modchorus_r;
 AudioModulatedEffectChorus   modchorus_l;
-AudioSynthWaveformSine   mod_sine1;
+AudioSynthWaveform       modulator;
 AudioConnection          patchCord0(queue_r, peak_r);
 AudioConnection          patchCord1(queue_l, peak_l);
 AudioConnection          patchCord2(queue_r, freeverb_r);
 AudioConnection          patchCord3(queue_l, freeverb_l);
 AudioConnection          patchCord4(queue_r, 0, modchorus_r, 0);
 AudioConnection          patchCord5(queue_l, 0, modchorus_l, 0);
-AudioConnection          patchCord6(mod_sine1, 0, modchorus_r, 1);
-AudioConnection          patchCord7(mod_sine1, 0, modchorus_l, 1);
+AudioConnection          patchCord6(modulator, 0, modchorus_r, 1);
+AudioConnection          patchCord7(modulator, 0, modchorus_l, 1);
 AudioConnection          patchCord8(queue_r, 0, mixer_r, 0);
 AudioConnection          patchCord9(queue_l, 0, mixer_l, 0);
 AudioConnection          patchCord10(modchorus_r, 0, mixer_r, 2);
@@ -241,12 +241,13 @@ void setup()
   // chorus modulation fixed
   memset(r_delayline, 0, sizeof(short)*CHORUS_DELAY_LENGTH);
   memset(l_delayline, 0, sizeof(short)*CHORUS_DELAY_LENGTH);
-  mod_sine1.amplitude(1.0);
-  mod_sine1.frequency(2.0);
-  mod_sine1.phase(0);
+  modulator.begin(WAVEFORM_TRIANGLE);
+  modulator.amplitude(0.1);
+  modulator.frequency(1.0);
+  modulator.phase(0);
   // chorus level fixed
-  mixer_r.gain(2, 1.0);
-  mixer_l.gain(2, 1.0);
+  mixer_r.gain(2, 0.5);
+  mixer_l.gain(2, 0.5);
 
   AudioInterrupts();
 

effect_modulated_chorus.cpp

@@ -131,18 +131,14 @@ void AudioModulatedEffectChorus::update(void)
 
       // linear interpolation
       x1 = int(mod_idx);
-      y1 = *(block->data + x1);
+      y1 = l_delayline[x1];
       if (x1 + 1 >= delay_length)
-      {
         x2 = 0;
-        y2 = *bp;
-      }
       else
-      {
         x2 = x1 + 1;
-        y2 = *bp + x2;
-      }
-      *bp = (*bp >> 1) + (int((float(y2 - y1) / (x2 - x1) * (mod_idx - x1) + y1) + 0.5) >> 1); // mix original signal 1:1 with modulated signal
+      y2 = l_delayline[x2];
+      
+      *bp = (int((float(y2 - y1) / (x2 - x1) * (mod_idx - x1) + y1) + 0.5) >> 1); // mix original signal 1:1 with modulated signal
       bp++;
       mp++;
       l_circ_idx++;