dynamic string tuning

src/synth/Synth.hpp

@@ -6,6 +6,7 @@
 #include "NoteQueue.hpp"
 #include "Voice.hpp"
 #include "Scope.hpp"
+#include "Filter.hpp"
 
 #include <vector>
 
@@ -25,6 +26,7 @@ private:
     Voice* findVoiceByNote(uint8_t note);
 
     std::vector<uint8_t> sustainedNotes_;
+    Filter filter_;
 
     // voices
     static constexpr size_t MAX_VOICES = 32;