Non PWM pin defined as channel B!

[boylesg]

In file synEngine.h

#define CHA 3 #define CHB 4

Pin 4 is not a PWM pin on Uno, Mini, Nano or Pro.

You need to change it to this:

#if defined ARDUINO_AVR_UNO || defined ARDUINO_AVR_PRO || #defined ARDUINO_AVR_MEGA #define CHA 9 #define CHB 10 #else #define CHA 3 #define CHB 4 #endif