Distortion in TDA2030 circuit
The problem with your sketch is that there is no DC-path for pin 2. Any small bias current in or out of pin 2 will charge up the 22 uF capacitor bringing the voltage at pin 2 to either the positive or negative rail. 

Since you discovered that you can fix the problem by pulling pin 2 low it seems as though the 22 uF capacitor is charging towards V+. In this case the amplifier will be running in saturation and probably only the negative half-cycles of the music(?) are being amplified.



Figure 1. Application note example. Note feedback resistor giving DC discharge path from the pin 2 capacitor.

The application notes shows a feedback resistor to the inverting input, pin 2. This also acts as a DC discharge for the capacitor.