I am using a TDA2030L audio amplifier to make my own subwoofer at home. The amplifier works well with the sound input (from a PC) at around 14 percent. The power input is 19V and 2A which is about 38W and the gain for my amplifier is 50 since am using a 100k resistor as feedback between pin 2 and 4 and I have grounded pin 2 with 2k resistor grounded with 22uF capacitor (25V).
When I increase the volume beyond 24% in my PC the output of the amp at the speaker (4 ohm) is ok while playing in high frequency. BUT when I increase the bass the output gets distorted with the speaker playing in "PULSES", (some audio is not heard and it only booms at certain points with diaphgram of the speaker vibrating in a large displacement).
I have tried using a filter capacitor at the output to avoid DC output into the speakers but it doesn't help. When i use 20V, 1A source the problem still persists. Below is the circuit that I am using (I have not included the bass and volume control, but I am basically using potentiometers of 10k)
The output from the pc at 100% Volume is about 0.5~0.7v with a current of about 0.02mA