Here is a picture from the [datasheet](https://eecs.oregonstate.edu/education/docs/datasheets/LM386.pdf) of the LM386.

Obviously, the input signal is swinging above and below the ground, but pin 4 is not connected to a negative supply. It is connected to the ground (while pin 6 is the positive supply.) How can this amplifier follow signals below ground? I don't think this IC has an internal positive to negative DC converter.

[![LM386-AM](https://i.stack.imgur.com/8utZ1.jpg)](https://i.stack.imgur.com/8utZ1.jpg)