The following diagram is 16W audio amplifier circuit. The circuit built based 2 pieces of power IC LM383 in bridge connection, so this amplifier is an bridge amplifier.
This is an old amplifier, LM383 is discontinued, so this LM383 might be difficult to find. You can use ECG1232, TDA2002 or TDA2003 as the replace for LM383. Take a note that a heatsink plate is required to avoid overheating on the ICs.
Download LM383 datasheet.