The Radio Board.org
This is a great shortwave Radio
In trying to use an op amp designed for audio, I've run into a lot of problems implementing them. On the surface, they look easy to configure. But in practice they are finnicky to make right. They oscillate and carry on to the point of exhaustion, requiring way more engineering in layout and components than I want to do.
I came upon this class AB headphone amp that looked simple, so I gave it a try. It uses the 2N3904-2N3906 transistors that are so easy to get. I thought, this is going to sound cheap. What a surprise. This amp is amazing, clean, easy, and a wide frequency response. It sounds awesome. And it behaves. You can really beat it up and it works fine, no crazy oscillations, The only big change I made was R2, which was connected to the positive rail through the speaker, which made me go bonkers trying to set up a stereo amp on one battery. As shown, it's easy to use in stereo. Also, I did not use R3, R4, and C3 , but you could if you want. I measured the current draw for stereo (2 circuits, one battery) at 10 ma using 3 volts, so I used the voltage regulator for 3 volts. At 5 volts, the draw goes way up. At 9 volts, it draws over 20 ma. One circuit in mono at 3 volts draws about 5 ma. The 3 volt supply gave crushing volume into any earphone or headset. Be careful with your hearing. I really like this amp.