4-watts of AF output and with a frequency response almost suitable for Hi-Fi applications.
http://w1.859.telia.com/~u85920178/use/afamp-4w.htm
The output transistors are complimentary (the original design used MJE2011 and MJE2021)
http://www.4qdtec.com/pwramp.html
Use any general-purpose NPN with high gain. It will drive low impedance headphones directly.
http://www.geocities.com/tomzi.geo/2tr_amp/2tr_amp.htm
The circuit amplifies and filters the voice audio signals from an electret microphone.
http://www.discovercircuits.com/PDF-FILES/voicex1.pdf
10 Watt Audio Amplifier Circuit Diagram
http://www.freeinfosociety.com/electronics/schemview.php?id=1108
High Quality, very simple design No preamplifier required
http://www.redcircuits.com/Page61.htm
You can use this powerfull amplifier in any small audio project. It is very small (6.5 x 4.5 cm).It outputs 10W and uses a 9V battery.
http://www.electronics-lab.com/projects/audio/016
110 mW Audio Amplifier Schematic Diagram
http://www.freeinfosociety.com/electronics/schemview.php?id=1065
A 15 watt amplifier made using discrete components.
http://www.zen22142.zen.co.uk/Circuits/Audio/amp15.htm
This circuit provides 16 watts of amplification. it is built using two LM383 power audio amplifiers.
http://www.reconnsworld.com/audio_16wattamp.html