I'm sure any beginner started out with this type of amp. I know I did, and unsuccessfully If I may add. I didn't understand the amplifier classes back then and had it biased in a very ugly class B region (very cold). Anyway here you are, a very good (in regard to simplicity) class A amp with an output power of 3.5W. Not very much, but the output should be considerably clean and good-sounding. The transistors, all but the two most right are BC550 for the NPN and BC560 for the PNP. The two most right transistors can be BD135 and BD136, but they'll be cutting real close to the maximum power dissipation, so more powerful transistors is beneficial but not necessary. To bias the amp correctly adjust the potentiometer until one of the output transistors draws around 1.1-1.2A. For the power supply I recommend using a laptop PSU, because they're regulated and quite resilient. That's it, plug and play
