The following diagram is the circuit diagram of 20W power amplifier which build based tube component EL34. EL34 is very famous tube and great for power tube amplifier. The circuit above is complete circuit contains tube amplifier circuit diagram and power supply circuit diagram. To make the stereo channel amplifier, build the similar amplifier circuit only and connect to the power supply using parallel connection with another same amplifier.
The following is a circuit of a power amplifier 140W. This Circuit using 741 IC-based circuit opAmp as strengthening early before the final strengthening by four transistors thereafter. Make sure you use a heatsink on the transistors to reduce excess heat in the transistors. Power supply used is the type of dual polarity power supply with (+), (-) and (0). For maximum performance, use a stabilized power supply with 40V [...]
The following circuit is a 5W stereo audio amplifier, built based on single amplifier IC TA7227. TA7227 can be used for dual mode (stereo amp) and single mode (bridge connection/mono amp). This IC type featured some circuit protection: thermal protection, over voltage protection, current limitter and BTL DC short connection. The circuit above is not completely drawn, there no the PIN numbers of IC. You must check the IC’s PIN [...]
This 300W OCL (ouput capacitor-less) power amplifier -i’m sorry for the blur diagram, but it shouldbe readable- use 4 pairs of 2N3055 dan MJ3055 transistor as the main power components. There are will be 8 pieces of them which should be attached on aluminium headsink. It’s will be better if you add small fan to blow the heatsink and transistors (just like fan and heatsink for computer processor).