About power+amplifier:

This is a Hi-Fi power amplifier circuit build based on single power amplifier IC TDA2040. The single TDA2040 has able to deliver 20W power output. The bridge amplifier which consist of double TDA2040 can deliver 30W power output (8 ohm loudspeaker).

About power amplifier IC TDA2040:

The TDA2040 is a monolithic integrated circuit in Pentawatt  package, intended for use as an audio class AB amplifier. Typically it provides 22W output power (d = 0.5%) at Vs = 32V/4W . The TDA2040 provides high output current and has very low harmonic and cross-over distortion. Further the device incorporates a patented short circuit protection system comprising an arrangement for automatically limiting the dissipated power so as to keep the working point of the output transistors within their safe operating area. A thermal shut-down system is also included.

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.

This is a high quality 65W power amplifier circuit based HEXFET IRF9540 and IRF540. The circuit is quite simple for amplifier with good sound quality. The component parts is easy to find at electronic store around your place. It uses split power supply. Q8, Q10, Q11, Q12, Q13 should be mounted on heatsink for thermic stability.

Here the circuit diagram of 50W power amplifier. The amplifier uses a pair of power transistors that are MJ2955 and 2N3055 to amplify the input signal. You must use a heatsink on those transistors.

Schematic diagram:

PCB layout: