20W power tube/tube amplifier circuit diagram with EL34

The picture below is a 20W power amplifier circuit diagram based on the electronic tube component EL34. EL34 is a very famous tube and is very suitable for power tube amplifiers.

The above circuit is a complete circuit, including the tube amplifier circuit diagram and the power supply circuit diagram. To make a stereo channel amplifier, just build a similar amplifier circuit and connect it to the power supply in parallel with another identical amplifier.

The EL34 tube is a power pentode type thermionic valve or vacuum tube. It has an international octal base (indicated by "3" in the part number) and is primarily used in the final output stage of audio amplification circuits and is designed to be suitable as a series regulator due to its high allowable voltage between heaters and Cathode and other parameters. The US RETMA pipe designation number for this pipe is 6CA7. The Russian analogue is 6P27S (Cyrillic: 6?27C).

The tube EL34 was widely used in high-power audio amplifiers of the 1960s and 1970s, such as the very popular Dynaco Stereo 70 and the Leak TL25 (mono) and Stereo 60, and was also widely used in high-end guitar amplifiers because of its incomparability with other octals. It is characterized by greater distortion at lower powers (considered ideal in this application) compared to tubes [citation needed] (such as 6L6, KT88, or 6550).