The EL34 is a vacuum tube of the power pentode type. It has an octal base (indicated by the '3' in the part number) and is found mainly in the final output stages of audio amplification circuits. The American RETMA tube designation number for this tube is 6CA7. Russian analog is 6p27s (Cyrillic: 6п27с )
Unlike the 6L6, (EIA base 7AC) the EL34 has its grid 3 connection brought out to a separate Pin (Pin 1) (EIA base 8ET) and its heater draws 1.5 Amps compared to the 0.9 Amp heater in the 6L6. The EL34 is a pentode, while the 6L6 is a beam tetrode which RCA often referred to as a beam power tube. Power pentodes and beam tetrodes are functionally equivalent.
The EL34 was introduced in 1953 by Mullard and its parent company Philips and, although no longer made by them, is manufactured by JJ Electronic, Svetlana and Reflector (Sovtek, Electro-Harmonix and some brands), amongst others. Some firms make a related tube called an E34L which is rated to require a higher grid bias voltage, but which may be interchangeable in some equipment.
The EL34 was widely used in higher-powered audio amplifiers of the 1960s and 1970s, such as the very popular Dynaco Stereo 70 and the Leak Stereo 60, and is also widely used in high-end guitar amplifiers because it is characterized by greater distortion (considered desirable in this application) at lower power than other octal tubes such as 6L6, KT88 or 6550. The EL34 is found in many British guitar amps and is associated with the "British Tone" (Marshall) as compared to the 6L6 which is generally associated with the "American Tone" (Fender).