The EL-34 is smaller in diameter and taller than the 6L6, but it runs on a higher plate voltage, which gives the EL-34 its unique output stage properties. The EL-34 is a high output pentode tube as opposed to other output tubes like the 6L6 and the 6550, which are beam tetrode tubes..Mullard, which was a subsidiary of Phillips, originally released the EL34 in 1953. EL34's are most commonly used in pairs in a Class AB1 push-pull configuration. This EL34 is found in many amplifiers that offer the "British tone", like Marshall and Hi-Watt, where the 6L6 is more commonly found in American made amps like those from Fender and Mesa Boogie