Mesa Boogie Tubes

The 6L6 is the single most common power tube used in American-made tube amps with power ratings above 30 watts. This tube originally had its casing made of metal and was commonly used for radio and amplifiers druing the WWII era. Later it was housed in glass and the letters GC were added, standing for Glass Container. The metal tubes haven't been made in 30 years, and incidentally were terribly microphonic and sounded lousy in guitar amps.

The GT-6L6 that was the standard for many years was a specially rugged version that was designed to hang upside down in close proximity to a loudspeaker. It was developed at the request of Fender, and designed by the engineering staff of Sylvania, in particular Tom Ruberto. The best tubes that went on Fender, Peavey, Acoustic, Mitchell and Boogie were often custom-designed and so given a STR number (Special Tube Request).

American factories discontinued all 6L6 production in 1987. European factories manufactured reasonably high quality 6L6 tubes during the 1990s and even China got into production of 6L6 with the 6L6C version. Arguably, the best quality 6L6 tubes made today are the 6L6C version imported from Russia.