What are the main differences in the various 6L6 tubes?
(The following posts include some overlapping information, but reading them all will give you the full picture. -ed) 6L6 is the metal version, made from beginning to end. 6L6G is the large glass version, ST-16 envelope, made from the 30s into the 60’s. 6L6GA is an ST-14 version from around WW2, same ratings as the 6L6G, just smaller glass envelope. I like them as they look right with 5V4G rectifiers. 6L6GB is the T-14 version of the 6L6G and GA. Size is the same as the GC version except the published ratings are the same as the GA and G versions. 6L6GB has the crimp seal where the element mount is like earlier production glass tubes, and GC has a glass seal at each pin like a big compactron with a bakelite shell base on it. Seem to be from 1958-63 (RCA) 6L6GC has increased voltage and power dissipation ratings compared to the other glass and metal 6L6 versions and uses the new construction element mount. This construction lets more heat escape through the pins, I will remember it’s pro
