The 6L6B is perhaps the most reliable of the currently made types of 6L6s, with slightly less power and a more aggressive edge when pushed into distortion. These are currently used for the GT Fender® amp tubes.

6L6 Type (typical power ranges from 20 to 25 watts)
The Choice of most all medium powered Fender® amps, and the many Fender® "wannabe" amps. This specially designed pentode with a beam-forming electrode was invented by RCA and has many variations available. Its response is rounder, with a more pronounced midrange character, very chesty, and very old time rock ’n’ roll.