6L6GB

The 6L6GB is a beam power tetrode vacuum tube. It is a medium-power audio amplifier tube and was an early development in the 6L6 family. The 6L6GB was designed as an improvement over the original 6L6, offering increased plate dissipation and a longer service life. It features a glass envelope and typically a metal base with a octal pin arrangement. This tube is well-known for its warm and robust tone, making it a popular choice in vintage and modern guitar amplifiers.

Introduced by RCA in the late 1940s, the 6L6GB was intended to replace the 6L6 in many applications, particularly where increased reliability and power output were desired. Its construction utilizes internal beam-forming plates instead of a separate suppressor grid, a characteristic of the 6L6 family that contributes to its efficiency. The 6L6GB has a maximum plate voltage rating of 500 volts and can typically deliver around 20-25 watts of audio power in push-pull configurations.

While it shares many characteristics with its successors like the 6L6GC, the 6L6GB has a slightly different sonic signature, often described as having a more pronounced midrange and a smoother top end. Many guitarists and audiophiles seek out 6L6GB tubes for their vintage sound. It remains in production by various manufacturers and is a commonly used replacement tube for amplifiers that originally specified this variant or for those seeking its particular tonal qualities.