Gallien-Krueger, also referred to as 'GK' (as in their logo), is an instrument amplifier manufacturer. The company is based in Stockton, California, and was founded in 1968.
Robert Gallien started his company, then named GMT, from his garage in San Jose, California while working as an engineer for Hewlett-Packard. His first amps were the GMT 226A and 226B (named after their power output) and were unconventional in their design because they were built around transistors instead of tubes. Carlos Santana was one of the first to buy a GMT 226A (serial #6) and it can be clearly seen in the Woodstock movie. In the early 70's Bob Gallien teamed up with fellow HP engineer Rich Krueger and the company was renamed Gallien-Krueger, although Rich Krueger is no longer involved in the company it has retained it's name.
In 1983 Gallien-Krueger launched the bass amplifier that would define the future of the company, namely the 800RB. The 800RB set the standard for modern bass amp design and construction, and this influence is still vital today. The GK sound is defined by a dry "growl" and a quick reaction from the class H power amplifier.
The guitar line died out, but the company became a powerhouse in bass amplification. Its products are used by many professional bassists including: Dave Dreiwitz, Flea, Dave Holland, Charlie Haden, Joe Lally, Rick Johnson, Tony Kanal, Greg Lake, Duff McKagan, Justin Chancellor, Fabio Meridiani and Colin Greenwood.