O1 Tube Squasher designed by Thomas Blug with FET-based overdrive circuitry which allows O1 realistically emulates the smooth overdrive characteristics of a good vacuum tube amp. When playing, its sound is like a tube sound. The Tube Squasher is a very powerful tone-shaping tool and a internal supply voltage step-up which allows more dynamic range and headroom with tight bass tones. It is also a great low to medium gain overdrive and great clean boost.