Tube amps produce a sound which is distinctive. In the reinforcement of the aural signal they can be pushed to overdrive their circuits and create a world of distortion. As more guitarists started to turn up and use this amplifier effect, the demand for a pedal that would reproduce that same type of distortion was created. One of the original pedals to accomplish this was the Ibanez TS 808. Released in the late 70s, it is an overdrive/distortion pedal which has a variable mid range emphasis. The 808 became the TS9 from 1982 to 1985. The TS 9 became the basis for an entire family of pedals: TS 10, TS 11, but it remains an original sound.1
The TS9 has three knobs. The first (left) is drive which adjusts the amount of distortion. The second (middle) is tone controlling the high frequency contour. The third (right) is level. This controls the level of the distorted signal but not the normal signal. This is effective in matching the distortion level to the normal level when switching on and off. It is also effective as all out crank.