Guitarists use EQ pedals to get more tonal control over their sound than othersise possible with the basic "Tone" knobs on their guitars and amps. Equalisers work by adjusting the balance between the different frequency elements of an electronic signal, or more simply, the tone. This is achieved boosting or cutting particular frequencies or groups of frequencies (bands). The most common type of EQ pedal for guitarists is the graphic equaliser, which have sliders for specific problem frequencies, but simpler fixed band and also more complex multi-band parametric equalisers are available.