Effects such as equalisation or EQ pedals, wah pedals, auto-wah or envelope filters and talk boxes all filter the sound of an electric guitar or bass. An equaliser or EQ effects pedal adjusts the frequency response in a number of different frequency bands. An EQ pedal can be placed after a distortion or overdrive pedal to offer more control over preamp distortion voicing. A wah-wah pedal is controled by rocking your foot backwards and forwards. This allows lower and higher frequencies to pass through alternately creating a 'wah' like sound. An auto-wah pedal is a wah-wah pedal without the foot controler. An auto-wah is an envelope filter which uses the level of guitar signal to control the wah filter position. This is an EQ related effect and can be placed before a distortion pedal. A talk box is an effects pedal that a player can change the shape of the frequency content of their sound and apply speech sounds to their guitar.
