Sledgehammer was a massive hit for Peter Gabriel in 1986, and Tony Levin's bass line (processed through an octave pedal, a compressor and some chorus) provides the main backbone of the song. In the studio, Levin played a fretless Music Man Sabre with a pick through a Boss OC-2 octave pedal. 
The synth-like bass line is the result of fretless slides and the sub-octave effect, while the pick gives the sound its sharp attack. ?
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