a standard acoustic guitar. More rarely, some bass techs might have to set up a bass synth (e.g., as used by the bassists in some alternative bands) or bass pedal keyboard such as a Moog Taurus pedal, as used by Sting or Led Zeppelin. Both upright basses and acoustic bass guitars usually use piezoelectric pickups rather than magnetic pickups, and in some cases, the instruments may use condenser mics to pick up the higher range sounds. To amplify instruments with piezo transducers and condenser mics, specialized impedance-matching preamplifiers are often required. Also, since both piezoelectric transducers and microphones are more prone to unwanted feedback than magnetic pickups, the bass tech may have to set up a notch filter with a parametric equalizer to reduce the frequency that is feeding back. References Occupations in music Road crew Guitars Rock music Audio engineering Technicians