A power trio is a rock and roll band format having a lineup of electric guitar, bass guitar and drum kit, leaving out a dedicated vocalist or an additional rhythm guitar or keyboard instrument that are often used in other rock music bands that are quartets and quintets. Larger rock bands often use one or more additional rhythm sections to fill out the sound with chords and harmony parts.
Most power trios in hard rock and heavy metal music use the electric guitar player in two roles; during much of the song, they play rhythm guitar, playing the chord progression for the song and performing the song's important riffs, and then switching to a lead guitar role during the guitar solo. While one or more band members typically sing while playing their instruments, power trios in hard rock and heavy metal music generally emphasize instrumental performance and overall sonic impact over vocals and lyrics.[1] An example of a power trio is Nirvana, whose lead vocalist, Kurt Cobain, played guitar and sang lead vocals. Although four-piece bands such as the Who or Led Zeppelin may function instrumentally as a power trio, with three instrumentalists and a dedicated lead vocalist, these bands are not usually considered as power trios.