Def FX were an Australian pop music group, formed in Sydney. The core of the group was Sean Lowry, Fiona Horne (vocalist and lyrics) and Martyn Basha (bassist and co-writer). Top 50 ARIA hit "Psychoactive Summer" is exemplary of Def FX's music, combining elements of electronica and heavy-metal instrumentations and grunge vocals. Their music throughout their career can be described as a fusion of elements of psychedelia, industrial, grunge, electronica, and heavy metal, and in their early days, even reggae and disco. In fluctating degrees their sound has similarities to that of, Cliff Burton-era Metallica, Soundgarden, Jesus Jones, The Prodigy, INXS, Garbage, Rammstein, 1990s Wollongong grunge band Tumbleweed, Marilyn Manson, and especially Evanescence.