The Mesa/Boogie Mark III is a guitar amplifier used by Prince in the late 1980s and early 1990s. It replaced his older Mesa/Boogie Mark II amplifier heads. The Mark III was released in 1985, and is assumed that Prince adopted the amplifiers in the mid-to-late 1980s. He was using two Mark IIIs on the Nude tour, one for clean and one for dirty sounds.
Like the Mesa/Boogie Mark II, the Mark III was paired with Bag End D-12M cabinets. Around the Act I & II tour, Prince replaced his Mesa/Boogie amplifiers and Bag End cabinets with Soldano amplifiers and Marshall and Peavey cabinets.