Moog announced its inexpensive mini synthesizer in 1970 by proclaiming, “Here it is!”. Its compact design made it a completely new instrument. The signal paths are hard wired, meaning it is only capable of the basic sounds of a modular synthesizer, a concept geared towards ease of use on the stage. By 1981, 12,000 fourth model (Model D) units were produced in one series. Keith Emerson made the Minimoog one of rock music’s standard instruments. The Minimoog can be heard on the following records: "Thriller" (Michael Jackson), "Autobahn" (Kraftwerk), "I Feel Love" (Donna Summer), and "Catch a Fire" (Bob Marley).