Robert Arthur Moog is probably the inventor of the monophonic subtractive synthesizer as we know it. He started building theremins in upstate New York and by the mid 1960s got in contact with a number of of artists particularly Herb Deutsch, who convinced him to add a keyboard to the new instrument, a circumstance that made the Moog synthesizer popular among musicians. We owe to Bob Moog the invention of the resonant low-pass ladder filter (which provides the signature Moog sound and was his only filed patent); as well as the ADSR envelope, the pitch and mod wheel, etc. By 1971 and in an attempt to save the company from bankruptcy, the Minimoog Model D was born as a simplified, portable, hard-wired version of the large modular systems, which became the template for many monophonic synths to come. After his death in 2002, Moog Music is an employee-owned company operating from Asheville, North Carolina.