The term 'Synthesizer Brand' can be answered by two crossword solutions: Moog (4 letters) and CASIO (5 letters). Moog is an American company founded in 1953 by Robert Moog, which produces electronic musical instruments such as synthesizers, theremins, and other electronic music equipment. CASIO is a Japanese electronics company founded in 1946, which produces a wide range of products including calculators, watches, digital cameras, and synthesizers.