The Well-Tempered Synthesizer is the second studio album from the American musician and composer Wendy Carlos, originally released under her birth name, Walter Carlos, in November 1969 on Columbia Masterworks Records. Following the success of her previous album, "Switched-On Bach" (1968), Carlos proceeded to record a second album of classical music performed on a modular Moog synthesizer from multiple composers, including Johann Sebastian Bach, Claudio Monteverdi, Domenico Scarlatti, and George Frideric Handel. Its title is a play on words from Bach's set of preludes and fugues named "The Well-Tempered Clavier".