The Chamberlin is an electro-mechanical keyboard instrument related to the Mellotron. It was created by Harry Chamberlin in 1946.
The Chaimberlin has a piano-style keyboard. Underneath each key is a small tape deck. Each tape is prerecorded with various musical instruments or special effects. When the player press down a key, the tape deck begins to play through an amplifeid speaker. When the player releases the key, sound stops, and the tape rewinds. Each tape is only a few seconds long (on many units 8 seconds).
Some controversy exists about the origin of the Mellotron, but most of the accounts tell of Chamberlin associate Bill Fransen (sometimes described as his gardener, sometimes as an employee) bringing Chamberlin's design to England and selling the design without Chamberlin's knowledge in the early 1960s. After this somewhat dubious beginning, Chamberlin and the company that produced Mellotrons later came to a financial arrangement.
The royalty payments Chamberlin received from the Mellotrons helped Chamberlin to continue producing instruments in his garage, and later in an Ontario, Canada factory. In 1981 (shortly before Chamberlin's death), the company ceased production, after making approximately 700 units. Harry Chamberlin's son, Richard, later sold the original tapes and plans to the Mellotron company.
The later Chamberlin model M1 is reputed to have superior sound and reliability to Mellotrons. It is rumored that several famous recordings which purportedly use a Mellotron actually use a Chamberlin. One popular music group that openly used a Chamberlin is Ambrosia.