You’ve probably heard of the MELLOTRON; the lil tape loop keyboard from the 1960s-70s, but there’d be no Mellotron without the CHAMBERLIN. Harry Chamberlin designed his instrument as early as 1949 after converting a walk-in closet into a home studio and spending all of his time experimenting with sounds.
After modifying the acoustics in the “studio”, and in other rooms in his house, the first Chamberlin recordings were made. Soon after, all Chamberlin recordings were contracted and performed by members of the Lawrence Welk Orchestra (throughout the 1950s). Welk was impressed with the idea of a tape playback instrument and offered to fund its manufacture if it was called a "Welk" machine. Chamberlin refused Welk's offer.
In 1962 a sales employee of Chamberlin named Bill Fransen fled to Europe with two Chamberlin 600s and without Henry Chamberlin’s knowledge, claimed that the instrument was his invention and made a deal with the Bradley brothers from the UK to build upon the design and manufacture the machines. So although the Bradleys introduced some modifications, the Mellotron Mark I was born in 1963, essentially as an illegal copy of the Chamberlin 600.
The 3 violin samples were even the same from the Chamberlin (the other instruments were newly recorded). Chamberlin would receive some royalties for the original design and for some period Chamberlins would be sold in the US and Mellotrons would be sold in Europe.
In retrospect Mr. Chamberlin probably regretted this point, the Pop and Prog music scene during the late-1960s was more innovative in Europe than in the US so by the time the instrument really kicked in, it was the Mellotron and not the Chamberlin which got the limelight. By its heyday in the 1970’s few people remembered the Chamberlin at all. (from various sources online, 120years.net & progarchives.com)