Kai-Thomas Roth was born in Germany. From the age of eight he knew he wanted to become a violinmaker and made his first instrument at the age of thirteen. After training as a cabinetmaker in Switzerland he came to England to study at the Newark School of Violin Making. Following work experience in the trade he established with his wife Caroline Crowley their business as makers of fine instruments of the violin family in 1990. 
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Anna Shuttleworth wrote in ESTA ‘news & views’, summer 2002 in a review about the Cello Course at Eton College 24-31 March 02:

“Here I would like to mention that at least six wonderfully sounding cellos made by Kai were brought on this course, including a copy of my Tononi cello, which I prefer to the original.”