Al Carruth respected in the guitar making world for his scientific approach. He started instrument building with a mountain dulcimer kit in 1971, while still in the Navy. A guitar bought from George Bowden in Majorca, encouraged him to think about making guitars. On leaving the Navy in the early 1970s he took a guitar making class with Thomas Knatt, near Boston, and went on to work with him doing repairs for a number of years. He also took a lute making class through the Museum of Fine Arts in Boston, in '77, and started making hammered dulcimers and lap harps around that time. Tom introduced him to Carleen Hutchins in the late 1970s and he started taking her classes in violin making and acoustics about a year later. During that time he also met Fred Dickens, who started Carruth in research on guitar acoustics.

He worked out of a basement shop at his home until 1992, when went into partnership with Tom Knatt in a shop in Waltham, Mass. In 1996 he moved out on his own. In 2002 he moved up to a farm in Newport NH, and set up a much nicer shop in his barn where he divides his time between building guitars and other instruments, teaching classes in instrument making, and doing research on guitar acoustics.