Sigma Guitars is a guitar manufacturing brand originally released by C.F. Martin as a line of guitars at affordable prices to compete with the increasing number of imported guitars from Japan and elsewhere. The Sigma line was discontinued by Martin in 2007. The rights to the name was acquired by German company AMI Musical Instruments GmbH, which relaunched the brand with guitars being produced in China.

Since the U.S. rights to the Sigma brand name and trademark had been allowed to lapse by C.F. Martin & Co. prior to selling the brand to AMI, and had since been picked up by St. Louis Music of Missouri, AMI is not allowed to use the brand name “Sigma” in the U.S. for their current line of guitars. They were distributed and sold in the U.S. as Kindred Guitars.

The current range of Sigma instruments include acoustic and classical guitars, acoustic basses and ukuleles.

History
American company C.F. Martin created the brand Sigma in order to compete with cheaper guitars that were imported from Asia. Sigma released a wide series of acoustic and classical guitars, which initial construction was in Japan by various manufacturers/factories from 1970 through 1983.

The first Sigmas were typically dreadnought acoustic, although Grand Concert Series (GCS) and classical models were also produced from the early 1970s (1971?) onward. Though other models were produced the most common two throughout the 1970s were the Dreadnought models DM-5 (DM12-5) and DR-7 (DR12-7.) D for dreadnought, R for rosewood, M for mahogany and the number denoting the grade of wood.

Construction moved from Japan from 1970 to 1983, to Korea from 1984 to 1994, to Taiwan in 1994 (made in both Korea and Taiwan for the 1994 model year) and finally Indonesia (?–2007).

In 1978, model designations were added to capitalize on Martin model numbers: the DM-18, DM-19, DR-28, DR-28H, DR-35, DR-41, and DR-45. They are called ‘Second Generation’ Sigma’s by C.F. Martin and featured solid wood top. The “First Generation” DM-5 and DR-7 (laminate wood bodies and tops), as well as other early models (e.g., the GCS-7/CS-7), remained in production during this time as well.

The 2006 and 2007 models showed a marked increase in quality, as it is thought Martin was prepping the company for sale.

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