Serial numbers for Sigma guitars built in Korea and Taiwan are perhaps meaningless, though again some seem to indicate the year of manufacture e. Martin factory in Nazareth, Pa alongside the regular production line. These instruments were constructed using preformed and sometimes partially assembled imported parts, built or completed in the C.
It is widely assumed by owners and Sigma historians that this is correct, though C. However, while some models lasted the entire run from throughothers did not and were only offered for a limited number of years, so that most models' construction dates can be narrowed down to a reasonable range. This may be due to them being built in several Japanese factories at the same time with no coordination in the serial numbering system. Sigma serial numbers do not provide an indicator of the year in which a particular model was built.
Interestingly, while playing a Sigma guitar the 'sideways M' becomes 'right side up' suggesting 'M' for Martin.
D for dreadnought, R for rosewood, M for mahogany and the number denoting the grade of wood, 5, 7, 9, 11, The DM-5 and DR-7, as well as other early models continued to be built during this time as well. The first Sigmas were typically dreadnought acoustics, although Grand Concert Series GCS and classical models were also produced from the early s onward.
