Product Description. For 25 mL from serial-number 01K. For 50 mL from serial-number 01K. Further, DR-7's with a four digit ink stamped label serial number and a zero fret strongly suggests a very early build date. Some early 70s Sigma guitar serial numbers started with 7. Suggesting the 197. Build date (e.g. 75XXXXXX possibly equates to a build year 1975.).

1. Sigma Guitars Serial Number Lookup
2. Sigma Serial Number Lookup

Additional Models Approximately 1975 To 1978

Some of these guitars still had the early peghead logo, instead of the 'Second Generation Sigma' Martin style logo that started in approximately 1976.

Sigma Guitars Serial Number Lookup

Sigma Serial Number Lookup

DT-22 Dreadnought. Spruce top. Tiger-striped maple sides and back. Maple veneer on Martin style peghead. Tortoise shell binding around back and sides. Black pickguard. Fixed bridge has diamond shape inlays. Fingerboard has snowflake and diamond shape inlays. Pearl inlay between 19th and 20th fret (inscription not described in catalog).

DR-7S Dreadnought sunburst. Martin style peghead bound in white. Spruce top. Rosewood back and sides. Rosewood fixed bridge. Adjustable truss rod.

DM-5S Dreadnought sunburst. Unbound Martin style peghead. Spruce top. Mahogany back and sides. Rosewood fixed bridge. Adjustable truss rod.

GCS-4 Grand Concert. Martin style peghead bound in white. Spruce top. Mahogany back and sides. Rosewood fixed bridge. Adjustable truss rod.

CS-4 Classical Guitar. Spruce top. Mahogany back and sides. Mahogany neck. Rosewood fingerboard and bridge.

Sigma produced numerous 'DR-*' models from the mid-70s on through 1984: DR-8; DR-9; DR-11; DR-14; DR-15; DR-28; DR-28S; SDR-28; DR-35; DR-41; and DR-45.

During this period Sigma also produced a line of guitars with model numbers starting with 52S: 52SDM-5, 52SDR-7 and 52SGCS-7.52S guitars had laminate backs, and sides and solid tops.