Martin completed and finished them alongside the regular Martin production line. Some consider the DR-35N to be a prototype of the inexpensive laminate Martin Shenandoah line of guitars, it appears only 2907 of these Sigma Martin USA guitars were ever produced in total, though there may have been others that did not make final inspection and hence were not serialed (I personally know of one such Sigma-Martin,) and are the only Sigma related serial numbers publicly available from Martin at this time.
Bridges and tuners may have been installed, as well final sanding and finishing before strings were installed and a final set-up was done. Serial numbers for Sigma guitars built in South Korea, Taiwan and Indonesia are perhaps even more meaningless, though again some seem to indicate the year of manufacture (e.g.
The sigma symbol is often described as a "sideways M."By the mid 1970's (c1976) the headstock logo design changed to a gold "Martin style" decal that said, "Sigma Guitars" in script with "Est. The headstock shape was also modified to a deeper taper and shaped to resemble the Martin instruments. Black pickguard (later examples have Tortoise shell pickguards.) Fixed bridge, some with diamond shape inlays. These rare, hard to find models were actually made in Japan and imported to, and guaranteed by Levin in Sweden.
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. The early 70s models (1970 -1975) can be distinguished by a more squared peghead, shaped similarly to that of a "spatula." The logo consisting of a gold decal with the single word in block lettering SIGMA surmounted with the Σ symbol (the Greek letter sigma), in mother of pearl. They have a 3 piece back ala' D35, and the fret markers are different as well.
750XXXXX possibly equates to a build year 1975.) These were eight digits long, the third digit always a place-holding 0, while all others by then were still only five digit serial numbers further adding to the confusion. and to this day remain the only Sigma related serial numbers that are publicly available. There were only two models, labeled "Sigma Martin USA DR-28N and DR-35N," "N" for Nazareth. The original factory brochure also states components were processed and finished on the same production line as regular Martins.
It is widely assumed by owners and Sigma historians alike that this is correct, though C. Martin cannot, or will not confirm this."Sigma-Martin USA" guitars built in 19 only, had specifically assigned serial numbers ranging from 900,001 to 902,908 (2,907 in total.) These serial numbers are documented by C. These "N" instruments, of which only two models were ever produced, the DR-28N & DR-35N partially assembled in Japan and were imported to Nazareth ("N") and the Martin guitar factory as kits. A Martin factory sales brochure shows the DR-28N retailed at $600.00 and the DR- 35N retailed at $650.00 The DR-35N had a 3-piece laminate rosewood back and sides and a solid spruce top. The peghead logo reads "Sigma Martin USA" and inside the sound box is on the neck block " made in USA" with Martin address etc.
rights to the Sigma brand name and trademark had been allowed to lapse by C. Louis Music of Missouri, AMI is not allowed to use the brand name "Sigma" in the U. The model and serial numbers were usually stamped on in ink, but some are known to have been hand-penned. These will have a 4, 5 or 8 digit (7*0XXXXX) serial number stamped or hand written on them. The 'Purple' label (c1972 onward): These are again white labels that had gold & black lettering but this time with a border, often pinkish-brown or violet in color. Pearl "SIGMA" block inlay between 19th and 20th fret. They have a paper label stating "Inspected and Guaranteed by Levin" and "Sigma Guitars" "est 1970" is inlaid on the headstock in abalone.
prior to selling the brand to AMI, and had since been picked up by St. Labels and Brands Sigma's made in Japan from 1970 through 1979 used a paper label to identify the model and serial number of the instrument. Laminated asian chestnut sides and back with matching wood veneer on Martin style peghead. Fingerboard has snowflake and diamond shape inlays. They cost more than the top of the range DR-41 at the time.
These inspections and adjustments were made in the "old" Martin building on North St. The DR-28 was manufactured in Japan, Korea and Taiwan while the SDR-28 and the SDR-28H appear to have been manufactured in Korea and Taiwan only, starting in early 1986.
The DR-28, has a solid top with laminate side and back, and the SDR-28 having a solid Spruce top with solid Rosewood sides and back. Pearl/pearloid inlay position markers on fingerboard. Chrome closed back tuners (11:1 ratio.) The first year is known to have a zero fret. Truss rod adjustment location is on peg head at nut until 1980.
The first Sigmas were typically dreadnought acoustics, although Grand Concert Series (GCS) and classical models were also produced from the early 1970s (1971? Though other models were produced the most common two throughout the '70's 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, 5, 7, 9, 11, 15. Pegheads & Logos Sigma guitars made in Japan from 1970 through 1983. The very rare DR-14 was often confused with the DR-41 but it was a different model.