I would say it's copy of a Martin D-28 (I'm not sure). If the back is 2 piece- then it's the D-28 clone. A 3 piece back (like my DR-9) is a D-35 clone.
Since it's constructed in Korea- it's probably alittle younger than 30 years old, but I'm not exactly sure when Sigmas were stated to be made there, as oppopsed to Japan (where mine was done). I purchased mine in Jan. Of 1978 and it has the late 70's style logo/lettering font on the headstock.
I removed that lable from the soundhole many, many years ago, so I don't have any other info. Here's what I've pieced together about Sigmas over the years, this information could be true or false. I still have not found a definitive, reliable reference source on the history of the Sigma guitar: Sigma was the Asian import manufacturer of 'low end' guitars for Martin before Martin established their own 'low end' series. Sigmas were not assembled in or shipped to the Martin factory (Shenandoahs on the other hand were). Since Sigma did not use a consistent dating system, there is no way to determine the age of a specific guitar from the serial number. I have two Sigmas, one's a beater, one was a beater until I made some modifications, now it's a D-18 in the rough. For the money, Sigmas can be very good guitars, but some do sound better than others.
Mar 18, 2014 - During this time period, they actually had 'Sigma Guitars by Martin & Co. I've even heard that, on some of the '70s Yamaha FG models, they would make some. And had a very clear, rich tone for a guitar in this price range. Up for sale is a very early 1970s Sigma DM-5S, Martin D-18 copy made in Japan. Pretty rare guitar to begin with and sunburst even moreso. It's in pristine shape.
My DM-4 is an exact duplicate of the D-18 down to the same rosette pattern, so you may want to check yours against the D-28 pattern in use during the 70s and 80s. It is my understanding that the Sigmas made in Japan are of greater market value than those made later in Korea. Sigma guitars were Made in Japan from 1970 to 1983 Made in Korea from 1984 to 1993/94 Factually, Sigma Martin Acoustic guitars were made in Korea from 1970. Here's lots more info, based on my own research into the Korean-made Sigma DM-3S that I bought in 1969. This was the earliest model, before they printed Sigma on the headstock. It is burned into the body interior. It was from Sigma's first entry into the Canadian market.
Here's the link to my research: Lots more info on that site from other Sigma guitar ownerss. I also own a Made-in-Japan Sigma CS-6. An absolutely superb classical acoustic guitar, with a beautiful voice. Both my DM-3S Dreadnought and CS-6 Classical are in mint condition after almost 40 years. No cracks, no loose joints, no rattles, no buzzes, no crazing. And they've been moved from one climate to another over the years.
Put these beside the equivalent Martins (and play them with your eyes closed) and you can't tell them apart. Absolutely wonderful acoustic guitars IMHO. The Korean and Japanese ones are superb. The Taiwanese. One day, collectors will wake up to these and the prices will skyrocket. But you can't buy mine at any price.
Here is some more of my personal research into Sigma Martin Acoustic and Electric Guitars. Sigma Martin Guitar Model #s - Here's What they Mean “ B” = Bass (or “Black” if used at the end of a model name as in TB-1B) “ C” = Concert “ CE” = Cutaway/Electric “ D” = Dreadnought shape “ E”= Electric “ G” = Grand (as in GC Grand Concert) “ H” = Herringbone purling around body edges and usually the sound hole.
“ M” = Mahogany (usually the back and sides) “ N” = Natural finish “ R” = Rosewood fretboard “ S” = Solid back and sides “ SB” = Solid Body (electric guitar) “ ST” = Solid Top (usually Spruce) “ STB” = Solid top and bottom (probably Spruce, but maybe Spruce on top, Mahogany or Rosewood on bottom - but solid wood, not laminate. “ T” = Translucent finish “ TB” = Thin Body as in TB-1B ( Thin Body, Model# 1, Black color.) “ 12” = 12 strings Codes designating color or finishing details ( R, H, B, etc.) are usually the last letter in a model name. Therefore, a Sigma SDR28H Acoustic Guitar, for example, has solid (as opposed to plywood) back and sides ( S), a Dreadnought shape ( SD), a Rosewood fretboard ( SDR), model # 28, which compares to the Martin style it copies, although I don’t have a comparison list ( SDR28), with Herringbone purling.
So its an SDR28H. Model numbers usually designate quality and price, within a model range. For example, a DM-3 is higher in price, and better in quality, finish and detail than a DM-2. My CS-6, for example, is top-of-the-line, compared to its CS-3 cousin. As for prices, the solid woods fetch more than the laminates (i.e.
Plywood); the higher model numbers (within a model range) usually have more details and features (like purling, enclosed tuners, etc.) and so fetch higher prices. But, in the end, condition is everything. A mint and ORIGINAL condition, low-end Sigma will fetch more than a beat-up high-end model with non-vintage tuners. An original hard-shell case also adds value. Check eBay completed auctions for current selling prices. In the end, a thing is only worth what someone will pay for it. There are always exceptions to the above list of model codes, because Sigma guitars were made in different countries over a number of decades.
You might, for example, find that ' S' means 'Spruce' on some models and ' M' might mean 'Maple'. So look carefully at an instrument and use your good judgment when interpreting the model names.
Find out why other Sigma guitar owners love their instruments by browsing the reviews (listed by model name) at this link: More info on a few older Sigma models here: Hope this helps all you Sigma Acoustic guitar players and collectors out there. Factually, Sigma Martin Acoustic guitars were made in Korea from 1970. QUOTE From Wikipedia-'Construction moved from Japan (1970 - 83), to Korea (1984 - 93/94), to Taiwan (1993 - 2007).'
As you say, yours may have been something just for the Canadian market, but as a rule they didn't produce from Korea until '84. You're in big trouble if you believe everything you read on Wikipedia. The editing and fact-checking is abominable!
Contributors can write anything they want. And most of them do. Wikipedia is opinion, not fact, and certainly never worth quoting as a reliable source.
I have a DM-5 I got in the early 80s. It's as good as any D-18 I've ever played (with the exception of the GEs). I also have a DR-41 which is nicely constructed and beautiful to look at.
The DM-5 loves a flatpick and is deep and warm sounding with a lot of bass. The DR-41 likes a lighter touch, but sounds nice as well. I'd never sell them because they are worth a lot more to me than their value in the marketplace. On thing that makes a HUGE difference on the mahogany models in particular is replacing the saddle and pins with bone.
Remarkably better.