Saturday, March 19, 2016

1990s Sigma SDM-18 Acoustic Guitar Review


We are going to look at something a little different today - a pretty cool budget acoustic guitar that I picked up at the monthly flea market they have by my house. This is an early 1990s Sigma SDM-18 6-string dreadnaught.

Sigma guitars were introduced in 1970 as an attempt by the venerable Marin guitar company to get a toehold into the entry level guitar market by licensing the production of instruments from overseas. This was particularly important to them as around that time many Japanese companies were building guitars that looked just like theirs, and it was hurting their business. So, the Sigma brand was their effort to fight back.

The Sigmas were good guitars, though not wildly successful, and in 1984 production moved to Korea. Seeking further reductions in labor costs, in 1994 they stated importing instruments from Taiwan, and then Indonesia by the time Martin folded the brand in 2007. A German company (AMI Musical Instruments GmbH) bought the name and started selling made in China guitars.

The SDM-18 guitar that we are looking at today was built in Korea, though it is hard to get an exact date as the serial numbers seem to have been issued with little rhyme or reason. The model name is a little easier to figure out, as this is pretty much a copy of the Martin D-18 dreadnaught. The “M” in the model name stands for mahogany side and back, and the “S” is a mystery. Maybe it stands for solid wood (top and/or back and sides), or maybe it means that there are scalloped braces, but I am not exactly seeing any in there…

The body has the traditional broad-shouldered shape, and there are 14 frets clear from the body. The top is solid spruce, and as I said earlier the back and sides are mahogany, though I cannot tell if it is solid or a laminate. I am going with laminate until I figure out otherwise. The neck is mahogany with a rosewood overlay and an inlaid logo, and the bridge and fretboard are rosewood too.

This guitar had been sitting for years before I got my mitts on it, and it came with a plastic case with foam that had completely disintegrated. So, there were little foam bits stuck all over it and piled up inside the body too. I did a quick cleanup on it, but when I am done with school it will need a more thorough cleaning and fret polish. It is otherwise in good shape with no cracks or repairs and the frets show very little wear. The spruce top has darkened nicely, and it is very attractive.

It plays very well, too. The neck has a pleasantly rounded profile that is fairly slim and fast, and the tone is very rich and loud. The sounds is pretty well balanced from string to string, though I think it would be nice to find a compensated bridge saddle as the intonation is just a touch off. It is certainly good enough for anything I will be doing with it, especially at the bargain basement price I paid for it.

I rarely see Japanese-built Sigma guitars on the market as once players get their hands on them they do not let them go. I di see Korean ones every now and then, and generally they are solid instruments, but it is a good idea to try before you buy (be careful with eBay), as I have run into a few clunkers and shoddy repairs. If you have one, post a comment below, I am curious what you think!



  1. Hello, I've had my eyes out for one like this. Is it for sale?

  2. Hi Joseph, it sure is! Shoot me an email at and we can chat about it


  3. I have one I like to find more about it is a 12 string it looks like paper labor

  4. I've had one for about 10 years. It's been a fantastic reliable instrument for years. Never had to do any adjustments. Handles weather changes very well. It sounds fantastic. From my research the S does stand for atleast a solid top.. possibly all solid woods. Whenever I stop at a guitar store and play other guitars there really isn't many that stand up to the sound of my Sdm-18. Definitely a quality dread. Something about old guitars that draw me in. They have an aged sound. Mine is the early 90's Korean made also. Paid 200$ for it one of the best acoustic purchases I've ever made. If you ever find one of these Korean made aged lacquer ones snatch it up.