I've recently acquired an old Sigma.
Made in Japan so I'm guessing 70's.
There are very small traces of the serial number left but not enough to read,so nailing it down to a year is pretty slim that way.
On the center strip is burned/printed "SIGMA GUITARS Made in Japan for C.F.MARTIN & CO."
The model # is a DM 3.At least I'm about 90% shure it's a 3.
Anyone here know if & when Sigma made a DM 3?

I haven't done an in depth search on the subject yet,but so far I haven't found any info on a DM 3.

This guitar was offered to me as a "parts" guitar for ten bucks.
It was stripped of all it's hardware & had spent the last 15 years of it's life sitting in a barn. Luckily,it appears that some of that time must have been in a case.
Once I cleaned off years of dirt & grime,I discovered I'd actually purchased a good solid instrument with an amazingly straight neck.

It's got plenty of character in the way of nicks/dings/scratches,but once I rounded up & installed the necessary hardware,she came back to life with a very sweet voice.

This Sigma never was & never will be a high end guitar,but I'm real happy with this old ten dollar "beater".

   DB.