Re: Information on a 1918 Martin?
Martin mandolins are indeed well-built and sweet-sounding instruments. They're just not fashionable, as compared with Gibsons and mandolins patterned on Gibsons. I just bought a 1920 Style A, and like it a lot. It's not as loud or as percussive as a carved-top Gibson. Most of the Martin mandolins, once they stopped making bowl-backs around 1924, were flat-back, canted-top (or "bent-top"), oval-hole instruments made with mahogany or rosewood back and sides, quite different from the carved-top, maple-back-and-sides mandolins Gibson built. As mandolin playing became more and more associated with bluegrass, the softer, sweeter-sounding Martins passed out of favor. Martin did make some f-hole, carved-top mandolins in the late 1930's, but not a significant number, and World War II brought an end to that production.
According to Mike Longworth's Martin Guitars: A History, the company made over 17 thousand Style A mandolins between 1914 and 1973. So there are lots of them out there. And because -- despite what you've seen -- Martin made many instruments for Oliver Ditson Co. and labeled them "Ditson," I would say that the "Ditson" stamp wouldn't make a great deal of difference in the mandolin's value one way or another. It's a bit rarer than a "non-Ditson" Martin, but not enough so to be significant, IMHO.
Hope you enjoy your Martin; I'm having lots of fun with mine. It's a well-made instrument, with an easy-to-play short scale, and very comfortable to learn on. My 1920 Style A probably is valued at about a quarter of an equivalent Gibson A-1 from around the same time; all that price differential signifies, is the way mandolin tastes have developed over the past 90 or so years.
Gibsn: '54 F5 3pt F2 A-N Custm K1 m'cello
Natl Triolian Dobro mando
Victoria b-back Merrill alumnm b-back
Stradolin Vega banjolin
Sobell'dola Washburn b-back'dola
Eastmn: 615'dola 805 m'cello
Flatiron 3K OM