Martin's Transitional OM-28

George Gruhn
"The Vintage Catalogue"
Frets Magazine, September 1983

Today many musicians and collectors, particularly fingerpickers, consider Martin OM models to be among the finest flat-top steel-string guitars ever manufactured. The OM-28, produced from 1929 through 1933, was Martin's first model offered with a 14-fret neck. This is an instrument of extremely fine quality as well as great historical interest, since it is the first model offered by any manufacturer that can be considered a thoroughly modern flat-top steel-string guitar. Prior to the introduction of the OM model, all Martin guitars were made with 12-fret necks. It was not until 1928 that Martin began to brace most of its guitars for steel strings -- prior to this time Martin guitars were designed for gut strings.

The 1920s and 1930s were a period of rapid evolution in guitar design. At the start of the 1920s the guitar was a gut-string instrument used for parlor music. By the early 1930s musical trends had changed and the guitar had evolved into a steel-string instrument designed to be played in a band. The popularity of the guitar surged in the late '20s and early '30s and remained high throughout the Depression.

(Although Martin was not the first manufacturer to utilize a 14-fret neck -- Gibson introduced the style L-5 guitar in 1923 -- Martin was the first to make a flat-top guitar with a 14-fret neck and slanted bridge saddle.)

The body size and shape of the OM models are the same as those of the current size 000: 4-1/8" deep at the end block, and 15" wide. The body length on a 12-fret 000, by contrast, is 20-7/16", whereas on an OM or 14-fret 000 it is 19-3/8". Essentially, Martin achieved the 14-fret design by shortening the upper bout of the body, whereas Gibson's approach was to keep the body shape the same, and move the bridge position.

OM models were cataloged in styles 18, 28, 45, and 45 deluxe. Although they were first listed in Martin literature in 1930, production records indicate that a few OM-28s were made in 1929, while the other models first appeared in 1930. Today they are very scarce, since they were manufactured for a short period of time and production levels were very low by modern standards. Compared to the production levels of other Martin guitars at the time, the OM models were very successful -- so much so that by 1934 most Martin guitars were made with 14-fret headstock necks. Essentially, the 12-fret 000 was discontinued, the OM designation was dropped, and the "new" 14-fret 000, adopted, in early 1934, was for all practical purposes the same as a late OM.

OM models have a 25.4" scale length, whereas 000 14-fret models made after early 1934 have a 24.9" scale. Many players find the long scale of the OM to be especially desirable and prefer these guitars over the standard 000 models. The only other pre-World War II Martin guitars that featured the 25.4" scale were the late model 12-fret 000s, the early 1934 14-fret 000s, and the D models.

The 1930 OM-28 illustrated in this article is an exceptionally fine example of this model. The wood and ornamentation are typical of all style 28 Martins of this period. The back and sides are Brazilian rosewood, the top is Adirondack spruce, the neck is mahogany, and the fretboard and bridge are ebony. The top and bottom edges of the body are trimmed in white ivoroid and the top is trimmed with herringbone purfling in the manner typical of all pre-World War II style 28 Martins.

The early OM-18s and OM-28s have no peghead decal and have fretboard inlay only at fret positions 5, 7, and 9, as on the 12-fret models of the period. By 1933 they were inlaid in the more modern style at positions 5, 7, 9, 12, and 15. Banjo-style tuners gave the peghead a very distinctive appearance. At the time the OM model was introduced, fine-quality, modern-style right-angle guitar pegs were not available. By 1932, OMs were fitted with the standard right-angle pegs, and the headstocks bore the now familiar Martin decal.

The early OMs have small pickguards. They first appeared as common features on Martin guitars in 1929, but interestingly enough, on other Martin models of this period, the pickguards used were similar in size and shape to those used on today's guitars; the OM pickguards are highly distinctive. By 1931 the OM models featured standard-type Martin pickguards.

A few of the earliest OM-28s were fitted with the same type pyramid and rectangular bridge as was typical of all early Martins; but by late 1929, the modern-style belly bridge was standard for OM models, as well as for other steel-string Martins of styles 18 or higher. The OM models are fretted with the same type bar frets used on all Martin guitars prior to the introduction of modern fretwire in late 1934. OM necks are reinforced with an internal ebony bar, as are other Martins prior to the introduction of the steel T bar in 1934.

During the relatively short period during which OM models were produced, their design evolved rapidly. The early OMs were lightly braced and looked clearly different from the 14-fret 000s, but a review of OM specifications by year reveals that the model was rapidly transformed to a modern conformation.

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