The D-18 is the Mahogany dreadnought in Martin’s Standard Series of professional-level acoustic guitars.
The only thing standard about Martin’s Standard Series is the consistently excellent hand-made construction and high-quality materials, including solid quartersawn tonewoods, solid bone hardware, and a solid Sitka spruce soundboard with tight, straight, even grain and loads of cross silking. And today’s D-18 is a stellar example.
Martin recently performed a makeover on the venerable D-18, giving it a sleek, fast modern neck matched with a vintage Martin look, and upgrades including fuller, more resonant tone thanks to the ebony bridge and forward-shifted, scalloped bracing under the high-quality spruce top.
I always enjoy watching a guitarist’s face light up with surprise and delight when they get their hands on a new Martin D-18 for the first time. The model immediately impresses with its ring off the strings, then it charms with its depth and definition, and wows with its power and projection.
Specs include solid wood construction throughout; genuine South American mahogany back and sides; Sitka spruce top; 5/16” scalloped, forward-shifted braces; one-piece mahogany neck with a hand-fitted, dovetail neck joint, modified low oval profile, Performing Artist taper with a 1-3/4” width at nut tapering to 2-1/8” width at 12th fret; two-way adjustable truss rod; ebony fingerboard and vintage-style bridge, with a bone nut and drop-in compensated bone saddle, 2-3/16” string spacing, Vintage Style 18 fingerboard markers, soundhole rosette, tortoise color pickguard and body binding, headstock brand decal; open-gear vintage-style tuners; full gloss nitrocellulose lacquer finish on the body, satin finished neck.
When Martin introduced the 14-fret dreadnought size in 1934, the D-18 with its mahogany back and sides became an instant success, outselling the more expensive rosewood models and endearing itself to countless working musicians because of its versatility and relatively low price. With warmth and definition in the bass, bright and chiming trebles, and a projecting, punchy midrange, mahogany dreadnoughts excel as strummers, fingerpickers, and are the primary choice for super-fast lead guitar in Bluegrass bands. And with its considerable clarity across the fundamentals matched with an open, woody undertone, and that uniquely Martin resonance and sustain, the D-18 is the ideal choice for the studio. D-18s of one variety or another can be heard on well-known recordings of Elvis Presley, Doc Watson, Clarence White, Earl Scruggs, Simon and Garfunkel, Gordon Lightfoot, Kris Kristofferson, the Grateful Dead, Jimmy Buffet, Nirvana, and Mark Knopfler, just to name a few.
As the least expensive dreadnought in the Standard Series, the D-18 spent decades with non-scalloped braces, and a fingerboard and bridge made of rosewood, which were cost-cutting measures from the war years of the 1940s. Today this model has scalloped, forward-shifted braces, and a fingerboard and bridge of solid ebony, just like the legendary pre-war D-18s.
The dense ebony of the solid-wood bridge acts as a sonic filter for the vibrations traveling from the strings to the soundboard, adding fullness and warmth to the otherwise bright, dry mahogany tone. The top braces have been scalloped, meaning they were carved to remove more wood, so they resemble suspension bridges, allowing more flexibility, which leads to greater resonance as that spruce soundboard vibrates freely with a lighter touch. And having the main X brace forward-shifted away from the bridge plate and closer to the soundhole further increases the flexibility at the widest part of the top, increasing bass response, and an overall sonic presence behind the distinct fundamental notes. The D-18 excels with medium or light gauge strings, taking a pounding or a delicate touch as required.
While the fundamental notes ringing off the strings project forward with power and clarity, they also fire down into the body of the guitar, thanks to those scalloped, forward-shifted braces, igniting a vibrant and expansive undertone, glimmering with woody mahogany tone like an aurora behind the well-defined top notes popping out of the soundhole.
This vibrancy is more noticeable with new strings. But mahogany guitars also like old strings much more than rosewood guitars, and as strings age on a Martin D-18 the guitar takes on a mellow quality, with a roundness to the thumpy bass notes and an old wooden box resonance down in the body that makes even brand new examples sound like an older, well-seasoned guitar.
And while the D-18 has other vintage Martin features, such as tortoise colored binding and pickguard, a 30’s style look to the bridge and fingerboard markers, and open gear tuning machines, it has the practical advantages that come with Martin’s modern high performance neck.
The high performance neck debuted with Martin’s Performing Artist series of acoustic-electric guitars, combining features of traditional strumming Martins with traditional fingerstyle Martins to provide a playing experience both versatile and comfortable. With a width of 1-3/4” at the nut and 2-1/8” at the 12th fret, the overall result is a sleek, fast player’s neck that has a little extra room down near the headstock, where the player’s wrist bends at the most extreme angles. And the 2-3/16” string spacing was introduced to work best with the PA taper.
The neck on the standard D-18 is carved into a modified low oval profile. Compared to the PA Series neck, it has a slightly more curved shape, with a ghost of a ridge running down the very apex of the profile. As such, it has a traditional feel to it when thumb-fretting, without the bulk or pronounced V shape found in many vintage-reissue Martins that can make barre chords a pain. And it is made with a two-way adjustable truss rod to ensure many years of trouble free playing.
Mahogany is less complex than rosewood or koa when it comes to harmonic overtones, so the emphasis of the large, loud, lovely voice of the D-18 is focused on the strong, immediate fundamentals that leap out into the room with wonderful clarity, matched by an open, resonant undertone given a booster shot by the forward-shifted bracing that increases complexity in the voice without ever getting muddy. The pure trebles, round woody lows, and nicely defined mids give off a clear harmonic chime, but there is nothing thin or brittle about the voice of a Martin D-18. The fundamental notes provide ample body and warmth, thanks to the Sitka spruce used for the top and the ebony used for the bridge. And from the throb of the lowest E string to the violin purity of the highest E string, the D-18 is a classic, mahogany dreadnought offering effortless roaring power when necessary and mellow melodies when desired.
Today’s D-18 is an extremely successful design and execution, and best of all it is a flat out bargain when it comes to price. I should know; I own one myself. Only, mine is the acoustic-electric version, the D-18E Retro, which I absolutely love.