Introduced in 1898, the Martin 5-18 was often considered a "junior" guitar. With 12 frets clear of the body and only a 21.4" scale, its easy to understand why this 11-1/4"-wide guitar seems like it's meant for smaller players. But in the '50s and '60s amid the rise of Country and Folk music, players such as Marty Robbins and Dolly Parton used these interesting guitars extensively on stage. Originally intended to be tuned a minor third above a regular guitar (G to G, like capo 3), the Terz guitar also produces unique and inspiring tone when tuned E to E. With such a small, accessible size, it's an ideal go-to guitar—just as manageable in the living room as it is on the road.
Martin ended the standard production of the 5-18 in 1989, but you can still order one of these cool small guitars through the Custom Shop. This Custom Shop 5-18 was modeled after one of the instruments in the Custom Shop's 2026 NAMM collection. By Custom Shop standards, it's a fairly straightforward design—a Size-5 guitar built to traditional Style-18 specs—but with an Engelmann Spruce top to improve the tone. Engelmann tends to be more flexible than other types of Spruce, which helps this guitar produce a big sound with a small body. It also lends excellent dynamics and touch-sensitive response, which helps this guitar fit a wide range of playing styles.
Part of the fun with Terz guitars is finding the right tuning that works for you. We really like this one tuned F# to F#, which is capo 2. At that tuning, there's plenty of tension with light gauge strings to have a full, punchy sound. It can definitely handle higher tunings, and for a lower tension feel, it would be cool in standard E-to-E tuning. But in the higher tuning, consider using a capo to explore further... If you capo 7 at F# tuning, that's basically capo 9 on a regular guitar. Safe to say this 5-18 is an inspiring instrument that encourages you to try new things and push your music in different directions.
This Custom Shop 5-18 was built with a 1-3/4" nut width and a Modified Low Oval neck profile. When you tune up, the nut width lets you get the capo-ed tuning with the spacing of open position. Like everything you'll find from the Custom Shop, the attention to detail was executed on a high level. The guitar plays nicely, and the fit and finish are top shelf. It includes a custom-fit TKL hardshell case. This 5-18 would be an inspiring songwriter and a great small-body guitar to keep around the house or the studio. You'll love its woody, balanced Mahogany tone.