Martin D-18. Guitar Gallery has the Martin D-18 in stock and available for you to experience. The Martin D-18 features a sleek, modern High Performance Neck for enhanced playability. The D-18 adds a Sitka spruce top to the genuine mahogany back and sides. Perfect for the intermediate and advanced player. Standard ''X'' Scalloped, Forward Shifted bracing pattern. Tuners are nickel open-geared with butterbean knobs. Visit Guitar Gallery to view and play this amazing Martin D-18.