Both the D555 and D550 feature a dreadnought body shape design, which delivers crisp trebles, round mid-ranges and powerful bass. The body measures 20 inches long and 4-7/8 inches deep. The upper bout on these guitars measures 11-5/8 inches, the waist measures 10-7/8 inches and the lower bout measures 15-3/4 inches. The top material on both the D555 and D550 models is solid spruce. The backs and sides of both guitars are made out of mahogany. Both guitars also feature a scalloped-x soundboard bracing system. This style of soundboard bracing stabilizes the guitar's soundboard and provides openness of voice.
The necks on the D555 and D550 are made in the same style, out of materials that are exactly the same. Both guitars are built with a neck made of solid mahogany. Nut width on both guitars is 1-11/16 inches. Both models feature a solid rosewood fingerboard, a two-way adjustable trussrod and glass-fiber rail reinforcement. Adjustable trussrods allow for string height control. Glass-fiber rails add strength and stability to the guitar neck.
Walden's D555 model features the same appointments as the Walden D550 model. Both feature black plastic binding and two-ring inlay rosettes. Tuners on these guitars are made of die-cast chrome. The Walden logo on both guitars is made out of pearl. The nut and saddle on the D555 and D550 guitars are manufactured by Graph Tech. These nuts and saddles increase the depth and warmth of the guitar's harmonics and tone.
Aside from the fact that the D550 model is in production and the D555 is not, as of August 2011, there are not many differences between the models. One major difference is the finish applied to these guitars. The D550 features a satin nitrocellulose lacquer finish, while the D555 features a semigloss nitrocellulose lacquer finish. Nitrocellulose lacquer vibrates along with a guitar's moving soundboard, the reason it has been used since the late 1800s in finishing guitars. Satin finishes are smoother than glossy finishes, allowing musicians to play with greater speed and ease.