The Washburn SBT21 was introduced around 1987 as part of their solid body acoustic series. It offered a slim, rock maple neck with rosewood fingerboard. The mahogany body was routed using CNC machines - and the design aimed to enhance the acoustic properties of the instrument. The SBT21 had a spruce top. Electronics were a master volume, master tone a midrange "fat" control to increase the presence of the instrument. The design of the SBT21 offered a acoustic tone without feedback even when performing at concert levels.