An open-back banjo is basically the same type of instrument as a resonator banjo, however, the back of the banjo is open. Besides having an open back to the sound chamber, there are other subtle differences with an open-back banjo as compared to the closed-back, resonator version. Typically, the setup on the open-back banjo incorporates the strings having a higher action than the closed-back version. This means that the strings are positioned higher off of the fingerboard than is typical with other stringed instruments. The open-back models are known to have a more mellow tone, weigh less and can also be less expensive than a resonator or closed-back banjo.
Some of the earliest versions of the banjo were created as an open-back banjo. As time passed, some musicians attempted to increase the volume of the banjo by installing a closed back, also known as a resonator. The closed back forced the sound out of the front of the instrument and actually made the tone a little more twangy. Many banjo pickers, however, continue to enjoy the open-back banjo for its simplicity and softer and mellower tone, as well as its lighter weight when compared to a closed-back model.
It is generally the type and style of music that is being played that determines if a closed-back or an open-back banjo is used. With modern amplification, open-back banjo players are able to amplify the sound being produced by the instrument to match the level of the other players in the band. This leaves the decision to play an open- or closed-back banjo to the personal preference of the musician. Some players choose to use a closed-back banjo that can be easily converted to an open-back version by removing a few thumbscrews and removing the resonator from the back of the banjo.
Many times, an open-back banjo is recommended for the beginning banjo player due, in part, to the lighter weight of the instrument. The less expensive price of the open-back, beginner's banjo is also a motivator for some consumers. Not all open-back versions of the five-string instrument are inexpensive, however. Some open-back models are as expensive or more expensive than the resonator versions. This is usually due, in part, to the use of more expensive, exotic woods and different metals used in the production of the open-back banjo as compared to those used in the manufacture of the resonator model.