In order to keep guitars and basses in top shape, we recommend that they be professionally setup and checked out every six months. Since most guitars are made of wood, seasonal climate changes can make some adjustments necessary. Also, normal wear and tear (such as fret wear) should be addressed before it causes any serious problems.
Nothing makes an instrument sound better than being freshly set up. All of a sudden everything feels, plays and sounds great. No need to put up with buzzing or an instrument that is difficult to play.
Due to the changing nature of wood's reactions to string tension and climate, set ups should be made periodiacally to keep your instrument at it's best! Change of strings, action adjustments, intonation, neck angle, sadle height, etc. are just a few examples of what is included in a set up.
Most stringed instruments have a slim steel rod embedded in the neck. At one end of the neck there is an adjustable nut that can be tightened or loosened. Adjusting the nut serves many functions. The action of an instrument or how high the strings are from the fretboard, buzzing and other annoyances can be resolved by these and other types of manipulation.
Changes in climate, string guages, or simply adjusting to a players taste are all good reasons to regularly have your truss rod adjusted to keep the action just how you like it.