What is an instrument setup?
A setup usually involves adjusting the truss-rod within the neck to alter or remove any bow or curvature and then adjusting the bridge to set the action (height of the strings from the fingerboard) and intonation (ensures the notes expected are produced all the way up the neck). It’s often an idea to check the tightness of the tuners on the headstock and squirt some switch-cleaner into the controls too
Occasionally the frets will need levelling as they wear with use, or if the instrument is brand new. On many new instruments the frets are fitted and forgotten about, never really being checked to ensure accuracy. Variations in manufacturing processes and the fret-wire itself mean that they are very rarely all the same height along the neck after first installed
When and why to have an instrument setup
After buying a new instrument
Especially after buying online. Brand new instruments generally leave a factory with a standardised or template setup, even those costing into the thousands will only have had the briefest of attention given to them before despatch, so a little attention to a new instrument can help bring it to a more playable condition and tailor it to the player
After buying a second-hand instrument
If the instrument’s been well looked after by the previous owner, a setup can help adjust it to your playing style. If it hasn’t, then even just a little care and attention can usually bring a poorly treated instrument back into excellent health
After changing strings
If strings have been on an instrument for some time their characteristics will have changed slightly from when they were first installed. Brand new or even just different strings will subtly change the load on the neck, consequently checking neck relief and intonation is worthwhile each time strings are changed. If the old strings are replaced with a set of the same type and gauge, then the effect will generally be small, but if different gauges are fitted, or roundwound strings replaced with flatwounds for example, neck relief and intonation will likely need adjusting
Regular maintenance
Neck relief is worth checking throughout the year as the seasons change too; the slight changes in humidity between summer and winter for example can cause changes in the woods, resulting in a variation of neck relief and string height