How to adjust the action of a guitar or bass (a guide for dummies)

Hello and welcome to this week's article!

Today we are going to see how to adjust the action of a guitar or bass, and this is to be considered the "prequel" of our article about how to set the intonation of our instrument.
Small disclaimer: this is more an article to explain how things work, if you want to have a professional work go to a luthier and have him set up the guitar for you, while if you're a DIY lover, proceed at your own risk :D

First off the definition: the action is the space between the top of the 12th fret of our guitar and our strings, and it determinates the comfort and the speed of our playing: a higher action will allow us to be more precise and with a cleaner sound, but a lower action will allow us to go faster with less effort, so the right distance varies according to our taste and there isn't a height that fits perfectly for everyone (even if Gibson suggests, for its guitars, a minimum string height at the first fret of 1.22mm for the high E and 1,98mm for the low one)
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Beware that if the action is too low we will have fret buzz or mute frets, meaning that in some part of the keyboard the string gets muted (the so called "dead note"): in this case we'll have to raise slightly the string height or adjust the truss rod.

The normal position of the neck is either absolutely straight or with a very, very slight bow ("u" shape), in an almost imperceptible way; if the neck is too bent backwards (the so called "n" shape) or forward (the so called "u" shape) we will need to adjust the truss rod (which is a metal rod that lies inside the neck and counterbalances the string tension) with a hex key:

If the neck is bent "n" shaped, the frets will buzz in the certral part of the fretboard, meaning around the 5th to 12th fret, while if the neck is bent "u" shaped, it will buzz in the lowest and highest frets.

In both cases we can solve by finding the screw of the truss rod, which is usually located in the headstock, and sometimes it is covered with a lid, and turning the screw with the hex key.

By turning the truss rod screw COUNTERCLOCKWISE you will add relief, meaning that the neck will make less resistance to the tension of the strings and it will become more "u" shaped, while by turning it CLOCKWISE you will reduce relief, meaning that the neck will make more resistance and will become more "n" shaped.
By adjusting the neck curve what we are looking for is the sweet spot in which there is no fret buzz nor dead notes when playing every string in every fret of the fretboard: when this happens, it means our instrument neck is straight.

Once the neck is straight it's time to adjust the string height of our action: we need to turn the screws at the sides of the bridge (in case of tune o'matic bridge) to raise or lower the string height until we find the perfect action that is not too uncomfortable to play and that lets every note ring perfectly.
There are also bridges (like the Fender ones) that lets us regulate the height of each single string by raising or lowering the individual saddles.

Once our guitar is straight and the string height it's perfect it's time to work on the string intonation (click here for a dedicated article)!


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