Guitar string action is an important matter. The lower it is, the easier it is to play the instrument, but the higher you set it the fuller and richer your guitar will sound.
How to measure string action
You can use a ruler to measure the distance between both E strings and the 12th or 14th fret of your guitar as shown below.
What's a really low string action
Vigier Excalibur Shawn Lane Signature is a good example here - 0.7mm treble, 1.0mm bass, measured at 12th fret. In an Ibanez RG series manual it says that their typical factory setup is 1.5-2.5mm measured at 14th fret. Personally I prefer 1.0-1.5mm, measured at 14th fret.
How low I can go
The lower the string action is the less bass response and sustain there is and the more buzzing sounds appear. It's a matter of compromise, taste and your playing style. Buzzing is not neccesarily a problem, especially when you can't hear it in the sound coming from your amp. Without the guitar plugged into an amp it can be less or more irritating. Its tone depends on the materials used to build the guitar. To me it's more apparent in dark sounding, set-neck or neck-through mahogany guitars. Inbolt-on bright sounding constructions with maple fingerboards it's almost like if it wasn't there.
What does string action depend on
String action depends on:
- Bridge height
- Nut height
- Neck curvature
Bridge height is the easiest to manipulate as it only requires a screwdriver or an allen wrench. You can change the neck curvature by adjusting truss rod. Nut height is a bit of a problem because nuts aren't adjustable and most guitars have too high nuts. In theory the nut should be so low that pressing a string against the 1st fret is as easy as pressing the same string against the 2nd fret when its already pressed against the 1st fret.
How to check if a neck needs truss rod adjustment
You can easily check if your guitar's neck needs adjustments. Follow these steps:
- press and hold the G string against the 1st fret using the index finger of your left hand
- press and hold the G string against the last fret using the thumb of your right hand
- take a look at the G string above the 10th fret - the string should not be touching the fret, but the distance between the two should equal 0.3-0.5mm (this is what is called relief)
- if the relief is too small - relieve the neck a little bit by unscrewing the truss rod, if the relief is too big - screw in the truss rod a little bit
How to adjust truss rod
Truss rod is located under the fretboard and it's designed to help the neck withstand string tension. In most instruments it can be accesed from the headstock, in Music Man and some Washburn guitars it's located between the neck pickup and the end of the neck. Vigier Guitars do not use a truss rod but an additional carbon strip that reinforces the neck - read more here.
To adjust the truss rod:
- loosen the strings
- remove the truss rod cover
- adjust the truss rod using an allen wrench
Turn the wrench clockwise to bend neck backwards.
Turn the wrench counter-clockwise to relieve the neck.
How to adjust bridge height
Bridge height adjustment depends on its type. Usually it takes a flat screwdriver (Tune-o-Matic) or an allen wrench (some Tune-o-Matics, Floyd Rose, standard fixed bridges). It's a good idea to loosen the strings before raising bridge - this will endure their life.
How to change nut height
Nut height cannot be easily adjusted. If the nut is too high you'll probably have to remove it and use sandpaper.
Locking nuts can be fine adjusted with locking nut shims.
Fretting out, buzzing
When going down with string action it's possible to reach a point where some notes will become fretted out. These are possible scenarios:
- Neck needs truss rod adjustment - you can do this by yourself, the symptoms could be dead notes on every string at first few frets
- Neck is twisted - this needs a luthier to remove the frets, even the fretboard and refret the guitar, if it's twisted just a little bit then fret polishing could do the trick
- Frets are uneven, worn or damaged - conisder having your guitar taken to a luthier for fret polishing or refretting, it's also possible to do the polishing by yourself, there are plenty of tutorials on this on YouTube
- Fretboard radius is too small for such a low string action - you know this pretty much for sure when everything is fine except for when you try to bend, read this article on radius