An Introduction to Acoustic Guitar Setups
The single most important issue when you are hiring or buying an acoustic guitar is that it is properly set up!
The video to the left shows a guitar going through a full premier setup, including nut, saddle and fret work.
What Exactly Does ‘Setup’ Mean?
For an acoustic guitar to work properly, it is very important that the gap between the strings and the frets (called the ‘action’) is set correctly. If the strings are too close, they will rattle against the metal frets when they’re played and the guitar will sound horrible. If the strings are too far from the frets, the player will have to push down much harder on the strings, which will make the guitar uncomfortable to play and can often bend the notes out of tune.
To get the right gap between the strings and the frets all the way along the guitar’s neck, several fine adjustments have to be made – these adjustments are known as the ‘setup’. To set up an acoustic guitar properly requires specialist tools, accurate measurements, and expert knowledge – so it needs to be done by an experienced guitar technician.
Why new acoustic guitars need setting up
In theory, all acoustic guitars should be set up perfectly when they leave the factory – however – in our experience, very few of the guitars delivered to our shop arrive in this condition.
Why? There are several reasons for this:
- Poor factory setups – Setting up an acoustic guitar properly takes skill and time, but factory setups (particularly on budget instruments) are done as quickly as possible, to keep the manufacturer’s labour costs down. Often the manufacturer will cut corners, and sometimes mistakes are made that don’t get picked up by the factory’s quality control department.
- Moisture / Humidity – wood is a volatile material that expands when it’s wet, and contracts when it’s dry. Most acoustic guitars are made of several different species of wood, with different densities and grain patterns, and different degrees of reaction to moisture. If the humidity of the environment in which the guitar is stored changes at any point, it can have a noticeable effect on the setup.
- Transport and storage times – nowadays, most acoustic guitars – particularly budget instruments – are made in the far east, mainly China, South Korea, Indonesia and Taiwan. Some are sent by air freight, but most arrive in the UK on cargo ships, after a journey taking several weeks. They then wait in an importer/wholesaler’s warehouse until they are ordered by a shop. During this time, the tension of the strings and the truss rod in the neck can cause the geometry of the guitar to move around, even if the temperature and humidity are kept constant.
So, even if an acoustic guitar was set up perfectly at the factory where it was made (and not all of them are), there’s no guarantee that it will arrive at a shop in the UK in this condition. In our experience, almost all the acoustic guitars that are delivered to our warehouse need some work doing to them before they can be hired.
A look at the setup process
For anyone who’s curious to know how an acoustic guitar is set up, here’s a step by step guide to how we do it.
Unpack and inspect the guitar
Before starting any work, we need our repairer’s expert eye to check over the guitar carefully to make sure there are no major problems and issues, such as cracks in the wood, or anything that will prevent the guitar from being set up properly.
Over the years we have seen various problems, or issues, that if not picked up on at beginning can lead to expensive repair bills further down the line.
At this stage, any instrument that doesn’t meet our high standards is sent back to our supplier, who will exchange it for a new one.
Check string gauge and tune up
Most acoustic guitars are factory-fitted with light gauge (12-53 or 12-54) strings, although some of the high-end manufacturers, notably Taylor and Collings, now fit medium gauge (13-56) strings as standard. Using a set of micrometers, our repairer measures the string gauge, and makes a note of it on our set-up tag.
It’s also very important at this stage that the guitar is tuned up to concert pitch, as the pitch affects the tension of the strings, which in turn affects the geometry of the guitar, particularly the curvature of the neck.
If you are planning on having your guitar set up then deciding on your preferred gauge and even your most used tuning can have a bearing on how the guitar is set up. Equally different strings work for different things, we are always happy to advise on this.
Once the strings are tuned correctly, the repairer can set the curvature of the neck by adjusting the tension of the truss rod – a long metal rod that’s built into the neck behind the fingerboard to counterbalance the tension of the strings.
Loosening the truss rod increases the curvature of the neck, tightening it makes the neck straighter. When set correctly, the neck should have a very slight concave curve to it, which our repairer measures by resting a long, metal straight-edge along the fretboard.
The depth of the grooves in the nut (the block of bone or hard plastic at the end of the fingerboard) affects the guitar’s string height or action, particularly on the frets closest to the nut. If the grooves are left too shallow, the strings will be too high above the first fret, making it very difficult to play certain chords such as a barred F. If the grooves are cut too deep, the open strings will catch on the first fret when they vibrate and sound like a sitar!
On rare occasions when guitars come in with the grooves cut too deep, our repairer will make a completely new nut from a blank block of bone – most of the time, though, guitars are shipped from the factory with the grooves cut too shallow, and our repairer uses a special set of narrow metal files to cut them to the correct depth.
A standard acoustic guitar saddle is also curved when viewed end-on, creating a smooth surface for the string to run across. However, many manufacturers have now switched to ‘compensated’ saddles (see image) with a ridge that alternates between the front and back edge of the saddle, allowing for the difference in string tension between the plain and wound strings, and thus improving the intonation.
Nowadays, nearly all guitar manufacturers use moulded plastic saddles, with the correct profile. Occasionally though, a second hand guitar will need the saddle replacing or re-shaping, particularly if there are grooves where the strings have cut into it.
This is the final adjustment to set the gap between strings and frets along the length of the neck. To do this our repairer measures the distance of the bass (6th, thickest) and treble (1st, thinnest) strings from the 12th fret. For a good, general purpose playing action that suits fingerpicking and strumming styles of playing, the ‘action’ at the 12th fret should be a little under 3mm* for the 6th string, and around 2mm for the 1st string.
Because the 12th fret is exactly half way along the string, the repairer will note the amounts by which the action needs to be raised or lowered for the 1st and 6th strings, and raise or lower the saddle at the point where the 1st and 6th strings cross it by double this amount. If the saddle needs to be lowered, this can be done by grinding material away from the base of the saddle. If the saddle needs to be raised, a hardwood shim of the required thickness is attached to the base.
The repairer must also ensure that the base of the saddle is completely flat, particularly if the guitar is an electro acoustic model, as an uneven saddle can lead to problems with the pickup response.
*If the guitar is only ever to be used for very light fingerstyle playing, it’s possible to set the action a fraction lower than normal, but this will mean the strings will rattle if they are ever played hard. On the other hand, some players may prefer a slightly higher action, for example if the guitar is to be used mainly for slide playing. Either way, we can adjust the action to suit a player’s specific needs.
If the guitar is electro-acoustic, the pickups need to be checked to make sure they are working correctly. If there is a problem with certain strings sounding too loud or soft, our repairer checks the base of the saddle to make sure it is completely flat, and also for any dirt or unevenness in the bottom of the saddle slot. Occasionally the saddle slot needs to be routed out to ensure that it’s properly flat, although thankfully this is rarely a problem with modern guitars.