Acoustic Guitar Set Up's
Adjusting Action For Playability & Tone
Action is a term used to describe the way an instrument is adjusted and how well it plays. Action is most commonly thought of as how high the strings are from the frets.
A Basic Guitar Set Up Includes:
A good set up can:
- Increase comfort by decreasing pressure on the players finger tips
- Eliminate or decrease buzzing
- Improve sustain and tone
- Improve intonation
Depending the abilities of the instrument and the needs of the player adjustments can be made to improve the instruments action and increase the comfort of playing. I like to have my customers play for me, even if they're just beginning. The opportunity to communicate and watch someone's playing style is essential to getting it right. The feel that's right for you is as unique as the instrument you play.
Setting Up An Instrument
3/32" = .093 = 2.3mm = .23cm
1/8" = .125 = 3.18mm = .32cm
Let's start with a few measurements...
String Height At 12th Fret
Saddle height directly affects how high the strings sit above the frets. Saddle radius/contour also affects the instruments action as the curvature of the saddle changes the strings height.
Not all instruments play the same with the identical set-up and a player's pick attack and style will certainly contribute to how an instrument is set up. I mention this because it can be the difference between a professional set up, and one "done by the numbers".
Measure Distance Between
Top of 12th Fret and Bottom of String
Place a ruler on top of the 12th fret and measure the distance between the top of the fret and the bottom of the outer E strings.
High action on an acoustic guitar not only affects the intonation, it can make the instrument difficult, if not painful, to play.
String Height At The Nut
String height at the nut should be as low as possible without causing open string buzz. The distance between the string and the 1st fret would nearly always be below .020 (.5 mm). When I am certain of the condition of the frets I set action at the nut as low as possible. String height at the nut can also be affected by the condition of the frets, string gauge and pick attack.
To check string height at the nut, fret each string on the 3rd fret and check the gap between the string and the 1st fret. While some instruments may still play clean if the string is touching the first fret, most will require a gap of a few thousands to avoid buzzing.
Proper Nut Specs
- Outer string positioning to prevent fret edge roll off
- Equal string to string spacing
- Bottom slot angle provides sustain and clarity
- Slots width keeps strings from binding
- Depth to provide lowest action and best intonation.
Correct Neck Relief
Appropriate relief (bow) in the neck gives the strings amble room to vibrate without hitting the frets. Too much relief and a neck feels "mushy" towards the center. Read more about this adjustment on the truss rod page.
An instrument that is not intonated properly will not play in tune when moving up and down the fingerboard. Even after tuning the guitar, players will notice certain notes are sharp or flat. Correcting intonation issues obviously makes a big difference in the way an instrument sounds.
Level and Well Crowned Frets
Frets need to be perfectly level and have a nicely formed crown. Frets of inconsistent height can cause buzzing, also know as fretting out.
Worn or flattened fret crowns can affect intonation and cause buzzing.
Things That Can Raise or Lower String Height
Humidity / Dryness
Moisture causes the woods of an instrument to swell, loss of moisture will cause them to shrink. Most will find that during the summer or times of high humidity the top may swell and lift the strings higher off of the fingerboard making it more difficult to play.
On the other hand, instruments that have been left without proper humidity will often become dry, which can cause the top to drop and create buzzing problems. You may also encounter sharp fret ends that are now exposed due to the shrinking of the fingerboard. During times of low humidity it is essential that you keep your instrument properly humidified. Read more about humidity.
Wear and Grooves
The grooves of the nut and/or bridge saddle will wear as the strings pass over them. As the strings pull to and fro across the nut and saddle they are slowly but surely deepening the groove. Excessive wear in the nut slots may cause the strings to buzz when played open since they are now too close to the frets. Grooves in the saddle can affect intonation and cause strings to break
Tension and Top Bellying
It is particularly common for the action on flat top instruments to raise over time due to the tension placed on the top. The strings continual pull on the bridge and top can create a slight arching which raises the action over time. While a slight arch is quite normal, greater changes in the tops shape may be and indication of structural problems such as loose braces or a warped or cracked bridge plate.
Changing String Gauge
If you change the gauge of strings you are using, be it heavier or lighter, there will be a change in tension on the top and neck of the instrument. When setting up an instrument you must choose what gauge of string you will be using so that the action can be adjusted accordingly. Changing the string gauge will effect your set up.
Loose braces, loose bridges, loose necks, cracks and other structural problems may first become apparent when a player notices a significant change in an instruments action.
Acoustic Guitar Repairs
- Action / Set Up
- Bridge Plate
- Bridge Pins
- Buzzing - Noise
- Care / Maintenance
- Convert Rt. to Lt.
- Fret Replacement
- Fret Types
- Neck Damage / Issues
- Neck Angle
- Neck Resets
- Part Glossary
- Strap Buttons
- String Changing
- String Choices / Effects
- Truss Rod
- Tuning Machines
- Tuning Troubles