Keeping your guitar in tune is essential for any guitarist. You meticulously tune your open strings, but sometimes, something still sounds off. If your guitar sounds out of tune even after tuning the open strings, the culprit is likely poor intonation. Intonation, in simple terms, is your guitar’s ability to play in tune with itself across the entire fretboard. Getting your intonation right might seem like a complex task, but understanding the basic principles makes it manageable.
Understanding Guitar Intonation
When a guitar is correctly intonated, every note you play, from open strings to the highest frets, will be in tune. If the intonation is off, you’ll notice that notes higher up the neck sound sharp or flat, even though your open strings are perfectly tuned. This issue, while sometimes subtle, can be irritating and detract from your playing experience. Think of it as your guitar being out of tune with itself.
Wonky intonation is a common issue. Guitars are instruments that react to their environment, and various factors can affect their setup over time. Like any machine, guitars require regular maintenance, and intonation adjustment is a key part of this. Environmental changes, particularly temperature and humidity fluctuations, significantly impact your guitar’s intonation. Even under stable conditions, periodic intonation adjustments are necessary. In fact, intonation is a crucial element of a proper guitar setup, which is arguably one of the most beneficial maintenance procedures for your instrument.
Why Does Guitar Intonation Drift?
Guitars are designed with adjustable mechanisms precisely because intonation is prone to shifting. Adjusting intonation involves slightly altering the speaking length of each string. This adjustment is achieved using mechanisms located at the guitar bridge. Most electric guitars and basses feature bridge saddles that can be moved forward or backward—closer to or further from the nut. These saddles allow you to fine-tune the length of each string individually, ensuring accurate intonation. Additionally, saddles can often be adjusted vertically to modify string height, also known as action.
How to Check Your Guitar Intonation
Checking your guitar intonation is straightforward and requires an accurate tuner. The process involves comparing the pitch of the 12th-fret harmonic to the pitch of the note fretted at the 12th fret for each string.
If both the fretted 12th-fret note and the 12th-fret harmonic are in tune according to your tuner, that string is correctly intonated. This means the string is in tune “with itself.”
However, if there’s a noticeable difference in tuning between these two points, the string’s intonation needs adjustment. The fretted 12th-fret note will either sound sharp (too high) or flat (too low) compared to the 12th-fret harmonic, indicating the direction of adjustment needed.
Adjusting Guitar Intonation: A Step-by-Step Guide
When adjusting intonation, remember these two key principles:
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12th Fret Note is Sharp: If your tuner shows the fretted 12th-fret note is sharper than the 12th-fret harmonic, the string is too short. You need to lengthen the string slightly. To do this, move the bridge saddle for that string away from the nut.
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12th Fret Note is Flat: Conversely, if the fretted 12th-fret note is flatter than the 12th-fret harmonic, the string is too long. You need to shorten the string slightly. Move the bridge saddle for that string towards the nut. In some cases, slightly raising the saddle height can also effectively shorten the string length enough to correct intonation.
While electric guitars and basses come with various bridge designs, almost all incorporate a system for easy intonation adjustment using movable bridge saddles. Typically, a small screwdriver is all you need to make these adjustments.
Pre-Setting Basic Intonation
For a starting point, you can pre-set your guitar’s basic intonation using a tape measure. Measure the distance from the inside edge of the nut to the center of the 12th fret. Double this measurement to determine your guitar’s scale length. Then, adjust the bridge saddle for your high E string so that the distance from the inside of the nut to the center of this saddle is approximately equal to the scale length you calculated.
For the remaining strings, you can incrementally adjust saddle positions based on string gauge. Starting with the B string saddle, move it back from the high E string saddle by a distance equivalent to the B string’s gauge. For example, if your B string is .011 inches in diameter, move its saddle back .011 inches from the high E saddle. Repeat this process, moving each subsequent saddle back from the previous one by the gauge of the corresponding string. The G string saddle is often set roughly parallel to the B string saddle. Continue this method for the lower strings. This pre-setting method provides a good starting point, after which you should fine-tune intonation by ear and with a tuner as described earlier.
Maintaining proper intonation is crucial for getting the best sound and playing experience from your guitar. Regular checks and adjustments will ensure your instrument always plays in tune across the fretboard.
