Have you ever meticulously tuned your guitar only to find that chords still sound off as you play further up the neck? This frustrating scenario often points to a common culprit: incorrect Guitar Intonation. While it might sound technical, understanding and adjusting your guitar’s intonation is crucial for achieving accurate and pleasing tones across the entire fretboard. This guide will walk you through the essentials of guitar intonation, why it matters, and how to ensure your instrument is playing in tune with itself.
What Exactly is Guitar Intonation?
In simple terms, guitar intonation refers to the accuracy of pitch as you play notes up the fretboard. A properly intonated guitar ensures that every note, from open strings to the highest frets, plays at its intended pitch. Think of it as your guitar being “in tune with itself.” When intonation is off, your open strings might be perfectly tuned, but as you fret notes, they will progressively become sharp or flat. This discrepancy, even if subtle, can be quite noticeable and detract from your playing experience, making chords sound dissonant and melodies sound off-key.
Image alt text: Detail of adjustable bridge saddles on an electric guitar, highlighting intonation screws for string length adjustment.
Why Does Guitar Intonation Drift Out of Adjustment?
Guitars, despite their seemingly static nature, are actually quite sensitive instruments susceptible to various environmental and mechanical factors. Think of your guitar as a finely tuned machine – and like any machine, it requires periodic maintenance to perform optimally. Several factors can cause your guitar intonation to go out of whack:
- Climate Fluctuations: Changes in temperature and humidity are major culprits. Wood expands and contracts with environmental changes, affecting the neck relief and string tension, which in turn impacts intonation. Significant shifts in climate, especially between seasons, often necessitate intonation adjustments.
- String Changes: Switching to a different gauge or brand of strings can alter the overall tension on the neck, disrupting the intonation. Even replacing strings of the same gauge can sometimes require minor tweaks.
- Neck Adjustments: Adjusting the truss rod to correct neck relief (the amount of bow in the neck) directly influences string height and tension, thereby affecting intonation.
- General Wear and Tear: Over time, the bridge, nut, and saddles can shift slightly due to string pressure and regular playing, leading to intonation changes.
Regular guitar intonation checks are therefore not just a one-time setup procedure but an ongoing aspect of guitar maintenance, especially if you live in an area with fluctuating climate conditions.
How to Check Your Guitar Intonation
The most common method for checking guitar intonation involves comparing the pitch of the 12th-fret harmonic to the fretted note at the 12th fret. The 12th fret is chosen because it is exactly at the halfway point of the string length, making it an ideal reference point. Here’s how to do it:
- Tune Your Open Strings: Ensure your guitar is accurately tuned using a reliable electronic tuner. Pay close attention to tuning each string to its standard pitch (E A D G B e).
- Check the 12th Fret Harmonic: Gently pluck each string directly over the 12th fret to produce a harmonic. Check the pitch of this harmonic with your tuner. It should ideally match the pitch of the open string one octave higher (e.g., the 12th-fret harmonic of the low E string should be E one octave higher).
- Check the Fretted 12th Fret Note: Now, fret each string at the 12th fret and pluck the note. Compare the pitch of this fretted note to the 12th-fret harmonic you just checked.
Interpreting the Results:
- Perfect Intonation: If the fretted 12th-fret note matches the pitch of the 12th-fret harmonic, your intonation for that string is correct.
- Sharp Fretted Note: If the fretted 12th-fret note is sharper (higher in pitch) than the 12th-fret harmonic, the string is effectively too short and needs to be lengthened.
- Flat Fretted Note: If the fretted 12th-fret note is flatter (lower in pitch) than the 12th-fret harmonic, the string is effectively too long and needs to be shortened.
Image alt text: Guitarist fine-tuning guitar intonation by adjusting bridge saddle screws using a screwdriver.
Step-by-Step Guide to Adjusting Guitar Intonation
Adjusting guitar intonation involves modifying the string length, which is typically done by moving the bridge saddles. Most electric guitars and basses feature adjustable bridge saddles specifically designed for this purpose. You’ll usually need a small screwdriver or Allen key, depending on your bridge type.
- Identify the Problem String(s): Using the intonation checking method described above, pinpoint which string(s) require adjustment and whether the fretted 12th fret note is sharp or flat.
- Locate the Intonation Adjustment Screws: Examine your guitar’s bridge to find the screws that control the horizontal position of each saddle. These are usually located at the back of the bridge, behind the saddles.
- Adjust for Sharp Fretted Note: If the 12th-fret note is sharp, you need to lengthen the string. Turn the adjustment screw to move the saddle away from the nut (towards the tailpiece of the guitar). Make small adjustments and re-check the intonation after each adjustment.
- Adjust for Flat Fretted Note: If the 12th-fret note is flat, you need to shorten the string. Turn the adjustment screw to move the saddle towards the nut (away from the tailpiece of the guitar). Again, make small adjustments and re-check.
- Re-tune and Re-check: After each saddle adjustment, retune the open string and re-check the intonation at the 12th fret. Repeat the adjustment process until the fretted 12th-fret note accurately matches the 12th-fret harmonic for each string.
- Repeat for All Strings: Work through each string individually, adjusting saddles as needed until all strings are properly intonated.
Pro Tip: Make small, incremental adjustments. Intonation is a fine-tuning process, and over-adjusting can lead to frustration. It’s often better to make several small adjustments and re-check frequently than to make large adjustments at once.
Basic Intonation Pre-Set: The Tape Measure Method
For a very basic starting point when setting up your guitar, you can use a tape measure to roughly pre-set the intonation. This method is not a substitute for fine-tuning with a tuner, but it can get you in the ballpark.
- Measure Scale Length: 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.
- Set First String Saddle: Adjust the high E string saddle so that the distance from the inside edge of the nut to the center of the saddle is approximately equal to your guitar’s scale length.
- Offset Subsequent Saddles: For the remaining strings, incrementally move the saddles back (away from the nut) by a distance roughly equivalent to the string gauge. For example, if your B string is .011 inches thick, move its saddle back approximately .011 inches from the high E string saddle. The G string saddle is moved back from the B string saddle by the G string’s gauge, and so on. The D string saddle is often set roughly parallel to the B string saddle as a starting point.
Remember, this tape measure method provides a rough starting point. You will still need to use the tuner and harmonic method to fine-tune the guitar intonation for optimal accuracy.
Maintaining Spot-On Intonation
Once you’ve achieved proper guitar intonation, it’s beneficial to check it periodically, especially when you change strings or notice your guitar sounding slightly off. Regular checks and adjustments will ensure your guitar consistently plays in tune across the fretboard, enhancing your musical enjoyment and performance. For comprehensive guitar maintenance, consider a professional setup by a qualified technician. A setup includes intonation adjustment, along with other crucial adjustments like neck relief, action, and pickup height, ensuring your guitar plays and sounds its absolute best.
By understanding and maintaining your guitar intonation, you’ll unlock the true sonic potential of your guitar and enjoy playing in perfect harmony, all the way up the neck.
