It’s surprising to me how many of my students have no idea what intonation is, or why your guitar should be properly intonated. If you’ve ever wondered why your guitar sounds perfectly in tune on some of the frets, but out of tune in others, chances your guitar needs to be intonated.

It’s surprising to me how many of my students have no idea what intonation is, or why your guitar should be properly intonated. If you’ve ever wondered why your guitar sounds perfectly in tune on some of the frets, but out of tune in others, chances your guitar needs to be intonated. Fortunately, fixing the problem on electric guitars is very easy to do; all you need is a good digital tuner. Adjusting the intonation on acoustic guitars is more involved and beyond the scope of this article. Intonation is the guitar’s ability to play in tune all over the neck. Setting your intonation refers to adjustments made to the length of each string by moving the saddle (on the bridge) either forwards or backwards to compensate for how much the string stretches when you fret a note.

So here’s how to do it: Put on new strings, break them in a bit, and tune each string to the 12th fret natural harmonic with your digital tuner. Once they’re all in tune, start with the first string and check to see if the 12th fret note fretted normally reads exactly the same as the open string harmonic produced at the 12th fret. If your fretted note is sharp compared to the harmonic, you need to increase the length of the string by moving that string’s saddle back. If the fretted note is flat, you need to shorten the string by moving the saddle forward (towards the neck).

Move the saddle in very small increments, retune to the harmonic, and check the 12th note fretted again. Once you get the harmonic and fretted notes to match, you’re money. Do this for every string and your guitar should sound delicious up and down the neck. Every time you put on new strings, you should check your guitar’s intonation. Any time you change your string gauge, change your action (string height), adjust the truss rod, or decide to play in some alternate tuning for a period of time, you should re-adjust your guitar’s intonation and it should always be performed last, after doing any of these modifications.

Still out of whack? You may have a misplaced nut, or your frets may need to be grinded and polished, or even replaced. These problems are not uncommon on cheap guitars. This type of work should be done by a qualified repairperson.

By local guitar instructor Ryan Jerzak, kazrej@hotmail.com