ChasingGuitars

Intonation is what keeps your guitar in tune when fretting notes. Easy with any tuner, be it clip on, pedal or good ears to get your guitar’s open strings set to standard tuning. But as you fret up the neck you want your guitar to stay as close to in tune as possible. If your guitar sounds out of tune when playing some chords or when playing fretted notes up at the higher frets your guitar’s intonation needs setting. Depending on what type of bridge, strings your guitar has plays a big factor in this setting.

When checking intonation and playing your guitar “in-tune” it is important that you fret notes or chords evenly and not use too much pressure. Especially if your guitar has high jumbo frets it is easy to press down too hard and actually stretch the strings out of tune. One reason why your touch is so important in your playing. You strive to fret notes by pressing down the string to the fret, but not push the string down further to the fretboard bending the note out of tune. Be careful with your fretting hand so you don’t inadvertently pull one or more strings out of tune by applying uneven pressure. If you press too hard you can make any chord or note play out of tune.

String action (height) and neck adjustments (truss rod) should be made before intonation!

Checking your Intonation

After tuning your open string with a chromatic tuner, play an open E chord across all six strings. If that sounds in tune, then strum a G barre chord at the third fret, then at the fifth fret play A barre chord. Seventh fret chord and right down to the twelfth fret. If you hear your guitar’s tuning getting farther out as you play up the neck, your guitar’s intonation probably needs adjusting.

Note that guitars are not perfect instruments and it is impossible to get every single fretted note to play in perfect tune. BUT we can get this pretty close and compensate for this.

There are several nuts, bridges and methods that have been designed to get this as close as possible. Some builders even use a fanned fret design to compensate for the temporal design of the guitar.

Basically the twelfth fret is the half-way point of the scale of your instrument. At the twelfth fret there is a harmonic that can be played by lightly touching each string. These harmonics being the halfway point should play in tune with the open string just at a higher octave. If this harmonic is off it could mean your bridge (or bridge saddles) are in the wrong place and not the halfway point of your guitar’s scale. In the case of an archtop or any guitar with a moveable bridge, not pinned or anchored to the guitar top, it may have been pushed out of place. A ruler and tuner can help right this.

At the twelfth fret the harmonic should match closely with the fretted note at the twelfth fret. If it does not match your intonation needs to be adjusted. Before I get into explaining a method of setting your intonation, I want to discuss if the strings you use matter.

Wound vs Un-wound G string!

Years back, it was common for strings sold for guitars to have a wound G string. The plain G string became popular when music changed and guitarists wanted to bend string more. Many guitar players started using multiple string sets to get the gauges to their liking and a plain unwound G string. Eventually, companies like Ernie Ball started selling string sets in lighter gauges with a plain unwound G string. These days this is the norm, but many players still use a wound G string, especially Jazz players.

The reason this matters is that when setting intonation, the wound G string has different requirements. If your guitar has a bridge with adjustable saddles you will need to adjust for the wound G string (plus the string gauge). When this becomes a bigger issue is if you would a guitar where the bridge is fixed.

Top shows usual intonation for a Wound G string. Bottom for a plain G string.

Acoustic guitar usually use a wound G string while many electrics use a plain G string. On some guitars, like older archtops, the bridge may be fixed and set-up for a wound G string. To get intonation spot on you would need to change the bridge if you plan on using a plain unwound G string.

Some examples of bridges for designed for wound G strings.

Gibson ES-125CD with rosewood bridge for a wound G string

Guild X-175 with rosewood bridge for a wound G string

Gretsch Acoustic – Wound G String

Some examples of bridges for designed for unwound plain G strings.

Gibson ES-295 with replacement bridge for unwound plain G string

Gibson ES-335 with adjustable AB-1 bridge set for plain G string

Strat tremolo adjustable bridge

PRS adjustable bridge

Fender Jazzmaster with Mastery Bridge with unwound G string

Fender Telecaster bridge with compensated saddles

Can the gauge of a guitar string have an effect on its intonation?

Changing the string gauge set can slightly effect the intonation. When making this change it is a good idea to check the intonation and make any slight adjustment. Having a wound G string will have a bigger effect.

Setting Intonation

Many players just check the intonation at the twelfth fret, but it is a good idea to check for crest tuning at the fifth, seventh frets as well. If your D string can play in perfect tune open it should be able to be a well tuned G at the fifth, an A at the seventh and an octave D at the twelfth fret. If this is still out after setting intonation, makes sure to check that your string are properly installed. The strings need to be set firmly at the bridge and the nut needs to be in good condition. Worn bridge saddles can cause issues.

Humidity is a factor, since most guitars are made of wood and if it is too dry wood can shrink or swell if humidity is too high. Making sure your neck relief is reasonable will be quite important as too much relief can distort fretted notes. Bridge must be solid and secure. Not loose, uneven and pulling away from the guitar’s top.

How to measure neck relief by Fender.

Accurate placement of the bridge and saddle must be done. Reason I mention ruler below. Yes, I have seen some lower-end guitars from the factory with this problem. Even some older vintage acoustics. If you have this issue and do not have a moveable bridge, your next stop should be to a competent repair person. This can be fixed.

For basic intonation and setup most people can adjust their own guitars with a few tools and some knowledge.

You will need a few tools:

• Screwdriver, hex key, etc for adjusting your bridge saddles closer or further from the nut.
• A tape measure is optional, but can be helpful

1. If you have a moveable bridge meaning one that is not pinned or anchored to your guitar’s top. You might want to measure from the nut to the bridge to see the scale. You can measure from the twelfth fret to the bridge for the half-way point.
2. Tune the open strings to standard tuning.
3. Using a light touch, play a 12th-fret harmonic and ensure it is also tune.
4. Using just enough pressure to cleanly sound a note, gently play a fretted note at the 12th fret. Make sure not to press too hard bending the note out of tune. Using the tuner, compare the difference in pitch between the harmonic and the fretted note. Basically they need to match.
5. If the fretted note is sharp compared to the harmonic, the bridge saddle (or a fixed bridge) will need to be moved back, away from the headstock. If the fretted note is flat compared to the harmonic, the saddle will need to move forward, toward the headstock.
6. You should loosen the string enough so that the bridge saddle can move freely. Use the screwdriver to turn the bridge adjustment screw so that the saddle moves either forward or back, as needed.
7. Tune to pitch, and repeat until the fretted note and the harmonic note are both perfectly in tune.

Perform these steps for each string until they are all intonated. Once your guitar can play in tune across the fingerboard it will sound much better. Chords will play in tune and resonate cleaner.

Also see Scale Length and Why It Matters.