Guitar Intonation Setup

Have you ever wondered why your guitar sounds good on some chords but sounds out of tune on other chords? You checked your tuner and you are in tune, but the problem still persists. Maybe you asked yourself: is there a problem with the tuner? Is there a problem with my ears? Is there a problem with my guitar? To answer those questions, let’s investigate: borrow a tuner and tune your guitar—If the tuner yields the same result, your tuner is working properly; since you can distinguish between good-sounding and bad-sounding chords, your ears are fine; now that we have eliminated the two possible problems, we can now rule out that there is something wrong with your guitar… probably intonation.

If you haven’t heard about “intonation” before, this is the right time to learn about it. The common symptom of a guitar that is not intonated is similar to the one described above-it is inconsistent of “sounding in tune”.

Definition of Terms

Intonation

  • It is the process of adjusting the bridge saddle, either away from the nut or towards the nut; thus, altering the string’s working length.
  • It is the process of compensating the string’s working length.

Compensation

  • An adjustment of the actual calculated scale length of the string, from the nut up to the bridge saddle, to make up for a deviation in tune when the string is pressed.

Tempering

  • It is the process of compromising the perfect tuning of a musical instrument—to a certain degree—so that all chords, in all keys and positions sound pleasing—albeit slightly out of tune. A “perfectly” tuned instrument sounds good in the key it was tuned; but sounds awful in all other keys.

The Purpose of Intonation

The goal of intonating a guitar is to make it sound “in tune” with itself as well as with other instruments. It is a fact that the guitar will never play “perfectly in tune” in all keys, chords and fret positions. To rectify the problem, “tempering” was developed. The guitar is said to be equally tempered because the fixed frets are mathematically spaced, based on its scale length, to produce pleasant sounding notes in all keys, chords and fret positions.

Intonation Setup Prerequisites

You should accomplish the following procedures in order, before attempting to setup the intonation:

  1. Neck setup
  2. Truss rod setup
  3. Action setup

Tip: You can refer to my previous articles for the aforementioned setups.

Note: You may also adjust the pick-up height (for magnetic pickups only), so that the magnet on the pickup doesn’t attract the string which will cause intonation problems.

Caution: If you skip one of the setups above, your hard work of intonating will be wasted because you will never get a desirable result.

Materials List

Steps in Intonating a Guitar in General

Setting up a guitar’s intonation is the same for all guitars regardless of its type; however, the process of adjusting the bridge saddle varies. You should follow these steps to intonate your guitar effectively:

  1. Tune your guitar with a tuner in the playing position.Note: You have to tune your guitar to the type of tuning it will be used for. For example: tune your guitar to concert pitch if you use standard tuning; tune your guitar to open D tuning if you use your guitar exclusively with that tuning; and so on. Tip: A good quality tuner works well, but a strobe tuner works better if you can afford one.
  2. Match the open string with its octave on the 12th fret.Note: Some people match the 12th fret natural harmonic with the 12th fret note. Tip: Remove your hand from the tuning peg while tuning; the weight of your hand will affect tuning accuracy.
  3. If the reading on the 12th fret is sharp (#), adjust the bridge saddle away from the nut; if the reading on the 12th fret is flat (♭), move the bridge saddle towards the nut.Intonation RuleCaution: Always loosen the string when adjusting the bridge saddle to eliminate string tension and to prevent possible damage to the saddle, adjustment screw or the string.Note: Refer to the sections below for a detailed instruction on how to adjust a specific bridge saddle.
  4. When the open string and 12th fret octave matches, it is already intonated; move on with the remaining strings.Note: Expect to have staggered (not lined up) bridge saddles upon completion.

Adjusting an Adjustable Bridge Saddle

Here is the general rule in adjusting an adjustable bridge saddle:

    1. Use an appropriate tool to adjust the bridge saddle depending on the type of adjustment screw your guitar has. The common tool for adjustment is a Phillips or flat head screwdriver or an Allen wrench.

Adjusting the Bridge Saddle

  1. If the note is sharp on the 12th fret, tighten the saddle adjustment screw to move the saddle away from the nut; if it is flat, loosen the saddle adjustment screw to move the saddle towards the nut.

Adjusting a Fixed Bridge Saddle

Acoustic guitars usually have fixed bridge saddles. The saddle is usually compensated in the factory that is why you see acoustic guitars with angled bridge saddles. However, due to several factors, the intonation will eventually need to be reset.

In order to move the bridge saddle for compensation, do the following:

    1. Use a small file to adjust the peak of the saddle where the string sits.

Filing the Bridge to adjust its peak location

    1. If the note is sharp, file the saddle at an angle that will offset away from the nut. On the other hand, if the note is flat, file the saddle at an angle that will offset towards the nut.Tip: Be careful when filing. Protect the bridge and body with masking tape and a thin sheet of plastic to prevent scratches and dings. Caution: Avoid filing the top of the saddle; doing so will alter the guitar’s action.

Note:Filing the saddle is only applicable to a guitar with slight intonation problem; for a guitar with severe intonation problem, replacement of the saddle or repositioning the bridge is necessary.

Intonating a Guitar with Floating Bridge

Floating bridges, such as the Floyd Rose and its copies, are quite tricky to intonate because a slight adjustment on a single string affects the tuning of all the rest. The saddles are also difficult to adjust because they do not have an adjustment screw; rather, they have a screw that locks them in place.

In order to intonate a guitar with floating bridge properly, the bridge should not move. To do this, follow these steps:

    1. Remove the spring cover on the back of the guitar.
    2. Loosen the spring claw screws until the bridge tilts forward.
    3. Shove the wedge between the bridge block and the cavity wall until the bridge is parallel with the body.Inserting a Wedge between the cavity wall and the bridge block Note: The wedge prevents the bridge from tilting forward due to string tension.
    4. Tune the guitar then adjust the saddles accordingly.Note: Use a tool called “the Key” to adjust the saddles more easily. If you don’t have the tool, you can push or pull the saddle using your finger or a screwdriver with its tip bound with a soft material like rubber or a piece of cloth.Now, Let’s get started:
        1. Loosen the screw that secures the saddle using an Allen wrench.

      Loosening the Saddle Lock

        1. Hook one side of the Key to the back of the bridge and the other side to the saddle.

      Using a tool called "The Key" for easier saddle adjustment

      1. Turn the thumbwheel of “the key” clockwise to move the saddle back; counterclockwise to move the saddle forward.
      2. When the intonation is set, lock the screw to secure the saddle.
    5. Secure the guitar on the edge of a workbench so that the wedge can fall freely. You’ll see what I mean after you’re done with the next step.

Clamping the Guitar to the edge of a workbench

    1. Tighten the two spring claw screws gradually with equal turns; move from one screw to the other. When the wedge falls, you’re done.

Tightening the two spring claws until the wedge drops

Now that you know how to intonate your guitar, you can play with much more confidence knowing that your guitar is pleasantly in tune.

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