Intonation
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Intonation

Hi there,

Following on in my series of basic guitar set-ups, this one is about setting the individual string lengths to give an accurate octave of the open strings exactly at the twelfth fret.

As all the strings are of a different mass and also tuned to a different frequency it follows that the vibrational nodes of each string are going to fall in slightly different places and as the frets are fixed in one place, the way of compensating  for the difference is achieved by having slightly differing string lengths. The heavier and lower in register the individual string is, the longer it needs to be to obtain a more accurate intonation over the scale of the frets. The most obvious outcome of this maladjustment is that you tune your guitar’s open strings perfectly but when you play some chords particularly higher up the fretboard, it sounds out of tune!

Different types of guitar have different methods of reaching this adjustment, this video covers a Gibson type bridge with angular saddle pieces that are adjusted by an ordinary flat blade screwdriver. Some guitars have hex wrench screws and some cross head screws but the principal remains the same.

Acoustic guitars do not generally have individual adjustment so you have to rely on the quality and accuracy of the manufacturer. This issue will be covered in a later post

I love to hear your comments so please do post your thoughts.

{ 4 comments… add one }
  • Farouk August 15, 2010, 1:27 am

    for me that’s brand new information since i am a newbie
    thank you for posting it 🙂
    [Guitartisan]´s last [Blog] ..[How to remove fret buzz]

  • Benjamin Blue November 20, 2010, 3:47 pm

    Hi Pete,

    Thanks for this great video. I have always known about intonation but have always had fixed bridge saddles. I have a Martin acoustic which I feel is some what out. When I got it a few years back they said at the shop that Martins usually need setting up to marry up with the gauge strings you use. I never did get it set up though. I would really like to get rid of a bit of fret buzz too. I guess this get sorted when intonation is being done at the same time?

    Thanks again for the excellent explanation of Intonation.

  • Pete November 20, 2010, 10:40 pm

    Thanks Benjamin, I appreciate your feedback, it spurs me on to go further and one of the things that are pending is in fact “How do we do intonation on an acoustic?” well a lot comes down to the manufacturer!, they have to get it right in the the first place. You are right about the string gauge, the guitar is designed and built with a particular string set so obviously if you do not match it when replacing them, there are going to be differences. What you have to realise is, the guitar is not a perfectly intoned instrument anyway, maybe you have noticed that if you are playing in one particular key it sounds great because you have tuned it up for that key, then, you switch to another key and you may have to make slight adjustments for it to sound in tune, this is quite normal. If you look at some guitars like the one played by Robert Taylor http://www.youtube.com/watch?v=0OH5U3q0KFI&feature=channel you can see that that guitar has splayed frets and a really sloping bridge. This is partly because the guitar is a “Tenor” guitar and when tuned to a lower pitch the tuning and intonation becomes much more critical.
    To find the best match for your own guitar rule of thumb is – if your fretted note sounds higher than the harmonic – you need to increase the mass to bring it down i.e use a heavier string.
    I have seen an instructional video where they actually recommend slackening the truss rod to make let the neck be slightly ‘banana’ shaped in order to relieve fret buzz and I suppose if it is playable like this and it sounds good, they have a point.

  • Mandy R. Solomon June 4, 2013, 9:08 pm

    All things remaining equal, that is using the same guitar, if I go from a set of 0.13’s to 0.008’s (just an example to see the effect) generally how will intonation settings change? Do the saddles go towards the nut as the guage gets lighter? I understand how to intonate the guitar, and do so with a strobe tuner. Why I’m asking is, if working with a guitar that has a limited intonation range or at their front or rear limit, can I select a string guage that will help minimize the problem?
    [Guitartisan]´s last [Blog] ..[How to remove fret buzz]

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