#1
Hey! I'm a beginner, and I've noticed that the 5th and 6th strings do not play the same note when played open, and when fretted at the 12th. What could the problem be? The guitar is only about 6 months old!

I've just switched from using light gauge strings to mediums. Could that be the problem?
#2
Yes. With acoustics, you can't really set the intonation, since it's set by your bridge saddle, which is molded, or carved. So the only other way to affect intonation is by neck relief, so you might have to tighten the truss rod a tad. Heavier strings will pull on the neck more, thus raising the action, changing the intonation.
#3
lol well the 5th and 6th strings should not play the same note when struck open.

The only two notes that should be identical when you strum them open are the 1st string and the 6th string.

If they are not, then they are not tuned correctly. Simple. Not an intonation issue.
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#4
Quote by Vypor
lol well the 5th and 6th strings should not play the same note when struck open.

The only two notes that should be identical when you strum them open are the 1st string and the 6th string.

If they are not, then they are not tuned correctly. Simple. Not an intonation issue.


I think he means the 5th and 6th opens are not the same as the 5th and 6th 12th fret, respectively...

Its harder to get this fixed on an acoustic. Try going back to the former strings and see if that fixes it. If it does then the new strings are the issue.. if not you may want to have it taken to a guitar tech for a proper inspection.
#5
So I tightened the truss rod. Still not too much of a difference. I should try changing the strings when I get a chance, because I get a feeling you guys are right. Are the medium gauge bass strings too thick for the nut? Looks like I need a guitar tech. Problem is, we don't have too many of them where I stay. I would've liked to have my guitar set up right when I bought it, but I wasn't aware about these intricacies back then.

Thanks for the help!
#6
Quote by Bloodravenez
Hey! I'm a beginner, and I've noticed that the 5th and 6th strings do not play the same note when played open, and when fretted at the 12th. What could the problem be? The guitar is only about 6 months old!

I've just switched from using light gauge strings to mediums. Could that be the problem?

First of all, that isn't really how you check intonation!

It goes like this, the octave harmonic should appear directly above the twelfth fret.

You don't fret the note..! I use the back of a kitchen knife or any piece of metal with a narrow contact area, that could be used as a slide, and just touch it to the string at the twelfth fret. Then you pluck the string to reveal the harmonic. The closer to the 12th fret that the harmonic is the strongest, reveals how close the guitar is to correct intonation.

If you fret any string at the 12th fret, because of the sting being pulled and bent, it will sound higher than it should, and certainly higher in pitch than the natural harmonic that occurs there!

So, more force is required to fret medium strings, so the higher the pitch deviation would be.

The truss rod actually doesn't have that much to do with intonation, it simply allows you to adjust the bend of the neck, so that string buzzing doesn't occur.

A guitar neck needs a few thousandths of an inch relief at about the seventh fret, and the truss rod adjusts this. It isn''t really to be used for the height of the action, the bridge saddle has to be ground down for that.

As to intonation, all acoustic guitars are an approximation. Only the individually movable saddles found in electrics will set intonation exactly.
Last edited by Captaincranky at Oct 3, 2011,
#7
Wow. The harmonic is perfectly alright! I've been reading a lot of stuff online, and it seems that this issue could be because of the saddle height. Captain's got it spot on, I think. :P
I do have a high action that I'm unable to fix using the truss rod alone, and the height at the nut seems fine. Guess I'll buy myself a few saddles and experiment with sanding them down a bit before I go to the nearest guitar tech!

Thanks for the help guys!
Last edited by Bloodravenez at Oct 4, 2011,