Hi there, mates!

I'm trying to tune an old guitar I gave but here is the obstacle:

After tuning it with harmonics, the two strings seem to be in tune (there are no vibrations when playing the two harmonics). But as soon as I try a few power chords with those two strings I get oscillations in the sounds, it is not linear...

Does these vibrations mean the guitar is not in tune? If so, what can I do to fix that?
It's an old classic guitar.

Mucho Thanks!
No idea what you mean, more information please?
R.I.P. My Signature. Lost to us in the great Signature Massacre of 2014.

Quote by Master Foo
“A man who mistakes secrets for knowledge is like a man who, seeking light, hugs a candle so closely that he smothers it and burns his hand.”

OK, so

Tune your guitar with a guitar tuner, first of all. Being able to do it by ear is good but you should regularly use a tuner to do it.

If that still sounds bad, I'm not sure what's wrong. A perfect fifth is a pretty strong interval.
Are you talking about tuning based on the 5th & 7th fret harmonics? If so then that is probably your problem. Tune using the fretted 5th fret or an octave, or as was mentioned get a tuner.
I'm an

I'm Good at Math
here's what's happening. Assuming your ear is good when tuning with the harmonics the guitar's intonation is out of whack. What this means is that when you press on a fret the note is either sharp or flat (This problem usually gets worse and worse the high up the fretboard you are)

How can you fix this? If it's an electric guitar you can adjust your Bridge Saddles (towards the neck to make the note sharper, and away from the neck to make the note flatter.

If you need more info just Google how to properly intonate a guitar

hope this helps.

A very quick method of figuring this out is this:

use a tuner
pick a harmonic on the 12th fret and tune your guitar to it using the tuner
now hold down on the 12th fret and pick the note with your tuner still on
is the note sharp, flat, or is it still in tune?
If the string is properly intonated it will still be in tune.

If you do your research and it all sounds a bit too in depth you can always go to guitar center and pay them about $70 to set it up for you.
Last edited by iduno871 at Dec 20, 2013,