Fixing the g string intonation problem

[Huda]

Okay, this is a weird one. My two G strings have different intonations!

When I play an open G, both G strings sound exactly the same. But when I play G an octave higher (at the twelth fret), one G string is a quarter-tone higher than the other G string.

I can understand the E and the G strings having different intonations, but how is it possible for the two G strings to have different intonations?

And how do I fix this?

[Martin Jonas]

Three possibilities: poor nut slots, poor bridge slots, or a duff string. First change the strings. Then have a very close look at those slots to make sure they terminate cleanly precisely at the leading edge. Sometimes a slot looks fine, but on a close look you notice that the place where the string first makes contact with the nut/saddle is some small distance away from the edge. This may or may not give you buzzing, but it certainly will throw your intonation out.

Martin