First...this is a great site with prompt and good responses.....thanks.
My previous question was not quite clear (sorry) so here goes again.
When tuning my acoustic guitars with a guitar tuner (not chromatic) there seems (on some strings) to be a slightly higher pitch reading when I just pluck the open string than there is when I use the 12th fret harmonic on the same string.
It's a twenty year old tuner but I'm assuming that I'm doing something incorrectly or from reading the responses to my previous submittal that it may have to do with the guitar setup. The inherited guitars are also twenty (+) years old and were stored properly bet the setup(s) have never been checked by a qualified person to my knowledge.
Thanks for your help.
Braindude
Basically that means the intonation might be off. Try comparing the open string and each string fretted at the 12th fret and see how it acts.
If they are way off you will need to have the bridge reset unless the bridge actually has adjusters on it. That however is rare on an acoustic. It is adjusted by changing the angle of the bridge which is not easy because most of them are glued down. Best option is to take it to a good repair shop for a setup.
tuning to the octave and open and 12th fret can be off for a number of reasons, old strings and bad intonation, misplaced bridge are a few.
But why would they be different you ask? Well you are listening to a different frequency.
You can adjust a saddle on an acoustic. Take it to a luthier if it bugs you.
Umm, intonation isn't going to fix the difference between the fundamental and the 2nd harmonic. Bad intonation is observed when the fretted note is different than the harmonic at the 12th fret.
I'll have to think about this some more. With heavy strings or soft saddles (or nut), the end of the string doesn't vibrate "purely", which tends to change the frequency higher (shorter effective length). That's why you need to move the saddles farther down with heavier strings. But would the 2nd harmonic be lower than the open string? I don't know.
-Laz
