Why is guitar G string sharp at octave?

Question

Hi, have any guitarists or luthiers ever gotten the lowdown on exactly why the G string on a classical guitar does not divide correctly at 12th fret octave ? It's always sharp and therefore 'beats' when compared to the G on the 10th fret, A string..Guitar makers have been issuing guitars with a notch where the G goes over the saddle..It dawned on me that another way to handle this mystery would be to have a special 12th fret mounted instead of changing saddle..I.E. 12th fret would be in 3 pieces; 2 of them in normal position and small 3rd piece in its own slot under G, right behind the other two..Thus 12th fret would be zig zagged, not saddle..But ,again, why does this phenomenon occur in the first place ?

Answer 1

And what, pray tell, is an expensive classical guitar to you?



I've got a fairly nice classical, which I paid $1200 for. It's not a professional level instrument, but it's nice. It has wonderful intonation.



I've played much less expensive classical guitars that have fairly good intonation as well.



You're doing a lot of whining, but how much do you know about our modern 12-tone equal tempered tuning system? It sucks. It's very problematic, especially on instruments like the guitar.



Ever seen anything like this:

http://www.truetemperament.com/site/images/stories/tt_whol_lay.jpg



No? Then shut up. There are tons of shortcomings with equal tempered tuning, if you can't hear them, then your claim that "every classical guitar has a sharp G at the 12th fret" just goes out the window. Your ear clearly isn't that well developed yet, otherwise you'd be upset about how bad major 3rds sound.

Answer 2

Drop B tuning. First - a little music theory. You can get perfect 5ths, Major 3rds, and the octave of the harmonic series at the 7th, 9th and 12th frets respectively. Double octaves at the 5th fret. Do you know how to strike a harmonic? Just touch (don't press) the string over the fret (NOT behind it - right over it) while plucking with a pick. A harmonic will sound. You need to learn to touch the string with the first finger of your RIGHT hand, and pluck the note with your second finger. That will allow you to fret a note at the second fret and sound an octave at the 14th without needing a third hand. If the third string is "E" -- the fourth fret (fretted) on that string is your open G# of the second string. You can tune string-to-string just like you do in standard tuning. Will get you close. From there - strike a harmonic at the 9th fret of the E string - that will be the major third G#. Strike the 12th fret harmonic of the G# string - (g#) - same pitch. Tune until the pulses disappear. Then try it open. For the F# - Play the 12th fret harmonic (f#) - and play that against the second fret of the E string. Tune for "pulses" Always start low and work up to the notes. C# is the second (or 14th) fret of the "B" string. Either fret the second fret and strike an octave harmonic at the 14th, or just learn to tune the octave interval by ear. I would also get myself a couple of tuning forks. An E, B and A will come in handy. Keep them in your case.. You bang them on something and hold them in your teeth to hear the tones. You should be able to tune any normal interval by ear. When I was studying classical guitar in college we were not allowed to use anything else - it helped develop the ear. But seriously- a chromatic tuner solves all these problems -and it's not $50- it's $20. I bought a little Korg at a piano store for $20 - I needed to get a rough tune an an upright piano and didn't want to hire a tuning specialist for $150 when I knew it was going to slip and need to be tuned a couple times before it stayed in tune. The thing works so good I just tuned the whole piano with it and it's fine. If you can spend a little more - get one you can leave in your signal path right on your pedalboard. There are a couple that are easy to see standing up and work great. But don't rely on those things as a crutch.. learn to develop your ear too. Good luck.

Answer 3

You have a defective guitar. The string cannot be sharp on only the 12th fret, unless all the strings are off on the 12th. If the saddle isn't correctly placed or cut, any number of strings will be off (including just the G), but they will be off all down the neck. It's more noticeable on harmonics. Have you checked all the strings and all the frets with a good freq. counter?



edit:



I admit to having experience with steel strings only. What happens if you replace the G string with a D or B string (tuned both to G and then to their intended notes) ? There is possibly something in the construction of the string that extends the dead end further than the other strings, but it should be easily correctable.