Choosing Which Two Frets to Use For Saddle Adjustment
In order to select which two frets to use when comparing pitch for adjusting the saddle(s), a player should carefully consider what portion of the fretboard needs the most accurate pitch, based on what portion she most often uses.
It's not usually a problem for acoustic guitars, because they usually are not played much above the neck joint. Compare pitch at the fret where the neck joins the body to the pitch at the 2nd or 3rd fret. That would be frets 12-2 for a classical guitar (it does not need to be an octave) and usually 14 - 2 for a steel string acoustic. That should give you good results up to about 4 or 5 frets above the high test fret. You need to use an accurate tuner - see:
Comparing Two Notes - Cents-Off.
For very proficient acoustic players, needing accuracy well above the neck joint on an acoustic guitar (perhaps with a cutaway) it is first necessary that the fret levels above the neck joint are in good alignment with the rest of the neck, with no excessive falling off of the fretboard away from the strings. If that is a problem with a particular guitar, the options are to repair, upgrade, or just treat it as stretch tuning in the upper register (it's a feature, not a defect).
It is possible to use a higher set of test frets, such as 15-3, 16-4, or 17-5. Normally, the base strings are not played above the neck joint on an acoustic, so don't use a higher range on those strings that don't need it. The range does not have to be the same for all the strings.
Electric guitar players are much more likely to play higher up. For someone regularly playing all the way up to the 24th fret, I would reccommend using 17-5. One luthier recommends, on his website, using 19 - 7, but I don't concur, because the highest frets are likely to go a bit sharp (see:
The Clothesline Effect) and to try to correct them downward would end up causing pitches, starting a few frets down, to be flat. There is no easy remedy for the sharping, so I suggest just calling it stretch tuning in the higher register. (I have read that playing a high lead a bit sharp causes it to stand out from the rest of the band, which may be a good thing.)
The saddles on electric guitars are usually easy to adjust, so use your best choice of test frets and make the adjustments. It's a good idea to then take various sample measurements of the results, and if you could improve the intonation with a different set of test frets, go for it!
Return to top
Stretch Tuning
Stretch tuning means progressively making higher notes more sharp. Pianos are usually stretch-tuned. That is because, at the highest octaves, there are problems with the overtones matching the notes on the octaves below, and at the lower octaves, there is a problem matching the overtones with the lowest octaves. Correction for these problems results in an S-shaped curve of intonation, with the higher notes being raised even higher, and the lowest being lowered even more. On a piano, each note is intoned separately. Because of longer string length, concert grand pianos need the least correction from equal temperament.
On a guitar, however, notes cannot be intoned separately, so, in order for a particular note to be the same on multiple strings, for stretch tuning, it would be necessary to stick with a constant rate of pitch increase, the same on all strings. The guitar does not have nearly the range of the piano, so there is really no need for stretch tuning. The piano plays 8 octaves, while the guitar plays only 4.
Stretch Tuning should not be tied to nut compensation, but it could be used in conjunction with nut compensation. As I understand the Buzz Feiton System, it does not seem to use overall stretch tuning, but uses stretch on some strings in order to effect particular harmony tweaks.
Still want to try it? To effect stretch tuning, the strings are shortened at the saddle so that the notes from low to high are progressively sharpened - by how much? Pianos stretch about 2 1/2 cents per octave, on the lowest and highest octaves. It would depend on preference – try it and see if it sounds nice to you (usually not difficult on an electric guitar, unless you reach the saddle adjustment limits). Remember to consider what other instruments you will be playing with, and how they will be tuned. Oh, and you’ll need a special tuning procedure!
As an acoustic guitarist, stretch tuning holds no appeal for me, but if I were playing high, soaring solos on an electric guitar, I might possibly think differently.
Return to top
