Alan writes:
>>The bridge insert has about a 2mm
>>offset for the 3rd (G) string to make it that much longer in the speaking
>>length. I understand string physics and music theory but I don't understand
>>this since the fret spacing is the same for all strings. (?)
>>I don't know how much
>>inharmonicity there is in nylon strings, but there must be some. So what
>>have the luthiers done, here?
Greetings,
The fingers play into the guitar's intonation in a way that pianos are
free from. The amount of pressure downward behind the frets can have a lot
to do with the pitch of the string, (and this effect changes between the 1st
fret and the others), the height of the frets, and the gauge of the string,
and the way an individual plays the instrument. It is not uncommon for an
"untunable" guitar to suddenly become tractable and pleasant with a change to
a different set of string gauges. I have also seen guitars that sounded much
cleaner with a fret job, and in one particular case, all that was done was
lower the frets. How does all this work together?
The importance of string height comes into play when listening to pitch at
the first fret, since depressing the strings this close to the nut can really
increase string tension more than when fretting higher up on the neck. It is
not usually necessary to press the string all the way to the fingerboard
here, and even so, there is considerable range of pitch that can be had with
varying the downward pressure. How much variety will depend on the strings
and action height, which depends on how the guitarist wants to play: ie, the
bluegrassers here like max. power, so they usually have high actions and
heavier strings, the session guys like a more sensitive feel and usually use
lighter strings with lower actions. The high action brings more variable
tension into play, since the fretboard is farther away.
So, the neck set,which determines string height for a give particular
style of play, also is a factor in how cleanly a guitar intonates. String
weight also bears on this and fret height too.
Keith, (with a prodigious memory) writes:
>>Ed Foote has explained this sometime in the past. Something to do
>>with balancing out the intervals for the 2nd string
I find the guitars are most usable in ET. The secret to finding a happy
place for the B string depends on the G-E sixth not being too wide. If it
is, there is no place for the B string to simultaneously make a satisfactory
fourth with the E and a usable third with the G.
The only way to keep the G-E sixth small enough for this is to make sure
that the open fourths are all stretched wide, which allows the upper E to be
low enough. I do this with fourth checks, using the 1st fret on the string
below to check both notes, ie, compare Bb(on the Astring) to both the D and
the G, making sure that the Bb-G is beating just a hair faster. Then use the
F(on the E string) to check the A string against the D, same test. The low E
hasn't a test note below it, but can be brought up to stop any beating
without narrowing the E-A fourth. When done correctly, the high E string can
be tuned as a single and double octave to the other E's (low string and 2nd
fret on the D string). The B-E fourth will have a beat of about .5 BPS on my
guitar, though I find that Gibsons tend to run a little faster. Check that
the G-B third is slower than the G-E sixth, your 2nd fret on the A string
makes a nice octave with the open B, and you are ready to go.
When my guitar is really speaking, there is only a barely perceptible roll
in the D-G fourth, the other two fourths beat so slowly that it isn't
apparent they are tempered. (I have a 1946 Martin D-18 and it sounds its
absolute best with the Marquis light gauge).
Regards,
Ed Foote RPT
This PTG archive page provided courtesy of Moy Piano Service, LLC