| Subject: | Re: [RESOGUIT-L] Intonation question | | Date: | Thursday, January 5, 2006 07:23:33 (+0000) | | From: | reso-man <reso-man @.......net>
|
Hiya Dick,
And a HAPPY NEW YEARS to you too!!
unsigned and in hiding!
-------------- Original message --------------
From: Richard DeNeve <richard_d13132@yahoo.com>
> John,
>
> The reason the bridge saddle on a flattop is slanted
> is due to the dosplacement of the plucked string.
> That is, the side-to-side movement of the strings.
> The treble strings have little side-to-side movement,
> so they can lie closer to the fretboard without
> buzzing against it. The heavier strings have gfreater
> amplitude of movement, and are more prone to buzzing
> or rattling against the frets. These strings are
> raised by elevating the bridge, to give them more
> clearance. But then, as you pull the string down to a
> fret, you increase tension on the string, which causes
> the note to go sharp. Slanting the saddle lengthens
> the string from the fret to the saddle, flattening the
> note again to bring it back in tune. It is a
> compromise, but usually a pretty good one.
>
> In the reso, we don't have that problem, as the bar
> places approximately equal tension on all strings,
> stretching (and sharpening) them all to an
> approximately equal amount. I don't know about other
> builders, but I offset my bridges about 1/16th of an
> inch to compensate for this, while keeping it
> perpendicular to the strings.
>
> Another problem those folks have is the stretch
> inparted to a string between frets. That is, the
> frets behind and in front of a fretted string holds it
> above the fretboard. Finger pressure pushes it down
> to the fretboard, adding more stretch. I recently
> "adjusted" an electric guitar for the above mentioned
> string sway, saddle height, etc., but the G string
> especially went sharp when fretted. I told the owner
> that she could use lighter finger pressure or use a
> heavier string, that would stretch less, but would
> also press into her finger more and hurt her
> uncalloused fingers. We replaced the .017 plain 3rd G
> string with a .022 plain. The problem went 90% away;
> she could live with the compromise.
>
> On the reso, we trade in these problems for other
> ones. When we play, say, a D note on the 3rd string
> while doing a roll on the first two strings, the bar
> has to be placed just a bit flat of the 7th fret,
> because the tip of the bar is depressing the 3rd
> string more than it would if we were fretting all the
> strings. This causes the 3rd string to go sharp, so
> we slide down a bit to compensate. The amount varies
> from player to player (due to differences in bar
> pressure) and from guitar to guitar (different mass in
> the 3rd string will require different tensions to
> bring them in tune, and they will be varied in the
> amount of added tension by the same amount of bar
> pressure.) Practice with your own machine will
> minimize these effects in your playing.
>
> Some folks have written about flattening the B string.
> This is done because we can. Most guitars are tuned
> to frequencies that are what are called "equal
> tempered" chromatic scales. That is, each note's
> frequency is increased by a given amount (105.9463094
> times the frequency of the next note lower) to attain
> the next note. All notes are separated by the same
> mathematical amount. But chords sound best to our
> ear when the notes are exact multiples of ofe another.
> This results in a D note not being a D note. That
> is, on the tempered scale, with a 3rd string G note at
> 196.00 cycles per second (Hz for you modernists), a D
> first string is listed as 293.66 cps. But if you tune
> them to unison with harmonics, twice the 1st string
> frequency should be 3 times the 3rd string harmonic.
> That is, if the 3rd string is tuned to 196 cps, the 1
> string should be 294 cps, not 293.66cps. Now, 0.33
> cps isn't a lot, but the notes will "clash" once every
> 3 seconds.
>
> The case is a bit more extreme for the B string. You
> can tune to the harmonics of either the 3rd string, or
> the 4th. I prefer to use the 4th harmonic of the D
> string (chimed at the 4th fret) to the 2nd harmonic of
> the B string (chimed at the 7th fret). That is, 5
> times the frequency of the 4th string (146.63 cps)
> should be 3 times the frequency of the B string.
> Doing the math says the B string should be at 244.38
> cps, but the tempered scale of your electronic tuner
> would have you tune to 246.94 cps. Using your tuner,
> you would clash about 2-1/2 times a second with a B
> and D note which most ears would detect as dissonance.
>
>
> The difference between A# (233.08 cps) and B (246.94
> cps) is 13.86 cps. The 2.56 cps difference between
> the tempered scale and the mathematically derived
> value based to a G or D note is about 18% of the
> difference between the A# and B notes. Quite a bit, a
> sixth of a fret. So we tune flat ==> because we can,
> and because it sounds better! We tune to an oipen
> major chord, and the straight bar maintains this
> mathematical relationship all up and down the neck.
> (It might get a little off on slant chords, but still
> isn't bad.) On a flattop, and other instruments, they
> try to deal with the lack of proper frequency with
> compensated nuts and bridges; we compensate by tuning
> the B just a bit flat. The B note is a different
> frequency in a B chord than in a G chord; both are
> different than than the B note in an E chord. They
> vary the lengths of their different strings (by
> fretting them at different frets at the same time)
> trying to get a good sounding chord, but it is always
> a compromise. We tune true to an open chord, and
> shorten all the strings the same amount at the same
> time. Makes things easier.
>
> Using the G of the 3rd string at 196.00 cps, and
> chiming the other strings to get the guitar in tune
> with itself, the first string D would be 294.00 cps,
> the 4th string D would be half that (147.00 cps), and
> the 6th string G would be 98.00 cps. The second
> string B would be 245.00 cps, and the 5th (B) string
> would be 122.5 cps. Neat and easy.
>
> Once again, more than you need to know.
>
> Dick DeNeve
>
> --- John Risdon
> wrote:
>
> > I have what may be a silly question, however here
> > goes:
> >
> > On non-reso electric guitars the bridge is either
> > adjustable for
> > individual string intonation, or on most acoustics
> > (and some electrics)
> > the bridge is at a slant to allow for the
> > differences between the high
> > strings and the low ones. Resonator guitars that I
> > have seen all appear
> > to have a bridge that is straight (perpendicular to
> > the body).
> > Shouldn't it be at a bit of a slant to compensate as
> > in other acoustic
> > guitars? or does the use of a steel across the
> > strings reduce the
> > difference in the strings that occurs when they are
> > played by pressing
> > down against the fretboard?
> >
> > John
> >
> > John Risdon, B.A., PMP, CRM
> > PM Consultant
> > (613) 282-5240
> >
> >
> >
> >
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>
>
>
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