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A reader in The Steel Guitar Forum asked
about the effect of "gearless" (also called "keyless") steel guitar heads
on pedal action. Here Ed Packard answers with an excerpt from his
upcoming book on the past, present, and future of the pedal steel
guitar and virtual instrument controller.
| Most of today's "Gearless" devices
are based upon a "lever" system as opposed to the traditional tuning peg
with the mechanical advantage being obtained via gear ratio. The more
common Gearless systems allow shortening the length of the string that
is not being played (behind the nut). On guitars that increase and
decrease the tension on the strings, the whole string stretches, including
the part behind the nut. This brought about the need for "rollers" as the
"nut" to reduce friction on the string when tension is changed. The less
string behind the nut, the less the amount the string is stretched behind
the nut, and the less the rollers are needed; This also means that the string
is more likely to return to "true" pitch after release. Please note that the
rollers should be "compensated" for the diameters of the strings used in order
to make the strings "flat" at the low frets (1,2 etc.) or the strings will
buzz against the steel. |
| The high strings are tensioned to about a pound of pull for each inch of
string "between the nuts" when tuned to G# or E. This is an approximation
for the purpose of easily thinking about the neck length issue. The actual
tension is a function of the string material and diameter. light gauge
strings require less tension to obtain a given note than heavy gauge strings.
The 24 inch neck would have about 24 pounds, and the 25 inch neck would have
about 25 pounds on the same string. The longer string must be stretched
farther to get the same pitch change; The length of string "behind the nut(s)
must be stretched too, ..the shorter this length the less the stretching
required. The amount of string stretching is visible, ..put a mark on the
string and push the pedal. You can see the string move. Try this at each nut;
do you see a difference? Which end moves most? |
| The tension on the strings attached to a "change" (pedal or lever) is
determined by the string gauge, material, neck length, and the pitch to
which it is tuned. The "stiffness" of the pedal or lever used to get the
"change" is a function of the "mechanical advantage" (leverage) of the
changer, bell cranks, the distance from the shaft center that the pedal or
lever rod is attached, the distance from the pedal or lever pivot point that
the pedal rod or lever arm is attached, and how far it is from the attaching
point to the place where the pressure is applied. The leverage within the
changer is also a "controllable variable" inasmuch as the raise and lower
holes for a given string are different distances from the pivot point of
the changer; and then there are the "return spring" tensions. This is a
complex mechanical system, ..mess with it at your own peril! |
| The "stiffness" issue is a matter of taste. Some like it hard, some like it
soft. The length of throw is also a matter of taste, some like it long, some
like it short. For a given guitar design (all are not alike), you can change
the "feel" by changing some of the afore mentioned leverage lengths; The
length of string behind the nut(s) will have relatively little effect upon
the total amount of "stiffness", and a bit more on the required amount of
travel required for the change. For the "fast" change players, adjust for
short pedal and lever throws, and remove any strings from the change that
you do not need; You are probably a "lick" oriented player, and minor in
getting multistring chords. For those that use half (less than full) throws
to get passing tones (1/2 P1 etc.), and those that like full chord changes,
adjust for the longer throws; This will reduce the "stiffness" for your added
string count per change. |
| Sustain: If the length of the vibrating string is considered as just two
parts (between the nuts, and between the left nut and the string termination
point), the following visualization can be formed; If the left nut is very
thin (narrow or pointed), and the open string is plucked, the string length
behind the left nut will also vibrate. The amount of vibration will depend
upon the length of the string behind the left nut, and the way that it is
terminated. If the length of string behind the left nut is the same as the
length between the nuts, the string vibration will decrease less with time,
viola, we have sustain increase, ..but only with open strings or open string
chimes (harmonics). When the steel is used and the left hand deadens (damps)
the string behind the steel, the sustain advantage from this cause is lost.
No PSG has that much string behind it's left nut. If that part of the string
were half as long, the open string second harmonic would be emphasized. If it
were one third as long, the open string third harmonic would be emphasized,
etc.. If it were of zero length, it would have zero effect except for the
damping in the termination method. |
| If in the above case, the nut were of large diameter, and of soft material,
the sustain would be less (for open strings and open string harmonics), and
the effect of the string length behind the left nut would be reduced; Both
the large diameter, and the soft material tend to damp the string vibration.
Sustain is also a function of pickup type and placement, string type, string
age, and string cleanness (skin oil, dirt, and body acid etching), ..We will
deal with these at another time. |
| Basically, a biting E9 is best obtained from a short neck, light gauge
strings, narrow nuts, and a pickup set far to the right. Mellow C6 like
sounds are best obtained from long necks, heavier gauge strings, larger
nuts, and a pickup set not so far right. Some of this is explained in the
study of the physics of vibrating strings. On BILL STAFFORD's brand of steel
guitar strings, it says "the tone is in your hands", ..fast, biting tone,
E9 pickers tend to use smaller diameter bars, ..mellow tone C6 players tend
to use larger diameter (heavier) bars. There is a definite difference in
tone and sustain when using each type of bar as opposed to playing open
strings. The tone and sustain is also a matter of where and at what angle
you pick the strings, and what the pick material and thickness is. There is
only one open string condition (fret zero and related harmonics), there are
24 frets to be used with the bar; How important is the sustain and tone for
the open string condition (without bar) as compared to the sustain and tone
of the remaining 24 frets (with bar)? The same might be asked about the
"tuning" scene (tempered et. al.). Tempered won't correct for uneven bar
pressure, or for non fret parallel bar alignment. It becomes lost in the
"vibrato", and our inaccuracy in bar position re one and two note clusters.
Maybe we can address the tuning issue under the heading of "the physics of
vibrating strings" at some other time, till then, tune for "maximum
happiness". For most types of music, pay more attention to what happens
at frets one thru twenty four than what happens at open strings. |
| Stiffness of changer action, and returning true, can also be a function
of friction in the mechanism(s). The changer is particularly susceptible
to collecting grit, grime, tars, sand, etc. Oil can make this worse if not
accompanied by frequent cleaning. |
| Ed Packard
(Edpackard@aol.com) is an engineer
who spends a lot of time thinking about pedal steel guitars. He is the
inventor of the PST "13 Series" Tuning which grew from a computer program he wrote to analyze the possibilities
of the instrument with regards to music theory and complex jazz chord forms. |
| Copyright 1997 by Ed Packard, HTML by Bobby Lee |
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