|How to build a Superior Airfoil Banjo Bridge.
The reason for banjo bridges having openings is to cut down on the mass of the bridge. Heavier bridges make
for a mellower tone. Very light bridges make a bright sound. My experiments with different woods indicate what
most banjo players and builder already know it takes a very heavy (dense wood) to give a good banjo sound.
Maple has been tradition but it has to be shaved very thin to compensate for the heaviness of the wood. My
doing this it gives a quick response without sacrificing depth of tone. In my work I have found that Rosewood is
superior to Maple for banjo bridges. I have tried Ebony and found that it too dense, but that not to say, that a
shrill sounding banjo might benefit from an Ebony bridge. Ralph Stanley used to give lessons on how to sand
down Ebony for banjo bridges. He played an arch-top banjo.
The reason for breaking the banjo bridge into separate
feet is to allow the bridge to flex to the concave shape of
the head, keeping the contact pressure even crossed the
base of the bridge, the looser the head the more of a
curve the bridge has to conform to. Neither the number of
feet, nor the sizes of space between feet openings in the
bridge base seem to affect the tone.
|Pictured is my four-legged bridge on my
You will note where the bridge feet contact the head of my
banjo it is a symmetrical elliptical airfoil shaped. This
shape came from Michael Kasha work on classical
guitars. He states that the bridge needs to be tuned to the
frequencies of the strings. So the head contact under the
deepest lowest strings of the bridge base needs to be the
widest, and under the highest-strings the base needs to
be very narrow. The airfoil shape was an accident
because banjoes have it peculiar fifth-string the highest
string above most bass string; or in my case the six-string
String saddles: On my pictured bridge I have none. A very hard substance will add to the brilliance, overtones
and sustain of a note. Ivory, many plastics, pearl which is what will I recommend in individual block under
above even deeper bass string. So, I shave the bridge to points on either end leaving the widest parts under
the bass-strings. I was rewarded with incredible improvement in sound of my banjo and it cause me to go
back and review Dr Kasha work and my work on guitars. Because of propagation speeds and other factors
the best width for a banjo bridge is about ¼” I have tried wider and thinner and it about right. I believe the
best height is about ¾”. The lower the harsher the sound becomes; if you have to make an Ebony bridge
make it less than ½” high.
|John Alden Robinson
17415 N. 75th Ave
Glendale, AZ 85308