Fig. 1. This creatively rearranged headstock
creates a longer low-B 5th string.
Fig. 2. Two systems for lengthening the 5th
string at the bridge. The commercial model
on the right is an aluminum tube.In the “good old days,” basses had four
strings, the music grooved, and bass players
knew their place and role in the band. And
then someone gave them a 5th string, and
before long the first bass soloists showed up
and demanded a 6th string (or even more).
While adding higher-pitched strings to a
bass was a no-brainer, the low B often caused
problems. Players found it too floppy and
undefined, or complained that its sound
didn’t blend in with the rest of the strings.
Many manufacturers—and especially smaller
custom builders—answered this complaint by
making fretboards with extra-long scales, or
adding fanned frets and so on. In the process,
some less-than-brilliant ideas popped up.
Ever heard the “longer is tighter” argument?
The reasoning behind it goes like
this: For a given scale length, string, and
pitch, you can increase tightness and bass
output by adding string length behind
the bridge or nut. For many, this conflicts
with what they learned in their first school
physics classes, but the argument pops up
so often (even among well-known luthiers)
that it’s worth taking a closer look.
Fig. 1 illustrates one manufacturer’s
attempt to put the longer-tighter theory
into practice. In this headstock drawing, the
low-B tuner is moved to the top to increase
the 5th string’s length behind the nut. The builder must have been very convinced
of the concept because in the process of
executing this design, he scrambled the
succession of the tuners, mixed rotational
directions, and surrendered the straight
alignment of the strings.
Fig. 2 shows two DIY ways to lengthen
the 5th string at the bridge. The commercial
model—an aluminum tube—was called
the “B-string extender” and well promoted.
So do these approaches work? Let’s look
at the extremes: If extending the 5th string
at the nut truly tightens the tension and
increases low frequencies, a headless bass
would have the floppiest B with the least
amount of bass.
Or imagine this: You have a standard
headstock, but instead of attaching the
string normally, you bend it around the
headstock, lead it all the way back to the
body, and tune there. It’s a great way to
get a tighter string and bassier tone, right?
Just think, in the studio, you could attach
a bass to a stand and run the string across
the room. It might be so tight, you’ll need a
hammer to pluck it, but the tension would
tear down walls! Or how about bringing a
cable drum with a rolled up string onstage?
Yes, this sounds like nonsense.
Why doesn’t this work? Here’s the formula
for calculating tension (T) or pull of
a string of a specific weight (w) per inch or
centimeter, at a given scale length (l) and
frequency (f ): T = x* w* (l* f )²
Note: (x) is a simple constant, depending
on your numerical system. FYI, the tension
of a .130" B string at 30.9 Hz is about 32
pounds or nearly 15 kilos.
Use a thicker string with increased specific
weight and get more tension. Same
thing if you tune higher or use a longer
scale length. Sorry for all the math content,
but you can easily see there’s no mention of
any extra length behind the nut or bridge.
Now let’s consider elasticity—essentially
the technical term for the “tightness” we
feel when plucking a string. We’ll skip
the formula, but elasticity is a term that’s
defined by length: the longer, the more
elastic—at least for an “ideal” friction-free
bridge and nut. Once there is measureable
friction, there will be no difference at all.
So once we add length to that passive
part of the string using this kind of B-string
extender, all we get is less tuning stability
and in the worst case, even less tension.
There are ways you can beef up your
low B. These include getting a new, stiffer
neck, improving the body-neck connection,
or simply trying a different set of strings.
(D’Addario offers an extensive list of string
parameters, which can be helpful as you
explore and experiment with strings.) If you
like a particular set of strings, but the low B
doesn’t work on your bass, why not simply
try out a variety of individual B strings?
If you’re still not convinced about the
low-B extender, give that cheap, multi-nut
DIY mod a chance. But keep in mind it
will add mass to the bridge. Whatever
that does to your tone, it will not alter the
string tension.
Heiko Hoepfinger is a German
physicist and long-time bassist, classical
guitarist, and motorcycle enthusiast. His
work on fuel cells for the European orbital
glider Hermes got him deeply into modern
materials and physical acoustics, and
led him to form BassLab (
basslab.de)—a
manufacturer of monocoque guitars and basses. You can
reach him at
chefchen@basslab.de.