Round Core Guitar Strings History

The theory of round core wires has roots in violin family instruments and piano/harp strings. Those
instruments virtually always use round core wires instead of hex shaped cores. There is a sonic
difference that is 'probably' noticeable to most listeners. I suggest 'probably' because there will
always be some point where other factors overpower the small differences in sound
that hex vs round cores demonstrate.

Typical electric guitar strings, and most steel string acoustic guitar strings use
core wires (for the wound strings) that are HEXAGON in cross section. That is, the wire
is not ROUND but it is hex shaped with six 'corners'. The theory behind the hex shape
core wire is that the mild points or corners of the hex shaped wire 'bites' into the winding
wire which is wrapped around the core. That mild bite helps to lock the winding to the core.

There are some strings, both electric and acoustic, that use ROUND core wires
rather than HEX shape cores. DR strings, Tomastik Infeld (TI) are the two strings
that I am most familiar with that use round cores.

TI Roundcore Swing and BeBop Electric   -   DR Sunbeam Roundcore Acoustic

Round Core Guitar Strings Construction

Round core wires have more even contact with the windings. Imagine wrapping a piece of
wire around a piece of round pipe. The wire, like the windings on guitar strings,
contacts the pipe with equal pressure throughout the entire circumference of the pipe.

Now imagine wrapping a piece of wire around a rectangular piece of lumber, like a 2 x 4.
The wrapped wire will 'dig in' to the square corners of the lumber. The wrapped wire
contacts the 'flat' sides of the lumber with a lot less pressure.

Imagine the same thing happening with guitar strings. The outer windings, when wrapped
around a hex shaped core, will contact the 'points' with more pressure than when they
contact the 'flats'. But do the same thing on a round core wire and the contact pressure will be
equal everywhere winding meets the core.

Tomastik Infeld, The Austrian string manufacturer, takes this process one step further.
They wrap the round core with not ONE but TWO layers of winding wire.
That results in a more flexible string, with less overall tension.

Dbl Flatwound TI Roundcore        Dbl Roundwound TI Roundcore 

More evenly distributed pressure in the windings typically results in:

1 - Lower overall tension

Round core strings have lower tension than hex core strings. The perceived 'work'
required to fret the strings is less with round core strings. If your fretting hand is bothered
a bit by what you perceive as a lot of string tension, switching from hex cores
to round cores will reduce that tension a bit.

2 - More sustain

Because all of the stresses of core to windings are more equally distributed, round core strings
can use more of their physical energy to produce SOUND. Hex core strings produce
more friction between the core and the winding. That means that some of the physical
movement of the string is wasted in producing HEAT instead of SOUND.

3 - Even Harmonic Overtones

Like the difference in tube vs solid state amplifiers, round core wires emphasize the
even or 'sweet sounding' harmonic overtones. This characteristic will be a little harder to
sense than the other two above. But we can measure it on a spectrograph. The resulting
tone is a little more 'bell like'. Consider that orchestral bells are made of tubular material.
Vibraphone bars are made of rectangular material. A subtle but noticeable difference.

Installing Round Core Strings

DR suggests, when you install these roundcores, be sure you have a wrap or two around the
tuning post before you cut off the excess length. The reasoning is that since the core is not
hex shaped, the windings are not locked to the core except at the distal crimp. I've
deliberately cut them at the windings to see if they seem to unravel. I can't measure any
increased diameter that suggests they are unwinding and I don't see any changes under
visual magnification. But it's probably worth considering doing. I install them the way DR
suggests, not cutting them until I've got them locked to the tuner posts, just to be safe.

As always, feel free to contact me about anything string or
music related. Or anything else, related or otherwise.

Craig 'Lumpy' Lemke - eBay songthief