Acoustic guitar strings

How guitarists stay in tune with a sonic miracle

Image credit: Dreamstime

Guitar music may not dominate in the way it once did, but guitars are still a billion-dollar industry with the strings that go on them a feat of engineering in their own right.

With 2.5 million units sold annually in the US - and the UK pitching in with an extra 750,000 - guitars are a billion-dollar business. Which means that the strings that go on them are big business, too. If every new American and British six-string had their strings changed at the recommended frequency of once per month, they would in their first year alone consume sufficient length of metal wire to reach the 384,400km it takes to get to the Moon.

Before the air around the string even starts to vibrate there is a lot going on. A guitar string may look like little more than a humble length of wire, but it is the apex of a music technology evolution. Given the extent of the engineering that goes into producing decent guitar strings it’s hard to believe that a set by marquee brands such as Ernie Ball, D’Addario, and Rotosound comes in at under a tenner – that’s a quarter of the cost of a set of violin strings.

Unfortunately, remarks one string manufacturer, the majority of today’s guitar players “don’t know s%$t about guitar strings”. But you need to have a grasp on the five key factors that make up a guitar string’s tone: gauge, material, core, winding and coating. This is because, as all seasoned pros will tell you, it’s better to have a bad guitar with good strings than a good guitar with bad strings.

Your choice of string material depends on your choice of guitar. The two main categories are acoustic (which have been around for about 500 years) and electric (since about 1930). The vast majority of guitars use strings made of metal (the main exception being classical acoustic guitars, which use nylon strings). In general, electric guitar string sets are made up of two unwound and four wound strings (we’ll get onto windings later), using either nickel-plated steel, pure nickel or stainless steel (although titanium, cobalt, chrome and copper are sometimes used). The different materials produce a variation in sound, with the most popular – nickel-plated steel – characterised by warmth and brightness of tone with a strong attack.

When it comes to acoustic guitars the three most popular options are 80/20 bronze (i.e. 80 per cent copper, 20 per cent zinc), phosphor bronze (which is more durable) and the ‘hybrid’ silk and steel variant that represents a crossover with classical strings that were once made of ‘catgut’ (actually sheep intestines), but are now nylon.

The manufacturing process at D’Addario starts by examining the high-carbon-steel core wire under a zoom stereo microscope to verify its hexagonal shape. Cores were originally round, but innovations in string design have moved towards the hex profile because the outer winding wires grip this shape better. The diameter of the core is checked with a digital micrometer, checked for its extension properties, followed by a twist test on a torsion meter to test its ductility. Then the core is cut to length and automatically assembled from two components: the core wire and the ball end (which holds the string in place on the guitar’s tailpiece). Today, ball ends are colour-coded to make the strings easily differentiated. The softer alloy wrap wire is then inserted by hand to the winding machine and drawn down the length of the core. A computer-controlled winding carriage ensures a consistent wrap, with sensors monitoring tension, speed and wrap angle.

Of the five critical variables in string construction, the most important is arguably gauge. This is simply how thick the strings are. This affects the guitar’s playability and action, string longevity and tone.

Quite apart from the fact that the six individual strings on a standard guitar (E6, A5, D4, G3, B2, E1) are of different thickness (and are measured in thousandths of an inch), you also have a choice over the ‘weight’ of the set. String sets are sold as ‘extra light’, ‘light’, ‘medium’ and so on, with guitarists referring to a string set by a shorthand number such as ‘10s’ or ‘11s’ (where 10 would be the ‘top’ E in a light set in which the individual strings come in at 0.010/0.013/0.017/0.026/0.036/0.046).

The reason for there being a variation in the overall weight of string sets is simply that different guitarists prefer different strings for different jobs.

In general, heavier string sets will be preferred in unamplified applications (because they’re louder), by slide or bottleneck players (because the strings are under higher tension) and by jazz players (who typically prefer a firmer ‘action’). Lighter strings are more responsive to finger-style playing, hurt less and are easier to work with for soloing high up at the dusty end of the neck.

Manufacturers routinely use string strength as a sales benefit and will include taglines in their advertisements such as “now 30 per cent stronger”. These statements are based on ‘break tests’ where the tension of the string is increased and measured until it snaps. “But the truth,” says Scott from Stringjoy Guitar Strings of Nashville, “is that while this might tell you a little about the string’s overall strength and construction, it doesn’t necessarily give you an idea of how that string will wear in actual play.”

Guitarists apply extra pressure on strings while bending notes for example, but this is minimal, so a more important measure is how the string stands up over time to repeated play. “Strings die because they lose their elasticity, and this happens because of corrosion at the core of the string,” which is affected more by humidity, sweat and how often the strings are cleaned.

E&T visited the manufacturing HQ of pioneering UK guitar string company Rotosound to hear what - if anything - has changed over the last 50 years. 

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