Chapter 8. The Problem with Tension

Chapter 8. The Problem with Tension

This section delves into the intricacies of string tension, explaining its measurement and the inconsistencies in tension categorization across different brands. It emphasizes the importance of understanding the relationship between string gauge, tension, and scale length in achieving desired playing comfort and sound quality. It also highlights the challenges of finding reliable information on string gauges and tensions from manufacturers.

 Balancing Playing Comfort and Tone

In their choices of strings, all players of classical guitars, regardless of musical genre, face the task of finding a desirable balance between playing comfort (finger pressure in relation to string tension/stiffness), tone production, and projection.

If a guitar already has the “Right Fit” from the start, the need to search for alternative brands and tensions is somewhat of a luxury. However, many guitars require experimentation, sometimes with the tension and tone of a single bass or treble string.

Strictly speaking, string tension is measured in terms of the weight (kilograms or pounds) required to stretch a string of a given diameter to a required pitch. Some string companies, notably D’Addario, provide details of both “tension” and gauge (diameter) for each string on their packaging, although many do not.

For example, Luthier and Paulino Bernabe have never published the statistical gauges and tensions of their strings, either on string packets or on their websites. Ramirez string gauges etc. are found only on the company's website. La Bella and Aquila do not print gauge details on string packs, so one needs to search their websites. Big string companies like Hannabach and Savarez are very inconsistent in providing gauge/tension information on their string packs. Searching out this information can be time-consuming. Thankfully, a lot of this obscure data has been assembled by Stringsbymail, which I often use.

 Using String Gauge as a Surrogate

Regarding “string tension,” I find it easier to use string gauge as a surrogate for tension statistics. In the world of steel-string acoustic and electric guitars, strings and string sets have always been identified by their numerical gauge (fractional in inches or mm).

For example, a 6-string set of acoustic steel strings can be abbreviated as “12-53,” summarizing the string set range as between .012 inches (high E string) and .053 inches (low E string). By contrast, nylon strings are marketed primarily in very generic tension categories.

Players of classical guitars face the annoying fact that there is no uniform system of matching tension descriptions such as “Medium/Normal,” High, or “Medium-High” consistently to numerical string gauges (i.e., diameters). This is further complicated by the different guitar scale lengths used by various string companies to categorize string tensions.

It took me some time to discover that this discrepancy was why “Normal Tension” in the brands of Savarez, D’Addario, and La Bella all felt different when fitted on my 650mm scale length guitars (the standard scale length for most classical guitars).

Savarez tension/gauges (like Hannabach) are based on the standard 650mm string/scale length, whereas D’Addario string categorization is based on 648mm (equal to 25 ½ inches, the same scale length base used for their steel-string acoustic guitar tension measurements). La Bella uses 655mm as its base for tension measurement. This may appear statistically minimal, but it does make a difference.

So, for example, on a standard guitar of 650mm scale length with nylon string sets, changing from Savarez crystal nylon to D’Addario will give a slightly harder tension, while La Bella feels slacker in tension.

 Understanding Tension Categories

So, what is “Normal” or “Medium” tension? Let’s compare a few well-known brands of conventional nylon treble strings labelled “Medium/Normal tension,” showing their relative string gauge/thickness/diameter (in inches) and tension (lbs. in brackets). Note that the higher the number in gauge, the thicker the string.

This table clearly shows gauge/tension variations between brands within the same generic tension category. In terms of lb. tension, they are not entirely comparable due to disparities in scale length measuring baselines between D’Addario, La Bella, and others.

The high E strings for the Royal Classics and Augustine Imperials stand out as having notably higher lb. tension than the other brands. That said, some of the statistical differences in gauge are very minor; the tonal characteristics of the strings will depend on how they differ in sound, projection, and feel when fitted to a given guitar.

It is possible to select four or five nylon strings (or carbon strings) with the same statistical gauge and test them on your guitar, only to find subtle differences in texture and musicality. This has to do with the particular differences in the nylon polymer compounds used in their manufacture.

One point of interest is that the current set of Royal Classics Sonata “Normal tension” SNT strings was originally classified and sold as “Medium-High Tension.” One wonders how and why these decisions are made. Interestingly, this set is very close in gauge and feel to Luthier Concert Silver (Blue) strings, which are labelled by that company as “Medium-high” tension.

We find similar variations of gauges in bass strings among string brands within the same general tension categories. Not surprisingly, differences in tension levels between given categories (i.e., between medium and high tension) vary according to string brand. Annoyingly, in some brands, the increase in tension category of string sets actually only applies to bass strings and not trebles.

 Early Music and String Tension

Guitar devotees of “Early Music” (Baroque to early 19th century) are more attuned (forgive the pun) than modern classical guitarists to the need to calibrate and calculate string tensions to the overall kg. or lb. tension tolerance of their instruments. This is partly due to the delicacy of the instruments (even replicas), attention to early music pitches, which varied considerably from the established modern concert pitch of A=440 Hertz, and the diverse scale lengths of these guitars (for example, see EarlyRomanticGuitar.com).

There is an excellent string calculator for early string instruments produced by the well-known Finnish lute maker Lauri Niskanen. This has been very useful to me in working out string gauges for my lutes and baroque guitars because it calibrates gauges of various string materials to string length variables. To my knowledge, nothing equivalent to the Niskanen String Calculator has been made available for the modern classical guitar.

 Deciding on String Tensions

Guitarists make decisions about preferable string tensions for treble and bass strings based on a range of considerations, extending from “feel,” volume, projection, sustain, and timbre. All of these factors interact with the capacity and features of the instrument they are playing – string height/action, level of neck relief, neck angle, etc. And of course, their playing technique – the embouchure of their thumb and fingers, strength of attack, etc.

The general rule is that the higher the tension, the greater the volume at the expense of tonal richness. This is certainly the case with bass strings. However, this depends on the particular construction of the guitar and its resonance capabilities.

In my case, although two of my own favourite high-end cedar-top guitars are fitted and perform well with standard string sets of Savarez 510 CR (Cantiga basses with nylon trebles, except for the addition of Savarez Alliance carbon G strings), I have a Spanish-made spruce top guitar that so far works best with a mixture of different brands of high-tension basses and normal to medium-high tension trebles, as follows:

 E - Royal Classics Sonata Normal Tension SN10: 0.029” NYLON

B - Luthier Concert Silver (Medium-high tension): No gauge indicated. NYLON

G - Paulino Bernabe (Medium-high tension): No gauge indicated. CARBON

D - Royal Classics Sonata High Tension SF70:  Silver plated wound 0.032”

A - Arunjuez Concert Silver 400 High Gauge: Silver plated wound 0.037”

E - Arunjuez Concert Silver 400 High Gauge: Silver plated wound 0.045

 I won’t tell you how long it took me to work out this tension/brand configuration for the best strings for this guitar. I know it looks a bit weird, but it works! Thankfully, I was listening to a good audiobook that helped me cope with the tedious process of string winding, testing, and unwinding.

Deciding on the “best” string tensions is a trade-off between musical considerations and playability. In most cases, it is not about finding the “best” strings, but about finding the “optimum” combination.