A Question Of Scale
Scale length has a big influence on a guitar’s performance, Paul Reed Smith tells Jamie Dickson – but string gauge and tuning are just as vital
Anyone who spends enough time around guitars will run into the term ‘scale length’ eventually. But what does it mean and how does it influence a guitar’s performance?
To deal with the first question, scale length describes the theoretical length of the ‘speaking’ part of the string – the bit that vibrates when struck by a plectrum: in other words, the section that is stretched at high tension between the guitar’s top nut and the saddle. We say theoretical because the scale length is simply used to calculate the position of the frets. The actual string length between the nut and saddle is longer and requires local adjustment for intonation otherwise the guitar wouldn’t play in tune.
Scale length often varies between guitar models: most Fender electrics have a scale length of 25.5 inches (648mm), for example, while PRS Custom 22 and Custom 24 models have a scale length of 25 inches (635mm). Classic Gibson electrics such as the Les Paul are usually described as having an even shorter 24.75-inch (628.7mm) scale though, as we shall see, that figure is a little misleading.
So, how do you measure scale length? Well, most measure the distance between the nut and the 12th fret and multiply that by two. That assumes the nut is in the correct position, of course, and some makers use compensation – the nut is brought forward very slightly (and sometimes is slightly angled) towards the 1st fret: PRS is a good example.
So, why does scale length matter? Put another way, how does a guitar with a longer scale length behave differently from a guitar with shorter scale length?
“It depends on the gauge of strings,” says Paul Reed Smith, founder of PRS Guitars. “If you take a guitar with a Gibson scale and you put a set of nines on it, when you hit the low E hard, it goes almost up to F and then goes back down to E. But if you fit a set of nines to a guitar with a 25.5-inch scale and hit the low E, it doesn’t go very sharp. So one of the things that happens when you increase the scale length is that the strings are tighter.”
Tuning & String Gauge
This is the first thing to remember: tuning and string gauge being equal, a guitar with a longer scale length will feel stiffer to play but will have more stable pitch when hit hard than a guitar with a shorter scale. As the frets are spaced more widely on a longer-scale instrument, it will also feel a bit more of a stretch to play at times. Subtle stuff, it is true – but tangible and with real impacts on the sound, feel and playability of the guitar. And if you start altering the string gauge used on the guitar and its tuning as well, the picture becomes more complex, as Paul explains: “Here’s an example for you – Machine Gun [by Jimi Hendrix] was played on a 25.5-inch scale guitar, strung with 10s but tuned down a whole step. When you do that – when you tune it down – it loosens the strings.”
Listen to Machine Gun, as Paul recommends, and you’ll hear that the classic Strat tone is still there but it’s fatter and looser-sounding than if it had been played at standard pitch. The effect is subtle but noticeable and very cool.
The takeaway here is that if you want a looser feel from a guitar with a 25.5-inch scale and keep your nice, chunky 10s on it, you’re going to have to tune the guitar down. However, if you want to stay at standard pitch and achieve a looser feel, you need to either select a guitar with a shorter scale-length or use lighter-gauge strings. Fitting lighter strings can make the guitar sound different, however, so choosing which way to go is not as simple as it might first appear. The main thing to understand here is that a guitar’s scale length doesn’t deliver a fixed set of characteristics all by itself – tuning pitch and string gauge also come into play. Why? Because all three things influence the
“Tuning and string gauge being equal, a guitar with a longer scale length will feel stiffer to play but will have more stable pitch when hit hard”
tension of the strings and, in so doing, interact with each other in a pretty complex way.
“Let me give you another example,” Paul says. “You can take a 25.5-inch scale guitar and you can put really big strings on it and tune it down to C# and it’s one of the best baritones you’ll ever hear.” He continues by saying, “We got given a hard time by the internet when we did the Mark Tremonti Baritone,” referring to the fact that baritone electrics often feature something like a 29¾ inch (755.65mm) scale. According to forum lore, making a baritone with a mere 25.5-inch scale, as on the Tremonti, shouldn’t work. But that wasn’t what Paul and Mark found when they tried it. “He thought it sounded monstrous. I thought it sounded monstrous, but the internet said, ‘Oh, you can’t do that at that scale.’ Well, yes, you can.”
In this case, fitting heavy-gauge strings (0.014 to 0.068) to the Tremonti Baritone gave Paul the right feel and usable string tension when that 25.5-inch scale guitar was tuned down to C#. That’s because the increase in string tension generated by using heavier-gauge strings balanced out the decrease in tension caused by dropping the tuning – permitting a relatively conventional 25.5-inch scale to be used. But, of course, a 25.5-inch scale also sounds great when tuned up one-and-a-half steps to standard E tuning with normal, light-gauge nines or 10s fitted. After all, that’s what a Strat uses. So you can see that it’s the interplay between all three factors – string gauge, scale length and tuning – that determines whether a guitar is suitable to be a baritone or a conventional electric tuned to plain old vanilla E. Adjust just one parameter slightly and you change the playing experience of the instrument; orchestrate all three intelligently and you enter the realm of advanced guitar design. “It’s a very complicated but very beautiful little equation,” Paul concedes.
Next month we rejoin Paul to discover why he chose a 25-inch scale for some of his most famous electrics, such as the Custom 24 – and learn why many people have misunderstood the correct scale length of vintage Les Pauls for years.