What’s the difference between a hex core and a round core string?
Today, electric guitar and acoustic guitar string sets comprise of a mix of plain steel strings and wound strings. Plain steel strings are simply one piece of cylindrical steel wire running the entire length of the string. However, when we refer to strings that have a central core, we’re referring to the thicker ‘wound’ strings. These strings are (in almost all cases) made up of two parts: a central core wire and an outer wrap which travels around the core. This central steel core wire can come in two main shapes: hexagonal shaped and round shaped (or more commonly referred to as hex core and round core). But what’s the difference? Is there a difference? How do they compare in playability and sound? We’ll try and tackle all these pressing questions below to help improve your ‘core knowledge!’
Round Core Strings
If we were to slice through a round core string, you’d notice that the core is (as the name suggests) round shaped. Because of its smooth edge the outer wrap wire travels around the core and remains in complete contact with the core’s entire surface.
“That’s great, but what exactly does this mean from a tone and playability standpoint?” we hear you ask. Well, because these two components are in complete contact, when you strike the string and it vibrates, the core and wrap wire move ‘as one’ which gives a nice flexibility to the string. We liken the core and wrap wire of a round core string to two professional salsa dancers… both in sync with each other, they move with a lot of fluidity and flexibility. Another advantage this property gives is that when you strike the string, this “togetherness” delivers a big, boomy tone.
Above: The outer wrap wire remains in contact with the entire surface of a round core string.
Many years ago, strings were exclusively wound over a round core, however, in recent times hex core strings have become the most popular choice for most string manufacturers. Despite being less favourable, round core sets are still available today from brands including Thomastik, Pyramid, Martin and DR strings. In fact GHS Boomers (the company’s flagship electric string line) are constructed using round cores too. This is actually quite unusual as most of the sets on the market today utilise hex cores…
Hex Core Strings
As you will have probably guessed, instead of being circular, the core of a hex core string is shaped like a hexagon with 6 sides and 6 corners. Because of its shape, the outer wrap wire doesn’t make complete contact with the core’s entire surface, instead it digs into its corners.
Above: As you can see the wrap wire only makes contact with the hex core’s six corners rather than being in complete contact with its entire outer surface.
This gives the outer wrap wire and the core a “tighter” bond which makes the string feel slightly stiffer but also gives the string a brighter tone.
This tighter grip also means that hex core strings benefit from greater tuning stability. That’s not to say round core strings inherently have tuning issues, however, on the whole hex core strings do tend to stay in tune a little better. In fact, GHS state on their website that “round core strings need larger core wire diameters to equal the same amount of stability and strength as hex cores”
As mentioned earlier, hex core strings are more or less the norm nowadays when it comes to the manufacturing of guitar strings. Most of the popular brands including D’Addario, Ernie Ball, Elixir and Rotosound favour a steel hex core for all of their strings whether they be for electric guitar, acoustic guitar or bass guitar and there is good reason for this.
As you can imagine, for manufacturers the benefits of increased tuning stability is a massive advantage, not to mention, the production process for round core strings is more time consuming so hex core strings have also helped improve manufacturer’s efficiency too.
If you’re not sure whether a set of strings has a hex core or a round core, be sure to check out the listing on our website as we specify this attribute on each of our sets.
Don’t trim too early!
Being made aware of when to trim your guitar strings is something that may seem unrelated to a blog explaining the differences between the types of core, however, it is quite a significant matter.
As explained earlier, hex cores ‘grip’ hold of the outer wrap wire much tighter than a round core guitar string does. So, if you were to trim a hex core string the wrap wire is able to maintain its strong hold on the inner core and therefore its ability to stay in tune effectively.
However, when you trim a round core string, if care is not taken, the tension holding the core and the wrap wire can easily be lost and as a result these two parts become detached from one other. Tonally the string sounds ‘dead’ and unfortunately this cannot be recovered and therefore a new string will be required. When these two parts do become detached, we’ve seen instances where you can actually slide the winding up and down the length of the string, almost like a sock running over the core.
Trimming the string correctly is particularly significant for players with instruments that have slotted (vintage style) machineheads. These machineheads require the string to be trimmed prior to winding them around the post. So does this mean that you can’t use round core strings on guitars with these machineheads? The answer is actually no, use round cores, you just need to be mindful to take an extra step prior to fitting your strings. So rather than just trimming your string at the desired point, before you do this, be sure to bend the string at 90 degrees and trim the string about 1 inch beyond this point. This bend maintains the tension between the core and wire ensuring it doesn’t slip when the string is trimmed.
So it’s a case of ‘bend then trim’ ‘trim then bend’ when it comes to round core strings.
As you can see there’s a little bit more to cores than initially meets the eye. Both types of strings certainly have their advantages and individual quirks and you may find that one particular type lends itself more to your style of playing. Although there is a far greater choice of gauge and wrap material on the market when it comes to hex core strings, round core strings certainly offer something different in terms of feel and tone so it’s certainly something worth exploring further.
Be sure to check in with us next time where we’ll be talking more about cores and in particular the ratio in size between the central core and the outer wrap wire.
Thank you so much for reading our blog in 2018 and thank you for all your comments. We always love to hear from everybody and look forward to writing more this year. Happy New Year from all of us here at Strings Direct.