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Round Core vs. Hex Core Strings

Which Are Better For The Blues?

There is a lot that goes into the construction of guitar strings. Manufacturers alter a wide range of elements during string construction, and each of these has an impact on the tone their strings produce and also on the way they feel.

In my last few articles I have addressed some of the most significant of these factors - including string gauge and material. So if you are new to this topic, I would recommend having a look at those articles first:

• Are Light Gauge Strings Better For The Blues?
• String Gauge Of The Blues Greats
• Pure Nickel Vs. Nickel Wound Strings: What Is The Difference?

If you are in search of the perfect set of guitar strings though, there are a couple of final factors that are worth taking into consideration. These are the shape of the core wire in your guitar strings and also the way that the strings have been wound.

Both of these are quite lengthy topics, and as a result I will cover string winding separately in a future article. Here then, I will look at how string manufacturers alter the shape of the core wire in their strings.

This is a topic that is much less frequently discussed than string gauge or even string material. However despite this, it does have an impact on tone and playability, and is therefore worth taking into account.

So without further ado, let’s get into it! Here is everything you need to know about core wire shape and the impact it has on guitar strings.

What is core wire?

To understand why altering the shape of a string’s core wire is important, we first need to appreciate what core wire is, and the different shapes in which it comes.

Almost all electric guitar strings (at least of which I am aware), are made from a type of high-carbon steel wire.

In a ‘normal’ set of electric guitar strings, the core wire of the low E, A and D strings is then wrapped in a different material. Conversely, the G, B and high E strings are normally left ‘plain’. They are not wrapped in any other material, and are constructed just using steel.

As I explained in much more detail in this article - the core wire of the bass strings is then wrapped in a different material. And the material that is used has an impact on both tone and playability.

It is not just the material of the string wrap that manufacturers alter though. They can also change the shape of the core wire used on the bass strings. And this too changes the feel and tone of the lower strings.

Round core and hex core strings

There are two main shapes of core wire used by manufacturers - round core and hex core.

Traditionally, guitar strings were manufactured using round core wire. As the name suggests, the core wire in these string sets is cylindrical and this core wire is then wrapped with another material. As a result of the cylindrical shape of the wire, with round core strings, the entirety of the core wire comes into contact with the material that is used to wrap the string.

In more recent years however, string manufacturers have moved towards using hexagonal shaped core wire. This is usually referred to as 'hex core'. In contrast to strings constructed with a round core, only the corners of the hexagonal core come into contact with the material used to wrap the string.

D’Addario were the first company to move towards using hex cores in their strings. They did so way back in the 1930s and have only been followed by other string manufacturers in more recent years.

Once other string manufacturers followed suit however, they did not look back. And so at the time of writing, the vast majority of guitar strings on the market are constructed using hex cores. As such, the likelihood is that you are currently playing strings with a hex core.

The widespread move towards hex core was partly for practical reasons. In short, this is because it allows string manufacturers to machine wind their guitar strings more consistently. Having said that, the hex core does give strings a particular set of characteristics. These are notable both from a tone and feel perspective and could be either beneficial or otherwise - depending on your personal playing context.

Hex Core Strings - D'Addario NYXL logo depicts the core shape

Hex core strings

There are a number of notable characteristics of hex core strings. And these are as follows:

From a tonal perspective, hex core strings have a brighter and sharper tone. They also have a more pronounced attack.

This makes them a great choice if you like to play with a higher gain tone, whilst preserving the clarity of individual notes. After all, if you play with a higher gain tone that is also quite dark, you risk ending up with a muddy and mushy sound.

Equally, if you often play complex chords or a lot of single note lines on your bass strings, hex core strings can work very well. They will help the individual notes to ring out and push through the mix.

Finally, regardless of whether any of the above points apply - if you generally prefer a snappier and brighter guitar tone, then hex core strings could be the way to go.

Looking at feel and functionality, there are two important points worth noting.

The first of these is that hex core strings have great tuning stability. The corners of the hexagonal core wire ‘grip’ the material in which the strings are wrapped. This maintains tension across the string and prevents them from slipping out of tune. This is very useful for blues guitarists, who typically use a lot of bends and apply a lot of vibrato - both of which can quite quickly pull strings out of tune.

The drawback of this stability however, is that hex core strings can feel quite stiff under your fingers. And this makes them slightly more challenging to use when using techniques like bending and vibrato on the bass strings.

Some of examples of sets with round cores

Round core strings

Compared with hex core strings, those with a round core have a darker and more mellow sound. As most vintage guitar strings were constructed with round core strings, these strings are also generally associated with warmer and lower gain vintage tones.

If you are in search of a vintage sound then, opting for round core strings could be a great choice.

In addition to the generally warmer and darker tone of round core strings, they also have a more pronounced bottom end. The design of the string means that the string vibrates as a single piece of wire. The round core is pressed right up against the string wrap, and so there is no disconnect between the outer and inner sections of the string. This results in greater vibration, which in turn increases the output of the bass strings. So if you like quite a beefy and powerful bottom end sound, round core strings could also be the way to go.

In comparison with hex core strings, round core strings are also more flexible. This makes bending and applying vibrato on the bass strings easier, which is likely to be beneficial if you are playing blues and blues rock music.

Finally, round core strings have a longer shelf life. When you are playing your guitar - oil, sweat and dirt from your skin gets transferred to the strings. In the case of hex core strings this can permeate the outer string wrap and get stuck between the wrap and the hex core. This takes some of the brightness out of the tone and requires you to change strings more frequently. With round core strings this doesn’t happen. And so all things being equal, the average lifespan of a set of round core strings will be greater than that of hex core strings.

However, just as with hex core strings - there are some drawbacks to round cores. Firstly and significantly, if you are playing with a higher gain tone, or if you are playing lots of chords, you risk your tone becoming muddy and washed out. The round core strings lack the clarity of hex cores, and this can be problematic in some circumstances.

Secondly, the increased flexibility of round core strings makes them more likely to fall out of tune. And so whilst you might be able to bend and use vibrato freely on your bass strings, you risk pulling them out of tune.  If you are playing at home, this might not be such an issue; you can simply re-tune whilst you practice. However if you are gigging, it could be something to take into consideration.

The verdict

As is typically the case when it comes to guitar gear, there is no obvious ‘winner’ or right choice when it comes to deciding between round core or hex core guitar strings.

Round core strings have a warm and more vintage tone. They have a longer lifespan and are also more flexible than hex core strings. So if you are looking for a mellow and rounded tone, and you are less interested in brightness and the clarity of each individual note, then round core strings could be the better choice for you.

Conversely, if you are looking for strings that have a little more snap and brightness, or if you like to play with higher gain blues rock tones, then hex core guitar strings could work well.

Putting tone and playability aside for a second, there is one final factor that could sway you towards hex core strings. And it is that of the two types of string, hex core strings are by far the most common.

For example, if the concept of string core shape is new to you, it is highly likely that you have only ever played hex core strings. The vast majority of major string brands produce strings with a hex core, and many brands like Ernie Ball and D’Addario don’t even offer string sets with a round core.

As such, you might find that your favourite brand of string does not offer round core string sets. And depending on your brand loyalty, that might prevent you from even wanting to experiment with round core strings.

Some practical recommendations

Assuming however that you are open to some experimentation, the best way to decide if you like the tone and feel of round core strings is to try out a variety of different sets.

When it comes to brands that offer round core strings, there are two which really stand out. And these are GHS and DR.

The former offer the ‘Boomer’ range of strings, which come in a variety of different gauges. The latter offer both the ‘Pure Blues’ and ‘VERITAS’ range of strings. Again these are round core strings and they come in a variety of different gauges and also different materials. Some great choices to try out are as follows:

• DR VERITAS Strings (.010-.046)
• GHS Boomers - ‘Thick N’ Thin’ (.010-.052)
• DR Pure Blues Strings (.009-.046)
• GHS Boomers (.009-.042)
• DR Tite-Fit Strings (.011-.050)

Brands like Fender, Curt Mangan and others also offer round core string sets. So if for whatever reason you don’t want to try out DR or GHS strings, you can see the full range of round core options here

Putting it all together

As we dig deeper into some of these more nuanced elements of string design, it is important that we don’t forget the impact that elements like string gauge and material have on tone and playability too.

In my opinion there are three important points to keep in mind here:

Firstly,  the impact that different elements of string design have on tone and feel combine with one other. For example, one of the potential benefits of round core strings is that they have a warmer and more vintage tone. Yet as I noted in more detail here, pure nickel strings also have a warmer and more vintage tone than many of the ‘standard’ guitar string sets out there.

So if you choose a set of strings which are made from pure nickel and which also have a round core, you will end up with a potentially very dark and mellow tone. This could be exactly what you have in mind, or equally you might find that your tone becomes too dark and mellow for your liking.

Secondly, you will often find that there are various ways of achieving the same result. Let’s say for example that you currently play nickel plated strings, and you are in search of a darker and more vintage tone. You have the option of looking at pure nickel strings, round core strings, or both. In this way you can play around with a variety of elements to discover what works best for you.

Lastly, try to experiment with new elements like core shape in isolation. If you start changing the string core shape, material, gauge and brand all at the same time, it will be impossible for you to pinpoint which changes you find favourable (or otherwise). Always try to change just one element at a time. Experiment, adjust and take it from there.

Now, given that not that many brands offer round core strings, I appreciate that this might be tricky. However, if possible try to test out round core strings that are the same design as your current strings, apart from the shape of their core. So if you currently play pure nickel strings in a .010-.046 gauge, try and find the same type of strings with a round core.

Closing thoughts

When it comes to guitar strings, I do think that it is useful to understand how they are constructed, and the impact that this has on tone and playability. If nothing else, this helps you to appreciate the differences and characteristics of the many different string sets out there. You can then make informed buying decisions and hopefully find the perfect set of strings for your setup.

The potential risk of this knowledge however is that you suffer ‘paralysis by analysis’. You can easily fall into the trap of assessing all of these different elements in great depth. And if you combine those with decisions that you are probably also making about picks, guitar pedals and amps, it can quite quickly become overwhelming.

As such, try to relax and simply enjoy the process of experimentation. Give round core strings a go and see how you get on.  If you find you love them, brilliant! You are now one step closer to finding that perfect set of strings. Conversely, if you find they aren’t for you - or that you can create similar results by altering gauge or string material - that is also useful to know.

Either way, you will know more about how your strings are constructed and why they work well for you. And in my next article I will look at string winding, which in my opinion is the final piece of the puzzle when it comes to string design and choosing strings for the blues. See you over there!

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Aidan Bricker
The Happy Bluesman
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