Guitars are absolutely central to mixes across a wide range of genres, but they are notoriously difficult to mix. Mixing is about creating individual space in the frequency spectrum for each musical element. It can be difficult to integrate guitars into a mix because they create sound across such a wide range of frequencies, and this is particularly true if they are distorted. This means that while you do need to pay attention to the tone of the guitar you are mixing; it is even more important to make sure that the guitar isn't masking other musical elements. Below we discuss some techniques that will help you with this.
It is well known that guitar recordings can pick up low-end rumble, whether the guitar is acoustic or electric. Distorting a guitar can further increase the presence of these unwanted frequencies, and your mix can become cluttered with this messy low-end. You can often remove everything under 200Hz or even 300Hz with a high-pass filter without any negative consequences, but do be careful that you are not removing too much warmth from your guitar part. In some mixes the low-mids are really important to the guitar sound, and in some mixes they aren't; evaluate each individual mix and its needs. While most engineers know to remove the low end from guitar parts, far fewer remove troublesome high frequencies. Guitars, and especially lead guitar parts, contain a lot of messy, high frequency information that can actually reduce the clarity of your guitars in a mix. On lead guitar parts, try using a low-pass filter to remove frequencies above 10kHz. You should find that this brings additional high-end clarity to both the guitar part itself and to the mix in general.
A great thing about electric guitars – and about distorted guitars in particular – is that we are used to them sounding pretty weird! If you use a drastic EQ on a violin or a piano, it will draw attention to itself as sounding unusual (this is not always a bad thing, but most often, you will not want to take this route). With an electric guitar, we are far more likely to accept a sound we are presented with, as we have heard so many weird and wonderful guitar tones in the past. Take advantage of this – you can be pretty brutal with your EQing, so make sure that your guitars aren't masking other important mix elements. When you do this however, make sure that your guitars retain character. Most of a guitar's character lies in the mids, so if you cut all of these out, something could be lost.
If a guitar is playing an important part, such as a key riff or chord pattern, it is tempting to pan it close to the centre of the mix. If you pan it too wide, it could unbalance things. The problem with this approach, is that if it's right there in the centre, a guitar can start cluttering the mix up – and in particular it can get in the way of a lead vocal. A solution to this is to pan the guitar to one side of the mix, and then send it to a delay that is panned to the opposite side of the mix. Set the delay to 100% wet and set a very short delay time. Your ear will be tricked into thinking that you are hearing two different parts panned opposite one another. Your mix will remain balanced, but you will have created space in the centre.