Mixing Acoustic Guitar
Here’s a quick look at how to make acoustic guitar sound better in your mixes. I personally find acoustic guitar one of the hardest instruments to mix and produce well. For me live acoustic guitars are up there with vocals in terms of the challenge in achieving a professional sound.
As with live vocals, the recording and performance can vary so much with each new recording session. Because of this you can’t really apply a painting by numbers approach. Instead here are 7 principles I recommend that you explore to try to make your acoustic guitar sound better in your next mix.
Before discussing the mixing techniques below, some readers asked about the microphone I am useing for Acoustic Guitar. My main mic of choice which is a great all rounder for any studio is the AKG C414. It’s been my go to home recording mic for a few years now and I find it really versatile for a number of instruments.
7 Steps to Acoustic Guitar Heaven
Before starting mixing we need to listen to what’s been recorded and try to identify what is good and bad with what we’re dealing with. In this example I was working with a double tracked acoustic guitar part that I had panned hard left and right. These two parts were then grouped together so that I was working with a stereo Bus.
Things to consider when doing your initial listen:
- Role – Is the acoustic guitar’s role to appear exposed or sit within a busy mix?
- Audio File – Are there any knocks and bangs from the pick or strumming hand?
- Audio File – Are there any bumps and low thuds recorded in the sub or bass range?
- Tone – How do the lows, mids and highs sound on the raw recording?
- Tone – How does the tone balance compare with a well produced appropriate reference?
- Dynamics – How much does the level jump up and down in the raw recording?
At all stages you should be comparing what you’re doing with a reference acoustic sound in a mix you love. I used this John Mayer track.
Step 1 – First Aid EQ
The first step I recommend is performing a First Aid EQ on the guitar. This is a key step because it will act on the guitar sound before any compression or sound design we will employ in later steps.
The lower frequencies have the potential to carry the most energy in many instruments and for the purposes of mixing can pose two challenges:
- Low End Mud – The lows of multiple instruments can clash very quickly as a mix gets busy. Low end rumble is often a big problem in recorded instruments.
- Variability – In acoustic sounds like a vocal or acoustic guitar, the Sub range can have huge variance in energy with massive spikes when a low string is hit, and then gaps where the sub disappears.
With this in mind, it’s common to EQ out at least the very lowest frequencies. In the example I did this with a High Pass filter at 65 Hz. Note that I might not cut as much sub if the acoustic guitar is the main instrument in the mix. I also cut some lows at 105 Hz and low mids at about 225 Hz. (fig 1)
Step 2 – Start to Build Dynamic Consistency
Now that we have the very lowest Sub frequencies removed we can begin to compress the sound. We can now do this safe in the knowledge that our compressor won’t respond incorrectly to sub energy.
A plugin I highly recommend for use on guitars is Waves RAxx which is specifically designed for the home recording guitar situation (fig 2 below).
Waves RAxx is intended to optimise the dynamics and level of a guitar or bass guitar. I find it is a great first step to help smooth out a live acoustic guitar performance. Here I was typically going for around 3-5 dB compression (attenuation) on the middle meter.
Step 3 – Classic Compression
The next thing I recommend you try is using a more classic compressor to properly even out the main body of the sound. I think the Waves Puigchild 670 is great on acoustic guitars but you can experiment with any compressor hardware or plugins you have.
Here I went for the following but your settings should ALWAYS depend on the source material:
- 4-8 dB compression on average (watch the meter but trust your ears)
- Attack of 0.4 ms and Release of 2s (this is position 3 on the time constant dial)
When choosing attack and release times you must experiment and explore how the front and end of each note breathes and listen to how the stability of the sound changes as you modify the release. (fig 3 below)
I would add that I used to spend hours obsessing about which compressor is the ‘right’ or ‘best’ one with little to no idea of how to use any of them. I’m still learning. Remember that ultimately the default compressor in Logic or Ableton will sound better in the hands of a master like Tony Maserati than the most boutique compressor in the hands of an amateur.
You’ll learn more by feeding an acoustic guitar into one compressor and tweaking the dials all the way through their extremes than watching 100 YouTube tutorials that use 100 different settings on 100 different compressors and trying to copy those settings.
Step 4 – (Optional) EQ Post Compression
It isn’t uncommon to need to EQ a sound after it has been compressed or saturated. This is due to the compression changing the tonal balance of the sound. With saturation, it can often add in lows that you don’t want.
Here I felt the sound was now lacking a little in the Mids and High Mids so I boosted them slightly with the Fabfilter Pro Q2. (fig 4 below)
Step 5 – Mild saturation
This step might seem the most counterintuitive of the lot. The idea of distortion on acoustic guitar could sound like something you’d want to avoid. It’s really song and mix dependent and I’d hesitate if this was a solo recording of just guitar and voice.
Here I just wanted to add a tiny amount of saturation to the acoustic sound to help it sparkle and have a little more grit in an already pretty energetic mix. I used the Soundtoys Decapitator as follows:
Step 6 – (Optional) EQ Post Saturation
As I mentioned before, when we compress or EQ, it is sometimes necessary to EQ after these effects. In this case I decided that with the sound now compressed and saturated a little, I wanted to add some final EQ to further sculpt the sound. (fig 6 below)
I was attempting to do three things here:
- Remove any low end rumble created by the Decapitator saturation
- Add a little bite at the high mids
- Enhance the plectrum sound
Step 7 – The Secret Sauce
This is the final step and you could think of it as the secret sauce in this acoustic guitar processing chain. With the other plugins in place: compressing, EQing and saturating I still felt the guitar lacked a little consistency in the important 2.5 to 3.5 k where the ear locks in to the sound.
It felt as though this critical high mid energy would come and go and compared to the reference I was using which was much more consistent in this band.
To fix this particular issue you want to compress the sound in just one band. For this purpose any multi band compressor will work, but I am a big fan of the Waves C1-Comp-SC. Theres something about the simplicity of the single band and the interface that I like. (fig 7 below)
Although it looks like a lot is going on here it’s fairly easy when you break it down.
- Split mode engaged so that the compression only acts on the portion of the sound in the blue curve in the lower left (3kHZ)
- Going for 2-3 dB gain reduction in this band
- Makeup gain of 3dB to compensate for the level reduction when compressing
- A ratio of 3:1 on the compressed band
- I also played with the attack and release times and settled on 10ms attack and 100ms release
In essence here we are focussing on the 2.5 to 3.5 KHz part of the acoustic guitar signal, compressing it and then gaining back up that compressed portion so that the guitar is more consistent in this area. You have to be cautious with this and not overdo it.
This was a quick look at how to make acoustic guitar sound better in your mixes when working with raw acoustic guitar recordings. We used a 7 step approach:
- First Aid EQ – on the raw sound
- Compression part 1 – to prepare it for classic compression
- Compression part 2 – the main compressor
- Post compression EQ – to tweak the sound after it is altered by compression
- Saturation – to bring it a bit more bite in the mix
- Post saturation EQ – to correct any final EQ
- A little Multiband compression – for consistency
Have fun trying the technique and let me know how you get on or any questions you have in the comments below. For more on mixing guitars check out this post.