Some instruments benefit from an aggressive amount of compression to get them in line, bringing order to extreme dynamics and keeping them more present in your mix. Other instruments benefit from a more conservative approach which instead smooths out those dynamics a bit without crushing them. Acoustic guitar is the latter, so let’s talk the best settings for compressing acoustic guitar.
Compressing Acoustic Guitar
Here’s a snapshot of the best settings for compressing acoustic guitar:
Note that while these settings are especially intended for acoustic guitar strumming, you can apply them to picked or arpeggiated parts just as easily, thought you might want to be a touch more aggressive in the ratio. One last word – if you’re strumming with your fingers you may want to drop the ratio down slightly as you tend to get less dynamics than you would when playing with a pick.
Now let’s take a deeper look at each of the major audio compressor settings when it comes to compressing acoustic guitar and give my recommended settings for each.
Note that your mileage may vary and that these are just recommended starting positions for each of these parameters; you may need slightly more or less aggressive settings depending on the performance, guitar, microphone(s), even strings.
All that said, these settings are an excellent starting point for compressing acoustic guitar to get more thickness, cohesion, and sustain from the performance and often work as is without further adjustments in my experience.
Threshold
The compressor threshold determines what level the acoustic guitar needs to hit before any compression will occur. You don’t want to set this too low so that you’re compressing the peaks too much and room noise is getting turned up via the output gain.
In my experience, the best threshold when compressing acoustic guitar is at roughly the quietest musical part of the performance, meaning the quietest instance of the desired audio in the performance.
If done correctly and alongside the rest of these settings, you should be aiming for roughly 2-4dB on average of compression with peaks no greater than 5dB.
If you’re going above 5dB, you likely have the ratio and attack set more aggressively than I recommend, but speaking of ratio…
Ratio
The compressor’s ratio is the aggressiveness of the compression itself. This dictates the degree/how much the signal which exceeds the threshold is attenuated.
I recently did an overview of what is the best compression ratio in which I singled out a relatively average compromise ratio of 4:1 as being the best, and that certainly applies to compressing acoustic guitar.
This is a sweet spot where we’re not killing the dynamics or peaks but it’s more than a 2:1 nudge. A 4:1 ratio brings a very nice sense of cohesion to the acoustic guitar so it slots nicely into the mix regardless of virtually any purpose or intentions for the acoustic guitar in terms of how you want to use it in the mix.
As I mentioned in opening, if you’re strumming with your fingers then you may want to opt for a 3:1 ratio as there’s less dynamics without the added transient attack of the pick.
Alternatively, if you’re compressing a picked or arpeggio part, you may need a slightly higher ratio of 6:1 to keep every note present as you tend to get more dynamics from single string/note picking than strumming.
Knee
The compressor’s knee essentially determines how strictly that threshold is observed. A softer/higher decibel knee results in compression being enforced at a lighter rate leading up to the actual selected ratio as the level approaches the threshold.
This can result in a more transparent compression, so when compressing acoustic guitar I like a knee of 12dB to introduce a bit of a smoother “grade” as the level approaches that threshold.
Attack
I like a relatively average to slower attack of 25ms when compressing acoustic guitar to maintain the initial “bite” of the strings’ peaks before the compression engages.
To be clear, the compression attack determines how fast that compression engages after the threshold is met.
Adding a few milliseconds (or 25ms in the case of compressing acoustic guitar) works well to delay that compression long enough to allow the audio transients of the acoustic to push through the mix, helping the instrument to assert itself and draw the ear of the listener, keeping the instrument clear and present.
Release
The compression release is the off ramp, or how quickly we restore the audio to its uncompressed state after the threshold is no longer met.
Setting this to be instant can result in artifacts whereas setting it too long over-compresses everything and makes the performance a mess.
When compressing acoustic guitar, I like a release of 50ms with a short 5ms hold time as a buffer to keep that compression in place for 5ms after the threshold is no longer met before that 50ms off ramp is enforced.
Output Gain
While the output gain setting is oftentimes an afterthought, it’s essential to use this to ensure that the output level of the guitar after compression matches the input level pre-compression effect.
You can leave this set to auto makeup gain, but I much prefer to set this myself as I A/B split test with the compressor on and off to get that best compromise level.
Aside from keeping your acoustic guitar at the right level relative to the rest of the mix, this maintains gain staging, keeping the acoustic at a responsible level and more importantly feeding an ideal level into the next effect in your processing chain:
Speaking of which, check out my overview on how to mix acoustic guitar which covers everything you need to know in terms of processing/effects, including how to EQ acoustic guitar to carve out the frequencies which aren’t working and better emphasizing the ones which are.
Compressing Acoustic Guitar Tips
- Compressing acoustic guitar can help smooth out errant peaks and bring a sense of cohesion and even more energy to your acoustic guitar performance whether it’s strumming or arpeggiated parts.
- When setting your threshold, aim for 2-4dB and 5dB at most on the peaks in terms of gain reduction when combined with the rest of the settings. Oftentimes this is achieved by setting that threshold just at the quietest musical or intended part of the performance.
- A ratio of 4:1 works best for pick strumming when compressing acoustic guitar. If you are strumming with your fingers, you may opt to dial this back to 3:1, and if you’re compressing a picked part, you may find a slightly more aggressive 6:1 ratio is better suited for keeping every note present in the mix.
- Set the compressor knee to 12dB to allow a gentler compression on the signal as it approaches that threshold. This creates a smoother and more dynamic or better said reactive curve in how that ratio ramps up and affects the acoustic guitar for better sounding results.
- An attack of 25ms is more than enough of a delay on that compression to keep the transient bite of the strings themselves present and asserting the acoustic guitar in general in the mix.
- A release of 50ms with a 5ms hold “cushion” works well to create a transparent off ramp for the compression when the threshold is no longer met.
- Lastly, make sure to set the output gain to match the input gain. I prefer to do this manually by turning off auto makeup gain and instead A/B split testing the compression on and off and ensuring the level sounds the same whether the effect is on or off. This helps maintain gain staging to yield better sounding results for the next stage in the processing chain and keeps the acoustic guitar sitting just right in the mix.
