The bass guitar's popularity comes from its importance in many mixes, often serving rhythmic and/or melodic roles while offering low-end musical content to the mix. Compression is commonly used on bass guitar to help it sit perfectly in the mix. When it comes to compressing bass guitar, there are no simple step-by-step instructions; every mix is unique. However, there are certain considerations we should take into account when compressing the bass, which is what this article is all about.
Before we go any further, I should state that there are no hard rules with compression or any other mixing process. The tips mentioned in this article are simply suggestions and techniques worth considering when compressing bass guitar. No procedures work 100% of the time, and every mix is unique in its own needs.
Here are 11 pro tips for compressing bass guitar:
- Consider how the bass guitar was recorded
- Consider the genre
- Sidechain compression from the kick for space
- Consider compressing kick and bass together
- Transients and attack time
- Timing release time to the tempo of the song
- Compression for colouration
- Consider serial compression
- Think EQ before or after compression
- Always A/B Test
- Use your ears
Let's discuss each of these tips in more detail to give you important considerations when compressing bass guitar in your mixes.
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Consider How The Bass Guitar Was Recorded
The first tip I have for you in regards to compressing bass guitar is to consider how the bass was recorded.
Are we working with a clean DI signal? What about an isolated cabinet miked up with one or two mics? Is it the case that the bass guitar amp/cab was recorded in the same room as the other instruments and, therefore, has significant bleed in its signal? Are we dealing with an acoustic bass miked at its neck and/or soundhole?
Furthermore, we should ask ourselves about the bass guitar's signal chain before it was originally printed. What pedals was it running through, if any, and what effects were inserted between the mic or DI box before the signal was recorded?
For more information on inserts, check out my article Audio: What Are Inserts? (Mixing, Recording & More).
If the bass was compressed on the way in, it might be the case that we won't need to compress it at all. Note that distortion-type effects also have a compression-like effect on audio.
Also, if there's significant bleed from other instruments in the bass channel, compressing too much may over-accentuate the noise/bleed relative to the bass signal. Be cautious when dealing with bleed.
If, on the other hand, we're dealing with a dynamic and clean signal from a DI or an isolated cabinet, we could likely get away with more compression before negative side effects begin to arise.
Knowing how the bass was recorded can give us insight into how we may want to go about compressing it (or not), so I'm leading with this tip.
Consider The Genre
Consider the genre and the typical expectations of the mix aesthetic for the song you're working on. How does the bass generally sound in [insert genre here] music? For example, the bass guitar in a funk song will likely sound different than the bass guitar in a metal song, both in performance and in the way it's mixed.
Furthermore, because every mix is different, even within defined genres, it's important to consider the role of the bass in the specific song being mixed.
Sticking with the same example, just because it's a funk song doesn't necessarily mean we have a slap bass groove that needs to be mixed dynamically and upfront. Similarly, just because it's a metal song doesn't mean the bass needs aggressive compression and distortion, nor does it have to sit underneath the guitars the entire time.
But, there are general mix aesthetics worth being aware of between different musical genres. When it comes to compressing bass guitar in a genre you're not overly familiar with, take the time to listen to a few references in the same genre and gather an idea of how the bass is typically mixed.
Armed with such information, we can choose to either follow the “rules” or break them concerning mixing bass guitar (including the use of compression).
The bass element (often bass guitar) is usually an anchor in the song, so it's typically beneficial to keep its level steady and its dynamics within a smaller range.
To keep a bass track consistent, it's often the case that high-ratio compression with near-constant gain reduction helps.
Starting with a ratio of about 6:1 and an average gain reduction of a few dB, we can adjust to taste.
Sidechain Compression From The Kick For Space
Moving on to the more technical tips, we have one of my favourite techniques in mixing: sidechain compression.
Put simply; sidechain compression is the technique of inserting a compressor on one track but having another track control the amount of compression.
The sidechain signal of a compressor is typically the same as the input/program signal (taken either directly before or directly after the gain reduction circuit (see feedforward or feedback compression). The sidechain signal is effectively converted to a control voltage that controls the gain reduction circuit (the dynamic range compression) of the compressor.
However, in the “sidechain compression” technique, we utilize an external sidechain signal to control the gain reduction circuit.
Here's a basic diagram of a feedforward compressor with a switch to toggle between an internal and external sidechain. Hopefully, it helps to clarify what I'm writing about:
So, when it comes to bass guitar and kick drum, we have perhaps the two most important low-end elements of any given song.
It's critical to get these elements working well together within the mix, allowing both to be heard as distinctive tracks without too much competition and frequency masking between them.
I have a YouTube video dedicated to frequency masking. Check it out here.
By using sidechain compression, we can insert a compressor on the bass guitar and have the transients of the kick drum effectively compress the bass when present.
When done subtly within the mix, this allows the kick to punch through a bit more, particularly in the low-end, without reducing the bass guitar's overall perceived loudness or presence.
We can even go as far as splitting the bass guitar into low-frequency and high-frequency tracks. To do so, duplicate the track, and insert a low-pass filter with a specified cutoff frequency and slope. Insert a high-pass filter with the same cutoff frequency and slope on the original track. Use your ears to determine where this crossover/cutoff frequency should be (between 80 – 200 Hz is typical).
We can then act to sidechain compress only the low-frequency version to make room for the low-end of the kick without affecting the mid-range and upper harmonics of bass whatsoever.
This technique of splitting the bass into low and high controls is covered in more detail in my article Top 11 Best Tips For EQing Bass Guitar.
I have a video dedicated to using sidechain compression in the mix. Check it out below:
Consider Compressing Kick And Bass Together
On the topic of the relationship between bass guitars and kick drums in the mix, we can consider bussing the kick and bass together for common compression (among other processing).
After spending time honing in the separation between the kick and bass (with sidechain compression, mirrored EQ, high-pass filtering other elements, saturating the bass, etc.), it can be beneficial to “glue” them together with compression to help them sit even more cohesively in the mix.
Glue is the sense/perception that sounds belong together and exist within the same world in the mix.
This “glue compression” is one of several ways to make grouped track or, indeed, the entire mix sound more cohesive, which is the ultimate goal of mixing to begin with.
This happens because the compressor can be triggered by a single track (typically the transient of the kick drum track(s)) but affect all the other elements in the mix (the bass guitar track(s)). This simple relationship can help tie the kick and bass guitar together and improve cohesion in the mix, particularly in the low end.
Try this out by bussing the kick drum and the bass guitar together and compressing the bus. Even a subtle amount of compression can really glue these two important low-end elements together in the mix.
For more information on mixing kick and bass, check out my video below:
I also have a detailed video on the concept of glue that you can check out here.
Transients And Attack Time
A compressor is designed to reduce or “compress” the dynamic range of an audio signal by applying gain reduction to the peak levels of that signal.
However, compressors don't act instantaneously to such peaks, and we actually have an opportunity to increase the dynamic range of our bass guitar in the mix.
This is done primarily by altering the time parameters of the compressor and, more notably, the attack time.
The attack time is the amount of time it takes for a compressor to engage/react once the input signal amplitude surpasses the threshold. It's a rate of change whereby the compressor gradually reaches its full ratio over time. It's not a delay of action, where the compressor will clamp down fully after a set period of time.
With fast attack times, the compressor can clamp down quickly on the transient information and effectively reduce the peak levels of the signal. When done subtly, this can help thicken the signal and maintain a more consistent level. However, when overdone, it can have the effect of sucking the life out of the signal by immediately crushing the dynamics.
With slower attack times, the compressor will react more slowly to the transient information and actually allow some of the transient peaks through uncompressed before clamping down on the signal level. When dialled in correctly, we can shape the dynamics of the bass guitar to suit the mix better.
Pay special attention to the attack of the bass guitar. The transients are typically most present in slap-style playing, followed by picking, and finally, fingerstyle. Dial in the appropriate amount of attack time to shape these transients to the mix at hand.
For more information on transient shaping with compression, check out my video:
Timing Release Time To The Tempo Of The Song
We just discussed the power of compression attack times. Now let's discuss the other time parameter: the release time.
The release time is the amount of time it takes for the compressor to disengage (to stop attenuating the signal) once the input signal drops below the threshold. Like the attack time, it's a rate of change whereby the compressor gradually disengages over time. It's not a delay of action, where the compressor will suddenly stop compressing after a set period of time.
By timing the release time to the tempo of the song, I mean setting the parameter so that the compressor typically disengages fully just before the next transient in the bass guitar track.
Of course, this is easier said than done when the bass is playing different note lengths, but doing our best to time the compressor's release to the bass's rhythm can help make the compression sound more natural.
For one, it reduces the amount of perceived “pumping” caused by rapid changes in gain reduction. It can also help improve the perceived sustain of the bass guitar by maintaining a more consistent level as the compressor slowly disengages and the original signal level drops simultaneously.
Compression For Colouration
In addition to the main purpose of automatic gain reduction, compressors will have the effect of colouring the sound. While some compressor plugins are programmed to be as transparent as possible, many other plugins, and certainly hardware compressors, will impart their own sonic imprint on the audio signals passing through them.
This colouration is sometimes experienced as an inherent EQ curve, though perhaps more obviously, it's experienced as harmonic saturation, where new harmonic information is effectively added to the signal due to the distortion of the components (or programming) of the design.
Such colouration can help to enhance the character of the bass guitar, and utilizing compression for its characteristic “sound” is commonplace. It may even be the case that we introduce a compressor in-line without even applying any gain reduction only to add colour to the bass.
One issue to consider is the inherent noise caused by hardware compressors and analog plugin emulations. We must ensure proper gain staging to achieve a solid signal-to-noise ratio. This means we need to drive the compressor with enough signal level to avoid excessive noise relative to the signal while also keeping the signal level low enough to avoid excessive distortion.
For more information on gain staging, check out my article Mixing: What Is Gain Staging & Why Is It Important?
On top of the inherent sonic characteristics of certain compressors, the actual gain reduction applied by the compressor will also obviously alter the sound. In this way, we can apply subtle amounts of compression to add a bit of extra character to the bass guitar as well.
Consider Serial Compression
Serial compression, as the name suggests, has multiple compressors in series in a signal chain. In other words, having a compressor's output feeding another compressor's input (and so on) somewhere down the line.
Serial compression could be as simple as inserting two compressors on a single track or having a single compressor on a track that's ultimately being fed through a mix bus compressor. It could involve many more compressors in any given signal chain (a track into a bus into a mix bus, etc.).
To keep things simple for this article, we'll discuss compressors inserted back-to-back on a single bass guitar track.
Serial compression, in this way, is great for not overloading any single compressor. It can sound more natural and shave off more dynamics, leading to more consistent bass guitar levels without as many unnatural pumping artifacts. We can also get different colours of different compressors (see tip number 7).
Imagine pushing 12 dB of gain reduction on a single compressor. Chances are the bass guitar will sound pretty “squashed” and unnatural. The transient information will likely suffer along with the sustain. Although it can be done in some mixes, it's typically a losing battle attempting to get that much gain reduction without these negative side effects.
However, if we were to utilize two compressors to compress 6 dB of gain reduction each, we'd be able to get more natural results. The first compressor would tame the peaks, and the second would help round out the remaining higher-amplitude moments.
What if we applied that same 12 dB of gain reduction over three compressors (4 dB of gain reduction each)? When done correctly, it would lead to even less pumping, giving us a more natural-sounding compression and a more consistent sound.
Try this out for yourself the next time you need a significant amount of bass guitar compression to fit a bass in the mix appropriately.
I talk about and demonstrate serial compression in more detail in one of my YouTube videos that you can check out here:
Think EQ Before Or After Compression
Compression and EQ are two of the most-used processes in mixing, so it's worth addressing whether to compress the bass guitar before or after EQ or both.
If any notable resonances or low-end noise in the bass guitar signal could trigger the compressor, I would filter those frequencies out with EQ before sending the bass signal to the compressor.
Beyond that, it's largely a matter of taste. However, I'd still recommend investigating which order sounds best in your specific mix.
EQing a bass guitar before compression lets us shape the frequency content more aggressively, knowing that the compressor will help smooth it out. It's also good to have control over what the compressor “sees” and reacts to.
In general, EQ before compression will yield a smoother, warmer result with bass guitar.
Compressing a bass guitar before EQ gives us less control over what the compressor reacts to but more control over the tonal balance of the signal. Note that the EQ should be applied more sparingly here since the audio has already been smoothed out.
In general, EQ after compression offers a cleaner, sharper result with bass guitar.
So consider the genre and the song as a whole, and experiment with whether the compressor should come before or after the EQ if either process is used at all!
Always A/B Test
A/B testing is one of the best habits you can get into when processing anything in a mix, let alone the compression of a bass guitar.
A/B testing effectively tests two options (option A and B) and compares the two to make an informed decision on which is better. We can A/B test by turning the bass guitar compressor on and off (bypassing it).
Whenever we make any adjustments to a bass guitar compressor, it's worth A/Bing them against the original signal and listening to whether the compression improves the sound of the bass in the overall mix or not.
When A/B testing, bypass the compressor and listen for about 10 seconds. Turn it back on and listen for another 10 seconds. Repeat the process and decide whether to keep the compressor, readjust it, or get rid of it.
The human auditory system tends to adjust to whatever we're listening to. When mixing, we can quickly lose perspective and our objective decision-making skills. As we adjust parameters to achieve balance and any other goals in the mixing process, we can quickly lose our frame of reference of what good bass guitar compression actually is.
So use A/Bing to your advantage when compressing the bass guitar in a mix.
If you're interested, be sure to check out my video on the top 5 A/B tests worth incorporating regularly into your mixes:
To learn more about A/B testing, check out my article A/B Testing & Its Importance In Mixing (With 5 Best Tests).
Use Your Ears
Okay, perhaps this tip is a bit too obvious, but it's vital that we use our ears when using any processing on any tracks within a mix. This, of course, includes compression on bass guitar.
Any tips I could give you in this article are null and void if they don't serve your tastes or the mix as a whole. It's impossible to give instructions about specific parameter settings because every mix will demand something different.
While I can give you good starting points and general advice, the best piece of advice I could ever give you when compressing bass guitar is to use your ears.
If the bass compression doesn't sound good or serve the mix, either get rid of it, change the compressor being used, or adjust the parameters of the current compressor. Rely on your ears (along with A/B testing) to get the best results!
Other Compression Tips For Common Elements
- Top 11 Best Tips For Compressing Kick Drums
- Top 10 Best Tips For Compressing Snare Drums
- Top 9 Best Tips For Compressing Electric Guitars
- Top 9 Best Tips For Compressing Acoustic Guitars
- Top 9 Best Tips For Compressing Pianos & Keyboards
- Top 11 Best Tips For Compressing Vocals
- Top 11 Best Tips For Compressing The Mix Bus
Be sure to also check out my top overall 11 compression tips for mixing in this video:
Determining the best compressor for your audio needs takes time, knowledge and effort. For this reason, I've created My New Microphone's Comprehensive Compressor Buyer's Guide. Check it out for help in determining your next dynamic range compressor purchases.