Essential Bass Compression Guide

Bass is an essential part of any mix, carrying the foundation of the entire track on its back. However, controlling the dynamic range and adding color to the bass can be a daunting task. This is where compression comes in. By applying compression to the bass, you can even out levels, enhance the groove, and add character to the instrument that will end up benefiting the whole mix. By the end of the article, you’ll know how to effectively use compression on bass to get the professional sound you’re looking for. 

Follow along with iZotope Neutron, a powerful all-in-one mixing tool. 

What is the goal of compressing bass?

The goal of compressing the bass is to control the dynamic range of the instrument. However, bass compression is used to ultimately make the bass fit the arrangement or overall vision of the tune at hand. There are quite a few specific reasons for compressing a bass part. But these micro-reasons fit into the larger picture of servicing the entire track. Remember, as you begin your mixing journey, that everything serves the purpose of making the track achieve its vision.

Now, let’s move on to specific reasons for compressing the bass in a mix.

Why compress bass in a song?

The following is a list of reasons we might apply compression to the bass in a given mix.

• Even out the dynamics of a performance: sometimes an inexperienced bass player might be all over the place when it comes to their dynamics. One note might be too loud, while another is too quiet. In this case, compression can save the day, bringing a sense of evenness to the sound. Smoother settings, which will be described shortly, can work wonders on bass
  
• Enhance the sense of groove: sometimes we get a boring bass part that needs to be spiced up. The playing needs more attack, more bounce, more juice, or more groove. Here we can use compression to achieve that goal. There are a few ways to accomplish this goal. We can fine-tune the compressor’s attack and release controls to help the bass feel punchier on a note-by-note basis. If the groove at large must be corrected, we can sidechain the bass to another instrument, changing its overall feel in the process. More on this later. 
  
• Add character to the bass tone: Sometimes the sound is too clean, and we want to add more of a harmonic flair. Several compressors are notable for their ability not only to shape the dynamics, but to impart their own specific tones to the sound. A FET ‘76 style compressor is a classic, for instance, as are certain optical tube compressors and vari-mu boxes.
  
• Even out a particular frequency/amplitude range on the bass itself: Some basses will resonate in certain frequencies or fret positions (hot spots), while other fret positions will sound dead and thin by comparison (dead spots). Compression can help ameliorate this phenomenon. You can use multiband compression to tamp down overly resonant areas, and parallel compression to reinforce quieter dead spots. 
  
• Keep the bass out of the way of the kick: The kick and the bass traditionally occupy similar frequency ranges (the low end). This can cause problems when trying to balance these two instruments, for one can obscure the other. A common way to solve this problem is to duck the bass with compression whenever the kick hits. 

How to dial-in bass compression settings

Dialing in bass compression requires a working knowledge of both the bass instrument, as well as a compressor’s key parameters and settings.

Bass frequency 

First, it helps to know which frequency ranges are important to the bass. The heft of the sound is usually found around 120 Hz and below, and we often like to hear what’s happening in the 700 to 1200 Hz regions, as the attack of the notes usually resides there. Keep this in mind as you set your compressor settings.

Compressor parameters

It's important to know compression controls. Threshold, ratio, attack and release are the main ones, followed by the knee. The sidechain detector is also important. For more information on what each of these parameters do, visit our comprehesive compression guide for beginners. 

Let’s start at the top: When compressing bass guitar, the bass feeds the compressor’s input. When the bass exceeds a level that we’ve determined, the compressor will begin to do its job, attenuating the signal down. This level is called the “threshold.”

I can give no hard and fast rule about how to set your threshold. It depends on the bass in question—how loud it is, how bassy it is, and how dynamic it is. 

The ratio control will help determine how much compression is applied to the signal. The higher the ratio, the more drastic the compression effect will be. 2:1 and 4:1 are common ratios we use in compressing the bass. 

Attack and release determine how quickly the bass will be tamped down by the compressor, and how quickly the compression will ease up once the level is back below the threshold. I’ll show you how vital these controls are with the following example.

Here’s a bass part from a tune I recently mixed for Pete Mancini, called "Golden Hour":

If I choose a medium-fast attack with a slow release, coupled with a relatively high threshold, I can smoothen that sound out a good deal: 

However, if I go with a slower attack, a fast release, and a lower threshold, the sound will be noticeably more punchy. 

Listen with headphones to really hear the difference: in the second example, the front end of the transient is more exaggerated. There’s a point to the sound. To some degree, the phrases have been reshaped. 

Yet we can do more: the knee control, available in Neutron’s modern compressor, will define how sharply the circuit goes into compression right around the vital threshold point. At higher knee values, the ratio will be lower around the threshold. 

It’s a little confusing, so I tend to think of the knee as an attack parameter for my ratio control: a higher knee means the ratio will be lower for longer, before it raises—its envelope will be different. 

The last compression parameter has to do with sidechain compression. The sidechain detector determines which frequencies can be excluded from triggering the compressor. If the low end of the bass is causing the compressor to act rather quickly, you can filter the lows from the sidechain signal, and the compressor will not respond to those bassy frequencies.

In the actual signal path, you’ll still have the same amount of bass content. The compressor is just being told what to do from a filtered signal. 

Finally, use the makeup gain control to compensate for any changes in level after the compression has taken effect. If you’re using an emulation, the makeup gain control might have some saturation elements built in, which you can use to your advantage in the gainstaging process.

Bass compression settings

With these controls in mind, we can apply bass compression settings in the following manner:

Start with a low to moderate ratio (2:1 to 4:1), and begin by exaggerating the threshold till the compressor is working heavily. The moderate ratios will help the compressor react less drastically to the instrument.  

Next, fine-tune the attack and release until the behavior of the compressor is as smooth or as punchy as you’d like. After this has been calibrated, back off to the threshold till you are at a sensible level, and maybe tweak some more, depending on how it all sounds. 

In this video, I’ll show you how to set a compressor on bass for various purposes.

How much compression should I use on the bass? 

There’s no hard and fast rule for how much compression you should use on the bass. The amount of compression required depends on which goals you’re trying to accomplish, whether you’re trying to even out the dynamics of a performance, enhance the sense of groove, or add character to the tone of the bass.

But that’s only half the story: the original tone of the bass guitar and the genre you’re working within change how you’ll work. Remember the reasons we compress the bass in the first place. 

A jazz tune, for instance, might not benefit at all from heavy compression, as we then destroy the bassist’s subtle phrasing. Likewise, in dealing with a metal bass’s aggressive picked sound, we might need so much compression that we’re well into limiting territory.

Advanced considerations for setting bass compression

I’ve just given a basic primer for dialing in bass compression, but there are a few more things I’d like to cover before we move on to specific use-cases. 

Sidechaining the bass for clarity

The kick drum and the bass often inhabit similar frequency ranges. They can clash if left to their own devices, muddying up the mix. Because of this phenomenon, many engineers will sidechain the bass to the kick. So, every time the kick hits, the compressor will cause the bass to duck a little bit in amplitude.

Start by sending your kick drum to an auxiliary channel with no output on it. This is commonly called a dead patch.

Within the compressor you’re using on the bass, switch the sidechain input to the dead patch, like so. 

Now, when the kick hits, the bass will tamp down for a split second, letting the kick transient come through more.

Sometimes it pays to take this approach even farther. Perhaps we want to compress the bass for punch, and then duck it transparently when the kick hits. Here we might try a couple of tricks: series compression, and multiband compression.

First, a compressor with punchy settings, as illustrated above. 

Then we use another compressor, and this is what we call series compression: two compressors, one fed into the other. 

Next, the second compressor has a couple of special things going on.

First, the compressor is running in multiband; it’s only working on frequencies below 100 Hz or so. Second, the bass is sidechained to the kick, so the low frequencies duck ever-so-slightly when the kick hits. 

The kick comes through, and the bass is punchy without sacrificing lows.

Sidechaining the bass for groove

Sometimes the whole bass part needs more attitude. It isn’t a matter of redefining the individual bass notes, but the phrases overall. When this is the case, you have two options, one involving compression, the other involving more drastic means. 

The compression solution involves sidechaining the bass to another instrument in the mix. The process is similar to what I’ve described above, with a couple of tweaks.

First, try using the snare as your sidechain trigger, instead of the kick. This tends to add a more rolling, grooving feeling to the bass part. Secondly, play with slower attack and release times, so that the bass ducks down quite gradually when the snare hits, and raises in amplitude after the snare dies. 

This method can work wonders for subtly altering the feel of the instrument. 

Another way to improve the groove involves editing the part manually, phrase by phrase. That method is outside the scope of this article.

Color compression on bass

Finally, I wanted to provide more context on color compression for the bass. I already mentioned that iconic vintage compressors impart their own tone, as well as dynamics control. Here are three compressors in the Soundwide universe you can use for that purpose:

FET 76 style compressor

Repped in Soundwide by the Purple Audio MC77, a FET compressor has a lovely way of imparting aggression and punch to a sound.

Here’s the FET 76 with my starting point for bass. 

Opto compressor

Optical compressors have a unique way of handling compression, often resulting in a smooth operation. The tube stages of classic opto gear also imparts a certain warmth to the sound. In the Soundwide world, you’ve got a few choices. 

Variable-mu compressor

variable-mu compressors are also quite gentle and smooth, but their character is somewhat different to optical units. I would characterize them as less warm, and more glassy or creamy. They can be a perfect complement to a bass with too much going on in the low midrange. A mu compressor in the Soundwide universe comes in the form of a NEOLD V76U73. 

Punch compressor

iZotope Neutron has a compressor module called “Punch.” This isn’t a model of any existing compressor, but represents an interesting way of changing the envelope of the compressor’s behavior. Using it in series with other tools can approximate both the timing and the color of the aforementioned units, provided you know what you’re trying to achieve.

Genre bass compression settings 

Here are some general guidelines for using compression on the bass in a few popular genres. 

Motown-style funk bass

A slower attack, a faster release, a low ratio, and a threshold that doesn’t cut too much into the signal can accentuate the front end of the note nicely while adding smoothness to the part, all without messing up the bass player’s groove. Something like this could work nicely.

Slap bass

Slap bass is deceptively hard to compress since the transients are so fast that you run the risk of doing damage to what makes them exciting. Neutron’s Punch compressor, set in multiband, can do a pretty good job of keeping the transients in line without making too much of a mess of the part. 

Metal bass

Metal bass primarily concerns itself with preserving the pick attack. Making sure you don’t hinder the pick attack means using a slower attack, and usually a fast to medium release is helpful for keeping the dynamics in line. Something like this could work. 

For more on mixing metal, check out the guide I wrote about mixing metal with Joe Barresi. 

Rock bass

A classic combination on rock bass is an opto-style compressor to add an overall smoothness to the part, and an 1176 FET compressor to catch the peaks in a characterful manner. In the Soundwide universe, you can try the bx_opto compressor and the Purple Audio MC 77. 

Neutron’s compressors also work in series for this purpose. The vintage compressor set to a punchier setting, followed into the punch compressor set to restrain dynamics can achieve a similar vibe.

For more on mixing rock music, check out the rock n' roll mixing guide.

Experiment with the order of the compressors—sometimes the opto works better first, and sometimes the FET is the winner.

Please keep in mind that these are general guidelines. Much depends on the actual bass part in question. One thing’s for sure: you should familiarize yourself with material in your wheelhouse. 

Mistakes to avoid when compressing the bass

Now that you have a handle on compressing bass, let’s cover a couple of pitfalls.

Over-compression is a major mistake to avoid. If you squeeze the life out of your bass, you’ll have a lifeless bass (obviously). More than that, you run the risk of making it feel smaller, flatter, and less groovy. Remember that the bass is the foundation for your tune. If you take away its groove or its spirit, you’ll make your production feel duller and less musical overall. 

However, you can’t avoid overcompression if you can’t even hear it in the first place, which brings us to our second pitfall in mixing bass: many home-studio environments fail when it comes to reproducing bass accurately, simply due to the size constraints of the space. Standing waves cause badly placed resonant spots or dead spots in your room, and you can’t trust what you’re hearing. 

Making matters worse, the two-way nearfield monitors available to most home engineers have a nasty habit of compressing when driven hard—and the bass can quickly drive sound systems hard. You can’t hear a problem like overcompression if your speakers are already compressing of their own accord. 

Headphones could be the answer, provided you know how things translate from your headphones to the real world. Even the most expensive mastering-grade headphones have their own sonic imprint, either emphasizing or rolling off the bass; you have to account for this while working.

The only surefire way to get around this problem—other than having a professional space that’s been tuned and treated by a professional acoustician—is to know your monitoring intimately. Spend hours upon hours listening to all your favorite records from your childhood, making sure that the bass sounds exactly as you remember it from your youth. Having a few different monitoring solutions in the room can also help. I prefer to use one set of monitors, but I have three sets of cans I go between from time to time, and I’ll also listen to the sound coming out of my laptop speakers to see how it translates. 

Get started compressing your bass

Hopefully this has been a good primer for you when it comes to compressing bass. Perhaps you won’t be so intimidated by this most vital of instruments anymore. Maybe you’re wondering “what about synth bass? How do you compress that?” Well, if that’s what’s on your mind, let us know! We’ll be happy to follow up with an article geared toward modern-day synthetic bass.

For now, many of these concepts apply, so feel free to get busy putting these tips to the test with a free demo of iZotope Neutron.