It likely won't surprise you to learn that most people compress bass guitar incorrectly, if we define 'incorrect' as an approach incongruent with their goals.
The general goal behind compressing bass guitar is to even out the notes so that each one comes through at the same volume during a performance, with no 'dead spots'. Compression also offers us an opportunity to shape the tonal 'envelope' of the bass, so that we get the adequate amount of punch, while the body of the notes get nicely compressed. The key here lies in dialing our Ratio, Attack and Release settings correctly for the situation at hand.
Since bass guitar is such a multi-faceted instrument, there are a number of ways to go about this.
In this article, we'll talk about two of those ways: the 'simple' serial approach, and the slightly more advanced parallel approach.
As a bonus, if you make it to the end, I'll show you how to combine the best parts of both these approaches to get a professional, record-ready bass tone in no time at all.
Let's do it.
The 'Simple' Approach
The Compression
You begin with a bass guitar DI track in your session. The simple approach allows you to start by inserting a compressor as the very first plugin.
This will be the compressor which handles the bulk of your compression - as a result it's important to pick the right one for the task. A tried and true beloved classic is the 1176 - essentially a hybrid between a compressor and a limiter. The reason that it tends to be so beloved on bass is that its extremely fast attack time allows it to pin the bass, while its transformer imparts a very nice thick colour to the tone.
Another option could be the Distressor. A 'modern' VCA design, popularized in the 90s, the Distressor is known as the Swiss army knife of compression - allowing you to tailor it specifically to the situation at hand.
Both of these compressors have the Ratio, Attack and Release controls that we'll be tweaking.
We begin with the Ratio. On bass guitar, a compressor ratio of 4:1 is essentially the golden standard. This is where we start and work our way outwards.
Set the Attack to the fastest value and then slowly open it up until you hear the attack of the bass come through. Once it melds perfectly with the bass drum in the mix, that's when the setting is just right. In absolute terms this can be anywhere from 1ms to 6ms. Depending on the compressor type, these figures will all sound quite different. In fact on the 1176, 1ms is the absolute SLOWEST attack setting.
Once we've set the Ratio and Attack, we move on to the Release. Begin by setting the release to the fastest possible setting, and then gradually slowing it down until the bass stops 'pumping' and develops a steady-state, tight sound. The release is one of the major components which sets how 'even' the notes come through in a mix. In absolute terms, this will often come out between 50ms to 150ms, depending on the compressor. For most compressors, it will be close to the fastest they can go.
In terms of gain reduction range, for a very well-performed bass track you will generally find the sweet spot to be around 6dB, ranging up to 12dB for more incomplete... eh 'dynamic' performances.
The Problem
Herein lies the shortfall of the 'simple' approach.
Now that you have an, ideally, perfectly-compressed bass guitar, you can run it through the rest of your processing chain, which will likely involve pedals, amps and possibly even cabinets.
The issue is that you're running a pre-compressed signal into this chain, which will fundamentally affect how the bass sounds through them. The way that heavy distortion interacts in particular will be quite different. Depending on the tone you're chasing, this can either be a good or bad thing.
Compress Again
After you process your bass tone, it's quite common for it to develop some unintentional extra dynamics, based on that processing (especially after EQ). This is a good chance to go in for another 1dB to 2dB of finalizing compression. You can even use a limiter here to completely obliterate the extra peaks, if you so wish. You can have a high or a low ratio, depending on your preference, so long as the Attack and Release are both fast, and you're not knocking off much more than 2dB of gain.
The 'Professional' Approach
Because bass guitar is such a multi-faceted instrument, being required to both hold down the low-end of the mix, while still having a particular character in the midrange to glue the guitars to the drums, it can help to modularize how we process it.
A common professional engineer workflow is to duplicate the bass DI so that you end up with two, or even more copies of it. What this allows us to do is treat the low-end differently to the midrange, which can be very helpful if we want to get every last bit out of our bass tracks.
Low Track
We begin by filtering one of the two tracks into its low frequencies. This can mean a low-pass filter anywhere between 160Hz and 250Hz. My recommendation - for reasons we'll get into in another blog - is to use a linear-phase filter here.
Now, we can throw on a compressor just as we did in the 'simple' approach. The way we dial the compressor is exactly the same, so make sure to reference above if you skipped past it!
After the track is filtered and compressed, we can now recombine it with the 'mid' track on a bus.
Mid Track
Conversely to the low-band, what we're going to do here is filter the 2nd bass track into mid and high frequencies. This generally means by setting a high-pass filter anywhere between 200Hz and 300Hz (once again, linear phase if the situation allows).
Generally, we will not need to run any compression on this track, because we are actually relying on all of its dynamics to trigger our pedal/amp/cabinet processing chain in a more natural way. We will go into the reasons behind the 'professional' approach more deeply in a future blog, so make sure to subscribe to our mailing list to receive it as soon as it goes out, if you haven't already.
After processing, the mid-band is recombined with the low-band on a separate bass bus track.
The Bus
Now that the bass guitar is reconstituted, we can compress it lightly one more time. Ratio low or high, depending on your preference, with a very fast attack and release. The key is to not knock off much more than 2dB of gain.
So, why did we go through all of this extra parallel track work?
Well, in short, it allowed our compression to be far more efficient, and applied only where we need it. We heavily control the presence of the notes across the low-end, without ruining the character of the midrange with excessive compression - allowing the mids to trigger the pedals and amps efficiently, resulting in a far cleaner overall tone.
Best of Both Worlds
I hear you. You don't have time to faff about with parallel tracks and linear phase filtering. You want the cleanness of the 'Professional' approach with the directness of the 'Simple' approach.
Double-Tap is a two-stage compressor which encapsulates the entire 'Professional' approach to compression in a single plug-in interface, which can be dialed in less than 30 seconds.
The first compressor will only compress the low frequencies - keeping your midrange entirely intact. The second compressor will add that finishing touch across the entire spectrum - unifying your lows and mids back into a cohesive, powerful bass track.
Not only that, but it offers two flavors of saturation, specifically dialed for bass guitar on a handy slider for immediate application.
Think of this entire article rolled into a simple interface, which takes only seconds to dial, saving you crucial mixing time.
Conclusion
Since the sky is the limit with bass processing, you'll find that boiling down a few simple rule sets for yourself makes life a lot easier. Whether you're doing everything on a single track with DoubleTap, or splitting out a maze of parallel tracks, simply adhere to the basics of dialing a compressor and you'll be fine.
Fight the urge to overdo the gain reduction on any single instance of compression, and you will have a nice, tight, controlled bass tone which is full of life and punch.
