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Learn when to use compression on guitars.
Learn how to use compression to save a performance
Find out what kind of compressors are best for your tracks.
Compression for guitars has always been one of those subjects that is hard to wrap your head around. You need to learn about attack and release times, ratios, knee types, thresholds, and then get a feel for how these settings affect your playing.
Often articles and videos that focus on compression for guitars will look at how compressors work in general, but not so much why you should use them for guitars.
But in this article, I’ll be showing you how I typically use guitar compression in my mixes, and why I make the decisions I make. Let’s go!
How Do I Use Compression On Guitars?
Quick note: I’m mainly using analog emulations because that’s part of the feel and sound I’m going for. However, the principles I share in this article also apply to the stock compressor that comes with your DAW of choice.
1. Create Punch With Compression
When I mix a heavy rock track, the guitars are usually very distorted. Distortion adds a boatload of compression to the signal, greatly reducing the dynamic range and making the waveform look very flat.
There are usually no distinctive transients thanks to the distortion as well. But that’s not what I want – I want my rock guitars to sound like they’re hitting you hard, so I use compression to do this instead.
I typically grab a VCA compressor, such as the SSL Native Bus Compressor. I gravitate towards that compressor because it gives me a lot of control over the attack time, which is essential for this trick.
I turn up the attack time to 30ms and set a fast release of 100ms. I set the ratio on either a 2:1 or a 4:1 ratio because I don’t want to completely squash the signal. I typically compress with no more than 3dB of gain reduction.
This trick works because I’m artificially creating a transient. The attack time of 30ms ensures that the first 30ms of the signal won’t be affected by the compression. This basically creates a peak in the signal.
2. Determine Instrument Placement With Compression
This might sound rather confusing. What I mean by determining instrument placement is making things sound close by, or far away.
Sometimes I get guitars that sound like they are punching straight into your eardrum, or they sound like there is a mile between the cabinet and the microphone. While that can be just part of the song, other times it’s an issue that needs fixing.
Make Things Seem Farther Away
To make things sound like they are far away there are a few things you can do. You can reach for reverb, get rid of some high-end, or boost the mids and turn everything else down. But if the part has a lot of pronounced transients that might not be enough.
Another way to create an illusion of distance is by getting rid of that initial transient. So let’s grab a compressor.
For this trick, I like using a compressor that has a very fast attack time. I typically use an 1176 emulation, such as the T-racks Black 76 by IK Multimedia. The 1176 is known for its ridiculously fast attack time of 20 microseconds to 800 microseconds, which is perfect for what I want to accomplish here.
I usually set the attack time between 7 o’clock (close to 800 microseconds) or 11 o’clock (close to 500 microseconds). Again, I won’t compress more than 3 dB, because it needs to stay natural, but of course, sometimes you might need a little more.
This will tame the transients very nicely. I then set the release around 50 milliseconds, or a little slower, depending on how many notes are being played. When I get funky 16th note guitars I’ll go with a faster release time than when I get a guitar that’s playing quarter notes. Otherwise I would just be squashing the notes before they even start.
Make things seem closer
Sometimes a guitar part I’m mixing needs a little help to poke through the mix. You can use a high shelf to add presence, or you can use a transient designer, but you can also use compression for extra attack.
If a fast attack time means your guitar will seem farther away, a slow attack time will result in the opposite. When I want things to sound closer I know I’ll need something that gives me plenty of flexibility, and a quick response to make sure there’s no pumping.
For this purpose, I really like the Waves Scheps Omni Channel. This channel strip offers a compressor that emulates VCA, FET, and optical compression (more on compressor types later). I either use it on the FET or VCA setting. I then set the attack time to 15-30ms, and a reasonably fast release time of around 50-100ms to prevent pumping.
3. Use Compression For Glue
When I’m done with individually processing the guitar parts they might all sound great, but there seems to be an incohesive quality to them. Sure, they’re playing at the same time, but it just doesn’t sound like they were played in the same room.
One of the things that often helps is a tiny hint of compression on the guitar bus. This is where you can get creative with compressor types.
If I’m mixing a ballad, it’s usually a very slow tempo, so I can use an optical compressor, such as the CLA-2A, or the Klanghelm MJUC compressor (which is only 30 dollars!). When it’s a faster groovy tune that screams Boz Scaggs I might go for a VCA compressor like the SSL Native Bus Compressor.
When using a compressor to glue things together you need to know that subtlety is your best friend. I typically set the attack time fairly slow, because I don’t want to mess with the transients too much when doing bus processing.
I also use a fast to medium release. Sometimes I even dial the release to fit well with the song’s tempo. If you google “bpm to milliseconds” you can find some tables with bpm values and their corresponding times in milliseconds. This is a good move if you’re after “musical” compression.
4. Use Compression To Impart Color
Because I predominantly use analog emulations I not only employ compressors to compress. I sometimes just have an analog emulation on a track without it doing anything to the signal.
The 1176 is especially known for this. Engineers from back in the day would often just put one in the signal chain without using it for compression – using it purely for its extra “warmth”.
I often use plugins such as the Brainworx Townhouse, T-rack Black 76, or the Klanghelm MJUC. The Townhouse has a really nice mid-range, so if I find that my guitar tracks lack punch in the mids I’ll generally grab that one.
If my guitars sound a little too bright and could do with a bit more warmth I’ll use the Klanghelm MJUC. If I feel like my guitars need some more bite and body, I’ll get the Black 76 out. Of course, there are no rules to this approach, so experiment.
5. Use Parallel Compression For Extra Control
Another killer use for compression is parallel processing. With parallel processing, you are basically blending a heavily compressed signal with the dry signal. There are a few ways you can do this – by sending to a compressor on a return track or aux bus, or with a dry/wet control on the compressor (if it has one).
I use parallel compression very often when I’m mixing a guitar part that has a lot of intentional dynamic range but lacks overall body.
On a track I’m mixing now there’s a clean guitar solo that needs to cut through a very dense mix. You can hear everything in that guitar, from the strings rubbing against the frets to the pick touching the strings. When I compress it the old-fashioned way it’s guaranteed to sound weird and unnatural, but with parallel compression I have a bit more control over these quirks.
I’ll usually grab something characterful for this because I want to add body and thickness. This is another time where I really like the sound of the Klanghelm MJUC. I typically go for a medium attack speed with a fast release, whilst compressing at least 6dB.
That way the transients are greatly reduced, which allows me to boost the tail of the sound wave, thus thickening the sound of the guitar. I then blend the heavily compressed signal with the dry signal by moving up the aux channel’s fader until I notice a difference.
Do this last step in the context of the mix, because otherwise, you might end up adding too much-compressed signal.
It’s All About Flavors
When I add compression to my guitars, I don’t just compress for the sake of compressing. Usually, I listen to the song, and I find something is missing.
First, I check whether I can fix it with EQ, but if the issue is more to do with the dynamics then I will look at compression. After I make the call to use compression, I will decide what type of compressor I want to use.
Every compressor has its own vibe, which brings out certain elements of a track. It’s up to me to decide what flavor makes the guitars shine in just the right way.
VCA compressors are known for their fast and transparent quality. What I mean by fast is that a VCA compressor reacts very quickly to a signal.
You might wonder why one compressor reacts faster than the other, even when their attack and release times are set to the same time settings. That has a lot to do with the actual design and construction of each type of compressor.
A VCA compressor is based on a transistor design. An electronic signal can travel through a transistor very quickly, whereas it might need some extra time traveling through a tube. That’s why VCA’s, such as an SSL bus compressor, react quicker than a tube compressor such as an LA-2A.
I often use a VCA compressor if I feel like my guitars don’t feel like one strong unit. If I want something that sounds like a solid wall of guitars, I’ll reach for a VCA compressor.
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FET compression is often described as fast, and full of character. Many engineers have used FET compressors, such as the 1176 to completely crush a track to get that lovely saturation. But even when used in a subtle way a FET compressor can give you just that bit of mojo you were missing.
I typically use a FET compressor on guitar when I’m mixing tracks that seem a little lifeless. Before I apply the compression they often sound very bland, and not very lively.
This is when I realize that I need to add some spice to make the guitars feel like they actually contribute something to the song. Using a FET in a subtle way can give your guitars a very nice mid-range quality, but it can also add some extra definition, which makes them cut through without them sounding too aggressive.
Optical compressors are a little bit unusual, as they use light-dependent resistors to control the amount of compression.
The easiest way to grasp the principle of resistance is by picturing a pipe with water flowing through it. With no resistance, the water flows through the pipe without a problem. But if we add resistance by putting a small blockade in that pipe, the water will not flow as fast. This is similar to how electrical resistance works.
There are various ways to add resistance to an electronic circuit. You can use solid-state resistors, or you can add resistance with a light-based resistor, such as a tube, or an LED.
When using a light-based resistor you get a slower reaction, because the resistor has to be triggered by a light source before the compression happens. This reaction timing also varies when different light sources are used. An LED is a light source that turns on fairly quickly, but if you were to use a tube it would take longer. A tube is essentially a light bulb, and if you’ve ever seen an old school light bulb you know that it usually takes some time before the light shines at its brightest.
Optical compressors are mainly known for their slower, round, and warm quality. If I receive a guitar part that lacks warmth I usually reach for an optical compressor, but not all the time. If I get a guitar track with lots of fast playing I actually stay away from these compressors due to their slow nature.
If I were to use an optical compressor on a fast guitar part I might risk running into issues like pumping. So, I only use this type of compression on parts with a lot of space between the notes.
What Not To Do
Compression is one of those effects that takes some time to get the hang of. In the beginning, it’s very tempting to use a lot of compression with the assumption that is makes everything bigger, thicker, or bolder, so why not? But it’s very easy to go too far, and very often when we are learning something new we tend to overdo it.
It took me quite some time before I got the hang of using compressors on guitars, and along the way, I made a fair share of mistakes. So, I’ll share some of my mistakes so you won’t repeat them yourself.
1. Don’t Kill The Transients
This point comes up a lot with compression and it’s worth repeating here. This is basically what the attack knob on a compressor is for – making sure you don’t choke the sound off too quickly once it crosses the threshold. A setting of 8-20ms will safely ensure that no transients are harmed!
2. Don’t Compress If You Don’t Need It
Compression is one of the most essential tools in a mixer’s toolkit. Every record you’ve heard in your life has compression on it.
However, using a compressor on your distorted guitar just because you heard one of your favorite engineers doing this doesn’t mean it’s going to work on your track.
More often than not using compression like that will result in something that sounds muddy and out of place. So if you do use compression on your guitars, make sure the particular mix actually calls for it!
3. False Judgments Due to Increased Volume
One of the dangerous parts of using compression lies within the volume compensation. As you probably noticed, when a compressor does its thing, the signal becomes quiet.
So you have to turn up the volume to balance the level of what’s going into the compressor and what’s coming out. More often than not you are likely to turn up the volume too much, which gives a false sense of “improvement”.
Because of the way our ears work we perceive things that are louder as better sounding. In the context of compression that can be very dangerous.
You might think it sounds great, but you need to ask yourself: does it sound great because the compression has achieved the desired effect, or does it sound great because you boosted the signal by more than 3dB over unity?
Am I saying that boosting the volume is wrong?
No, but I am saying that if you are using compression to boost the volume you need to at least make sure the compression sounds good first. All the great engineers we look up to can get away with this stuff because they have used the equipment for years and know exactly what to do. But you’ll need to spend some time getting a feel for this balance before you reach that stage.