Compression 101
In this article, I'm going to cover Compression 101. It’s a fairly simple system once it’s broken down, so this is my goal today: I want to make this so simple you could teach your five-year-old about compression when we’re finished. Then teach them the epic guitar solo from “Bohemian Rhapsody.” Then start your family band’s world tour.
Hey, I don’t know what’s going on in your life right now. With this quarantine, we’ve got a lot of extra time on our hands. There are worse ways you could spend it.
Okay, let’s start with the basics.
History of Compression
In order to know how to use compression, we first have to understand what compression is. I’m talking about audio compression here. One of the very first applications of this technique was used after we invented a device called the telephone in 1876, roughly 100 years after America became a nation. Yeah, we’re going back to the very beginning.
Basically, when you used the telephone, you sometimes talked to a guy who talked super loud and blew your head off, and sometimes you talked to someone who was very quiet and you couldn't quite make out what they were saying. Engineers applied this compression technique to that audio signal and they brought the quiet person up and the loud person down, leveling them into the center. That’s what you call a win-win. That’s also why compression is often referred to as a leveling amplifier/leveling effect.
History marches on. In the 1930s, we saw compression enter the commercial market as well as the first ever instances of electric guitar being compressed by valve amplifiers. In the late 1970s, we saw the world's first ever guitar compression pedals hit the market. Before we go any further, let me brag on a few of those classics.
First up is the Roland AS-1 Sustainer. This is really cool because it's pre-BOSS. The packaging itself tells a little bit of a story. It actually says “distortion-free sustainer.” This is really significant, because up until this time in the ’70s, you only saw sustain as a control on a fuzz like the Big Muff. Not anymore. Here, Roland's basically saying, “Hey, no fuzz here, this is clean, compressed, and sustained.”
They come along later with the BOSS line, CS-1, CS-2, and so on, which are really great compressors. We’ve also got the MXR Dyna Comp, the classic Ross Compressor (which is a modified Dyna Comp), and my personal favorite: the Dan Armstrong Orange Squeezer. It's not a pedal. You literally just plug it in to your guitar, and off you go. It's fantastic. I even based my Pulp ‘N Peel off of this.
How It Works
You're wondering, how does compression work for electric guitar? Well, it works just like the telephone example that I showed you earlier. Some of your guitar playing is quiet and some of it is loud, so it's going to bring those loud parts down and the lower parts up so they can meet in the middle.
You could say that compression is kind of like the mom of your pedal board.
…Okay, I see those blank stares. Let me explain.
Little Timmy's upstairs blaring Pantera. Dad's in the cold, dark basement reading Mark Twain. But then Mom, the compressor, calls them together for a beautiful dinner. Suddenly, Dad in the basement comes upstairs, and Timmy from the second story comes downstairs. They sit together with Mom for a harmonious evening of roast chicken and carrots where their lives will never be the same, despite their near insurmountable differences.
Yeah, that got deep. That tends to happen in these articles.
Six Popular Compression Controls
To help you further understand compression, let me go over the six most popular controls that you're going to see on most any compressor pedal out there on the market.
Threshold
The number one and the most important control of any compressor is called the threshold.
Now, one confusing factor is that many manufacturers use a lot of different names for this control: BOSS uses the term sustain, MXR calls it sensitivity, Diamond calls it compression, and I also call it compression on my Pulp ‘N Peel and the Whitey Tighty. No matter what you call it, it's all the same function. It is a threshold. It is the control of how much guitar signal it takes to trigger the compression effect.
Basically, the average guitar peaks at 10 decibels (dB). Now, the way your guitar interacts with the compressor depends on the threshold it’s set at. For instance, if the threshold were set at 15 dB, then the guitar probably wouldn’t trigger the compressor, as it wouldn’t produce the necessary dBs to activate it. Alternately, if the threshold was set at 9 dB, then it would activate the compressor so that 1 dB is compressed. An even more drastic 3 dB threshold would smoosh way down on your 10 dB signal and only allow 3 dB of your signal underneath the threshold. That's a lot of compressed sound.
If you’d really like a scientific breakdown of this, take a look at the chart I whipped out in the JHS Show episode this article is based on.
Attack and Release
The number two control you need to know about is called attack. This is the moment that you hit the guitar to the point that that guitar signal hits the threshold. What will the attack be like, fast or slow?
Going back to the family analogy, when Mom calls everyone to dinner, attack is how quickly Dad and Little Timmy get to the table.
Number three is release. Release is the exact opposite of attack: how long does it take everyone to leave the dinner table? Once we've hit the guitar, it's compressed. Does it quickly leave compression, or does it slowly slope off away from compression?
Ratio
Fourth, we have ratio. You'll see this control say things like ‘one to one,’ which means no compression, and it goes up from there: ‘two to one’ is a little bit of compression, ‘three to one’ is more, ‘four to one’ is even more. You get the idea.
What’s really cool about this control is that, mathematically at least, you have infinite ratio controls, which is just a limiter. Limiting is, in essence, just a really harsh and aggressive compressor.
Volume / Makeup Gain
Next up, you have volume or makeup gain. When you compress a signal sometimes it can feel like your compressor made everything a little more quiet. After all, actual dBs of sound are being compressed. In that case, you just turn the knob up for volume gain or makeup gain, and that fixes it.
Most compressors also feature a great clean boost when you crank that volume knob. You can hit overdrives with them, amps, and so on.
Blend / Parallel Compression
I saved the best for last. My favorite compressor control is definitely the blend or parallel compression. The blend control like I use in my Pulp ‘N Peel and Whitey Tighty essentially lets you blend in untouched, clean guitar signal with the compressed signal.
This way, you always have the clarity of that original path. You’re welcome.
How To Use It
Here are the two biggest tips I can give you about integrating a compressor pedal into your guitar rig:
Put it before your drives. I can't tell you how many emails I've gotten over the years that say this compressor pedal is noisy, this one is noisy, this guy makes one but it's too noisy, or you read that on a forum and you find out that they have it after their distortion. The problem is that the compressor's not noisy. No compressor should be noisy within itself, but compressors bring up quiet sounds in the mix. This means that any hiss or noise coming from an overdrive pedal gets brought up equally as loud as your guitar signal, just a big no-no.
Fortunately, an easy solution is to put the compressor before your drive pedals.
When you play to the compression pedal, you'll notice that you feel it more than you hear it. That’s perfectly okay. In fact, that's where I like compression the most. I'm not a massive fan of always using it as a very audible effect, but I do love turning on a compressor and feeling the way that my guitar's pickups and my fingers respond differently through it to my amp.
It's all about feeling and when you find that you'll know it. Fun fact: “Hooked On a Feeling” was definitely written about a guitar compressor. Yeah. Just googled it.
One of my favorite uses of compression is to sustain my slide playing. I really got turned on to this by a song called “High Hopes” on Pink Floyd's The Division Bell. David Gilmour's guitar sound is epic there. In the same vein, when I put a compressor before an overdrive and combine that with a long quarter note delay, it adds a ton of life to my slide playing.
I also use compression as an “always-on” leveling effect. I have a tendency to make riffs out of the notes within chords, so as I'm picking through those it will be quiet, and then I'll go to those same chords and strum through them for bigger parts of the song. The compressor really brings those quieter passages together with the harder hitting loud passages, and it keeps my guitar perfectly in balance with the drums.
While compression is usually a very subtle thing, it can be a very noticeable effect in genres like country with chicken pickers or funk music where they really compress those clean guitars. You could also just invent your own genre like spaghetti western surf funk music. That’s basically what we did in the jam session at the end of this JHS episode.
Feel free to look up the video to truly appreciate the oddness.
Great Compressors
I want to lead out here with some of my own compressor suggestions for you that are out in the market. Number one is the BOSS CP-1X. BOSS has always blazed a trail in compression and this thing is outstanding, so be sure to check it out.
A boutique classic is the Diamond Compressor. I seriously can't recommend it enough.
And naturally, we have my Pulp ‘N Peel, which I have four versions of.** It has DI out for bass players and acoustic parallel dirt blend control. Basically, the Pulp ‘n’ Peel has lots of features. I’m proud of this one. I also released the Whitey Tighty, which has a smaller enclosure. You have a clean blend, three knobs, and not a bad sound in it, so obviously I'm going to recommend that.
**I’m not saying you have to buy all four, but I am saying that four is a nice round number of pedals to buy at the same time. Totally your call.
You could also grab the Warden by my friends at Earthquaker. It’s got six knobs, so tons of tweak-ability.
Keeley offers two: you can go with the Keeley Compressor Plus (which I call the Pro), which I highly recommend. If you want to have all the features of a computer plugin compressor where you can tweak it to death, this is the way to go. The standard Keeley Compressor is a more simplified, normal compressor, and it's still outstanding.
Lastly: the MXR Dyna Comp. It really doesn't get more simple than this.
Don't get hung up on what logo, what year the compressor is from. Basically, don't be a forum person like that. Just buy one and play it, because these are really approachable and easy to get to sound well. Play it because it’s fun.
Remember: we play our instruments. We don’t work them. Have some fun!