What does a compressor pedal do? This is one of the most common questions guitar students have when they first begin to experiment with stompbox effect pedals.
Compressors are one of the most mysterious pedals to new or expanding guitarists because what they add/do to your sound is not always as obvious as a distortion box or phase shifter.
What Is A Compressor Pedal, Anyway?
A compressor is known as a Dynamics Processor. That means it works with the relative loud and soft levels of your playing to keep things even-sounding. It boosts the quieter parts and tames the louder parts to keep it all in a certain dynamic range.
This is useful in a few different ways:
In styles like country and funk, a compressor is pretty much expected to keep those clean guitar tones popping without increasing distortion.
Country, fingerstyle, and hybrid-picking guitarists use compressors to even out the different attacks of their different picks and fingers.
Rock guitarists often use comps on those clean-toned arpeggiated song intros that build into heavier songs to make that intro even and perfect each time they perform it.
A classic rock rig of the 1970s is a Marshall head with an MXR Dyna Comp compressor in front of it to boost the input signal.
Amps back then didn’t usually have the multiple gain stages and modes that the amps of today do and the Dyna Comp was an easy way to kick your signal up, hit the preamp of your amplifier harder, and increase grit and sustain.
It’s a trick that still works very well and is part of the reason you can still get a new Dyna Comp right now.
How Do I Work It?
A truly basic compressor can have as few as two knobs on it, one that controls the amount of compression deployed that’s named something like Sensitivity, Ratio, or Sustain, and another that controls the overall loudness and volume of the pedal usually called Level, Output, or something similar.
You will need to do some experimentation with these controls to get your hands and ears around what they do, as both the sound and the feel of your guitar will change when you step on the switch.
Typically, we put compressors, distortions, and the like first in our signal chain, in front of time- or modulation-based effects like delay and chorus. Delays and chorus units are better served by being routed into the Effects Loop on your amp if you have an amp with that feature.
The more you turn up the Sensitivity, more and more of a limit is placed on how much louder you can make your guitar by hitting it harder or the reverse. With this knob all the way up, the only way to make your clean tone playing unpleasant will be to play a wrong note. Your level and dynamics will be rock solid every time.
If you want to use a compressor to boost a clean or distorted amp, just turn the Sensitivity down and the Output knob up.
With the compression turned off, a comp is just a killer boost pedal.
Try it and see how it sounds. You’re gonna like it. Here is a short video on how to use a Dyna Comp or other two-knob compressor pedal:
The other classic compressor is the Boss CS-3, which another pedal that has been used since pretty much the dawn of time. What makes it an evolutionary step forward past the two-knob comps of the world is the addition of a control for Tone that lets you make your sound brighter or darker and one for Attack which interacts with how hard or soft you hit the notes you play.
Some players like the extra knobs, as some players always do, and others love the simplicity of the two-control basic models. All that matters is the one you like the most.
Watch this video to get an idea of what the CS-3 sounds like:
Do I Need A Compressor On My Pedalboard?
Yes, probably. It’s important to understand what a compressor pedal can do, both for your guitar sound and for larger applications such as recording and live sound. A compressor pedal is one the basic guitar effects we should all have because somebody somewhere is going to ask you to play something that needs it. Clean and compressed tones are something guitarists are asked to deliver regularly.
In the studio or behind the soundboard, compressors are used on just about everything from drums to vocals and are one of the main tools used to control unruly signals and achieve a great-sounding mix. Of course, the comps used in these situations are rack units or software and not pedals but the basic principles are the same.
We hope you enjoyed reading this article. What does a compressor pedal do? You now know the two basic ways most players use them, as a level limiter or as a volume boost. Please comment and let us know how you liked the article and what compressor pedal you use.
All you really need to know is that you need to go and get yourself a compressor pedal, put it first in your chain of effects, and start playing and listening. Your questions will start to answer themselves.