Guitar Compressor Pedals


So the simplest explanation that we can use to describe the compressor pedal is that it helps to adjust the sound and volume of the signal, making the loud parts less intense so the overall volume will seem cleaner and more consistent. In that way the loud sounds will be softer, creating a more balanced sound. This feature is widely used when playing using the fingerstyle – creating magic with your guitar by plucking the strings with your fingertips. We can’t control all the levels of pressure from our fingers when plucking the strings and it can create many differences in the volume. We all want the notes to be at the same amplitude, and therefore nearly equal in volume. In this article we look at ;

  • The terms you need to know
  • How it works
  • Where to put the compressor in your chain of effects
  1. The terms you should know relating to compressor pedal and how it works
  • Threshold:

A threshold is a benchmark where you start applying the compressor pedal to lower or even out your dynamics and volume. It’s the level where any signal above the threshold will be compressed. So basically, it all depends on you, whether you wish to adjust your volume or which part of it you want to reduce the signal and make it less intense. The higher the level the less amount of signal you need it to be compressed then you only care about the extremely high tone and loud parts. By contrast, the lower the level the more available signal that the compressor pedal can work on.

  • Ratio:

Just like its name “ratio”, this is how people adjust and measure the proportions of how much the compressor will reduce the volume and sounds from the threshold level and it’s measured in decibels (dB). And it’s the ratio against the parts of sounds that are untouched, unaffected, and not adjusted. One example for further understanding, if the ratio is 8:1, it means that for every 8dB of the signal above the threshold level, the compressor will only reduce the volume and allow 1dB to come through the signal chain. So that would make 1:1 the uncompressed signal overall.

  • Knee:

You are probably wondering what is a knee? Why does it sound like a part of your body? Actually, there’s a reason why it’s called a “knee”. Technically, thanks to this part, it helps the compressor to switch between the non-compressed and compressed dynamics. There are two types: “soft” and “hard” knee. With the “hard” knee, when the signal first hit the level of the threshold. The compressor pedal immediately processes on that sound in full and faster. Therefore, it’s quite easy for you to hear and feel that change. On the other hand, the sound will come out very smoothly, gently, and slowly so you hardly recognize, feel or hear it as it gradually approaches the limit rising above the threshold. Some would prefer the “soft” knee better because it’s not desirable when the compression is too obvious to hear.

  • Attack time:

You must be wondering what happens after the signal reaches the threshold and exceeds it? If the knee is the point stand right before the signal begins to be compressed, then attack time must have something related to that order?

The answer is yes! Attack time is the time for the compressor pedal to process and fully complete its job compressing the signal. You can’t just expect that right at the moment the signal hits the threshold level and crosses the knee point on a graph that it can be immediately compressed. The compressor pedal needs reaction time – attack time. There are faster attack times (ranging from 20 to 800 microseconds) and slower attack times (between 10 and 100 milliseconds).

  • Release time:

There’s an attack time kicking in the sounds to the compressing part, and now we have the release time. It’s a completely different thing. Release time refers to the time it takes for the sound to switch back from being compressed to the non-compressed state. And it can be longer than the usual attack time. There are also fast and slow release times.

Fast release time is used when you feel like making some natural sounds or can take advantage of the loudness to make everything seem more intense. However, with the immediate effect of switching back and forth from the two states, it can cause the sound to be a little aggressive and create a pumping sound.

Slow-release time is all about making the sounds and dynamics smoother. Since it’s slower, it retains some of the dynamics, holding on more to the signal, creating the distant effect making it sound like it’s further away and drifting  from the listeners. However with longer release time, sometimes your sound can be flat or it can be less sharp.

  • Make-up or Output level:

Make-up output or we can also call it make-up gain is used to control the level of signal after it has been compressed. Since the compressor’s function is to turn all the loud parts down, some of the sounds coming out of your compressor can not be as high as when it entered. So the make-up gain (or output) will turn the overall level of the signal back to its original volume.

Or you can think of it as a gain staging process where making dB level of the sound consistent during the entire process. First, the signal coming through the gain reduction step through your compressors then you can’t just leave it like that for the rest of the performance, you need to push the overall level back up so that the signals fit in the mix is  suitable without sounding off or dull. And don’t worry if you find this function “make-up gain” or “make-up output” pretty difficult with too many details and additional steps to follow, some of the compressor pedals have the automatic makeup. They will turn the output up with prior settings, along with how much gain reduction you want it to be.

  • Multi-Band:

Since the beginning of this article, we have come to explain the main feature of a compressor pedal, which is to turn down and lower the parts that exceed the rest with high volume and sounds. So maybe you haven’t thought of this: What if we can have different adjustments for one overall sound and mix?

Compressor pedals are not just about “full-band”, which means you can divide and set up your frequency range into many categories like low, mid, and high bands. With only one signal, you can have three different compressors. 

So with three different filters, each type of frequency (low, mid, high) will go through its own compressor and then all are recombined later. The biggest advantage that you can think of is that when trying to turn down the volume of some of the loud parts, it won’t affect or trigger a gain reduction in the other parts/bands and pull the whole mix down. And by contrast, in some cases, only the low-frequency sounds will be adjusted, leaving the mid and high bands untouched. Moreover, if you feel that the final outcomes of the whole mix after coming through the compressor pedal can cause a little dissatisfaction then you can change the level of the three compressor bands according to your style and needs.

  • Where to put the compressor pedal in your signal chain?

With the compressor pedal, there are two ways that you can choose to put it in the signal chain: at the beginning or at the end. Compressors, gain-type effects are advised to be set before the modulation effects. By doing this, it helps to transmit a stronger, more intense signal to the rest of the signal chain.

And some prefer placing it at the end of the chain to boost the signal and sound right before reaching the amplifier. But you should consider carefully when trying this because after the signal has come through the previous effects, now with the compressor pedal, it can make the output once again increase. Therefore the option of putting it first is still  recommended.

Some of the compressor pedal models that you might want to check out!

Keeley Compressor Plus

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Xotic SP compressor pedal


Boss CP-1X compressor pedal


Fender The Bends compressor pedal


Wampler Ego Compressor


TC Electronic HyperGravity Compressor


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