Compression is used extensively in music. In fact, you’ll have heard it on most professional recordings where it is used to even out the sound levels.
As guitarists we find it useful to keep our levels in check and to even out the sound.
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What is a compressor and how does it work?
Compressors helps limit the amount of variation in volume from your guitar. Basically it will lower the volume of the louder signals and bring up the quieter signals. Think of the difference in volume between lightly plucking your top E string and hitting a heavy chord. A compressor will bring these two levels closer together effectively reducing the dynamic range. It has the added effect of adding sustain because it is lifting the signal that is fading as the note is dying off.
It’s an effect that is used extensively in the studio to even out the sound in recordings.
Do I need a compressor?
Compressors tend to be used where fast consistent playing is required, particularly where clean sound is needed and there is a mix of chords and single note picking.
For example, it is used extensively in country music where there is lots of fast playing that incorporates plenty of hammer-ons and pull-offs. Techniques like chicken pickin’ where you can be alternating between pick and fingers really benefits with the use of a compressor.
Funk music is another that can highly benefit from the effect as there is plenty of rapid rhythmic playing mixed in with single notes. Those single notes would just get lost without compression.
Conversely, if you are playing the blues then you are far less likely to need a compressor. Blues playing relies on much more expression a subtle dynamic changes, all of which get removed as the signal gets compressed.
So, what does it sound like?
Compressor Pedal Buying Guide
Types of compression
There are actually several electronic methods used to produce compression:
OTA (Operational Transconductance Amplifier)
Most common that you’ll find used for guitar pedals nowadays. Known for suiting guitars particularly well they tend to use CA3080 and LM13700 chips.
VCA (Voltage Controlled Amplifier)
Known for a fast and clean compression that is much less likely to alter your tone. You’ll typically find studio rack compressors using VCA, although some pedals do use this method – for example, the famous Boss CS-3.
This is an interesting method. A light source gets brighter as the signal gets louder. In turn, a photo resistor picks up these changes and attenuates the signal to bring the level down. The result is a smooth and natural effect.
FET (Field Effect Transistor)
Field Effect Transistors were designed to emulate valves (tubes) but adding in more reliability. They are subset of VCA compressors although are known to add a little more color to your sound. This can be good or bad depending on your perspective. Many like it because it can fatten the sound.
Tubes typically add a little more warmth to the signal. The fact that it is a tube is slightly misleading as the circuit is really based on the optical compressors with tube added to the gain stage at the end.
A digital compression technique allowing the individual control of certain frequencies, much like a graphic equalizer.
Now you know how a compressor works let’s look at the controls.
Controls and their names can vary between pedals so the most common ones are listed below.
Attack: Controls how quickly the compressor engages. If the attack is fast then you get a smoother sound and conversely, if it is set slower then you get a more pronounced articulation.
Threshold / Sensitivity: Sets the compression ratio. In simple terms this is how much a louder signal is turned down.
Sustain / Release: Adjusts how long the sound is held before it tails off. A shorter sustain will give you greater articulation of the note.
Tone: Some pedals will allow you to alter the tone. This can be handy because compressors tend to increase the tonal top end and you can therefore adjust to compensate for this.
Level / Output: Adjust the overall volume.
Cheap vs high end?
For many a budget compressor will do just fine especially if you want to try out the effect and see what it can do for your playing.
You will certainly find the more expensive ones will tend to make your sound less harsh particularly at higher volumes. However, bedroom players are likely to get on just fine with something a little cheaper. Note, that just like other pedals, when you spend more money you are also paying for a better made case and therefore increased durability.
Below is our list of some of the best compressor pedals on the market today.
Boss CS-3 Compressor / Sustainer
The CS-3 uses VCA technology and has amazingly been around since 1986! This Boss pedal has certainly earned its great reputation. For subtle compression use it’s very had to beat.
Some will criticise the CS-3 though. In an attempt to push the sustain qualities of the compressor (note they do call it a compressor / sustainer) it does generate a bit more noise when the sustain is at the higher end. So, beware that if you are using it to generate lots of sustain then this comes at a price.
However, saying that the CS-3 sits in that nice place where quality and value for money meet.
MXR M102 Dyna Comp
MXR’s Dyna Comp has been around for many years with this incarnation based on the 1995 release. It uses VCA compression and is a true bypass pedal.
Dave Gilmour of Pink Floyd fame is a fan of using compression and was using an MXR Dyna Comp way back in the 1970s. Although the newer models are said to lack the warmth and smooth sound of the original it is still a fine pedal.
The M102 is simple to use with just two controls but it will handle that 1980s New Wave squashed sound, the Nashville sound or smooth and mellow lead guitar tones with ease.
If you are using it for country chicken pickin’ you’ll probably love the way it adds that snap and pop that defines the sound. Plug in a Telecaster and it’ll be a perfect marriage.
12-String players will be happy with this pedal too and can really bring out the lovely chime.
One downside is it will color your tone slightly bringing out the mid-tones – that’s particularly great for country but some might not like it.
Behringer CS400 Compressor / Sustainer
As with most of the Behringer stomp boxes the case is plastic to keep costs down. Buy, hey is relatively tough so unless you abuse it then you’ll be fine.
Behringer design and engineer their own pedals in Germany, although many feel that they remarkably similar to other pedals on the market – most often those made by Boss. The CS400 would appear to be very much like the Boss CS-3 especially the layout.
So, what sort of job do they do of it? Well honestly not too bad. They are at a price point somewhat lower than the Boss equivalents sound pretty reasonable.
Some people will harshly criticise their construction and we wonder if there is a preconceived idea that the sound quality will automatically be rubbish. It isn’t! And while we are on the subject of case construction there really aren’t that many reports of these pedals disintegrating. But yes, you do have to treat them a bit more gently. It you are buying it for bedroom use and maybe the odd gig then you really are unlikely to see any problems.
Sound-wise we feel the CS400 holds up quite well against the Boss CS-3 with the latter perhaps sounding a bit warmer and coloring the original signal a bit less.
Donner Ultimate Comp
One of the first things you notice about the Donner Ultimate Comp, aside from its micro footprint, is the fact it has a tone switch in addition to a tone control labelled “normal” and “treble”. The thinking behind that is that there are two different camps of compressor users. Some just don’t like the usual treble boost you see with the effect and others like the fact that this happens. This switch solves this issue by providing an unaltered (tonally) signal or one that has a slight treble boost.
As a mini pedal there isn’t even room for a 9V battery which means that you’ll definitely be needing a 9V power adapter.
Sound-wise the Ultimate Comp uses optical compression and as such gives a lovely smooth compression that is favoured by many.
Where the Ultimate Comp potentially falls short is for those that want lots of compression. There is plenty of gain on offer but you might not get the amount of squash that want. For modest compression uses this won’t be an issue.
Build quality is reasonable at this price point although the jack sockets may not stand up to the same abuse as other, more expensive pedals.
TC Electronic Hypergravity
Another of TC Electonic’s pedals that features tone print technology. For those of you that are unaware it’s the ability to hook up the pedal the the TonePrint editor and dial in the exact sound you want. Not only that you can download a multitude of preset tones including many artist approved sounds.
It has a small footprint and is actually the baby sibling of the full-size hypergravity. You still have access to all the great sounds of the bigger model just slightly less control and obviously cheaper.
This leads us on to mentioning that although TonePrint gives you a lot of different sounds, it really isn’t something you are going to be changing during a gig. Yes, technically you could. You just have to hold your phone up to the pickup while it “transmits” a computer tone. You can do it but you need to be able to mute after the compressor and before the amp or the tones (unpleasant computer generated noise) will come through the amp. Don’t let it put you off too much because the reality is many of us choose the sound we like and run with it. You can still fine tune it with the control knobs just not change the entire preset over.
In use the Hypergravity Mini sounds great. The multiband technology really does offer a great deal of tonal control via TonePrint. You can even set the pedal up as a 3-band compressor allowing you to contour the tone. This can give you a nice mid scoop or even a nice mid boost.
Overall we loved the sound quality of the Hypergravity Mini and you could lose hours and hours just playing with all the possibilities via TonePrint.
If you want a compressor that will provide great value while producing professional quality sound that will also stand up to heavy road use then the Boss CS-3 is probably the pedal for you. Just don’t expect to be able to crank up that sustain without some compromise in additional noise.
If you just want a cheaper pedal to test the water and see if you like using compression but don’t mind the cheaper plastic construction, then the Behringer CS400 is a good choice.
Country fans should probably just grab the MXR Dyna Comp. While those that want to experiment with many different sounds will find the TonePrint technology on the TC Electronic Hypergravity great fun to use.
If you’ve never used a compressor then we urge you to try one. Many find that they don’t like the sound of their guitar when they haven’t got it on!
Where do I place a compressor pedal in the chain?
Generally you would place the compressor first in the chain. Note that some guitarists prefer to add their compressor at the end of the chain. This can give a nice boost to the signal. However, it can introduce some noticeable noise. But, like we often say with pedal, EXPERIMENT with position to get the sound you most enjoy!
Can I use a compressor with distortion / overdrive?
Be careful with distortion and overdrive as distortion already adds compression and it can result in over-compression. You’ll also find that the signal can be more noisy.