Extensive compressor reviews and FAQ

 
Is a compressor necessary? ("Another guy told me he never uses compression.")
 
Short answer: No, not for everyone. A compressor is a very useful tool, and just as with any other tool, the better you understand how to use it the more useful it can be. There are a lot of circumstances in which a compressor is the right tool for the job. But that doesn't mean you have to use one. Many people prefer to regulate their signal peaks as much as they can strictly through playing technique. And many amplifiers (especially tube amps) compress your instrument signal a bit just by the nature of the amp design. Overdrive and other types of distortion also compress your signal considerably. So under many circumstances it may not be "necessary" to use an external compressor. It's up to you to analyze your particular situation and determine if a compressor, as a tool, can be useful to you. Remember too that misusing a compressor will get you bad results, exactly the same as misusing any other sort of tool. If you apply a chainsaw when you needed a fine dovetail saw, it'll be bad news for your woodworking project. But don't blame the chainsaw!
 
So why would somebody want to use a compressor? What is it good for, and when? Here are the basic benefits, which vary from one comp to another:
 
-Peak limiting, to avoid clipping your amp or blowing your speakers.
-Evening out levels between strings or between soft and strong playing.
-Increasing sustain and/or "punch" (see my article about that), by increasing the average level of the signal without increasing the peaks. This can provide greater perceived loudness, fatter tone, more audible harmonics, and better placement in the mix.
-Changing the attack and other envelope qualities of your notes, making them squishier, rubberier, crisper, or other amplitude effects which may be difficult to achieve just with your fingers.
-Emulating some of the tone and envelope qualities associated with older recordings (Motown, early rock and funk, etc.) in which tube and transformer-based recording equipment and reel-to-reel tape recorders got "saturated" by the bass signal. That saturation compressed the recorded tracks.
 
Some amount of dynamic control can be achieved just using your fingers, and that is a really important goal to work towards while practicing. However some signal spikes can't be prevented with your hands, such as a resonant peak from an envelope filter, or a flanger or delay set to high resonance. And some players like to rock out with wild abandon, which means they need a limiter to keep their signal in check.
 
It's important to note that clipping your amp will never damage the amp, it just a question of whether it sounds bad or good with your amp. Clipping also does not fry speakers, that is a myth that gets repeated all the time, even by professionals. The only thing that fries speakers is sending into them more power than they can handle. Sometimes that happens when the amp is clipping, but note the distinction! It wasn't the clipping that did the damage, it was the excess power. Clipping is not a square wave and a square wave is not DC, so don't believe anyone who uses those arguments to explain why they think clipping blows speakers. Bear in mind though that tweeters are usually rated for a lot less power handling than the other speakers in a cab, so it is relatively easy to blow your tweeter with too much power in the form of a big signal spike. Also your amp can momentarily generate far more wattage than the rating it says in the manual or on the back panel, so even if your cab is rated to handle 300 W and your amp is spec'ed to deliver 300 W at that ohm load, sending a big momentary spike from your bass into the amp can cause the amp to briefly generate an output spike of a lot more than 300 W. So one way or another, it is a good idea to exercise control over your signal spikes, to avoid sending too much power into your speakers.
 
As far as the other qualities of tone and envelope changes, they are completely subjective. Either you want those changes or you don't, and that's fine either way. Sometimes that rubbery thump, or boosted harmonics, are exactly what the song needed! And one compressor may be good for getting the tone/envelope changes you like, while another seems to do nothing but deaden your sound and add noise. That's normal. Read my article about good settings, and if that doesn't help then try a different compressor. But don't assume that because you have good dynamic control with your hands, or because you tried a pedal in 1985 that sucked, that compression is no good for anyone. It's a very useful and powerful (yet subtle) tool, but you must pick the right tool for the job and learn how to use it properly. I don't think compression is for everyone all the time, but I do think a professional musician should have the ability to use a compressor well, as part of their tool box of skills.

 
 
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