Understanding the difference between a compressor and a gate

What is the difference between a compressor and a noise gate? They both have threshold, attack and release controls. What gives?

Ken
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Interesting question, sir. Compressors and noise gates are similar in some ways, but their uses are different. A compressor keeps a signal within a certain dynamic range, determined by the threshold and ratio controls. When the signal exceeds the threshold, the volume is lowered by whatever ratio the compressor is set to. This is used to smooth out volume levels.

The best way to think of a gate is like an actual gate; it opens and closes to let things (or signal) pass. The threshold determines the volume level at which the gate will open. The attack control determines how fast the gate will act once the threshold has been reached. The release controls how long the gate will stay open. A gate won’t pass any signal at all until the signal coming into it reaches the threshold. This is used to help eliminate unwanted noise (the hum from an amplifier, leakage from other instruments, etc.) by essentially turning off a microphone when all it’s picking up is something other than the source it’s miking.

Some gates can also be adjusted to open and close based on the frequency of the signal. These are called frequency dependent gates and are very helpful in keeping hi-hat out of a snare mic and cymbals out of tom mikes. Hope this helps.