The compressor’s attack setting controls how quickly the compressor turns the signal down once it has crossed the threshold. New comments cannot be posted and votes cannot be cast, More posts from the audioengineering community. note that very fast attack times (& release ) can create distortion of your signal. Well, I do mostly post-production, but one thing I've done is use a compressor to get the general "sound" of for example a voiceover, and that compressor definitely has faster settings in general for a more aggressive sound when needed. They're different things. Usually knee starts about 3dB before the threshold but that can vary from one model/design to another... Let's say you have a 4:1 compression ratio with a knee setting turned on or all the way up and your threshold is -20dBFS... the signal is at a 1:1 ratio when it is below the threshold, BUT... as it starts to approach the threshold the knee setting changes that... at -23dB (3 dB below threshold) maybe the ratio is now 1.2:1... at -22dB maybe the ratio is 2:1, at -21dB the ratio might be 3:1 and finally when you hit -20dB the ratio is at the preset 4:1 that you selected on the compressor. So would the knee be a function of the compressor ratio possibly? I also ride levels of course. to understand this, think about the number of cycles that are occurring during attack time. The X axis is the input signal, the Y axis is the output signal. You could for example have a sound that has too little attack, and by delaying the attack of compression, or the "start" of compression, you end up changing the ratio between attack and sustain.In other words the attack of the sound passes through uncompressed and then after the compressor begins compressing the rest of the sound. Since nobody mentioned it in much detail... Knee is not slower release... knee is essentially a variable ratio based on input level and threshold. The knee is the way in which the compressor reacts to the signal. Attack time is how quickly the compressor engages and reduces the volume of the audio.. Knee sets how the compressor reacts to signals once the threshold is passed. A knee that is 6 dB wide won’t fully compress the signal until it hits 3 or sometimes 6 dB above the threshold (knee shapes may be different from compressor to compressor). Hey there! The knee is the sharpness of the angle. No... with drums for example you are commonly using compressors to make the volume spikes of the drums even more pronounced. Soft knee compression. That has nothing to do with the knee shape of the compressor, which is more about how the compressor reacts to overall signal level increases at a steady state, rather than under fast, dynamic circumstances. I'm going to guess that #1 from Attack and #1 from Knee are most appropriate. attack is NOT linear and is logarithmic in nature and there is a difference between FET / OPTO / VCA in their behavior with respect to attack & release curves. To add to this, the attack time is the time it takes for the gain reduction to conform to the graph posted above. See this picture: https://media.uaudio.com/blog/2009/april/doctors_6.jpg. It’s going to do that based on where the compression action begins. Once the input goes above ~ -25 dB, the output is reduced. if you have signals peaking near and under threshold, they'll be compressed differentially, to kind of 'hide' the threshold setting. I think its worthwhile taking the moment to mention that the attack time isn't a delay before the onset of compression. Attack is how fast the compressor reacts to signal. this would be a 'soft knee'. Like a gain reduction ramp that affects the initial threshold signal at a slightly lesser ratio then depending on the knee setting moves into the normal ratio? once activity start is determined from the above, you then have attack time. Compressor knee vs. attack time Quick question: Is there any difference between the knee setting of a compressor and the attack time? so attack is the speed of response, which can be tailored to the material to lessen or allow leading transients vs. the following sustain of the sound. And just to add some information/confusion. You need an account to post a reply. It’s a measurement of how soon the compressor kicks in. if you have a signal going right over, you won't hear the soft knee. I'd be curious to hear what other uses it has. Press J to jump to the feed. Knee, attack time, and release time for expanders would all work the same as in compressors. Makeup gain is only really necessary for upward expansion. A knee is an amplitude-based number, usually in dB. Setting the attack to 50-100ms shapes the envelope of the bass to give it a bit more transient edge. That’s the technically correct definition, at least. We've got those too - click here to see an ever-growing list of community-voted "top ten" lists. You will be surprised how many people think this. Create a username and password below and an account will be created and your post entered. On the other hand, if you are a seasoned pro, please don't hesitate to jump in and offer your experience and wisdom. 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