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Compression, Why And What!?
| Good [+1]Toggle ReplyLink» ApR1zM replied on Mon Mar 31, 2003 @ 5:01pm |
 Coolness: 165520 | music school
What is compression and why is it needed... When you paint a window frame it is clear to the eye when the brush strays... since you see the paint on the window. Our hearing is usually not as good as our vision, and further singing or playing guitar is a little more complicated then staying in between the lines when painting. So it is easy to stray in the sound spectrum and when it happens we might not even notice. Compression is a tool to remove the errant paint off that window. Though instead of literally removing the error a compressor, compresses any errant paint that went on the window, compressing it small enough so that it never exceeds the dimensions of the window frame, paint that always stayed between the lines is not effected at all (the result is the loudest sounds are made quieter and everything else is not affected). Besides setting threshold (the db level of where you want the compression to happen) and ratio (the amount of compression you want to occur above that line), the other important elements are attack and release times. These are the amount of times it takes the compression to kick in and kick out. If they are too long or too short you have problems. In general, if the attack time is too fast you lose drums. If you want to preserve the original source sound you want to set the slowest attack and release times possible. It should be noted that this compressed/concentrated audio cannot be resurrected by adding water so don't overdo it with compression. And while mostly all cds are mastered, and music is often recorded and mixed with compression I think you should experiment for yourself whether you it is what you want. It is possible to exist without it if you record with precision. Also a close relative to the compressor is the limiter. Limiters are like extreme compressors. Whereas a compressor draws a somewhat malleable line of where your audio should not cross by setting both a threshold and a ratio, a limiter is a much more certain 'audio shall not pass this level' line where only the threshold is set. There are hardware compressors and software compressors. Cool edit pro and N-track come with bundled compressors that have real time preview so you can decide if it is right for you. T-racks is a complete software mastering studio program with built in compressor, limiter, and equalizer which has some really good presets that provide good starting points (I recommend downloading the demo to get an idea of what mastering/compression can do to your sound). Any of these options would probably be the easiest avenue for the pc-musician. Cool Edit and Ntrack also come in demo form, the later being a fully functional demo.... so experiment for yourself and make your own decision about compression. And remember that not all good art stays between the lines... HarmonyCentral has a more technical/broad explanation that is worth checking out here. taken from : [ music.multimedian.com ] |
| Good [+1]Toggle ReplyLink» nothingnopenope replied on Mon Mar 31, 2003 @ 6:40pm |
 Coolness: 201945 | werd, compression is the reason why I get the sound I do with most of my tunes |
| Good [+1]Toggle ReplyLink» OMGSTFUDIEPLZKTX replied on Tue Apr 1, 2003 @ 2:24am |
 Coolness: 67235 | Get that kick to sound like a kick! |
| Good [+1]Toggle ReplyLink» Toltech replied on Tue Apr 1, 2003 @ 2:39am |
 Coolness: 146140 | An effect that's really cool and that results from compression is, when that kick (usualy predominant in electronic music) is taken off, everything else gets amplified a few notches (depending on the compression applied) and it just makes everything stand out for that moment.
Compression is pretty much like an automated volume that turns down the volume of whatever it is that you apply compression on and then turns it back to where it was on before it went over the setted threshold...... ......am I making it sound simple? I'm just asking because I think I'm usualy at explaining stuff and shit. |
| Good [+1]Toggle ReplyLink» ApR1zM replied on Tue Apr 1, 2003 @ 4:36pm |
| Coolness: 165520 | man im happy you guys are fucking cool and we will soon have a Music production board especially to share stuff like this so that we can all reprazent and put MTL on the electronic music map :D |
| Good [+1]Toggle ReplyLink» Oliver_TwisteD replied on Tue Apr 1, 2003 @ 4:52pm |
 Coolness: 86405 | ~Toltech,
pretty decent explanation of what compression can do. More straightforward than the teachers at my old sound school made it out to be. Mind you they didn't specialize in electronic music. |
| Good [+1]Toggle ReplyLink» OMGSTFUDIEPLZKTX replied on Wed Apr 2, 2003 @ 12:24am |
| Coolness: 67235 | aone: wait till Psikon is up *smirk* |
| Good [+1]Toggle ReplyLink» Unknown User replied on Sun Apr 6, 2003 @ 8:11am |
| Coolness: 100 | Just to elaborate on the orignal post and provide further explanation of some of the 'typical' parameteres found on most software compressers:
"the result is the loudest sounds are made quieter and everything else is not affected" By "the loudest sounds" he means everything above the threshold level. Signals above the threshold level will be effected and signals below will remain untouched. Thus the lower the threshold, the more headroom the compressor has to do it's business. The "ratio" setting determines how much gain reduction is applied to signals above the threshold level. for example a 4:1 ratio means that for every 4 dB of input over the threshold, the output will only increase by increments of 1dB i.e. signals above the threshold are reduced by a factor of 4. The "make up gain" parameter boosts the overall level of the signal once the compression has been applied. The trick is to boost this until you constantly register a reading on the gain reduction meter while keeping the signal below 0dB (where clipping and digital distortion set in). Watch out for that unnatural, characteristic "pumping" effect. If you notice this, adjust your ratio, attack and release settings. The envelope controls (typically attack and release) determine how quickly the processing is applied and how long the processing lasts respectively. If I set a threshold of -20dB and an attack of 2ms, it will take 2ms for the compressor to process every signal above -20dB. Raising the attack setting allows more of the signal to pass through unaffected. Likewise with the realease setting. If I set it at 100ms, then the compressor will process any signals above -20 db for a duration of 100ms. "Gating" is a feature that allows you to reduce the level of low-level sounds. This is particularly handy for eliminating unwanted hisses and noise but may lead to trouble later on if your using heaps of fader automation. Basically how it works is by setting a threshold level. Sounds below the level will not be let through. Conversely, the gate will open when a signal exceeds the threshold and it will pass through. "Hard-Knee" vs. "Soft-Knee". A basic compresser does not affect the signal until it has exceeded the threshold volume. At this point, delayed only by the attack time, it fully applies the compression selected by the user. This type of compression is known as "Hard Knee" compression, where the ratio applies only to signals above the threshold. This may be sufficient for overall level control but the effect becomes too obvious on more heavily compressed signals at the front of the mix. "Soft-Knee" compression attempts to literally smoothen the input/output curve and the effect on the signal. In this case, the compression ratio gradually increases from 1:1 to the set value. This makes the transition from a compressed/uncompressed signal more subtle. There's also usually a 'range' parameter associated with the soft-knee option and this sets the difference between output levels surrounding the threshold over which the gradual increase in the compression ratio occurs. I'll post some more stuff on de-essing and ducking when I get round to it. BTW I thought the original post was quite brilliant in it's explanation and analagy. I'm in no way trying to "correct" it or anything... just filling in where I can:-) |
Compression, Why And What!?
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