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OK, So I guess I just don't get compression
Old 27th May 2006
  #1
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OK, So I guess I just don't get compression

Again, flipping though "The Mixing Engineers Handbook" I came across this quote from one of the interviewed pros.

On compression:

"Its the only way that you can truly modify a sound because whatever the most predominant frequency is, the more you compress it the more predominant that frequency will be."

He goes on to say that if the predominant frequencies are 1k to 3k. If you "Put a compressor on it and the bottom end goes away, the top end disappears and you're left with (a nasally sound)".

I thought compression evened out frequencies!?!???!? When I watch a spectrum analyzer while compressing something it seems to make the curve flatter which would make me think it would tuck in the nasally sound .

Can someone please enlighten me?
Old 27th May 2006
  #2
Gear Maniac
 

yes that quote does seem rather strange!.. I think it can go both ways.. I've often heard people say that compression removes alot of high frequencies.. and still other people say it takes away alot of bass..

they're all crazy though.. some compressors are particuarly biased one way or the other.. but mostly it depends entirley on the source and how the compressor is set as to how the frequency range will be affected..
Old 27th May 2006
  #3
"Pro," huh, that's a dangerous word right there.

Compression, I think, is designed to keep peak levels from ever exceeding a certain point (of your choosing), so the first thing compression does is squash levels, and this might translate as sounding like the top and bottom detail is lost, leaving you with the honky midrange content. Maybe that's what the quote is about?

I've found that if you work the attack setting, you can tame the unruly high end content, or unruly lows. The metaphor I like is "walking through a door." If you had a scruffy Russian revolutionary walking through a door with a huge beard, his beard passes through the doorway before he does... and if it's a truly huge beard, all you would see is a beard coming inside. With compression, you flatten his beard against his face, so it looks like a guy with a beard walking through a door.

Although Fletcher could probably explain this better than I.
Old 27th May 2006
  #4
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u b k's Avatar
 

Quote:
Originally Posted by dbm
Can someone please enlighten me?

well alright... but only because you asked.

the answer, as always, is "it depends". specifically, it depends on what comp you use, and how you use it.

run a nasally singer thru an la2a, step on the gas, and it will smooth out the honk quite nicely. do the same thing with a distressor and you'll get a very different result. a 2254 will roll off the top and darken anything you give it, an 1176 will push the high mids and put hair on the air.

i suppose it's worth stating that just because it's in print, and from a reputable source... well, you know where i'm going with that.

in short, compress away!


gregoire
del ubik
Old 27th May 2006
  #5
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proxy's Avatar
 

If I remember correctly from the context of those interviews, he's really talking about using compressors for color, and the relationship between the kind of information that is in the signal (frequency-wise), and how that has a relationship with what will happen when pushing that information through a compressor.

In it's most theoretical sense, yes you can think of compressors as evening out things, but once you start using it not just as a dynamic tool, but as a color tool in conjunction with EQ (placed before and or after), I don't think his comments are too esoteric. Experiment with EQ-ing things, perhaps even radically, before a comp, just to experiment, and it may make more sense.

Lastly, sometimes the "virtual" compressors are so versatile, that getting experience with a single piece of outboard can be more educational. At least it was for me.

- proxy
Old 27th May 2006
  #6
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Man, what the hell....... This sucks

I was under the impression that the fundamentals were the same in all compressors and the thing that gave them their character was the extra "stuff" they introduce to the signal. You set a threshold, anything that goes above that threshold gets reduced a number of decibels dictated by the ratio. Attack was how fast it jumps on it and release was how long it holds it. Wtf, so now it sounds like Im hearing that some compressors restrict the frequencies on which they work or something? (e.g. only look at certain bands)
Old 27th May 2006
  #7
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Zeppelin4Life's Avatar
 

Quote:
Originally Posted by dbm

I thought compression evened out frequencies!?!???!? ?

this is a really really common mistake, but no, compression EVENS OUT DYNAMICS! (loud and soft). For some reason people think it evens out freqs. It may sound that way though..our ears are most sensitive at arouind 3k...if you even out all dynamic range to one loudness for instance, our naturally 'loud' frequency (3k or so) will seem louder...like these guys said, it depends on the unit too...many engineers just leave the 1176 amps on with no compression..just for the extra analog sprinkle it adds to the mixes..to each his own!

PS, yes, there are compressors that work on seperate frequencies, they're called multiband compressors :-)



Old 27th May 2006
  #8
Like the man says... there are multi-band compressors that will work separately on different groups of frequencies... I think any normal compressor is squishing all the frequencies, and when you do that, the character of the sound changes, because some frequencies become more dominant than they were originally.
Old 27th May 2006
  #9
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Hey, not to hijack the thread, but Joel I just realized you're near Albany...thats cool..im in Latham...greetings !
Old 27th May 2006
  #10
Hey there! I heard there was a wreck yesterday on 787 that closed down the northbound lanes? That must have been a mess...
Old 27th May 2006
  #11
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u b k's Avatar
 

Quote:
Originally Posted by dbm
Wtf, so now it sounds like Im hearing that some compressors restrict the frequencies on which they work or something? (e.g. only look at certain bands)

it's simpler than all that: outboard gear has tone, often it has color. some comps are smooth, some are edgy, some are peaky, some are invisible. run a boxy signal thru a peaky comp and it'll cut better. run a peaky signal thru a peaky comp and HEY, ouch.

a carpenter has to know his tools.

analog compressors are truly magical beasts, and there's a lot going on inside those boxes that determines how they sound. is it a vca, opto, or fet? is it hard knee or soft? does the detector respond more to mids than to bass? is there a tranny or two in the loop? tubes?

just buy (or rent) a good hardware box and play with it... you'll get it right away. otherwise you're trying to understand experiential reality by talking about it, and i wish you luck with that approach!


gregoire
del ubik
Old 27th May 2006
  #12
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ubik speaks with great wisdom
Old 27th May 2006
  #13
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vernier's Avatar
Quote:
I thought compression evened out frequencies!?!???!?
Compression messes with dynamics of any or all frequencies, depending on the particular compressor.
Old 28th May 2006
  #14
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Just to add to this, remember the definition of a compressor is an amplifier who's output level decreases as its input level increases, that is it. Compressinion is used mainly as a tool for reducing peak level and raising rms level so we get a louder level.
On very dynamic pieces of music we are able to lower the high peaking levels and raise the lower overall levels so we don't constanly have to adjust volume on playback, it gives the listener a more enjoyable glued together type sound, stops sounds from jumping out of a mix and being overly dominant. Though too much will destroy any sound or mix.
Varying attack and release times is the way to either squash a mix totally or to let fast transients slip through thus giving the impression of making say drums sound punchy and fatter.
There are hundreds if not thousands of comps out there, all sound different, even the same model from the same manufacturer can sound different.
I suggest reading info on loudness versus volume to get a better understanding of compression. There is more than enough info here to learn the basics. Practice makes perfect. Also all circuits have different frequency responses, so yep every comp will sound different.
Old 29th May 2006
  #15
Gear Head
 

Quote:
Originally Posted by u b i k
it's simpler than all that: outboard gear has tone, often it has color. some comps are smooth, some are edgy, some are peaky, some are invisible. run a boxy signal thru a peaky comp and it'll cut better. run a peaky signal thru a peaky comp and HEY, ouch.

a carpenter has to know his tools.

analog compressors are truly magical beasts, and there's a lot going on inside those boxes that determines how they sound. is it a vca, opto, or fet? is it hard knee or soft? does the detector respond more to mids than to bass? is there a tranny or two in the loop? tubes?

just buy (or rent) a good hardware box and play with it... you'll get it right away. otherwise you're trying to understand experiential reality by talking about it, and i wish you luck with that approach!


gregoire
del ubik
I would have to second this advice and add my defnition of what a compressors does just because I'm not sure anyone said it like this and it may help someone on here as much as it helped me..

A compressor lowers the amplitude of a signal that surpasses the set threshold by the ratio and is activated once the attack time has passed and is deactivated when the release value has passed. This means that the attack value determines when the compressor will start reducing the amplitude of the signal. Once activated, the compressor will reduce whatever signal that runs through it by the ratio.

e.g. So if your threshold is set at -3dB and your meter is hitting 0dB and your ratio is set at 3:1, the compressor will reduce the amplitude by 1dB when it tops out at 0dB.. Does this make any sense?

Of course each compressor has its own color and flavor depending on the method it uses to compress the signal as well as the internal components. This may affect certain frequency ranges differently so a compressor can act as an eq although it is designed for reducin dynamics. Hopefully this is clear. If not, let me know what is unclear about what I wrote and I will try to clear up.
Old 29th May 2006
  #16
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atma's Avatar
if the point of compression is the reduction of dynamic range, and generally speaking, the loudest portion of a signal is it's transient peak, why would you use a slow enough attack to allow that transient to pass through uncompressed? if the transient (or part of it), isn't being turned down, it doesn't seem like compression at all, since you'd simply be turning down the signal after the loudest portion of the waveform had passed through.
Old 29th May 2006
  #17
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I vaguely remember when I was first learning compressors, I "visualized" in my head, a transient-less sound, thinking, if I just had that after-transient "body" it would sound huge... Wrong.

Transients are usually the good part, the part that's going to convey impact and percussive clarity/articulation. A release that is acting on the post-transient part is going to create a solid sound. How much you "choke up" on the transient (attack) without killing it, will alter the tone, and potentially enhance that pow-factor.

I say "usually" because sometimes you do want to tame them, like with a s***** sounding acoustic, but for other percussive elements, you're usually trying to retain them, if not enhance them.
Old 29th May 2006
  #18
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A compressor can be set up to do many different things. Depending on limitations of the device, you can set them up to be a Limiter, a Compressor, a Leveler, an Expander - or just use it to shape the envelope of a sound. It's not always about being a "Volume Maximiser".

If you have any Attack time, the Attack of the signal goes through uncompressed, but when the compressor finally kicks in, it compresses the sound that immediately follows. That might be musically useful, even if it's not actually "Maximising Volume". What it is doing is making the Attack portion of the sound relatively louder.

On a snare drum, varying the Attack can varies the amount of stick sound that comes through, so you can make it more punchy with longer attack times.

On a guitar, the Attack setting can control the amount of pick or finger sound you want.
Old 29th May 2006
  #19
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Simple, this is the aim of beefing things up with compression, if you use too fast an attack time on say drums then you will surely make them dissapear from your mix, so allowing some transient to pass through and holding back the rest of the sound envelope will give the impression of punchier drums, also using to long a release time in this scenario would result in residual compression on each consecutive drum hit which is undesireable when trying to beef up drums.. Using a very fast attack time under say 0- 5ms is more to be used when limiting, which is extreme compression.
A basic rule to compression is the slower the transients the slower the attack should be and the longer the sound envelope the longer the release should be.
Old 29th May 2006
  #20
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I'm more than likely wrong but the way I've always looked at this is that what the compressor sees is not the same as what the ear hears.

The human ear is pretty terrible at hearing low frequencies - a bass will usually be making the dB meter levels dance before it's loud enough, turn a triangle up to the same level and your ears will start to bleed. Trouble is a single band compressor sees both as the same thing, so in material with a reasonable frequency range, the low end will be tripping the compressor while the higher end stuff will pass by without being attenuated - providing they don't happen at exactly the same time, of course.

The higher end stuff will usually be all the overtones, less loud but more audible to us. So in my experience and to my ears, compression tends to brighten although, as everyone said, it depends on the compressor's native 'sound'.
Old 29th May 2006
  #21
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Right, and then you can get into side-chaining to make it even more interesting.

Where you send a hi-passed version of the signal to the side-chain, so what is triggering the dynamic envelope relates to a part of the sonic spectrum that is higher up.

Another variation on this is sending a "tilted" signal to the side-chain, when the lower end is part of the signal to the side-chain, but proportionally less than the higher end info. Some comps have that built in, like the API I believe.
Old 29th May 2006
  #22
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Quote:
If you had a scruffy Russian revolutionary walking through a door with a huge beard, his beard passes through the doorway before he does... and if it's a truly huge beard, all you would see is a beard coming inside. With compression, you flatten his beard against his face, so it looks like a guy with a beard walking through a door.
that has to be the most utterly bizzare compression-related analogy ever formulated :D
Old 29th May 2006
  #23
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so the concept of punchyness in relation to compressing drums for instance would be more akin to expansion rather than compression, in a sense.. ? what's you're aiming to do is actually phatten up the transient portion of the signal, which could be achieved either by compressing the post-transient section of a waveform, or actually using expansion on the transient section above a certain db threshold..
Old 29th May 2006
  #24
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u b k's Avatar
 

Quote:
Originally Posted by atma
so the concept of punchyness in relation to compressing drums for instance would be more akin to expansion rather than compression, in a sense.. ? what's you're aiming to do is actually phatten up the transient portion of the signal, which could be achieved either by compressing the post-transient section of a waveform, or actually using expansion on the transient section above a certain db threshold..

not quite. what you're doing is taking the helm and shaping the entire envelope, including the transient, to be your bitch. with rock drums, e.q., you allow exactly the amount of 'pop' thru that you want, then squish the remaining transient with the knee while sucking up the sustain and decay of the drum. if you've done your job, the pop is set perfect to make the drum snap thru the mix, and the tail is pulled up enough to make it sound bigger/fatter/whatever.

too little attack and the drum won't pop thru. too much attack and there'll be too much pop and you won't be able to push the fader enough to make things rock. too much overall compression and the drums will never go away, eating up all the space in your mix. too long of a release and you'll have the same envelope, just lower in level.

there's more, a lot more in fact, and that's just drums. vocals are a trick, and mix compression is the easiest to screw up, hardest to do 'just right'. compression is the blackest of the black arts. i love saying that, btw.


gregoire
del ubik
Old 29th May 2006
  #25
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Say what you want about that quote, but it came from Andy Johns... I think his track record speaks for itself. He's done some of my favorite records ever, but then again, I'm a huge Zep fan. Who isn't?
Old 29th May 2006
  #26
C/G
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Quote:
Originally Posted by u b i k
compression is the blackest of the black arts. i love saying that, btw.


gregoire
del ubik
Looks like I just bought myself a new sig. Thanks Ubik.

p.s.

Ubik, the songs are on the way to you soon.
Old 29th May 2006
  #27
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Obviously best to use one's ears first and ultimately ...

... but as a learning tool while you're still trying to get your head around what exactly different compressors and settings are doing to different types of source material, a lot can be learned from loading some unprocessed audio files into your DAW and SEEING what the different compressors/setting are doing to the waveform. This applies to hardware or software.

There are a lot of less productive ways to spend a couple of hours. Put it this way, it can't be worse than reading someone else's verbal descriptions, can it?

Old 29th May 2006
  #28
11413
Guest
Quote:
Originally Posted by dbm
Man, what the hell....... This sucks

I was under the impression that the fundamentals were the same in all compressors and the thing that gave them their character was the extra "stuff" they introduce to the signal.
i would say most of engineering is knowing what box to run what signal thru to achieve a specific result... this is why bigtime mix guys like Brauer have all those racks.

there is no do-everything box.. you're lucky if you can find one or 2 sounds a box is good at.
Old 29th May 2006
  #29
11413
Guest
Quote:
Originally Posted by u b i k
compression is the blackest of the black arts.
i would say mixing is... compression isnt that hard at all.

or possibly mic placement... but i think mixing is harder.
Old 30th May 2006
  #30
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u b k's Avatar
 

Quote:
Originally Posted by 11413
i would say mixing is... compression isnt that hard at all.

or possibly mic placement... but i think mixing is harder.

that's funny! mic placement has always been a no-brainer for me. i was building good mixes long before i understood compression. well, they were balanced and clear, but they lacked that urgency and presence of the good squeeze.

come to think of it, reverb is a bit of a bitch as well...


gregoire
del ubik
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