Why does compression squash sound? Thought it just lowered volume (dynamic range)

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wes480

wes480

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I am really confused on this. I understand all of the "basics" of compression...threshold, ratio (well, not sure what the two numbers are in the ratio...but, i get what it does), attack and release.

I understand that compressors only turn sounds down (expanders turn it up). Understand why using them for almost everything is essential to getting a nice hot signal, and a steady volume level. And also how they come into the mastering equation.

What I don't get - is where in this definition the famous "sqaushing" sound comes in. Now, maybe i am totally on the wrong thing here...but, when i listen to something that is compressed (to my ears right now, the most obvious thing is drums) - it gets to where at the extreme the snare drum and the kick drum start to sound about the same...and the cymbals are very "squashed".

Damn cool effect, i love it - but..why does it happen? If all a compressor does is reduce dynamic range...I just don't get it. It's like there are 2 totally different jobs that a compressor does - explain..explain!

P.S. - Anyone who wants to do some bonus work, check out the track "In a Little While", from the newest U2 album (deserves all the grammys it has coming to it). The drum sound on this song (and on a lot of the album) esp. when they first kick in has that kind of techno/breakbeat groove...makes it sound less like a real drum kit..etc. To me, that sound is largely "compression" - am i wrong?
 
you can use compression in varying degrees from mild to squashing......

that pumping is a side effect of an overly used compressor...this could be good or bad, depending on what your intentions were.......
 
wes480 said:
I understand all of the "basics" of compression...threshold, ratio (well, not sure what the two numbers are in the ratio...but, i get what it does), attack and release.
Click to expand...
Actually, you mustn't understand very well at all then, otherwise you wouldn't have asked that question!!! ;)

I suggest re-reading Shailat/Ed's article at ---> http://24.61.136.253/Compression.html


:)

Bruce
 
In simple terms Wes, most compressors are VCA based. These circuits look at signal, change them to voltage, and it is this voltage based on the compressors settings that apply gain reduction. The problem is, these circuits use high ratios which are more like Limiters than compressors. Real compressors should not really go over a 10:1 ratio.

Ok, what does this mean...Based on fast attack, hard knee or high ratio's, that tends to make the sound squash hard, or even pump. Why it kills the cymbals is that VCA circuits squash all the bandwidth out of the mid and high frequencies because they do not allow any transients to go above a certian threshold, so they kind of brick wall or limit these frequencies. The result is everything starts to sound the same as a result of the loss of the mid and high end content in the program material.

Not all compressors are like this. There are Photo-Optical units that do not limit mid and high frequency content, so all sounds come through unsquashed, but they also color the sound as a result of the light source generating a 2nd order harmonic, which is good on many sounds, but not on all.

I hope this helps you, and I hope I made it easy to understand.

Alan Hyatt
 
Gee, Alan, those photo optical units sound nice...know where i can get one?:D ;) :p :eek: :rolleyes: :)
 
thanks...that helps a lot alan.
now i am just hearing mixed reviews on this behringer composer...but, i feel like i need it.
 
Yah, that's a sampled drum loop on the U2 song. It sounds nothing like the drum sound for the rest of the album, has vinyl scratches all over it, and it's exactly the same every time, all good clues.

Hey Gidge, you already own 2 "photo-optical compressors!"
 
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