MeldaProduction

jmg8 · Post by **jmg8** » Sat Nov 12, 2016 9:59 am

Myth #1: Attack is the time it takes for a compressor to begin compressing once a signal crosses over the threshold

This may be my favorite audio myth of all time, because I think it’s the most pervasive. People who know a lot of things; people who’ve written books on the subject of recording and processing audio, have perpetuated this myth by writing about it, repeating it and passing it along as established fact so that you can read it passed off as fact in countless blogs and forums.
The only problem is that it’s completely, utterly incorrect.
in the pursuit of truth, justice, and all that is good in the world, I give you the correct definition of attack
And so, in the pursuit of truth, justice, and all that is good in the world, I give you the correct definition of attack:

Attack is the length of time it takes a compressor to apply roughly two-thirds of the targeted amount of gain reduction.
I say ‘roughly two-thirds’ because there is no agreed-upon, industry-accepted standard for what this spec actually is. Yes, you read that right: no two compressor designers will agree on exactly how to define, and therefore measure, attack. My definition above is within the ballpark of most thinking, so I’m running with it.
To understand this definition of attack better, you need to get some basics of compression established first. Let’s say your compressor is set with a threshold of -10dB and a ratio of 3:1. If you feed this compressor a signal at -11dB, nothing happens because the signal is lower than the -10dB threshold.
But if that signal jumps to -1dB things get interesting. Most notably, the instant the signal reaches -10dB the compressor begins attacking it. There is no delay whatsoever in this response, which belies the myth that attack is the time it takes a compressor to respond once a signal crosses threshold.

With a -1dB signal and a -10dB threshold, the signal is 9dB over threshold. Our 3:1 ratio means that for every 3dB coming in over threshold, the comp wants to allow 1dB out the backside. Since our example has a signal 9dB over threshold, our hypothetical 3:1 comp wants to compress those incoming 9dB into 3dB at the output, which would require 6dB of gain reduction.
Given that attack is the time it takes a compressor to apply roughly 2/3 of the targeted gain reduction, the attack in this case indicates how fast the comp will apply the first 4dB of the target 6dB of reduction.
If you don’t follow the math of this illustration, don’t worry. For now it’s enough to know that the compressor starts applying gain reduction as soon as the signal crosses the threshold. Which means that attack is not a delay before action, nor is it even a measurement of time per se; instead, it is a rate, a measurement of the speed at which the process of gain reduction is occurring.

Read the whole article here:
https://www.attackmagazine.com/features ... mpression/

jmg8 · Post by **jmg8** » Sat Nov 12, 2016 11:12 am

It would be great to hear peoples opinion about this article (especially Vojtěch)
I'm sure I completely agree with all of it. It definitely challenged some of my existing believes of compression.

Tagirijus · Post by **Tagirijus** » Sat Nov 12, 2016 1:49 pm

Thanks for sharing. Quite interesting. Also funny, that the hoster is "attackmagazine.com", hehe.

Also thanks for the summary and explanation. In the end I mainly use my ears combined with the great Melda graphs, while using a compressor. But it's also nice to understand things technically better!

DarkStar · Post by **DarkStar** » Sat Nov 12, 2016 1:55 pm

Hmm, I need to think about that.

To be impartial, the whole text should be in quotes, and credited to "Kush Audio guru Gregory Scott " - I thought that it was your own view at first.

Maybe this would be better in Effects or DSP and Plug-in Development; to get the views of other developers too.

jmg8 · Post by **jmg8** » Sat Nov 12, 2016 2:59 pm

DarkStar wrote:Hmm, I need to think about that.

To be impartial, the whole text should be in quotes, and credited to "Kush Audio guru Gregory Scott " - I thought that it was your own view at first.

Maybe this would be better in Effects or DSP and Plug-in Development; to get the views of other developers too.

OK, I have edited now. To be clear I did not write any of this. I just found it interesting to share and find out if anyone agrees or disagrees with any of it.

steve2KVR · Post by **steve2KVR** » Sat Nov 12, 2016 3:10 pm

...for me it's not so much about "agree/disagree," but more about finding myself as technician/"engineer" working in an environment of creators/"artists"...and I end up using a lot of "near miss metaphors" to get everyone on the same page

...try explaining to your mom the use of differential calculus concerning thermal gas flow temperature exchange to her while she's cooking dinner

...and you all know what I mean

.../s~

mabian · Post by **mabian** » Sat Nov 12, 2016 3:38 pm

I think there's no official rule about those "two/thirds"; we just have to get the main concept and use our ears - imo.

I believe you'll hardly find two compressors in which attack and release are implemented the same way, just because, as a matter of fact, there's no scientific standard rule on what they should do exactly to an audio signal.

That's it all for me...

- Mario

mvillemaire · Post by **mvillemaire** » Sat Nov 12, 2016 4:55 pm

Technical but very interesting read on compression/dynamics:

(web)
http://www.rane.com/note155.html

(pdf)
http://www.rane.com/pdf/ranenotes/Dynam ... essors.pdf

mvillemaire · Post by **mvillemaire** » Sat Nov 12, 2016 5:09 pm

Not on topic but about equalization:

(web)
http://www.rane.com/note115.html

(pdf)
http://www.rane.com/pdf/ranenotes/Expos ... hology.pdf

Someone can post it to the relevant topic/thread.

.jon · Post by **.jon** » Sun Nov 13, 2016 1:31 pm

So he basically pulled that 2/3s out of his ass and didn't even try to explain why it was in his ass in the first place.

Written like a true besser-wisser, bending myths into something they really aren't, not presenting any facts to back shit up... I call BS on this fellows mythbusting efforts.

pone · Post by **pone** » Sun Nov 13, 2016 3:06 pm

.jon wrote:So he basically pulled that 2/3s out of his ass and didn't even try to explain why it was in his ass in the first place.

The reason is probably a lengthy explanation of electronics that no one cares about on a user level.

.jon · Post by **.jon** » Sun Nov 13, 2016 8:19 pm

pone wrote:
.jon wrote:So he basically pulled that 2/3s out of his ass and didn't even try to explain why it was in his ass in the first place.
The reason is probably a lengthy explanation of electronics that no one cares about on a user level.

Unfortunately this guy lacks the credibility to present such claims without solid proof, and I won't be bothered to start testing.

steve2KVR · Post by **steve2KVR** » Mon Nov 14, 2016 2:14 am

...im like totally board, dude

...so what does it sound like? that's the real/actual question

...that's why i came here

...I had enough of the maths in schoo

l...im here for the chicks and the vibes

...please, give me a break

..../s~

.jon · Post by **.jon** » Mon Nov 14, 2016 6:45 am

...I'm also like totally buildingmyselfanewlongboard dude

It sounds great, with or without maths. I got no idea what you could possibly mean, but GL with the chicks mate

sfxsound3 · Post by **sfxsound3** » Mon Nov 14, 2016 7:08 am

A compressor is an envelope follower with side effects. Ideally, if you tell it to reduce 3 db within 11 ms, it should do exactly that. If it doesn't, these are the side effects - 'analog' imperfection due to material, implementation, etc. The 2/3rds part is bullshit. This guy is bullshit. I'm sick of 'audio gurus' building their reputation by selling fairy dust to the gullible. He gets his plugins coded for him in 3-rd world sweatshops, FFS!

MeldaProduction

KVR Audio

Compression Myths!