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Old 05-03-2017, 09:10 AM
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StiffMittens StiffMittens is offline
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Default Calling All Compressor Experts

Not a total n00b here, but everything I've learned about recording/mixing comes from going to the library and scouring the internet and so I have some gaps in my knowledge. The questions that have been nagging me lately are about the nitty gritty details of compressors. I understand the basic ideas: Threshold tells the compressor when to start and stop working, Ratio tells the compressor how hard to work, Attack tells the compressor how quickly to get to full compression, and Release tells the compressor how quickly to relax its grip. I also am familiar with Opto and Electro compressors and the different way they release (opto is a concave curve while electro is a straight slope - I think).

What I don't know: are all compressors electro style if they're not opto (or is there another flavor)? I'm assuming the attack time is generally a slope (as opposed to a delay), but does the knee setting (if present) make the attack a concave curve or convex curve (i.e. start slower and accelerate or start faster and decelerate)? And finally, the compressor settings are responding to the input signal, so the release time shouldn't have any affect on when the next transient triggers compression, right?

And before anyone says "just use your ears" - I'm the kind of guy that prefers to understand something as fully as I can, so I can formulate a hypothesis and then test that hypothesis with my ears.
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Old 05-03-2017, 06:45 PM
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DonaldM DonaldM is offline
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Default Re: Calling All Compressor Experts

Quote:
Originally Posted by StiffMittens View Post
Not a total n00b here, but everything I've learned about recording/mixing comes from going to the library and scouring the internet and so I have some gaps in my knowledge. The questions that have been nagging me lately are about the nitty gritty details of compressors. I understand the basic ideas: Threshold tells the compressor when to start and stop working, Ratio tells the compressor how hard to work, Attack tells the compressor how quickly to get to full compression, and Release tells the compressor how quickly to relax its grip. I also am familiar with Opto and Electro compressors and the different way they release (opto is a concave curve while electro is a straight slope - I think).

What I don't know: are all compressors electro style if they're not opto (or is there another flavor)? I'm assuming the attack time is generally a slope (as opposed to a delay), but does the knee setting (if present) make the attack a concave curve or convex curve (i.e. start slower and accelerate or start faster and decelerate)? And finally, the compressor settings are responding to the input signal, so the release time shouldn't have any affect on when the next transient triggers compression, right?

And before anyone says "just use your ears" - I'm the kind of guy that prefers to understand something as fully as I can, so I can formulate a hypothesis and then test that hypothesis with my ears.
Here's a little experiment you can try that might help you see all this.

Create an audio track. Highlight 1 measure with the selector tool. Use the Tone Generator in the Audiosuite and render a 1000hz tone at -5db. Skip a measure and repeat only at -10db. You'll have 2 tones and you'll see the 5db difference. Now, add a compressor to the track and set it however you wish. Render the results to a new audio track (or use track commit if you have 12.0 or higher). You can then compare visually, as well as hear the result. Rinse and repeat with various compressors and settings to get an idea of attack/release curves and such. Change the timeline from bars/beats to milliseconds if you want to see how the time length varies.

I created a simple session called "Compression Test" for this purpose so I can see as well as hear how various compressors behave.

You can repeat all of the above with a Kick or snare or any other audio. Just use two signals of the same source at 2 different db settings for comparison. I found this very helpful in understanding compression better as well as seeing how different compressors affect the audio.
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Old 05-06-2017, 05:28 AM
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StiffMittens StiffMittens is offline
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Default Re: Calling All Compressor Experts

Thanks for the advice, Donald. I will certainly be trying this experiment, and I expect it will be a big help.

I would still appreciate definitive answers to my questions, if anyone has them. Particularly the one about opto vs. electro
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Old 05-06-2017, 09:09 AM
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Default Re: Calling All Compressor Experts

The "knee" of a compressor is its "tone", and why there are so many.
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Old 05-06-2017, 07:26 PM
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Default Re: Calling All Compressor Experts

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Originally Posted by StiffMittens View Post

I would still appreciate definitive answers to my questions, if anyone has them. Particularly the one about opto vs. electro
I can't think of anyone who explains the 'nitty gritty' better and more comprehensive than Michael White;

Mixing With Mike Mixing Tip: Defining Compressor Attack and Release Times; https://youtu.be/uT4XPvZiA5g

Mixing With Mike Mixing Tip: Deeper Look at Attack and Release Times; https://youtu.be/kaa5Sj67Ft4

Mike's Power Compression Course; https://www.youtube.com/playlist?lis..._FEQwbUOSubqRz

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Old 05-07-2017, 12:56 PM
DDDaniel DDDaniel is offline
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Default Re: Calling All Compressor Experts

Hi
There are some other flavours , and even within one flavour the actual behaviour will depend on the design.
If you want to know all variables that make up a compressor you could try DMG Audio's compassion, you can use them in demo mode for a while.
Don't forget to download (and read ;-) the manual.
In expert mode you can design your own compression behaviour, and in the manual a lot is explained about the history and differences in design parameters.

Compassion has a graphical history view so you can see what/how it compresses (up to a certain extend)

Enjoy, Daniel
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Old 05-09-2017, 09:55 AM
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Default Re: Calling All Compressor Experts

Thanks for the input, guys. Michael White is now a bookmarked part of my online resources - great stuff. I also downloaded DMG's Compassion demo plugin and the graphic representation of the compressor's settings is extremely informative. Lots to mull over.
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