Just a question about Compression Ratio.

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PhilLondon

New member
Sorry guys, I know it's another compression thread, but this is confusing me and I'm just trying to understand it.

Say the threshold is -20 and the ratio 2:1 and the signal hits -10. It should end up being -15, right?

If the ratio was 4:1 would the signal be -17.5?

If the ratio was 5:1 the signal would end up being -18?

Am I on the right track or am I missing something?

What about if it was to go to -14 with the ratio at 5:1? Would the signal only affected for the first 5dB, and then allow the remaining 4dB to go through leaving me with a signal of -15? Sould it only attenuate the remaining signal if it were to hit -10?

Thanks.
 
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Compression Explained | Humbucker Music

Lots of good info in that link, but specifically regarding your question:

2. Ratio sets the degree of compression above the threshold level. A ratio of 2:1 represents mild compression and means that when the incoming level (that is, the level above the threshold) rises by 10dB, the outgoing level will only rise by 5dB. Ratios of up to 5:1 are regularly used for vocals and other instruments, and can pass by unnoticed by the listener if the other controls are set properly. Higher ratios are used for more serious limiting, where the level needs more severe control. Ratios of 10:1 and higher are nearly always noticeable to the listener.
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Thanks for the link. I'll check it out.

I think I understand, and a clarification on whether my calculations are correct will confirm this. Are they correct or have I got something wrong?
 
PhilLondon said:
Sorry guys, I know it's another compression thread, but this is confusing me and I'm just trying to understand it.

Say the threshold is -20 and the ratio 2:1 and the signal hits -10. It should end up being -15, right?

If the ratio was 4:1 would the signal be -17.5?

If the ratio was 5:1 the signal would end up being -18?
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Yes, yes, and yes (theoretically, though attack, release, and RMS times will tend to "smear" the gain reduction a bit, so that no real world application will actually conform perfectly to those numbers)

What about if it was to go to -14 with the ratio at 5:1? Would the signal only affected for the first 5dB, and then allow the remaining 4dB to go through leaving me with a signal of -15? Sould it only attenuate the remaining signal if it were to hit -10?
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I'm not sure that I understand this part. -14 is 6db over the threshold. 5:1 ratio should only let that go to 6/5db over the threshold, so it should end up around -18.8 Some classic compressors (and digital emulations of them) seem to be only capable of certain amount of gain reduction so that if you go way over threshold they start to sort of open back up and compress less than the ratio might suggest, but I don't think that's what you're talking about here.
 
Thanks. I was just wondering how it would affect the signal if it wouldn't be within the ratio parameters. It's okay, I think I get it.

I understand that attack and release will change the outcome, so in practical terms, should I be setting the threshold and ratio and then playing with the attack and release in order to achieve my desired output, while allowing some compromise due to the pumping effect that certain compressor settings can have on the overall sound?
 
PhilLondon said:
Thanks. I was just wondering how it would affect the signal if it wouldn't be within the ratio parameters. It's okay, I think I get it.

I understand that attack and release will change the outcome, so in practical terms, should I be setting the threshold and ratio and then playing with the attack and release in order to achieve my desired output, while allowing some compromise due to the pumping effect that certain compressor settings can have on the overall sound?
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I would say start with some reasonable low ratio and work with the attack speed. That determines a whole lot of where the compressor's action and style of it's effect lay. Low ratios are often enough.
 
I would say you should turn the knobs til it sounds good and not worry too much about the numbers. ;)
 
mixsit said:
I would say start with some reasonable low ratio and work with the attack speed. That determines a whole lot of where the compressor's action and style of it's effect lay. Low ratios are often enough.
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While obviously setting the threshold first right?


ashcat_lt said:
I would say you should turn the knobs til it sounds good and not worry too much about the numbers. ;)
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That's what I've been doing, but I like to understand what I'm doing. Like, I had been setting my mix levels, then compressing. Later on I've decided that the guitars need to come up a bit, and I didn't change the compression which means that it would have changed how it's compressing, right?

So if I know how to use it properly I can just change the threshold by a couple of db.

I'm guessing that the above is the case anyway.
 
I just "get a feeling" so I'm going in sideways here --

IF you're trying to keep the VOLUME of certain sources within a certain area, the first line of defense in that case is the fader / fader automation.

Just putting that out there... Just in case...
 
ashcat_lt said:
I would say you should turn the knobs til it sounds good and not worry too much about the numbers. ;)
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You can do that too -and should, 'cause the numbers are just good in helping at best guess starting points. But understanding the how and why's gives you better guesses. :D
 
No I've been automating. I use compression to bring the dynamics closer together.

Drums, guitar parts and vocals mainly. If I have a busy section I'll look to try and make everything a bit tighter in order to make the mix more coherent, for lack of a better word.

At least, that's what I thought it was used for.
 
PhilLondon said:
While obviously setting the threshold first right?
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Yes! definitely


That's what I've been doing, but I like to understand what I'm doing. Like, I had been setting my mix levels, then compressing. Later on I've decided that the guitars need to come up a bit, and I didn't change the compression which means that it would have changed how it's compressing, right?

So if I know how to use it properly I can just change the threshold by a couple of db.

I'm guessing that the above is the case anyway.
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You started with ratios and getting to 'desired reduction.
I make the example of attack being important in this.. For example. A low ratio, and a big peak at the head of the source.
If the attack is slow enough to let most of the peak slip by = very little reduction no mater what the ratio says. Now speed up the attack and even at low ratio = lots of reduction.. and a big effect of the style and sound. I.e. whether you're doing more 'wave shaping, or 'loudness control/leveling.



Massive Master said:
I just "get a feeling" so I'm going in sideways here --

IF you're trying to keep the VOLUME of certain sources within a certain area, the first line of defense in that case is the fader / fader automation.

Just putting that out there... Just in case...
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The ultimate (non-destructive - to the original) slow rider! :)
 
PhilLondon said:
That's what I've been doing, but I like to understand what I'm doing. Like, I had been setting my mix levels, then compressing. Later on I've decided that the guitars need to come up a bit, and I didn't change the compression which means that it would have changed how it's compressing, right?
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Depends on where you're adjusting the volume of those guitars. If you're turning them up before the compressor, then yes, it will change what gets compressed by how much. If this is an insert comp, though, and you adjust the track fader, then you're just turning the already compressed signal up or down, which won't itself change what the comp is doing. It might make you want to change the settings for one reason or another, but...

Don't worry RAMI, I have plenty of whacko ideas about compression and dynamics control in general, but especially for a newb, the only way to really understand the complex interactions between the various parameters is to actually get in and fuck with it.
 
ashcat_lt said:
Don't worry RAMI, I have plenty of whacko ideas about compression and dynamics control in general, but especially for a newb, the only way to really understand the complex interactions between the various parameters is to actually get in and fuck with it.
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Well, that's a relief. :)

But yes, I agree with you.
 
ashcat_lt said:
Depends on where you're adjusting the volume of those guitars. If you're turning them up before the compressor, then yes, it will change what gets compressed by how much. If this is an insert comp, though, and you adjust the track fader, then you're just turning the already compressed signal up or down, which won't itself change what the comp is doing. It might make you want to change the settings for one reason or another, but...

Don't worry RAMI, I have plenty of whacko ideas about compression and dynamics control in general, but especially for a newb, the only way to really understand the complex interactions between the various parameters is to actually get in and fuck with it.
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Yea, so this is what I've been doing.

Set mix, compress. Decide to bring guitars up, wonder why things seem louder or quieter, realise it's the compression!

I just need to make sure the mix is as I want it before I compress, or remember to adjust it afterwards. Well, I think I'm getting it a bit more.

Thanks.
 
So, you're talking about like a mix bus compressor? Yeah, how it responds will be pretty sensitive to changes in the mix. Some folks prefer to do like you say and mix the thing, then compress afterwards. Sometimes we leave that to a separate "mastering" session. Some folks (myself included) prefer to get the mix bus compression going early and then mix into it. There's nothing wrong with any of these approaches.

That's kind of the thing. There are so many different things that we can try to do with compressors, and the specifics of the settings are completely dependent on the ultimate goal. You need to identify what you think you're trying to do, and use the tools as necessary to accomplish it. In this case that you're discussing, I would start to wonder if some of what you're trying to do with the mix bus compressor might not be better handled at a track or sub-mix/bus level. Then again, I'd really need to have the thing in front of me to be able to say exactly what it needs or doesn't.

One of my whacko things is that for most of the things that I use compression -and especially on the mix bus, I don't really like to use attack and release at all. I set them to 0 and use the lookahead and RMS time to do something similar but kind of completely different. Course, that only works with a truly full-featured ITB compressor like ReaComp, which is the only compressor I ever use.
 
No, like on the individual channel inserts. So get the whole thing levelled right, then add compression and EQ, reverb etc On any individual channel that needs it, then add the mix bus compression later.

I'm really sorry if I'm confusing you, I should be more specific.

In any case, I'm aware that if I change the faders once I've added compression it will change everything I've done, as will changing anything after I added mix bus compression. I need to be set with the levels before I start adding compression etc. I'm not too familiar with RMS or Lookahead yet, just focused on this stuff at the moment.

All good info still. :)

If you have double or triple tracked guitars would you compress each track individually or do it via a send to a compression bus? I tried this with an EQ bus and it didn't really do anything, I'm not sure if you can even do it.

Do you add compression to the mix bus when before you master it, or are you talking about when you're mastering? Or could compression get added to both the mix bus and when it gets mastered, or either?
 
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Yea. Thinking about it I'm finding that distorted guitars generally sound pretty equal, I guess that this is because you generally play quite hard and steady due with distortion because you want to deliver impact?

I've often got clean intros and stuff that have more dynamics and they need a little bit of compression definitely.

Although I guess sometimes people would want to add compression to add the effect that it can give too maybe?
 
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