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Using a limiter
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| G-Con |
Hello all,
I have a few question about how a limiter works. Sorry if they seem a bit novice.
For example, on my latest track, I have set the output of the limiter to -0.3db. The threshold I have dropped to -4.5db. With the threshold set at this level, the track has increased in volume considerably but the gain reduction meter is only registering occasionally with approx -1db reduction now and then.
If the track has become louder but the gain reduction meter is barely registering anything then does this mean that the dynamics of the track haven't really become squashed in any way?
Seeing as the track gets louder and louder as I drop the threshold more and more, what exactly is the limiter doing to increase the volume?
Should I only be concerned with squashing the track too much if the gain reduciton meter is showing significant drops?
Thanks |
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| cryophonik |
Hey G-Con
What's happening with your settings is that you are not really squashing the dynamics (only -0.3dB), but essentially you're "pulling" the quieter parts up as you lower the threshold. This will give you a much louder track overall without squashing the peaks. You have to think of it almost as the opposite of compression, whereas compression squashes the dynamics by lowering the loudest portions, bringing down the threshold on the limiter squashes the signal by raising the level of the quieter portions. The output ceiling of the limiter controls the peaks. If you want to lower the overall output and control the transients better, bring this level down. As you pull the output ceiling down, you should see the gain reduction triggering more frequently as more of the dynamic range is being controlled by the output ceiling. I suspect that with your current settings, the gain reduction is only being triggered on the kick drum (assuming it's a trance tune) (?). |
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| Nightshift |
| quote: | Originally posted by G-Con
Hello all,
I have a few question about how a limiter works. Sorry if they seem a bit novice.
For example, on my latest track, I have set the output of the limiter to -0.3db. The threshold I have dropped to -4.5db. With the threshold set at this level, the track has increased in volume considerably but the gain reduction meter is only registering occasionally with approx -1db reduction now and then.
If the track has become louder but the gain reduction meter is barely registering anything then does this mean that the dynamics of the track haven't really become squashed in any way?
Seeing as the track gets louder and louder as I drop the threshold more and more, what exactly is the limiter doing to increase the volume?
Should I only be concerned with squashing the track too much if the gain reduciton meter is showing significant drops?
Thanks |
In a trance tune or any type of music you only want the gain reduction to really go off at the loudest parts of the mix to take care of any peaks that might be coming through in the mix. Even at the loudest part of the mix then the gain reduction light should not always be on.
The idea is to get the loudest parts of the track as close to the output to ceiling (usually -.02 or -.03db) with minimal gain reduction so that the music doesnt get squashed and lose its dynamics too much. |
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| Nightshift |
I am looking at your new track in Goldwave and for example this track could be a lil louder. Using Waves L2 with a Threshold of -3.0dB and a celing of -.03db I was able to in crease the overall sound level without too much of a dynamics loss. Alot of your peaks seem to be random percussion peaks therefore those can be snipped off to an extent.
Before:
After:
All that was done was I cut off the random peaks that were in the original version so that the bulk of the track can have more volume. becasue sacrificing perc peak signals (as long as its not the kick) to make the overall track louder is usually not a big deal and often encouraged becasue thats what a limiter's use is. To limit peaks while bringing the overall level of the sound up. |
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| G-Con |
Thanks for the replies. I think I understand it a little bit better now but what exactly is the threshold then. In a compressor, anything above the threshold is reduced in volume. Is a limiter boosting the signal below the threshold?
Nighshift, ironically, my new track has already had a limiter applied with the settings mentioned in my original post. I suppose this means I could have dragged the threshold down even more without squashing the track too much. |
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| Nightshift |
| quote: | Originally posted by G-Con
Thanks for the replies. I think I understand it a little bit better now but what exactly is the threshold then. In a compressor, anything above the threshold is reduced in volume. Is a limiter boosting the signal below the threshold?
Nighshift, ironically, my new track has already had a limiter applied with the settings mentioned in my original post. I suppose this means I could have dragged the threshold down even more without squashing the track too much. |
Yes sir in your original post you said that you had set it to -4.5 threshhold. well i set it to -3.0 after ur -4.5 so that makes it a total of -7.5db. then again double limiting is bad but i did it from demonstration purposes. In other words you coulda used a round -7.0db threshhold and yes it would tell you it had a couple decibals of gain reduction but that is only becase of your perc's peaks. not the entire track. Also you should always look at the waveform and listen to the before and after to make sure little to none of the magic is lost after applying a limiter. |
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| Nightshift |
| Also it seems like waht limiters like L2 (and alot more) are doing these days is auto-gaining the signal. So if you set a -3.0db threshold, all the peaks above -3.0db are trimmed and then the overall track gets a gain of 3.0db too to compensate for the headroom created when the peaks were cut. I'm not sure if thats how they work but it seems that way. |
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| evo8 |
A Limiter is just a compressor with a high (infinite) ratio. Any part of the audio signal that goes above the threshold wont get through - any part of the audio signal that goes above the threshold in a compressor will get through, but at a lower volume.
I think L2 is more of a maximizer as Nightshift was explaining, not really sure how they work myself, but i think its a limiter with auto-gain
maybe some of the other dudes on here can explain further, hope that helps a bit, just be careful not to limit too hard, youll know yourself if it starts to sound bad. |
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| thecYrus |
a limiter is nothing else than a compressor with a fixed ratio of 1:unlimited.
everything under the threshold will not be touched and everything above the threshold will be compressed pretty hard. |
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| derail |
G-Con, if the limiter's gain reduction meter is showing no activity, then it means all the sounds coming into it are below the threshold. In your example, it means that only very infrequently are there sounds that are louder than -4.5dB.
In this case, setting the threshold there will act like a very clean volume control - the dynamics won't get affected if there is no actual limiting taking place.
In the analog world, you'd want to ensure that the sounds coming into the limiter are as hot as possible while still being clean, since analog gear sometimes doesn't have the best signal-to-noise ratio. So in that case, you wouldn't want your hottest sounds peaking at -4.5dB, you'd want to raise the individual tracks so you're close to 0dB (without clipping/distortion - though some analog gear distorts very warmly/ smoothly and imparts character, so once again, it's not a hard and fast rule)
But anyway - in the digital world, things are generally much much cleaner - the signal-to-noise ratio will generally be excellent - if you happen to be working at -4.5dB, then raising the level at the input stage of the limiter shouldn't introduce any audible noise at all. (It's very hard to hear sounds which are at -60dB, and 24 bit digital audio has a range of -what, 100dB, 120dB? I'm sure there are people who have that information in their heads, I'd need to look it up). In practical terms, there's no way that lifting the volume by 4.5dB at the input stage of the limiter will affect sound quality.
In other terms, you shouldn't be concerned about where the threshold of the limiter is per se. It may be at -3dB for one track, at -12dB for another track (though generally if you have a set workflow, your tracks will settle into a tighter range over time) If the incoming signal is quieter, the threshold will be lower, if it's louder, then it will be higher. What is of interest to you is once it actually starts showing some gain reduction and working as a limiter.
How hard you can push the limiter depends on how well the track has been mixed before it hits the limiter. If it's not well balanced, like for example the kick is much too loud, it won't take long before the limiter "hits the wall" and the overall sound gets much too clippy/distorted/crunchy (whatever term you use). So you'll end up with this distorted track which still doesn't sound anywhere near as loud as your favourite tracks (if your favourite tracks happen to be loud). It's easy to hear the effects of over-limiting - just take the threshold way down and listen to the crunchy distorted mess. You don't want any of that in your track. If the crunchy sections are extremely short (a few ms) then the listener won't notice them.
To sum up: If you want hot levels, get the mix nicely balanced before it hits the limiter. To do that, it can help to either reference against your favourite tracks by ear, paying attention to where the lows, mids and highs are, or reference against them by using a frequency analyser, either in real-time or in a program such as wavelab or soundforge (I'm sure there are excellent freeware alternatives as well). See where a bunch of your favourite tracks are at (I'd suggest using a range of artists, rather than one, unless you're trying to sound exactly the same as another artist), then see where your tracks are in comparison. I generally use clips of the hottest sections of each track, maybe 15-30 seconds, long enough for the full melody to play once through.
edit: to briefly answer your question about what the limiter is doing - well, essentially, if you drive them hard enough, it'll turn your wave forms into clipped square waves - check out some loud wave forms, you'll see positive and negative sections of the waveform, which correspond to whether the sound is pushing or pulling air as it travels. At the top of the waveforms you may sometimes notice that the top of the waveform has been chopped off - it's square, it has hit digital zero. As I stated before, if this square, chopped-off waveform only lasts a few milliseconds, then the listener won't notice that the waveform has been chopped off. But drive a limiter too hard and you'll get heaps of these waves being driven into digital zero and ending up as square waves, and that will sound horrible indeed. But you can use your ears to tell you whether or not your sound is being adversely affected. if you can drive it loud without digital crunchiness, good. If not, work on your mix.
(Obviously, how loud you can make a track also depends on what style you're working on - you can't make a trance track as loud as a pop song because trance has these big kicks eating up a heap of headroom - if you tried to compete with a pop track your kick would become very small and non-trancey) |
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| G-Con |
Thanks for all the responses.
The only part that I'm not getting is that when I drag the threshold down, the track gets louder and louder whether or not any gain reduction is occuring.
With a compressor with really high ratio settings, the volume would drop significantly the more I drop the threshold and I would then have to increase the makeup gain to boost the signal.
This is not happening with the limiter. Would this be the auto-gain feature that Nightshift is talking about? |
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| Storyteller |
yes.
A normal limiter (without auto-gain) would just cut off the peaks resulting in a lower overall volume.
The limiter you use cuts off the peaks and then amplifies the track so it peaks to near 0dB or whatever you set it to. |
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