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Danny Wyatt
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Internal output limiter?

Mon Jun 14, 2021 12:37 am

I was wondering if Logic has some kind of "internal limiter" (or any other technical thing) on the output that prevents peaks from damaging the speakers?
The same way that for example when a track is showing the red "alert", but it's not actually peaking internally, you know?
I wonder if Logic has something similar on the output where if there's a peak that could damage the speakers, it's not actually sending that to the speakers. Hope it makes sense...

If it doesn't, do you guy always add a limiter to the output?
• Logic Pro X 10.4.6 • M-Audio Fast Track Pro 4x4
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David Nahmani
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Re: Internal output limiter?

Mon Jun 14, 2021 7:14 am

No, there's no such built-in limiter. The highest level any digital software can output is 0 dBFS, and the shape of the waveform can be anything you want.

I don't add a limiter to the output, I just mix at moderate levels.

If you're suffering from the white noise blast from hell issue, here's a related discussion along with a link to a free plug-in that can help prevent it: Logic devs: you have a safety problem
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Re: Internal output limiter?

Mon Jun 14, 2021 7:32 am

David Nahmani wrote:
No, there's no such built-in limiter. The highest level any digital software can output is 0 dBFS, and the shape of the waveform can be anything you want.

I don't add a limiter to the output, I just mix at moderate levels.

If you're suffering from the white noise blast from hell issue, here's a related discussion along with a link to a free plug-in that can help prevent it: Logic devs: you have a safety problem


So you’re saying that no matter how loud the Stereo Output is (even when is showing that’s peaking at +12dB, the level going to the speakers is always 0dBFS?

I’ve never suffered from the white noise issue. But sometimes I’m changing the gain and instead of typing -10dB, I accidentally type 10dB haha

So if the only output is 0dBFS no matter, then adding the limiter does nothing useful, right?
I mean other than avoiding digital clipping in terms of audible distortion
• Logic Pro X 10.4.6 • M-Audio Fast Track Pro 4x4
• MacBook Pro mid 2010 • macOS High Sierra 10.13.6 • 2.4 GHz Intel Core i5 • 8 GB 1067 MHz DDR3

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David Nahmani
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Re: Internal output limiter?

Mon Jun 14, 2021 7:41 am

Danny Wyatt wrote:
So you’re saying that no matter how loud the Stereo Output is (even when is showing that’s peaking at +12dB, the level going to the speakers is always 0dBFS?

Not exactly. I'm saying that no matter the level shown at the output of the Stereo Output channel strip, by definition, in digital, the maximum value of a 24 bit sample is 111111111111111111111111 which is 0 dBFS. That's a digital level. Then the digital signal is sent to D/A converters which produce an analog signal that can be measured in Volts, that is sent to an analog amplifier which applies its own gain (raises the amplitude of the voltage), and that analog signal is what is routed to your speakers.

Danny Wyatt wrote:
So if the only output is 0dBFS no matter, then adding the limiter does nothing useful, right?

No, it definitely does something useful, otherwise no one would use one! ;) A limiter gives you a better control over how your signal is handled when it reaches levels closed to 0dBFS as opposed to hard clipping the output of Logic Pro. That better control allows you to get a louder signal with less audible distortion.
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Re: Internal output limiter?

Mon Jun 14, 2021 8:09 am

What I mean is that, no matter how loud Logic is (0 or above it) the D/A converters always receive the same which is 0dBFS. Correct? Then what goes to the speakers is controlled by the analog output (the output on my interface, for example?

Regarding the second part, what I meant (and that's on my other reply) is that "useless" in terms of avoiding more voltage (if that's the right term here) going to the D/A converters. As I say, it does avoid the digital distortion and that's the useful part, but when it comes to protecting anything after the sound leaves Logic, it seems that you are saying that the level will always be 0dBFS BEFORE the D/A. Does it make sense?

That being said, using a limiter on the output to protect anything, is useless.
Using the limiter to avoid digital distortion, is useful.
Is that correct?

I also mix at moderate levels. I started having my kick peaking at around -9dB and since in dance music revolves around the kick, all the other instruments end up being around that volume as well. But I was concerned about weird peaks that may suddenly occur, out of a glitch in Logic or me typing the wrong value.
• Logic Pro X 10.4.6 • M-Audio Fast Track Pro 4x4
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des99
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Re: Internal output limiter?

Mon Jun 14, 2021 8:28 am

Danny Wyatt wrote:
What I mean is that, no matter how loud Logic is (0 or above it) the D/A converters always receive the same which is 0dBFS. Correct?


The *maximum* volume that can be output is 0dBFS, nothing higher, as this is the point the internal 32bit-float signal is changed to a 24-bit fixed point signal for your interface.

It doesn't mean Logic is always outputting 0dBFS, unless you are sending a maximum volume hard limited square wave at max volume(!) (Don't do that!) :)

And yes, your audio interface converts the digital signals coming to it via the system/driver into analog output levels, at whatever spec/analog level the line outputs are driving, and then whatever device ultimately amplifies that for your final monitors (whether a separate amp, or the amp inside active monitors) is the arbiter of the overall signal power level sent to your speakers.

Remember though a lot of this depends on how your monitoring is setup. If you are typically creating hard limited to 0dBFS mixes in Logic, with no headroom, then your monitoring setup is configured to make that listenable at a reasonable volume. If you use more traditional engineering practices, then typically you mix with headroom and have your monitors louder, so your lower level mix is still at a reasonable volume - this means that high spikes here are more likely to potentially damage monitors as you've got more headroom in the system and your amp power levels are higher.
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loopsinner
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Re: Internal output limiter?

Mon Jun 14, 2021 8:37 am

Danny Wyatt wrote:
That being said, using a limiter on the output to protect anything, is useless.
Using the limiter to avoid digital distortion, is useful.
Is that correct?.


It’s not useless. It does protect your speakers from playing it too loud.

To oversimplify, there’s 2 types of peaks. A clipped and a non clipped.

A peak will be clipped automatically when you go over 0dBFS OR when you intentionally do it with a clipper.

A limiter doesn’t do digital clipping, it turns the peak down.

A clipped peak gets reconstructed into regular peak in your D/A converter, now you have a higher peak than the digital peak after the reconstruction.

A limited peak is just that, it doesn’t get reconstructed by you D/A converter and isn’t going higher after going through your D/A converter, in general, BUT I oversimplify this - so to get real, there's a thing called true peak.

So true peak (what you speaker is playing) is closer to the height of a limited peak(when you use a limiter) than a clipped peak (when you go over 0dbFs or use a digital clipper), if it makes sense to you.
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Re: Internal output limiter?

Mon Jun 14, 2021 8:42 am

Ok so adding a limiter to my template is a good thing, right? Better safe than sorry.
I always have my output limiter at -1dB anyway, when I master my songs so I would never go higher than that, even if the true peak goes a little bit above it.
• Logic Pro X 10.4.6 • M-Audio Fast Track Pro 4x4
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David Nahmani
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Re: Internal output limiter?

Mon Jun 14, 2021 8:45 am

Danny Wyatt wrote:
What I mean is that, no matter how loud Logic is (0 or above it) the D/A converters always receive the same which is 0dBFS. Correct?

Ok let's be precise: the digital signal is made of many samples, and in order to make a waveform, the samples all have different values. The maximum value of any single sample is 0 dBFS. So that means that digitally, your signal cannot peak any higher than 0 dBFS. From then on, you're routing your signal to a converter, that determines what voltage it outputs to match the 0 dBFS, and how it handles intersample peaks (some converters are able to create a voltage that is higher than the voltage that is created when they receive a 0 dBFS sample). But we're no longer in the digital world, so we're no longer using dBFS as a unit, we're using Volts.

Danny Wyatt wrote:
Then what goes to the speakers is controlled by the analog output (the output on my interface, for example?

Yes, the analog signal produced by your D/A (inside the interface) then reaches an analog amp stage where its gain can be adjusted for more or less voltage.

Danny Wyatt wrote:
Regarding the second part, what I meant (and that's on my other reply) is that "useless" in terms of avoiding more voltage (if that's the right term here) going to the D/A converters. As I say, it does avoid the digital distortion and that's the useful part, but when it comes to protecting anything after the sound leaves Logic, it seems that you are saying that the level will always be 0dBFS BEFORE the D/A. Does it make sense?

If the goal is to protect equipment then the limiter can be highly valuable as what matters is not what dBFS your signal is but what shape your signal has. Digitally produced signal can be very harmful to analog equipment or speakers because it can have very unnatural shapes. It can sound very shrill and damage your speakers or even your ears.

Danny Wyatt wrote:
That being said, using a limiter on the output to protect anything, is useless.
Using the limiter to avoid digital distortion, is useful.
Is that correct?

Not really, because digital distortion can damage analog equipment. But it also depends on the level of gain applied with your analog amp before (or inside) your speakers. What can damage your equipment is a combination of the shape of the signal and the amplitude of the signal.
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Re: Internal output limiter?

Mon Jun 14, 2021 8:50 am

Danny Wyatt wrote:
Ok so adding a limiter to my template is a good thing, right? Better safe than sorry.

I don't think it's a good thing, because it changes the dynamic of the signal you're mixing and could end up allowing bad practices. Better learn to be careful without a limiter and have a transparent signal flow.

Consider a gymnasium with a trampoline. People get on the trampoline and jump up and down. If they jump high up they could potentially touch the ceiling and hurt themselves. Is the solution to attach mattresses to the ceiling so that in case they touch it they don't hurt themselves? No. The solution is to have a trampoline that is adapted to the size of the gymnasium, to have the ceiling high enough, and to have jumpers who are aware of the ceiling and the limits of how high they can jump without hurting themselves, and use basic common sense. That's why it's called "headroom". It's room for your head.

IMO, it's the same when working with audio in Logic.
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Re: Internal output limiter?

Mon Jun 14, 2021 9:12 am

David Nahmani wrote:
..That's why it's called "headroom". It's room for your head.


:lol:
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Re: Internal output limiter?

Mon Jun 14, 2021 9:17 am

David Nahmani wrote:
Danny Wyatt wrote:
Ok so adding a limiter to my template is a good thing, right? Better safe than sorry.

I don't think it's a good thing, because it changes the dynamic of the signal you're mixing and could end up allowing bad practices. Better learn to be careful without a limiter and have a transparent signal flow.

Consider a gymnasium with a trampoline. People get on the trampoline and jump up and down. If they jump high up they could potentially touch the ceiling and hurt themselves. Is the solution to attach mattresses to the ceiling so that in case they touch it they don't hurt themselves? No. The solution is to have a trampoline that is adapted to the size of the gymnasium, to have the ceiling high enough, and to have jumpers who are aware of the ceiling and the limits of how high they can jump without hurting themselves, and use basic common sense. That's why it's called "headroom". It's room for your head.

IMO, it's the same when working with audio in Logic.


My point is: since I work already way below 0dBFS (around -9dB as a starting point), I'm just saying that having a limiter set to -1dB would allow me to catch those very unexpected peaks, should they happen. Not that I'm mixing my music peaking at -1dB or anything and my music is constantly being limited. Not that.
using your trampoline example: let's say that the highest someone can jump is 5 meters (that's my -9dB). And the ceiling is 10 meters high. You could leave it like that, but just in case, you would put the mattress on the ceiling, just in case some super powerful person could jump 11 meters high, they wouldn't hurt their head ;)
As I said, even if I'm mixing with my peaks going up to -12dB, sometimes I may want to change the gain of a plugin (or audio region) to -30dB and by accident I type 30dB. In that situation, the headroom or my best practices are completely useless, because those 30dB went way above 0dBFS. So a limiter would prevent that going to my speakers. Trust me, it happened to me more than once (typing a positive number instead of negative) ;)
• Logic Pro X 10.4.6 • M-Audio Fast Track Pro 4x4
• MacBook Pro mid 2010 • macOS High Sierra 10.13.6 • 2.4 GHz Intel Core i5 • 8 GB 1067 MHz DDR3

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Re: Internal output limiter?

Mon Jun 14, 2021 9:23 am

You know, workflow is such a personal thing, and we're all different, our brains don't have the same shape, we don't think alike. That's fine. If that suits your workflow, why not. I would personally never work like this, but that's just me.

On my car, there's a speed limiter. I can set it to 90km/h for example, and then even if I push on the gas pedal like a mad man, the max speed the car will go is 90km/h. Some people love it, because it avoids getting a speeding ticket on roads where the speed limit is 90km/h. I used it once, to see how it worked, and hated it. I decided to never use it again. I almost thought it was dangerous: what if all of a sudden I see someone coming behind me at full speed and want to get out of the way but there are cars at my level on either sides? What if I'm trying to pass a car and have limited visibility and want to go over the speed limit for a second or two?

So like I said, it's a personal choice, and I agree that what will guide that choice is the way you drive ... errr ... hum... you mix. :lol:
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Re: Internal output limiter?

Mon Jun 14, 2021 9:40 am

Danny Wyatt wrote:
My point is: since I work already way below 0dBFS (around -9dB as a starting point), I'm just saying that having a limiter set to -1dB would allow me to catch those very unexpected peaks


Well, it would mean the maximum level sent to your audio interface would be -1dBFS, rather than 0dBFS... so you're not really saving a lot.

That 1dB difference is unlikely to be the the thing that saves your speakers, should you get a spike of death. A spike of death will be very loud either way...
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