Fabfilter Pro-L2 Explained: Every Parameter You Must Know for Better Sounding Masters 

Hey dude, I’ve been researching this too, here’s what’s actually happening with the attack and release: The attack and release settings can indeed be a bit confusing. Basically the limiting stage, or rather the stage of the limiter that recovers from the gain reduction, consists of two stages, a very fast "transient" stage, and a slower "release" envelope stage. The attack and release settings only control this second stage. The release setting of Pro-L 2 is basically exactly what you expect, it sets the time for the signal to get back to its original level after the signal does not exceed the threshold anymore. The attack stage however determines how fast the slow envelope stage takes over from the faster transient stage. On short settings, the two stages usually overlap seamlessly. The fast stage might recover a bit of signal really fast and then the release value take over. However, when you are using longer attack times, you are letting the fast stage do more recovery before the release is being applied. At some settings it is even possible that the release stage is never being used, because the fast stage already recovered from the gain reduction completely before the release will be applied. So in short, the attack button is basically just adjusting the time when the release stage should be starting. Source: I contacted fabfilter then copy and pasted their response

1:36 You're the only guy on RU-vid who explains the Attack, Release and Lookahead relationship correctly. Thank you!

The way you explain stuff is supreme, buying your course soon! 🔥🔥🔥

The "headphones" difference/null button is actually a really great way to hear how the styles affect your transient releases. Usually the peaks just sound like little "glitches" but at the same limiting level other styles will be limiting more than just the "glitch" transients.

The true peak isn't just a detector that reads what the true peak is and doesn't let it go above that, that is one aspect of it. In Pro-L the detector works in two stages. It is firstly detecting the true peaks as they exist within the waveform which, to me at least, means it isn't actually looking at the PCM data of the file as it is stored in the session. It seems like it in essence is reconstructing the real waveform as it were. The second part of how the true peak operates is by then detecting any further overshoot that happens after any fast limiting and further reducing that. You can see why there would be clear differences in sound then; the limiting simply is different. To perform a true A/B of which you would prefer at any one time, I don't know if it's appropriate to simply click the True Peak on and off but rather to set the limiter separately for both according to what you sounds best, level match and then compare.

Really cleared up my understanding of how the lookahead, attack & release functions interact. Thank you.

Old comment alert. I did find a niche case for using the solo button a while back. I had a bass guitar track that was super clicky and I wanted to smash the clicks down until i was just on top of the tone. The solo button was the only way that I could hear when I really started to cut into the tone. Backed off the ceiling a little and the track was saved. RX de-click and clipping didn’t do as well as the L2. I also didn’t have soothe2 at the time. Like i said - super niche.

As much as I can't stand how you say aliasing, I really really really love this channel. Thanks dude. Keeeeep teaching!

This is actually amazing, thanks for your effort and can only hope you continue to do this type of videos.

Best Pro-L2 video on RU-vid handsdown .

Metering Totally Rushed - First Half Of This Video Was Great (Similar To The Video 2 Months Ago) - You Know What They Say "No Good Work Gets Done After Lunch" 🤪🍻 Thanks For The Vids 🤘

You answer the unanswered that I have been questioning for ages! Thanks man!

I didn't know 0 lookahead clipped the signal until today. Always felt it sounded harsh with faster lookahead, so I ignorantly increase lookahead before touching the attack. I will play around with this. True peak is tricky for me too. I listen to the low-end and the width in general. It jumps out when true peak is on. I usually keep it ON while mastering and turn it off if my track is sounding slightly wider (which generally does) than expected.

I have a course for EDM producers on mixing and mastering, but mixing is more of my expertise. The last section of my compression part of the course is on limiters and clippers, and the last thing I need to do is go through FabFilter Pro - L, so I really appreciate this video because I just don't know everything there is to know about Pro L yet. So thank you!

thanks man, the manual and plugin hints do such an atrocious job of explaining whats actually happening, fabfilter should hire you lol

21:30 The headphone function is useful to quickly check what instrument or frequencies are activating the limiter. If you engage it and, for example, you only hear bass drum or low frequencies, maybe you can reduce it in the mix to achieve an even louder overall sound. The same, if you only hear cymbals, maybe you can avoid the clipper even inside a very tight limitated mix...

Your ears are fine. The source material already had such a heavy pumping/breathing effect, that it made it kind of impossible to judge. I’ve always had a problem with the way The Pro L sounds. I can always hear it. In other words, it always changes the overall tone, the size and depth of the mix. I do use it, but I’m always wary of it. Thanks for the video!

incredibly useful video!! Massively underrated channel, keep it up!

Hey Nicholas, this is an awesome channel. Im mixing and (trying, to be honest, lol) to master the music I record as a hobby and in just 3 of your videos I've understood so much more about workflow, compressors, saturation and so many other techniques it's unreal. If you ever do a metal mixing/mastering course I'd gladly pay for that. Thank you so much!

Sad that I’m just now finding this video. But if I recall correctly, the TP detector is just the normal detector engaging 4x OS for the detector only. TP with no oversampling, and non true peak with 4x oversampling should null. That’s why it’s so hard to blind a/b them. It’s the same detector algorithm just working at different sample rates.

The depth you go into it amazing and delicious and thank you man. Especially as a more creative mind I love learning this stuff to fill my gaps

I love this so much!!! Ive always used my ears to fund the right mode and settings and oversample at 4x just because but now I know exactly whats going on under the hood!!! Thanks for nerding out!

Thanks for doing that. As one of the people asking for this video I appreciate the time and effort you’ve put in. In particular, trying to demystify the attack parameter is incredibly helpful. I’m going to have to re-read the manual and see what they say about it because I don’t remember this explanation and it’s pretty bloody important! One thing I would have found useful would be a bit more discussion about how these parameters affect the sound. Especially the attack parameter because that is making the limiter do something pretty unique. And I know I should just set up my own tests (and will) but would be interested in your thoughts.

The TP test was a good idea. On my phone speakers turned all the way up, the TP kick had a little bit more attack and I could tell the difference by that

Ayyy this is a really dope breakdown of the Pro L2. I use it a lot so this is dope to see how it reacts and better understand

Great video breakdown. The True Peak -vs- NoTP Test was cool. I guessed right 100%. The no true peak sounds round. But the true peak sound like it hits a ceiling like a clipper would do. Thanks again!

Your content is really good, i just wanna give a tip, say more slowly and spaced, and you will get more audience around the world, for people that knows english, sometimes little hard to get what you say, congrats for the channel, and thanks for sharing your knowledge! big up from Brazil

Phenomenal research work

very informative channel. thanks from korea

I love your videos and the way you explain stuff. Thanks man!

good stuff man, keep em coming

Thanks so much And I have the same opinion about TP mode I found it’s even more on obvious when you apply more limiting

I was able to identify the true peak version every time. It makes the stereo image sound smaller and the low end loses a little bit of extension.

the attack time is always releated to the release time and vice versa, the sooner you set the attack time, the more it grabs into the weight of the sound and digs deeper, it has more work to do now. this is the reason that the release component engages appropriately. it follows the overall digging of the attack component. the sound being compressed has a certain amount of lenght, first the transient comes which is followed by the sustain and basically its decaying. so as of amount of frequencies theres is much and it gets lesser. when you set the attack time long enough it partly operates like an envelope shaper thats cutting the sustain. the difference is that a compressor/limiter also creates a "firmimant/glassceilling" for our perceiptions. everything thats limited is showing us shape. the deeper you dig in sand with your arm the longer it takes for you to pull it out moving horizontally and vertically at the same time.

Some of the best info on this stuff

Mad props that you are able to A/B w/ True Peak be totally honest with the results. It takes courage to test against your beliefs, great work! Once I tested my mixes on poor DA systems, I obtained an entirely new respect for true peak limiting. Have you ever tested the Ozone TP vs. Fabfilter TP? In my testing Pro-L2 TP was far superior to Ozone. Also even with true peak, some samples will sneak through when converting to Mp3, and lord knows what else happens during all the other conversions possible.

Top notch content as always man! Keep them coming

Loved the video .... can you do the same thing for Pro-C2? I'm sure this would help a lot of people

Thank you so much for this insight :)

Really good job man, thanks for it.

Genial! muchas gracias

Super Great revue ;-) Thanks

Any chance you will have time to show us how you set up and conducted this test?

Here is another caveat about Pro-L 2 that enables you to obtain louder and transparent masters with less distortion than the norm. In fact, this applies to any limiter that has this function. Disable Channel Linking. Why? When Channel Linking is enabled. the limiter applies the same treatment to both channels when attenuating the gain reduction since it perceives the output levels is identical. However, 99.999% of the time, no stereo outputs generate the exact same level, as well as immersive audio channels. Even if TPL is enabled, it is moot. It'll only attenuate once it reaches the output gain's threshold evenly on both channels/sides. With Channel Linking disabled, the limiter will engage its algorithm independently since the L and R channels output varies. That means the limiter works less when limiting, in turn, creating louder masters with less distortion. Depending on whether or not you want more distortion on the master, enable CL. Even if you have different percentages set on both channels, due to the style of each limiter mode automatically engages distortion (without lookahead), the outcome will be the same. Any limiter using independent channels will successfully have louder and cleaner masters, whether or not gain reduction is engaged.

Great videos! I'm a true peak hater too! (thought I was the only one) :) Focusing on the top end transients I can hear the difference more clearly.

Great video! Totally lost me on the sidechain though. Not sure what was done. Lol

Does the chanel link also work for m/s information? For example if a kickdrum which is 100% mono make the limiter work, will a hat that sit on the sides also get ducked with 0% linking?

Great video but is it just me or does something seem off about the side-chain stem limiting method.... if you have pro-l2 on eg. your drum bus, with the master mix feeding the sidechain, isn't that bus limiting going to affect the master signal which is triggering the sidechain? So you won't end up with the same amount of limiting (probably less, because the master is being fed limited bus signals) when you sum it back together? For this to work accurately, wouldn't you need to set up a second copy of the bus which wasn't feeding the master on which you could apply the sidechained limiting? .. Or does it somehow work itself out because the stems would need less limiting individually to reach the same overall gain reduction you'd get limiting the master? (but then there's clipping involved as well depending on what L2 settings you use, surely this willl change the tone of the mix if you're suddenly clipping individual stems rather than the master output?)

Just found you. Awesome channel. Thank you 😊

You, sir, are a fucking Saint

Would love for you to go in depth with the modern mode some time because I think its broken/faulty. The channel linking works completely different on modern and it can't handle low end at all. I've literally had clients complaining about distortion on their kicks only to find out I've accidentally had modern engaged.

Love your channel - this is the first time I have understood the interaction of the Attack and Release on L2. By any chance could you provide practical use cases for each? I get that I might want to clip my drums so I can just set a long attack and accomplish that. but when would I want the release to engage? Is it significantly more transparent with a release like 100ms+? I am using PRO-L2 to limit a vocal bus right now and I am unsure what good settings might be for a pop vocal. I imagine a little lookahead will keep it clean with gain attenuation, but I have no idea what to do with attack and release when I am just trying to catch the rogue peaks. 🙏

To be honest every time i load any plugins i have for ages from FabFilterBundle i always find/rediscover something new in them. Btw that thing with stereo linking... I thought that im idiot for not getting it right,so i always battled that either with mid/side or unlinked option in ProC before hitting the L

Very, very good video, learned a ton. The amount of trash you find on youtube about mastering from people who really should know what they are talking about is actually quite staggering.

True peak doesn't sound good - it's like aux track vs master faders in pro tools. True peak and aux tracks sounds really bad. Great content man!

Great stuff!!!

Hey, could you correct me if I'm wrong? So my understanding about the attack and release times is that: If the attack control is set all the way to the left (short attack time), it limits more gradually, preserving more of the initial sound and reducing clipping. Whereas, if the attack control is set all the way to the right (long attack time), it limits quickly and might result in more clipping. And It doesn't let much of the initial sound through before applying compression.

If you take suggestions could I request an examination of Soothe2? Would love to hear your thoughts.

26:04 i am so good :D... i did everything right with my Kali in8 + sub :D - the true peak function sounds bs

Thanks for the time serviced in exploiting and revealing the functionality of relationships and interactions with the controls, settings, and modes. It is quite an awakening for a purposed and productive approach when using the Pro-L2. Alternatively, it has always been using my ears and fiddling with the controls until something says, “Ah-ha” But in a rather drastic time-consuming manner. KNOWING EXACTLY what’s going on by way of the demonstrations and field tests is far more than half the battle. Meanwhile, I came here for the “Ah The Metering…the metering-the meteriiiiiiiiiiiiiiiiIhhhhhIIIIIIIIIIIIIIIIIIIIIIIHHHHHHHHHHiiiiiiihhhhhhhhhhIIIIIHHHHiiiiiiiihhhhhhhhhhhiiinggg #beatbreak wap…pop-chickah-chickah……snwap-thumpk-pop…chuck-chickah!”

Man, I dont get it that sidechain function. Do you use it all the time ?

True Peak Limiting actually turns off over sampling, I believe. That's likely why you don't like it, nor do I.

This is a good one to watch when I’m 💩ing 👍

Did you give away all those plugins yet?

seems like you missed the DC offset button 😅

Now i'm feeling like a Pro.L nerd 🤓

I don't follow what's going on with the sidechain - you said it should be keyed in to the output of your full mix, right? But if it is outputting into the mix then aren't you just increasing the amount of gain reduction from whatever it was before so how is that making the overall loudness of the mix higher than it would be without the sidechain? I didn't understand your example so that's probably the real issue lol

26:03 HAHAHAH

man, your mic is saturating.

Bro u death haha, training your ears.

Your attention to details man🤦🏻‍♂️ it’s great I don’t know if you own limitless or not, but if you do, please do these release tests with it Limitless is also has two stage release, that should be fun😅😅😅 And for audition feature, if you using L2 as a clipper, you can assure that you’re clipping just transient stuff not sustain and musical stuff, it’s just a use case so whatever😁 Great stuff be well🤍👌🏻