FabFilter User Forum
Pro-L2 Output level knob
I can't figure out the behavior of the L2 Output knob. Let's say my levels are peaking at around -3.0db, sometimes a little higher. I don't want them to exceed -3.0db, so I set the output knob at -3.0db to limit any signal from going above that level. But what Pro-L2 does is lower my levels by 3.0db, so now they are all peaking around -6.0db. Whatever negative level I set the output knob to, that's how much it lowers my signal. It's just acting like a gain knob. No limiting is taking place, it's just reducing my gain. If I set the output knob at -3.0db AND set the gain slider up to +3.0db, then the net effect is zero, null. If I push the gain slider up to +5.0, now it is indeed limiting at -3.0, but bringing up the overall rms level by about 2 db. I don't understand this behavior. Why does it drop the level of my input signal by the amount I have lowered the output knob to (assuming the gain slider is at zero)? Why do I have to offset the Output knob amount with an equal amount of gain slider just to get even? My other limiter doesn't do this, it acts like you'd think. If I set it at -3.0 it just limits what goes above that.
Hey there,
as far as I understood it: Pro-L does limiting always at 0dB when it is enabled. So to have some limiting below 0dB, you have to lower the output and higher the gain, as you described correctly.
I think technically it should be the same, since (again: my guess only) technically it should be the same in either way: if you lower a ceiling in other limiters some sort of clipping and saturation will happen. Same goes when boosting up the gain in Pro-L. It's just some kind of "the other way around", at least to me. But in the result it should be technically the same.
Again: just my guess. I am totally cool with this behaviour, though, hehe.
Hi Eric,
Manuel is correct. The limiting stage of Pro-L 2 is always limiting everything exceeding 0dBFS or 0dBTP, depending if you have TP limiting enabled. The gain slider just pushes the material into the limiter. The output knob turns down the signal post limiter. So if you do not want your audio to be louder than -3dBFS, you would need to set the output to -3dB. If you want to keep the same loudness, you would also need to increase the gain with 3dB, which would also give you 3dB more limiting.
Cheers,
Ok, thanks Ralph. My other limiter that I use sometimes does not work that way. Instead of an Output knob that works post limiter it has a Threshold slider and a gain slider. I love Fabfilter and I use the whole suite of FF tools for 90% of my mixing and mastering, but I will say my other limiter is much more intuitive in this regard.
But now that I know how it works I will just do the math. If I want the output limited to -3.0db, as is required by ACX, and I want to compress the audio as well, I'll just set the gain slider to something more than +3db to crunch it upward some. Thanks!
By the way: you can drag gain or ouput with the Alt (or on Mac maybe Option?) key so that they get linked inverted:
i.imgur.com/lXjS7iC.gif
I am still blown by the GUI Fabfilter provides. So intuitive. o-: