FabFilter

Hi -

I'm trying to understand exactly how the gain slider in Pro L works and was curious about whether or not the gain slider is simply a gain/trim knob or if there is something more to it to be aware of.

I already understand that you can hold down shift to make the output knob go down as you pull the gain slider up.

What I'm trying to figure out is, lets say you have something at a fairly steady volume going into the Pro-L (factory default settings) at -15db and you pull the gain slider up 4 dB and leave the output knob set at 0dB. So basically you got a resultant -11 db signal and it is nowhere near hitting or going over 0 dB.

In this case, would this be effectively the exact same thing as using a trim plug in set at +4db, or is the Pro L gain slider coloring or changing the sound in any way?

I ran my own tests by bouncing files of pro-L set as described above vs avid trim set at +4dB and then did a phase flip comparison of the two files and they cancel each other out, so I am thinking the answer is yes.

However, the manual for the fab filter describes the gain slider as follows: "The gain slider adjusts the threshold of limiting and the increase in output gain at the same time."

So I am wondering if there are other scenarios I need to be aware of where my phase flip testing might not hold up, aside from the obvious scenario where the signal is going above wherever the output knob is set at.

I think what they mean by threshold in their description of the gain slider is that if you increase the gain slider, you are pushing the signal toward whatever you have your output knob set at, so the higher you push the gain slider, the more of the signal you are pushing over the setting of the output knob, effectively adjusting the "threshold" level. But in that case the idea of a threshold would only apply if you are actually pushing the signal above whatever the output knob is set at.

Am I interpreting this correctly?

Thanks!