Just got FabFilter Pro-L.    I have a bass line that has a few notes that hit a bit too hard.    I want to limit those peaks, for example those going over -7db.   I don't want to make things louder, just cut off those peaks (in fact make it quieter).  How do I use Pro-L to do that?   It has a gain slider, but this makes things louder.  If I move the gain with ALT held down it seems to cut off the peaks, but there is no volume decrease.    What am I doing wrong?
 
 

There is no threshold control, you have only gain and ceiling. You're doing it right by using the Alt key when you push the gain up, as it simultaneously lowers the ceiling and thereby the threshold. If you don't want any gain added, just lower the ceiling until you see the peaks being reduced.
 
Tip: for drums, use the Dynamic model. It enhances transients before limiting.

Thanks bitflipper.    The ceiling is the Output, right?    So when lowering the output, this lowers everything by the amount I'm lowering.  And if I use Gain+Alt, this should cut the peaks off that level of the output whilst leaving the rest of the sound unaffected?   At least this is how it looks from the graphical output I'm seeing ...
So if I have for example a piano track where just one note is way to hiugh, I can cut off just its peak using Gain+Alt, and leave the rest of the sound the same as it was?

Yes, I was unclear before so please ignore my previous post. You are correct: alt-gain will adjust the amount of limiting while maintaining approximately the same output volume.

Great, all clear, thanks for your input.
 

Ultra , for this job , you should try multiband compression or limiter ...to preserve other freq if it's a complex material ..

Zo's right about that, for a bus anyway. Zo usually is. But the immediate problem is specifically a bass track, and the peaks are almost certainly low-frequency and can be easily limited by a broadband limiter without impacting harmonics. I've used Pro-L for just this purpose, and it works great. I've even used it for leveling a rock vocal, and it worked surprisingly well for that, too.
 
My only caveat is that with bass it isn't always rogue peaks that are the problem, but often specific rogue notes. For that, a multi-band compressor or dynamic equalizer might indeed be better.
 

dbl post <<content below>>

I don't understand, if it's just a couple of notes, in a few places? Why not use an envelope? The other tools, limiters and compressors are intended for other things.

And I'm not saying do not use MB, or Limiting? Just going back to the OP, "there's a couple of nasties in the bass line?" Handle those with an envelope... Then use compression and limiting tools as appropriate. Difficult to argue with that philosophy ;-)
 
Although some will try? Some will try...