FabFilter User Forum

Pro-L as Broadcast True Peak Limiter

Hi,

I was wondering is anyone using Pro-L as True Peak limiter for Broadcast ?
I'm pretty confused as, in my understanding, if I don't the peaks to "go" over -3dB FS, I have to set the output to -3 and set the input to +3.

Am I wrong ?


Thanks for your time.

Best regards,


Pascal Zander

Pascal Zander

Hey Pascal,

If you want the peaks not to go over -3dB then you should set the output to -3.

+3 To input will give you extra gain, ofcourse, but the "output" operates as the threshold (which nothing should exceed).

Cheers

Yroth`

Hi,

Thanks for your reply.

In the tests I did, as soon as I set the output to -3, Pro-L reduced the output level by 3dB that's why I had to set the input to +3

It looks like the output operates as threshold for the limiter and as a "normal" output fader.


Best regards,


Pascal

Pascal Zander

The one problem obviously is that Pro-L isn't a True Peak limiter (ie catching intersample peaks). I assume you want to implement Rec128 or similar for broadcast, and using Pro-L I don't think you'll strictly comply with those standards.
Although, depending on your intended use, you can argue that it's not that much of an issue.

Other than that, keep in mind that if you increase the gain with 3dB and decrease the output by 3, you'll have more limiting going on (ie, you'll decrease the dynamics).
It may be better to set the -3dB with a fader or a simple gain utility after Pro-L.

Bram

I'm sorry, that was wrong, Pro-L's output gain knob isn't the threshold. It's just a gain, so you can set that to -3dB. It seems Pro-L is internally limiting at 0dB.
But you will decrease dynamics if you amplify by 3dB going in, if you don't have enough headroom (at least 3dB) in the signal.

Bram

Hi Bram,

Thanks for your replies.
So it seems that Pro-L is not suited for what I need to do, "clean" limit at -3dB without reducing the overall output.

Thanks for your time.

Pascal

Pascal Zander

Hi Pascal,

You can just set the output to -3 dB: this will guarantee that peaks don't go over this level. Next, use the gain slider to increase the level of the signal that enters the limiter: this increases the apparent loudness of the output, but at some point of course the dynamics and transients will be affected. If you want a signal under -3 dB to go through without a change, you should set the gain slider to +3 dB.

Cheers,

Frederik (FabFilter)

Hi Frederik,

Thanks for your reply.
That's what I'll do.
Set the output to -3 and the input gain to +3.


Thanks for your time.


Bets regards,


Pascal

Pascal Zander
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