Threshold levels and Clipping

[yarrick19]

Hello,

I have been recording audio for about a year now using Cubase SX. I recently bought an MBox to see what ProTools LE was like.

I ran into an issue that I don't quite understand. I have audio tracks routed to a master fader and have inserted the digi rack limiter plugin on that master fader. Clipping in the digital domain occurs at 0db. I would like to set the threshold of my limiter at around -1 db to get increased volume levels. When I do this, the limiter does not activate at all and no limiting occurs, yet the clip indicators for the track light up! As soon as the signal gets to -1db ( or -2db or -5db) the limiter should kick in and prevent the clipping, yet the clipping occurs (signal >= 0db) and the limiter doesn't activate at all! I have to put the threshold at around -15db before it "limits" the signal at all.

What is going on here? Logically, this does not make sense.

Can someone please help me understand why this is happening?

Thanks for the help!
Paul

[Rail Jon Rogut]

Clipping in 32 bit floating point doesn't occur at 0dBfs as you're thinking of it.. the insert point has headroom above the 24 bit full scale value. The insert is 32 bit floating point - this allows you to mix multiple tracks without clipping easily in software.

I've discussed headroom on the DUC before - I'm sure you'll find the thread with a search.

Rail