FabFilter

I have a snare sample that peaks at 0dB. Using Pro-Q2 version 2.12, I place a low-cut band at 115Hz, Q of 0.313. At a slope of 24dB/oct using Linear Phase processing mode (resolution set to any of Low to Maximum), I get a peak of -0.25dB. Using either Natural Phase or Zero Latency processing modes, I get a peak of +5.20dB.

I was a bit taken aback by this approximately 5.5dB difference in resulting headroom and unsure as to the cause. Is there a good explanation for this?

I'm using Ableton Live 10, Mac OS High Sierra if that matters.

Hi Bill,

I understand that it feels very counter-intuitive that the signal peaks at a higher level while using a low cut filter... but actually, there is an explanation for this.

Any type if (non-linear phase) filtering, introduces phase changes to the signal. This means that different frequencies are delayed at slightly different rates... and can of course cause different (higher and/or lower) peaks in the signal.

This is not something specific for Pro-Q 2, but you'll see this when using other EQ's (with the same/matched curve) as well.

Hope this helps!