BIGTIME EQ Problem in HDX. Or, I may be stupid.

[SmokinBaldMonkey]

OK, maybe I'm an idiot. All these years, I thought that a high-pass filter on an EQ allowed highs to pass.

I also thought that the degree of slope you assigned determined how sharp a cutoff you would achieve.

So, imagine my surprise when I learned that in this session, the highlighted portion of audio, a snare hit, did not clip the meters until I turned on the HPF.

Once that HPF turns on in PTHD10, the signal level increased an easy 6db.

Get that? No HPF, signal is fine, no clip. HPF on, and the signal clips both the EQ3 output and the track level meter...because the signal is significantly higher....or at least, it is showing me that.

Am I misunderstanding something?

[Drew Mazurek]

Deactivate, reactivate. Relaunch PT.

[BasketCase]

A high pass filter in the real world isn't just a straight "cut". Part of the byproduct of it is a resonant peak at the cutoff frequency that is proportional to the steepness of the slope. It will actually boost as well. The steeper the high pass... the bigger the resonant peak.





What happens if you reduce the slope from 18dB/OCT to 12dB? Or 6dB? Does the channel still clip?

[SmokinBaldMonkey]

Originally Posted by BasketCase

What happens if you reduce the slope from 18dB/OCT to 12dB? Or 6dB? Does the channel still clip?

It does decrease when I change the roll to 12 and then 6db. OK, thank you for that lesson in filters.

But, while we're on the topic, why should that spike occurr in the box? would that not be an artifact of an analog processor? Shouldn't a digital EQ not have such a spike?

Now perhaps Avid should cause the Graphic display to draw whats actually happening instead of leading me to believe that its smoothly cutting away unwanted Frequencies. That was frustrating as hell.

[blairl]

Intersample Peaks

http://duc.avid.com/showpost.php?p=1802757&postcount=54