Subject:cutting low freq

Posted by: jdg

Date:6/14/2002 12:38:39 PM

ok.. EQ smarties, answer me this:
when i bring my track in to SF i usually roll off anything below 20hz.. doing so actually INCREASES the overall volumn of the track, sometimes clipping it. why? why does removing low end freq cause the track to get louder? also, the waveform usually changes (looks much more normal) after i cut below 20hz. sometimes i have wierd phase looking areas that just go away after i cut the low end.

anyone have some insite they'd like to share?

thanks!
john

Subject:RE: cutting low freq

Reply by: rraud

Date:6/18/2002 8:29:23 PM

The level increase has something to do with the SF-6 EQ. It did not do that in 4.5 or 5. I know, it's annoying... Adjust the output volume control so it dosn't clip. Naturally the waveform is going to change.... you cut some low frequencies and changed it.

Subject:RE: cutting low freq

Reply by: jdg

Date:6/19/2002 5:39:09 PM

wow.. thats a stoopid bug i hope they fix... i thought it was strange that cutting some EQ would boost the volume....

Subject:RE: cutting low freq

Reply by: Sonic

Date:6/20/2002 1:38:22 PM

On certain EQ's, particularly those using IIR filters, stringent filter parameters (narrow passband with high attenuation) can cause a 'lump' in the frequency response near the cutoff frequency, which, depending on the location of the cutoff frequency, could potentially change the volume.

If you want to get into the gory details create a single sample impulse in the middle of, say, 32,768 samples of silence. Open the spectrum analysis tool and modify it to do a single 32k FFT with no overlap, logarithmic scale, and make sure the caret is at the start of the data window. Now apply all your favorite EQ's and you'll see what's really going on in frequency domain.

Subject:RE: cutting low freq

Reply by: jdg

Date:6/20/2002 3:45:21 PM

awesome tip.. that helps me "see" whats going on a lot better. thanks!