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tester ·
In cool edit, there is a cool tool named FFT filter. It allows to filter/amplify very narrow bands of spectrum (like 4Hz or 1Hz or even less), and it really works that way (tested on sinus signals). Can looks like this (see attachement).
Is there a quick way to make a filter, that will allow to amplify small bands of spectrum that way? By small bands I mean like 1Hz wide, and with very sharp border edges of the filter (at such resolution they seem to be less than 1Hz between max and min).
I'm looking for a solution that will allow to specify a single spike filter like that, with the width selection of the band (Hz), filtering depth of surrouding spectra (volts or decibels) and the slope sharpness/ratio; at resolution similar or higher.
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Dell ·
Yes. Search for RBJ Peak Biquad filter. Or you can download the FFT in the post listed below that says nowrite.osm
Make My Pads/EQ Writeable?
You will need to create the given frequencies needed for your requirements. I hope such single digit frequencies requirements are for industrial purposes and not home audio related. Using a single digit frequency under high SPL can/will damage loudspeakers and/or have amplifiers ramp into DC Protect.
Cheers!
tester ·
No such file "nowrite.osm" there.
But I'm not interested in FFT display module nor graph EQ. I just need to specify cutoff frequencies (not according to "-3dB formula", just cutoff points) on a filter, and having very very high degree of resonance (at 24000 pts FFT resolution it's like a switch between 0 and 1 on 1pt value) - I wish to remove surrounding spectra without interfereing with remaining part of the spectra. Will the biquad filter do this?
In attachement - an example of such peak filtering done in cooledit (measured in different soft, at 512kpts to show it in detail)
Dell ·
What you are showing is nothing more than a Peak caused by specific boost in dB using a Parametric Equaliser at a given Q settings. It is offering a -3 dB point but at a very narrow Q point. So the width is below an octave appart. The RBJ Biquad Peak filter is what is used for parametric equalisers. What you are showing can be done with the stock Equaliser providing you configure the settings for your requirements.
The "nowritepads" in the link is there (I checked again) so you may want to look again if you would like the FFT.
Cheers!
tester ·
Okay, thanks, I check that.
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