Me and my noob questions

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#1

Hi I am making an effect for voice microphone. Hopefully I won’t be asking dumb questions that have already been answered, but I’ll try to google my questions first…

Currently I’m trying to figure out how to subtract one sound from another. I take audio from the mic in, and duplicate it (A and B). On B, I filter out all the high frequencies. Then, I want to subtract B from A so that A no longer has the frequencies that are in B (which also means B won’t have the frequencies in A)

I tried the simple expression: a - b, but it don’t sound like it’s doing what I want.

#2

Hey! From what I understand you try to high-pass your signal? Why not simply using a high-pass filter? You could also use a filter with 2 outputs, LP and HP.

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#3

Do you want to make a frequency splitter?

I’m not that good with filter stuff but as far as I know, if you subtract anything but a 1 pole filter, you won’t get what you expect from a frequency split.

I think Frequency splitting for multi band processing is usually done with separate high- and lowpass filters.

Keep in mind, Im just guessing this based on the results i goth while experimenting around with no education in this field.

#4

Almost all filters introduce frequency dependent phase shifts into the audio they are processing. After passing through the low pass filter, signal B has had phase shifts introduced. When you subtract it from A these phase shifts introduce peaks and lows in the frequencies that result. You would be better off using a pair of filters or a multimode filter that has both a low-pass and high pass output.

This is a state variable filter design that has a low-pass, high pass, band pass and band reject (notch) output.
Screen Shot 2021-03-14 at 6.34.07 PM
SVF Model 1.audulus (23.7 KB)

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