adding notch to SV filter

[Harry Bissell]

Summing the HP and LP outputs is THE way to go. If you subtract the bandpass from
the input, it only works for one "Q" setting. Adjust Q and you have to adjust the
gain also.

So this will work only at one point... part there the signal looks like a bandpass
again with
funny phase inversion.

This was a technique used on the old PAiA 2720... it did work, with the limitation
above.

H^)  harry

PS: IMHO the allpass (phase shifter) is more usable than the single notch.

"M.Ruberto" wrote:

> hi,
>
> i'm building a standard state variable filter and i would like to have a notch
> output in addition to the HP, LP and BP. is it acceptable to obtain it by
> subtracting the BP from the input signal? or is there some less simple but
> more correct way of doing this?
>
> thanks
>
> -<mike>-
>
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