Patching a Notch Filter from a Bandpass

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Patching a Notch Filter from a Bandpass

Post by c0rpse » Wed Sep 04, 2019 5:16 pm

I figured that if I subtracted a bandpass signal from the dry signal I would get a notch. Apparently this is not the case because of phase alignment.

Instead you must put the bandpass in a feedback loop on the subtractor.

Code: Select all

 INPUT+------->+     |
               | SUM +------------+--> OUT
+------------->+     |            |
|              +-----+            |
|                                 |
|                                 |
|  +--------+      +----------+   |
+--+ INVERT +<-----+ BANDPASS +<--+
   +--------+      +----------+

It's a pretty basic concept, but this forum section can use some love.
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Post by damase » Wed Sep 04, 2019 5:39 pm

nice one, thanks


Post by hinterlands303 » Fri Oct 04, 2019 6:57 pm

I gave this a go last night with an Intellijel uVCF and Happy Nerding MIA (to do the summing and inverting) and it sounded great! Thanks for the tip.

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Re: Patching a Notch Filter from a Bandpass

Post by authorless » Thu Dec 26, 2019 2:35 pm

The filter you are using is probably already inverting the signal, have you tried summing the filter output with the original signal without inverting either?
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