Page 1 of 1

Patching a Notch Filter from a Bandpass

Posted: Wed Sep 04, 2019 5:16 pm
by c0rpse
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.

Posted: Wed Sep 04, 2019 5:39 pm
by damase
nice one, thanks

Posted: Fri Oct 04, 2019 6:57 pm
by hinterlands303
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.

Re: Patching a Notch Filter from a Bandpass

Posted: Thu Dec 26, 2019 2:35 pm
by authorless
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?