Notch filter uses

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Durdee
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Notch filter uses

Post by Durdee » Wed Apr 07, 2021 5:49 pm

Hey everyone, I’m just kind of curious about how people use notch filters in creative ways. I know that they can be used to tame ugly resonant spikes and wider notches can carve out spots for different parts to sit in a mix, like an aggressive eq, but how about more creative or non-obvious ways you like to use them? I’ve got a WMD micro hadron collider that I finally found expanders for, so both sides now have notch filter outputs and I’m all ears for cool ways to use ‘em!

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Yes Powder
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Re: Notch filter uses

Post by Yes Powder » Wed Apr 07, 2021 6:15 pm

First thing that comes to mind control its CV with an LFO and you have a a sound similar to a two-stage phaser.

Feel like this thread would be better in “Synthesis Techniques” but no big.
I’m also interested in other uses people have for them.

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wuff_miggler
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Re: Notch filter uses

Post by wuff_miggler » Wed Apr 07, 2021 6:25 pm

A few uses for notches:

instead of cutting with them - use them to imitate the smaller resonant bodies of instruments like kemanches and the like.

also instead of cutting - running a lower pitched saw/rect/tri through a heftily boosted notch to get out of control peaks during automation - sounds great when in analogue and running into distortions.

notch filters are what's used in wah pedals - so good for leads too im guessing :-)

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Dave Peck
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Re: Notch filter uses

Post by Dave Peck » Wed Apr 07, 2021 8:30 pm

If your filter has simultaneous lp/hp/bp/notch outputs, use the LP for regular low pass duties and use the notch output for sending a filter feedback signal back to a spare input on the pre-filter mixer for added 'ooomph'. May require inverting the notch signal, depending on the filter type.

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Re: Notch filter uses

Post by Durdee » Thu Apr 08, 2021 6:53 am

wuff_miggler wrote:
Wed Apr 07, 2021 6:25 pm
instead of cutting with them - use them to imitate the smaller resonant bodies of instruments like kemanches and the like.
This is an interesting concept, can you elaborate a bit on it?

These are all great, I’m excited to try the feedback suggestion as well!

One thing I’m wondering, when you increase resonance on a notch filter, does it make pronounced peaks on either side of the notch, widen the notch, or something else completely? I feel like I need a spectrum analyzer so I can figure this stuff out better on a technical level without using equations.

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wuff_miggler
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Re: Notch filter uses

Post by wuff_miggler » Thu Apr 08, 2021 7:01 am

i just meant to boost instead of cut . keeping a few notches at certain frequencies (hence resonant instrument bodies).

Durdee
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Re: Notch filter uses

Post by Durdee » Thu Apr 08, 2021 7:05 am

wuff_miggler wrote:
Thu Apr 08, 2021 7:01 am
i just meant to boost instead of cut . keeping a few notches at certain frequencies (hence resonant instrument bodies).
Ah, ok, nice!

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pricklyrobot
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Re: Notch filter uses

Post by pricklyrobot » Thu Apr 08, 2021 12:25 pm

I think wah pedals are usually bandpass filters, aren’t they?
Though I guess bandpass and bandstop would be more accurate terminology. Since they’re both kind of a ‘notch’ doing opposite things...

Anyway, I’ve gotten cool, vocal-esque sounds running a bandpass and a notch in series.

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Dave Peck
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Re: Notch filter uses

Post by Dave Peck » Thu Apr 08, 2021 1:11 pm

Durdee wrote:
Thu Apr 08, 2021 6:53 am
wuff_miggler wrote:
Wed Apr 07, 2021 6:25 pm
instead of cutting with them - use them to imitate the smaller resonant bodies of instruments like kemanches and the like.
This is an interesting concept, can you elaborate a bit on it?

These are all great, I’m excited to try the feedback suggestion as well!

One thing I’m wondering, when you increase resonance on a notch filter, does it make pronounced peaks on either side of the notch, widen the notch, or something else completely? I feel like I need a spectrum analyzer so I can figure this stuff out better on a technical level without using equations.
On most 12dB/oct filters that have simultaneous LP/BP/HP/Notch outputs, increasing the resonance while using the notch output just seems to make the notch disappear and it sounds like the filter isn't doing anything. But you can take the LP and HP outputs and mix them at some ratio that is NOT 50/50 (so it's different from the notch output) to create an 'asymmetrical notch' (louder on one side of the notch, quieter on the other) and THEN you'll hear the resonance. It's one of the cool things you can do with a SEM filter's variable LP/notch/HP control, setting it at something like 65% LP and 35% HP.

To get a more pronounced 'two resonant peak' effect, I find it works best to use a separate LP and HP filter patching in parallel, with a 'gap' between their cutoff settings.

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Re: Notch filter uses

Post by Durdee » Thu Apr 08, 2021 1:15 pm

Dave Peck wrote:
Thu Apr 08, 2021 1:11 pm

On most 12dB/oct filters that have simultaneous LP/BP/HP/Notch outputs, increasing the resonance while using the notch output just seems to make the notch disappear and it sounds like the filter isn't doing anything. But you can take the LP and HP outputs and mix them at some ratio that is NOT 50/50 (so it's different from the notch output) to create an 'asymmetrical notch' (louder on one side of the notch, quieter on the other) and THEN you'll hear the resonance. It's one of the cool things you can do with a SEM filter's variable LP/notch/HP control, setting it at something like 65% LP and 35% HP.

To get a more pronounced 'two resonant peak' effect, I find it works best to use a separate LP and HP filter patching in parallel, with a 'gap' between their cutoff settings.
Excellent! This is exactly what I’m looking for. I love that I’ve got some cool experiments to do.

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