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-- The Cut Filter

Posted by meneedit on Oct-29-2004 01:45:

The Cut Filter

one thing that still baffles me to this day about the cut filter is the way it really works. many people just say "you can hear what its doing"... but do they really know?

now a "Fast LP/CUT" pretty much just muffles the sound but a cut filter on a 404 or a synth is different.

behind the scenes, what is it really morphing as you tweak the filter knob?

I'm just curious thats all

Posted by Zombie14 on Oct-29-2004 01:57:

Im not sure... But if i was to guess id say it raises something related to the high-end of the sound frequency.

Posted by Fast Turtle on Oct-29-2004 04:43:

A lowpass filter is like an equalizer that cuts out all the high frequency sounds, with the point where the sound is cut off varying with the cutoff knob. Resonance is how high the spike is in the part where the filter cutoff is applied. Usually the amount filters removed in the cut frequencies are -12 to -24 DB.

Lowpass filter
low frequencies allowed --------^\_______ high frequencies cut

highpass filter
low frequencies cut ________/^------- high frequencies allowed

bandpass filter
low frequencies cut ________/^\________ high frequencies cut
(only the frequencies at the cutoff are allowed)

The resonance effects how loud that little '^' spike is.

A cut on a 303 or whatever may sound a lot different because distortion is added after the filter is applied.

Posted by capricorn15 on Oct-29-2004 04:46:

quote:
Originally posted by Lephaid
A lowpass filter is like an equalizer that cuts out all the high frequency sounds, with the point where the sound is cut off varying with the cutoff knob. Resonance is how high the spike is in the part where the filter cutoff is applied. Usually filters are -12 to -24 DB.

Lowpass filter
low frequencies allowed --------^\_______ high frequencies cut

highpass filter
low frequencies cut ________/^------- high frequencies allowed

bandpass filter

low frequencies cut ________/^\________ high frequencies cut
(only the frequencies at the cutoff are allowed)

The resonance effects how loud that little '^' spike is.

i like your diagram =)

Posted by Fast Turtle on Oct-29-2004 04:48:

quote:
Originally posted by hadi ******
i like your diagram =)

thank you

Posted by tu_face on Oct-29-2004 08:12:

also there are envelope parameters to think about, where you control attack, sustain, decay and release of the filter, usually coupled with an 'env amount' knob. this can alter the way one LP filter sounds compared to another LP flter.

Posted by meneedit on Nov-09-2004 23:04:

no no no, im talking about the types of cuts that you find on synth lets say for example a 3xOsc... that cut seems way different

Posted by Fast Turtle on Nov-10-2004 05:11:

fast LP is a quickly and badly rendered low pass (12db)
lp is lowpass (12db)
lpx2 is lowpass(24db)
svf is a state variable lowpass filter (12db)
svfx2 is a state variable lowpass filter (24db)
bp is bandpass (12db)
hp is highpass (12db)

cut is the same thing on all of them...

Posted by isoterra on Nov-10-2004 07:43:

quote:
Originally posted by meneedit
no no no, im talking about the types of cuts that you find on synth lets say for example a 3xOsc... that cut seems way different

I *think* it sounds different because it's applied before the sound is generated/processed, as opposed to afterwards (like it would if you used a 3rd party filter), which makes it sound better. Don't quote me on that though... have no proof to back it up.

Posted by Fast Turtle on Nov-10-2004 07:46:

quote:
Originally posted by isoterra
I *think* it sounds different because it's applied before the sound is generated/processed, as opposed to afterwards (like it would if you used a 3rd party filter), which makes it sound better. Don't quote me on that though... have no proof to back it up.

No, they all work the same way pretty much.

Posted by josh4 on Nov-10-2004 07:47:

quote:
Originally posted by Lephaid
No, they all work the same way pretty much.
i agree

Posted by isoterra on Nov-10-2004 07:55:

quote:
Originally posted by Lephaid
No, they all work the same way pretty much.

Well they certainly sound very different. A quick demo:

http://terrafusion.artists.mpfspromotions.com/cut1.mp3 - automated the cutoff filter on the 3xOSC synth itself

http://terrafusion.artists.mpfspromotions.com/cut2.mp3 - automated the cutoff using a 3rd party filter plugin

Both LP.

Posted by tu_face on Nov-10-2004 08:50:

quote:
Originally posted by meneedit
no no no, im talking about the types of cuts that you find on synth lets say for example a 3xOsc... that cut seems way different

no, a filter is a filter what you may be confused with is the fact that there are usually attack, sustain, decay and release settings on an oscillator too. this again can make things sound very much different, for example if you wack the release right up the note will never stop. its the same control on a filter, but it uses it in a different way, i.e. the envelope is applied more and more as you move the filter frequency up.