[Csnd-dev] higher order filters

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[Csnd-dev] higher order filters

Matt Ingalls
hey everyone!

i’m still lurking here.. :)

i recently needed to implement some Nth-order butterworth filters
(well, with a resonance parameter too, so i think technically they aren't “butterworth” then?)

even though you cascade 2nd & 1st order filters to get the higher orders, each filter needs different
coefficients to get the proper corner/cutoff -

as far as i can tell, in the gamut of csound filter opcodes,
there are no csound opcodes that can do Nth-order?

if that’s correct, i could probably contribute some code for some new opcodes
(if someone could help wrap it into an opcode —  it’s been a too long for me!)

-m
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Re: [Csnd-dev] higher order filters

Doctor B
More filters would be more wonderful.  Hello Matt.  Hopefully the current developers help you to make this happen.
Hope you are well.  And... hope you are still using Csound for your work.  Always grateful to you for all the things you
did to make Csound - especially on the Mac and csound~ in MAX - so intuitive, so useful and so useable!  

Dr.B.

_____________________________________________
Dr. Richard Boulanger
Professor of Electronic Production and Design
Professional Writing and Music Technology Division
Berklee College of Music
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Author & Editor of The Csound Book - http://mitpress.mit.edu/books/csound-book
Author & Editor of The Audio Programming Book - http://mitpress.mit.edu/books/audio-programming-book
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On Fri, Apr 20, 2018 at 1:32 PM, matt ingalls <[hidden email]> wrote:
hey everyone!

i’m still lurking here.. :)

i recently needed to implement some Nth-order butterworth filters
(well, with a resonance parameter too, so i think technically they aren't “butterworth” then?)

even though you cascade 2nd & 1st order filters to get the higher orders, each filter needs different
coefficients to get the proper corner/cutoff -

as far as i can tell, in the gamut of csound filter opcodes,
there are no csound opcodes that can do Nth-order?

if that’s correct, i could probably contribute some code for some new opcodes
(if someone could help wrap it into an opcode —  it’s been a too long for me!)

-m

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Re: [Csnd-dev] higher order filters

jpff
In reply to this post by Matt Ingalls
Happy to do thw integration


On Fri, 20 Apr 2018, matt ingalls wrote:

> hey everyone!
>
> i’m still lurking here.. :)
>
> i recently needed to implement some Nth-order butterworth filters
> (well, with a resonance parameter too, so i think technically they aren't “butterworth” then?)
>
> even though you cascade 2nd & 1st order filters to get the higher orders, each filter needs different
> coefficients to get the proper corner/cutoff -
>
> as far as i can tell, in the gamut of csound filter opcodes,
> there are no csound opcodes that can do Nth-order?
>
> if that’s correct, i could probably contribute some code for some new opcodes
> (if someone could help wrap it into an opcode —  it’s been a too long for me!)
>
> -m
>
jmc
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Re: [Csnd-dev] higher order filters

jmc
In reply to this post by Matt Ingalls
Hi, Matt,

Filter2 and zfilter?

Jim C

> On Apr 20, 2018, at 1:32 PM, matt ingalls <[hidden email]> wrote:
>
> hey everyone!
>
> i’m still lurking here.. :)
>
> i recently needed to implement some Nth-order butterworth filters
> (well, with a resonance parameter too, so i think technically they aren't “butterworth” then?)
>
> even though you cascade 2nd & 1st order filters to get the higher orders, each filter needs different
> coefficients to get the proper corner/cutoff -
>
> as far as i can tell, in the gamut of csound filter opcodes,
> there are no csound opcodes that can do Nth-order?
>
> if that’s correct, i could probably contribute some code for some new opcodes
> (if someone could help wrap it into an opcode —  it’s been a too long for me!)
>
> -m