PreenFM Forum

PreenFM => PreenFM2 => Topic started by: Toltekradiation on August 11, 2019, 12:57:50 AM

Title: New filters
Post by: Toltekradiation on August 11, 2019, 12:57:50 AM
hi,
I finally dared to dig the preenfm code, and, it was worth it  8)
here is a firmware attached, that include some more filters :
- lp2 : lp with double filtering
- same for hp2 and bp2
- tilt : adaptation of this : https://www.musicdsp.org/en/latest/Filters/267-simple-tilt-equalizer.html
- allpass : simple allpass filter, need some more work, not sure what to do with this one...
- saturation : this : https://www.musicdsp.org/en/latest/Effects/42-soft-saturation.html
- sigmoid : a classic tanh distortion : https://www.musicdsp.org/en/latest/Other/178-reasonably-accurate-fastish-tanh-approximation.html

I hope you like it!

your ideas and bug report are welcome.

If you want to see the code, here it is : https://github.com/pvig/preenfm2

(edit 2019-09-11 12:45:37 PM : updated attachement)
Title: Re: New filters
Post by: kyoto on August 13, 2019, 09:23:16 PM
wow - great - now will try ;)
Title: Re: New filters
Post by: matrix12x on August 14, 2019, 03:22:47 AM
Awesome!!! I've been wanting to do an all-pass for a while. I also wanted to do a comb-filter with some distortion. I will try this out and let you know if I find any bugs.

Great work!
Title: Re: New filters
Post by: Toltekradiation on August 14, 2019, 10:41:22 PM
hi guys, thanks for the interest !
yes there is some room for experimentation !
but not so much cpu, so it seems we must keep it simple..
still finding my way through this, but yeah! i added foldback & xor distortion to this version.. + some tweaks and fine tuning around the sigmoid & distortion..

(edit : modified version with new foldback algo)
Title: Re: New filters
Post by: Toltekradiation on August 15, 2019, 02:47:23 PM
another version with some bug fixes :
all new filters can now be controlled with the matrix.
+ various tweak
i think i'm done for today  :P
Title: Re: New filters
Post by: kyoto on August 15, 2019, 05:04:16 PM
Toltekradiation, thank you very much for your work -- goodbye weekend  8)
Title: Re: New filters
Post by: matrix12x on August 16, 2019, 12:52:29 AM
The new filters sound great. I've been playing for the last hour and a half.
No crashes yet.

BTW, Where did the all-pass go?
Title: Re: New filters
Post by: Toltekradiation on August 16, 2019, 12:36:59 PM
hi, another version with a fix for lp2 & hp2 : better behaved self oscillation
@matrix12x : the allpass filter is used in the "Pann" filter ; the "pos" parameter is the filter cutoff and it's not very interesting
as i understand, the allpass filter is more a building block to create phaser, reverb.. it's not really worth alone.
I will study this a bit more, and i would also like to add some time dependant fx like delay, phaser, comb filter, chorus.. i must first figure how to know the amount of ram left for this  ;)
another thing i will investigate is the possibility to add the "filter reso" parameter to the matrix destination list..
Title: Re: New filters
Post by: Xavier on August 17, 2019, 08:49:58 AM

I haven't tried it yet, but thanks a lot for sharing this.  :)
Title: Re: New filters
Post by: Toltekradiation on August 17, 2019, 11:46:23 AM
hi Xavier,
thanks to you to make this even possible  :D
in this version, i added a waveshaper in some of the new fx to add a little bit more grit.
i had to rollback some of my improvements as the cpu overload..
now with some care and optimizations, all fx works well with 14 voices playing !
Title: Re: New filters
Post by: Toltekradiation on August 18, 2019, 01:04:25 PM
and another one with more fx :
wrap : extreme distortion, ready for metal ?
swap : adaptation of the puredata swap~ https://git.iem.at/pd/zexy/blob/master/src/swap~.c
swap work best on simple monophonic sine wave but it can work as a dirty distortion too ;)
Title: Re: New filters
Post by: matrix12x on August 18, 2019, 07:34:57 PM
good work. I'm enjoying wrap.

I played with this latest version for the last hour our so and no crashes or other bugs so far.
Title: Re: New filters
Post by: kyoto on August 18, 2019, 09:09:25 PM
great work man! - thank you very much  8)
Title: Re: New filters
Post by: superfake on August 19, 2019, 02:20:39 PM
Thanks for the great work!
Is it possible to implement a 6db and 12db low-pass filter?
Is it also possible to save performance parameters in a patch?
Title: Re: New filters
Post by: Zenman on August 20, 2019, 09:31:57 PM
Very cool. I´ll try it. Thank you!
Title: Re: New filters
Post by: Toltekradiation on August 20, 2019, 11:44:31 PM
@superfake : i tried to get that smoother filter but could not do it right for some reasons ??? .i fear i'm not so good at this kind of programming, i could nearly implement this one https://www.musicdsp.org/en/latest/Filters/23-state-variable.html, which is cpu friendly, but i could not get rid of a high pitch noise in the sound. Those filter equations are quite a mystery for me, i must say.
About the performance parameters, i'm not sure it's possible as it may change the patch structure, must have a closer look...