New filters

[Toltekradiation]

and then the master version.

while i was at it, i added a new filter : a crossfade between lp & hp across the frequency range.
enjoy !

[baxgas]

Wow, sounds Funtastick! Looking forward to try it out!

Thanks for improving this great little synth!

[kaosbeat]

I flashed it onto my Eurorack PreenFM2... so far so good
Sounds great, lot's of extra filters and CV mappings work!
no crashes or glitches so far

really great stuff

  

[baxgas]

The Filter improvements are really-really useful, thank you! I also found the original PreenFM2 Filter algorithms a bit weak...

A few thoughts:
- some infos about the implemented filters and the parameters they use (at parameters Cutof/Resonance) could be useful, so that it is easier to understand what is what (maybe at the git page  README.md?)
- any chance to implement some Flanger, Phaser, Chorus algorithms? Maybe even Delay and Reverb? Or even combination of Modulation/Delay effects (but I understand there could be some processing-power limitations)
- I don't know if it is possible, but could be very nice to modulate the Resonance (or any second) parameter also from the Modulation Destinations?

Keep up the good work!

(PS: hope these improvements will also get in the official version)

[Toltekradiation]

hi guys, thanks for the support !

added two new ones :
BP3 is another BP flavour
LPws is a distorted lowpass, to mix with the source to enhance presence

@baxgas : good idea, i modified the readme to give some infos about the fx (https://github.com/pvig/preenfm2)
about delays, phaser etc, these kind of fx require memory that we don't have left on the preen, i fear..
but you can already patch fm to sound like a chorus (kind of) with careful detuning, or simulate a delay with the free env 2 loop !
like this https://www.youtube.com/watch?v=GYFD1lmk-lo

i will have a second look at the possibility to modulate fx param 2 in the matrix, but at first sight it seemed quite some work..

[baxgas]

@Toltekradiation: Thanks for the infos!
Will check also the new Filters also. Btw. Are these flavours and different types just for testing and then at the end you'll leave the best one, or you plan to leave all of them?

[Toltekradiation]

@baxgas, yes it is quite crowded in the fx department now !
for me, the main use of filters is to fine tune the instruments, to make them work well with other instruments ; i want to use the preenfm in a minimal setup with a drum machine, the main output should be good enough as is, with its 4 instruments mixed. So i must cut the bottom of some, emphasize the mids of others, etc... to let the lead instrument have enough space ; this one can have some grit, unusual fx..

for now, i would nearly keep all, but I need to play with it more to be sure about this.
what one would you remove/keep ? what would be your use/need of the fx ?

[baxgas]

@Toltekradiation all the stuff is great, it really adds a lot to the richness of the FM synthesis
Haven't dug really much deep in all the uses (although my PreenFM2 is always on in my spare time, since you made these additions :-) ), but these are some experiences so far

- Txr1 and Txr2: seems just like adding some noise to the signal? Of course the filters will behave differently with different signals that are put through, so I believe the type of the source sound is also important.

- Can the Mix parameter (generally) be replaced to some filter changing function? (like eg. LPx1 that besides Frequency the other parameter changes the xor amount). I think these kind of effects are not like eg. Reverb/Delay or similar that dry/wet ratio is that important.

- Is it possible to implement algorithm for Notch type effects (inverse of Band-Pass, that it just removes the Frequency)

You are right about the mixing of the 4 instruments, it can really make a difference with the filtering. I also know that the PreenFM2 architecture is a bit limited in this regard, as it acts just at the end of the signal-chain as a per-channel filter/effect, although modulatable by the Modulation matrix. 
I wouldn't mind to have a lot of filters, why not :-) Just if some patches are saved with some effect, and they got replaced in the meantime, they will probably get back to the default, or switch to some other type.

As for the Chorus, and modulation effects, I know the trick of slight detuning, it is also very nice to detune a bit the modulator in comparison to the Operator, adds nice phasing effects that can turn to some waveshaping if modulated to more extremes. The FM is a great system for sound-mangling :-)

[Toltekradiation]

thanks for your insight,
the mix parameter was a quick way to use the parameter 2, but you're right, it can get better use. i will review the possibilities.
i'm currently working on a notch filter, which may be useful for sure (if i can get it working )

[superfake]

Thank you so much for the work! Preen plays with new colors. 

Is it possible to add the LP2 filter from firmware 1808 in addition?
I liked that the filter opened to higher frequencies.
The new version opens only up to about 7 kHz, like a standard LP filter. 
In version 1808, the filter opened up to about 14 kHz - and that was good for brighter sounds.
Of course, it would be nice if the LP filter worked in the maximum range up to 20 kHz. 

[Toltekradiation]

hi,
ok, i will try things with that in mind.

[Toltekradiation]

hi,
many thanks to @baxgas & @superfake to push me in the right direction, so in this version there is some more filters  :
Lp3 :  state variable filter, low pass mode
Hp3 : state variable filter, high pass mode
Bp3 : state variable filter, band pass mode
Peak :state variable filter, peak mode
Notc : state variable filter, notch mode
Bell :  state variable filter, boost if param amp > 0.5, else cut
BpDs: saturated bandpass filter

+ some rework on these fx to get a better use of the 2nd parameter  : Sat, Sigm, Fold, Wrap, Xor, Txr1, Txr2
+ the full range is back in lp2, hp2

[superfake]

Wow, thanks! 

At maximum gain, the filter is interestingly overloaded, the sound is somewhat similar to 303.
Oh, if it was possible to adjust the volume after the filter...  for balance with other parts.

Here is an example. Used custom saw.

[kyoto]

@Toltekradiation - wow - great work man!!!   

[pikseliahky]

Thanks, great stuff! Is there a CVin version as well?