[PD] Nice distortion

[Frank Barknecht]

Hallo,
hard off hat gesagt: // hard off wrote:

> most of the stuff that operator synth does looks fairly straight-forward,
> shouldn't be too hard to put together a basic pd clone.

I had a quick look at the Live manual, where I found, that Operator is
just a 4-op FM synth with some additional tweaks. A simple 4-op FM is on
my January TODO list for the RjDj library anyway. In general FM is
easy, but the more operators you have, the more you want to use
[mtx_mul~] from Iemmatrix, but RjDj only has vanilla objects.

> challenging bits will be the square and saw waves with variable numbers of
> partials, but i think that will probably just be a case of [tabosc4~] and
> making some tables with sinesum values.

Or some summation formulas, but tabosc4~ is easier.

> then that knob to alter the amount of aliasing, it could be using upsampling
> and then lowpass filtering like the nord synths do, or like the 'classic
> synth' example in pd's audio documentation.  but that approach quickly eats
> up cpu....or else it could be using an adjustable bandlimiter, something
> like the [blosc~ comparator] external, but with adjustability.  actually,
> this function is the hardest one for me to think of a solution for.

Yep, aliasing in FM always is tricky. It will be ignored for RjDj. ;(

> the filters shouldn't be TOO hard, although to get a good lowpass, notch,
> bandpass and highpass it might be best to dig through pd-extended's
> externals.  for lowpass i usually use [resofilt~] bandpass vanilla's [vcf~]
> is fine, although franks new resonz~ / resonr~ filters look super
> promising.  for highpass, i prefer [svf~ high].  not sure about the notch
> filter.

I'm a bit proud of resonz~ and resonr~: In the end they look very
simple, the hard part was digging J.O. Smith's Filter book. ;) I'll also
do some version with signal inlets later. 

If anyone knows which transfer function would make a good 2 pole resonant
lowpass filter (like lp2~ in Iemlib) I'd be super thankful.

Ciao
-- 
Frank Barknecht