Setting cutoff frequency in Hertz using vst~ fabfilter pro q 2

Ro_naut's icon

Hi there,

I'm trying to learn the equation to set the cutoff frequency in a vst~ loaded with fabfilter pro q 2.

I need to send the vst~ a number between 0. - 1. That then correlates to hertz inside the vst~.

How can I specify the cutoff frequency in Hertz first, and then convert it to its number between 0. 1. ?

What is the equation to scale hertz to 0. - 1.

Pro q range seems to be 10hz - 30khz

Any help greatly appreciated!

Arvid Tomayko's icon

Are you using the VST or AU version? I know - its hard to determine that these days when vst~ hosts either… but often AUs have their parameters normalized to 0.–1. and VSTs don't - they often use the actual number range. So see if directly specifying the VST version of ProQ helps.

If not and it's not a linear mapping that scale will help with, then maybe try using a combo of ftom (in case it uses same scaling as musical pitch) and scale.

If that doesn't work, I'd approximate by getting some data points - lets say, take a reading of ProQ's freq every 0.1 step of the parameter, then plug that data into a function object as x,y pairs and run your numbers through it.

Bunter Panther's icon

HI!!!

Same Problem here.
Scale isn´t useful. It is not linear and other workarounds dosn´t work.
f = 10. to 30000. Hz // Scale 10. 30000. 0. 1. 0.5 @classic
but i get wrong frequencies...

I think it is splitted in 3 parts from somthing about 10. to 300. // 300. to 1000. // 1000. to 30000.

dont know how to do that correctly.
I think i need some other stuff to fix this...

please help,
thanks ,
Oscar

Max Gardener's icon

Have you tried scaling modes other than classic?

Roman Thilenius's icon

the frequency part can always be solved by mtof/ftom when you dont know the right formula offhand. the rest is linear scaling. i wouldnt like to make up a log or exponential magig number since it will depend on the frequency range.

rather i´d´use the range of one of the two "standard" linear to frequency conversions, which are centered around the lowest midi key (key number 0 == 8.17 Hz) or a key of your choice (like in later versions of mtof)

the only uncertainty left is what the VSTs author used as low and high limit; his GUI might reflect slighty different values than what is actually happening inside in some cases.

Max Patch
Copy patch and select New From Clipboard in Max.

Roman Thilenius's icon

damn, just noticed you need it the other way round (of course).

Hertz
|
[ftom 0.]
[zmap 3.48682 142.095779 0. 1.]
|
Parameter

Bunter Panther's icon

Hey,
thanks for replay!

i will try it out these days. But the stylish way looks great for me.
could be, that i get some problems to find out wich frequency ist the right float out of the vst.

@ MAX GARDENER :
i tried booth modes, sure

@ ROMAN THILENIUS :
i will try ftom object! thanks for the screenshot...

Great Guys,
Cheers,

Oscar