How to change linear fader behaviour to logarithmic?

[grillo]

Hi all

it s a beginner question but i don t know how to change linear fader behaviour to a logarithmic behaviour?

I use osc lemur line.

Thank in advance

G

[Macciza]

Hi
Basic answer is you can't, there is no linear/log option as such . . .

But there are built-in functions for log() & log10() that give you natural (e) or common (10) logs . . .
Oh and also the pow() function . . .
These can be used in various ways in scripts, functions etc

Hope that helps, What exactly are you wanting to do?
MM

[Phil999]

I'm also interested in this question. In my case it is a softsynth that has logarithmic faders. I tried with the functions you mentioned, but failed to make it work. I should try again, invest more time and brain. Shouldn't be that difficult.

[grillo]

Hi
Basic answer is you can't, there is no linear/log option as such . . .

But there are built-in functions for log() & log10() that give you natural (e) or common (10) logs . . .
Oh and also the pow() function . . .
These can be used in various ways in scripts, functions etc

Hope that helps, What exactly are you wanting to do?
MM

Thank you for the answer.

I need to use a log fader to control a duration knob, in a (Usine Hollyhock) granulation patch. In the granulation pach, this knob must be in a log mod. the scale is 2ms to 750 ms, and if i use linear fader to control this duration knob, it isn t sound good.

G

[grillo]

So

can you explain to me how to use this log () function?
i imagine that i have to write it in a script.

G

[Macciza]

Hmm, I'm not a maths geek particularly . . .
It really depends on what exactly you want to do . . . (as always . . )
If you are using midi mapping type stuff to control things you are use values from 0-127 . . .
Things can interpret this differently to span various ranges in various ways . . .
Getting values to match up can be somewhat difficult in many cases . . .

Some specifics - first, Granulation can 'not sound good' quite easily depending on lots of variables....
Had a quick look a Usine H and the Granulator patch it also has a section that lets you alter its response
It looks like the Mapping pane lets you change how it responds to incoming midi from say a MultiBall in Lemur
This can give you a more linear response if that is what you are after - halfway across multiball is halfway through range
the other option would be to get Lemur to send its midi in a log/exp manner as needed . . .

Really need more info of what control or response you are after . . .
I'll see if I can do up some examples

[grillo]

Hi Macciza:

Hmm, I'm not a maths geek particularly . . .
It really depends on what exactly you want to do . . . (as always . . ):

It s certainly because my english is so bad.
Anyway i will try to be as clear as possible:

I need to use a log curve fader to control a grain duration knob, in a (Usine Hollyhock) granulation patch.
The scale is 2ms to 750 ms and i wish prefer a log curve to control this values.

"Some specifics - first, Granulation can 'not sound good' quite easily depending on lots of variables...."

I Know that,
Thank a lot if you can answer

G

[wul]

I'm working on it I'll have a answer very soon

[wul]

LogFader.zip

(1.06 KiB) Downloaded 136 times

Not sure if this is right or not , it certainly appears to act like a log pot you can also scale its max and min values

[Phil999]

nice one!

Although in my case, I need exactly the contrary. This logfader makes the softsynth's faders behave even worse. But it's a good start. I guess I need an exponential fader that starts slowly from 0 and ends quickly to 127. The math I haven't found yet, I admit that it's a bit too much right now.

And then I'd need the feedback from the softsynth, which will be another task. I think it's not worth the effort. It's not such an important softsynth for me. Rather some kind of challenge.

But I hope this logfader will be of good use for others.