Need a way to determine modifier settings

[straighteight2003]

I'm trying to control the level-parameter of a filter block (Null-Filter) with one expression pedal of my behringer FCB1010 between 0dB (min.) and +3.5dB (max.). What values do I have to set "start", "mid" and "max" of the modifier (since they are %-values and not the dB values of the selected parameter)?

I tried from 0% 50% 100% but that sounds as if the filter block works between its min and ist max (might be -12dB to +12dB or even more). So obviously I have to set the values in an different way. Is there a way to calculate those settings (because too bad the level parameter of the filter block does not show any changes, even if I hear them, I know other parameters in different blocks show the value change, when modified by the expression pedal)?

I thought of it like this: if 0dB is the middle between min. and max. I should set my starting point to 50%.
If the level parameter of the filter block works linear (and min and max are 12dB), my desired max of +3.5dB then should be something like (12+3.5)/24 = 65%.

Can anyone confirm if I'm on the right way here or how do I determine the correct settings, if the parameter doesn't show any changes?

Thanks all for your input.

 

[simeon]

0db = 50%
+3.5db = 58.7%

set start to 50, end to 58.7 and mid in between the two

if you use the editor, you can see the modifier value change once it's linked and you move the start knob

 

[straighteight2003]

Thanks a lot!

So I guess there is no way to calculate these when editing on the Axe? Then I'll have to go use the editor for those parameter changes that do not show on the Axe screen.

Thanks again.
Wolfgang

 

[simeon]

yes, you can use maths

the filter goes up to 20db, and you want to go to 3.5db, so

3.5/20 = 0.175

50*0.175 = 8.75

50+8.75 = 58.75 (which is your target value for the modifier)

 

[straighteight2003]

Thanks for the answer! Sorry, I wasn't online for a couple of days.

So I guess my calculating way was correct I just have to change 24 to 40 (I calculated with a range of -12 to +12 instead of -20 to +20) wich leads me to the same result with (20+3.5)/40 = 58,75%.

I just wasn't sure if you could calculate it this way, since sound and volume often do not change linear but logarithmic (sorry, if the word is wrong, I hope it's clear what I meant).

Thanks again.

 

[simeon]

I just wasn't sure if you could calculate it this way, since sound and volume often do not change linear but logarithmic (sorry, if the word is wrong, I hope it's clear what I meant).

Thanks again.

it makes no difference here. you just figure out what you want the level to be by ear and then calculate what that level equals as a percentage and plug it in.