From the original SynthMaker forum (2004–2014), with its members’ names and dates.
distante ·
I download this : Ideal log volume control, an example of a Know showing the volume scale 0-1 in dB.
I'm now sure why the K variable is used in that schematic, I mean If I use 20log(X) where 0< X <1 it gave's me the value in dBFS,
20Log(1) = 0 dBFS 20log(0.75) = -2.5 ( 1/4 of the voltage) 20log(0.5) = -6 dBFS (the equivalent to half of the "voltage")
and so on...
So, why Do I need to use the K factor?
cyto ·
Martin's knob is not simply a 0-1 to dBFS converter. Basically, it scales a 0-1 (linear) range to a 0-1 (exponential) range to use for smoother volume tapers. If you read the rest of the thread, you'll see that the goal was to have a volume taper that exhibited the same characteristics as an "audio taper" potentiometer, - exponential through the "travel" but "grounded out" at zero. You are right that you can just do a straight conversion from dBFS to 0-1, but since you cannot ever have a truly "infinite" range, your 0-1 will never reach 0. That's where the "K" comes in. It "pulls" the curve toward 0 at the low end of the taper, if my memory serves me correctly.
-cyto
distante ·
Oh! I didn't understand the "audio taper" part, thank you cyto.
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