About the VOX tone stack

[J M Fahey]

Well, sort of. As all analogies, this one should also be taken with a grain of salt.
To achive closer results to what you imagine, we should use dual, coupled, different value pots, one optimized for bass, the other for mids, and clearly that is not happening.
It would be somewhat more precise to say that on full bass, the mid resistor gets shorted and on minimum bass the bass capacitor gets the axe.
Now, on intermediate positions .... well, that's anybody's guess.
That's why you get a correlation between real life and simulation on both ends, (and also on "5"", if the bass pot is linear) but not, say, on 2 or 7.
Not *that* important either, since we tune by ear.
EDIT: I forgot. Personally I'm happy with "close enough" results, and mentally calculate, remembering= ".1 and 100K=16Hz." (my magic values).
Based on that you can go anywhere; in fact I calculated Fc would be "around 3200Hz", close enough.
What did I do?; please follow me: 100000pF(.1)/50pF(47pF)=10000/5=2000X higher frequency, *but* the resistor is 10X (1000000r/100000r) so the frequency shift is 1/10 of 2000.
So: Fc=16Hz(my "magic" value)x200=3200Hz. Close enough, faster than grabbing a (not always available) calculator and punching the numbers.
I also consider .22 approx. 2x .1 ; .47 2x .22 ; .39 practically the same as .47 and so on. Good to navigate quickly through a schematic having a quite accurate idea of where I am standing.
Anyway I *will* have to use normalized component values

[JohnnyMcFly]

Great Rules of thumb! Thanks for that..I got the VOX tonestack relatively close. I think I'll know more once I get this thing further along and can have some of you guys here try it out. I am especially interested in the mods that you all perform and seeing if our model performs.."Close" to what your mods do..I mean we all know that it is going to be different, but, what I really want to know is if it is close. As I say, this is only meant to give the user options that are not available without a soldering gun..I'm an old tube head from the 80's myself, got my first Marshall in 1982, then I got a Park but traded it for a beat up old Hiwatt...that was a mistake, but I thought at the time it was a cheap Marshall knock off...I didn't know it was made by Marshall...Dumbass me!

I had a conversation with a tube amp repair guy today on the phone. He brought up an interesting point about this project that I never really thought about. He said it might be good because it may get people to learn a little more about the electronics they are playing with, or at least it might generate some interest in them..