> On 11/29/2023 5:44 PM EST Jens Johansson <[email protected]> wrote: > > > Thank you for all your great advice so far! It gives some really good hints > which trees to consider barking up, so to speak. Well, I first have to become > multicellular, and evolve eyes, then find the trees, but you get the idea. > > I enclose the full schematic if anyone's curious, my guess was that the first > three filter stages (C1R1, C3R2R3, and C4UA2) could be approximated with > stuff from the cookbook. Just loading the schematic into LTSpice seemed to > confirm this somewhat. Also the stages after this more complex "fifth order" > section (C9R7?, C12C13R11R12C14A) looked like they either are inconsequential > or kind of map onto the more normal filter cookbook topologies too. The "N" > ground is the midpoint between the two power rails for the opamps. The > "ground ground" is the negative rail. > > (It's not the greatest distortion box and also not the worst. Peak 1990 > technology. On the other hand my hope is that a simulation could run in a > couple of hundred CPU cycles and not need either bluetooth, AI or a built in > web browser. I was planning to just slap the code on github if I ever got it > working. I would use JSFX because it's so easy to prototype stuff in this > language) >
Okay, so all questions got answered. Your original post was enough because it's 0 ohms output impedance driving the circuit from the left and infinite ohms input impedance for the tone circuit output. Are you gonna make one of use to node-voltage analysis and come up with an H(s)? It's a pain in the ass and because there are five separated capacitors, it's potentially a 5th-order transfer function. Might be a pain in the ass, but I could do it. Someone with access to something like SPICE can maybe do it. Anyway, once the transfer function is identified (with parameters associated with the positions of each potentiometer), then the transfer function can be broken into cascaded sections and maybe we can match it to the prototypes in the Cookbook. This analysis is something that I was anxious to do when I was younger, but I am lazier now. All I can tell you is that it is an LTI circuit and **must** have a consistent transfer function H(s). Whether there is any pole-zero cancellation (that will reduce the order) I don't know yet. -- r b-j . _ . _ . _ . _ [email protected] "Imagination is more important than knowledge." . . .
