One document I stumbled upon while googling is "The art of VA filter design", by Vadim Zavalishin (it's apparently a book he published for free). If I can even wrap my head around some of that stuff, might it be a recommended good place to start I wonder?
Cheers, J On Wed, Nov 29, 2023 at 11:44 PM Jens Johansson <jmobile...@gmail.com> 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) > > Cheers, > J > > > > On Wed, Nov 29, 2023 at 10:51 PM brianw <bri...@audiobanshee.com> wrote: > >> On Nov 29, 2023, at 1:49 PM, brianw <bri...@audiobanshee.com> wrote: >> > On Nov 29, 2023, at 1:28 PM, robert bristow-johnson < >> r...@audioimagination.com> wrote: >> >> On 11/29/2023 3:09 AM EST Jens Johansson <jmobile...@gmail.com> wrote: >> >>> and simulate the below circuit just with simple(r) feed-forward and >> feedback algorithms, or is it so complex that I would have to take the step >> how to learn to deal with those "Wave Digital Filters"? >> >> >> >> I am curious about C6. What does that "4n7" mean? Is that just a >> typo and it's just another 47 nanofarad cap? And what does R7 connect to? >> What is "N"? Is it another kind of ground? Or is it some buss somewhere? >> > >> > "4n7" is a shortcut that engineers like to use for "4.7nF" - the >> standard is to move the unit to where the decimal place belongs, and that >> saves a digit. >> >> It's also the case that a decimal point '.' can easily disappear on a >> printed or hand-written schematic, so placing another symbol in place of >> the decimal makes it much more visible. >> >> Brian >> >
