It’s a good source, but bear in mind that it doesn’t get you new kinds of basic filters, and its strength is in designs that give you good behavior while time-varying the parameters. In other words, it’s more important for synth filters with frequency controlled by envelope generators than for static filters for EQ. But a second-order Butterworth lowpass filter is still a second-order Butterworth lowpass filter, whether you get it from Robert’s cookbook formulas or a “VA” design.
> On Nov 29, 2023, at 3:07 PM, Jens Johansson <[email protected]> wrote: > > 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 <[email protected] > <mailto:[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) >> >> Cheers, >> J >> >> >> >> On Wed, Nov 29, 2023 at 10:51 PM brianw <[email protected] >> <mailto:[email protected]>> wrote: >>> On Nov 29, 2023, at 1:49 PM, brianw <[email protected] >>> <mailto:[email protected]>> wrote: >>> > On Nov 29, 2023, at 1:28 PM, robert bristow-johnson >>> > <[email protected] <mailto:[email protected]>> wrote: >>> >> On 11/29/2023 3:09 AM EST Jens Johansson <[email protected] >>> >> <mailto:[email protected]>> 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
