[Archit3ch]

> I have been on again off again doing a fairly intensive write up on this topic going into all the technical details (primarily the hardware side) complete with a fairly full featured/accurate digital recreation of the original MiniMoog VCF in PureData but it is not exactly a priority and progress on that is rather slow.

I'd be very interested to see your approach. So far, the most promising (non-NN) technique I've seen requires taking a symbolic inverse of a sparse matrix, which is just barely possible for a simplified pedal model.

[ofalkaed]

I am doing things in just about the most idiotic and inefficient way, break the circuit down into easy to emulate blocks then emulating how they interact by adding in stuff which mimics that interaction.

Essentially I break down the circuit into a series of blocks which are easy to model in isolation and then show how the interactions between these blocks are very complex and difficult to model. The starting point is essentially the classic simple moog model with some extra stuff and I add in bits between those blocks to mimic the interactions while comparing it to various digital models of the filter, spice simulations and the real deal.

So I slowly make up a big massive mess of a patch in PureData that eats my entire CPU but does a fairly solid job of the emulation then try and simplify things down to show how each part affects the whole.

[Archit3ch]

> The starting point is essentially the classic simple moog model with some extra stuff and I add in bits between those blocks to mimic the interactions while comparing it to various digital models of the filter, spice simulations and the real deal.

Yup, there are two main philosophies: start from a very accurate (e.g. SPICE) model and simplify it enough that it runs in real-time or start from a simple model (e.g. biquad) and add nonlinearities as required.

If you want talk more about the other approach, I just added an email in my profile. ;)

[ofalkaed]

The problem is that everyone implements those nonlinearities as isolated and largely static things, which they are not, they are dynamic and interact in complex ways. From what I can tell the vast majority of people who implement these models don't seem to really understand the analog world, they model the circuit in spice and run a simulation at a static setting with a single source and call it good, this kills the dynamics which are a fairly important part of the sound. This is also why many amp modelers are often said to do the high gain or clean sounds well but fail in some vague way on everything else, the simplified dynamics used for modeling are close enough to reality for those sounds.

The mini VCF is not the best option for my needs but it is useful in that I have a good many implementations to use as controls as the patch advances and I can show why it all matters well enough, I can provide musical examples which most anyone will be able to hear the differences between. Ultimately I think the software folks are making the wrong sacrifices which is why pedals like the Sans-Amp series and even the somewhat naive Run Off Groove [0] DIY offerings maintain a solid following despite not sounding much like the amps they attempt to mimic, they do respond like the amps, they maintain the dynamics or at least something close enough.

I am not sure we will have much to talk about but I will give you an email when I am back on the computer.

0) https://runoffgroove.com