It’s a question I always asked myself. Models in SPICE are usually for full models, or you can use a gain voltage gain as well. What are the implications of selecting one model over another for a real time model? Let’s go for the more complex model to the simplest ones.
In almost all analog modeling algorithms, we solve a (non-)linear system they require at some point to solve , with given and . Depending on the size of the matrix and its characteristics, computing an inverse can be costly and may incur numerical problems. Let’s tackle cost in this discussion.
I create a model of the Boss SD1 and the Ibanez TS9 some time ago. Now it’s time to get on modelling another pedal, the famous Boss MT2 Metal Zone.
There are many pages online that also analyse this pedal, but I’d like to start from the schema, split in independent pieces and analyze them with my Modelling Lite tool. The end result will probably end up as a new plugin, but this is currently outside the scope of this new subserie.
Last month, I presented my latest work on Audio ToolKit at ADC 2018, namely how I turned a SPICE netlist to a filter.
It is now time to present some of the results here.
Today, I’m presenting at the ADC my work on analog modelling for the past year.
I will make a more detailed post later this year, but I’d like to put some teasers here. SPICE net lists are an efficient way of representing electronics circuits and there are several very good free and paying simulators. Unfortunately, they are not easy to integrate in a VST plugin.
Audio ToolKit now has a sister project around this topic. The lite version is also licensed under the BSD and can generate a dynamic filter of a net list. The full project is now also capable of generating static filter, with a source file (and compiling it in memory) that can be manually tuned.
Future work on this project will include different solvers for the static filter, as well as a tuner that will be able to drop entries in the Jacobian (full entries or component contributions for a given pin) in the Newton Raphson solver.
After my previous post on SPICE modelling in Python, I need to use a good support example to go up to on the fly compilation in C++. This schema will also require some changes to support more than simple nodal analysis, so this now becomes Modified Nodal Analysis with state equations.
A few month ago, mystran published on KVR a small SPICE simulator for real-time processing. I liked the idea, the drawback being that the code is generic and not tailored like a static version of the optimizer. So I wondered if it was doable. But for this, I have to start from the basics and build from there. So let’s go.
More than a year ago, I started playing with the Bela board. At the time, I had issues compiling Audio ToolKit with clang. The issue was that the gcc shipped with the Debian image the BeagleBoard used was too old and didn’t fully support C++11. The one that ships now is GCC 6, which is even C++14 compliant. Meaning that everything is available to build Audio Toolkit with Python support.
Vinyl has become trendy again, and as such, I’ve been asked to add some new filters in Audio ToolKit. Here is a small dive in RIAA land.