# Some notes about how circuit modeling works in Kirchhoff-EQ.

I think I should write some notes about how circuit modeling works in Kirchhoff-EQ.

There are two methods for circuit modeling. The key is how to treat the non-linear distortion of the circuit. If we consider nonlinear things in the circuit, some kind of numerical integration should be used(as many many simulations did). Numerical integration will bring some high-freq cramping(similar to the bilinear transformation used by some EQ), and oversampling is generally used to avoid this problem.

The another way is to treat all circuit devices as linear (as many simulations did). This is acceptable because the distortion of most EQ hardwares are slight. This way better matches the lineared prototype, and we can do more tricks such as add a dynamic function.

Personally, I like preamp plugins to use numerical integrations, but don’t like EQ plugins to use it. The reason is still “round-error”, “high-freq cramping” and “anti-aliasing”. But for linear way, sometimes we need those distortions even if they’re not much.

So both methods have their own advantages and disadvantages, I totally agree about “every emulation I’ve tried don’t like real gear”. My idea is at least in Kirchhoff-EQ, not to do a simulate of distortions, DC Noises…. (since users may already have many of “100%” accurate simulations). Instead, keep it as a EQ, use linear models and with our “Robust Nyquist-matched Transform” and “Psychoacoustic Adaptive Filter Topologies”, give users “the taste” and give max freedom to use all the filter types together to see what will happened. Does the vintage models in Kirchhoff-EQ 100% like the real hardware? I can’t say that. But in plugin world, I have full confidence in all the vintage models in Kirchhoff-EQ.

Cheers!

Hundred percent agreed. What we needed was a revolution in EQ, not randomized noise – with which we’re already satisfied.

Well done on the work you guys have done.

Samuel

Audio Engineering Lecturer