ot: Voltera-Wiener nonlinear system analysis was: RE: [sdiy] ot: rotating speaker simulation or stupid approach

[Antti Huovilainen]

On Fri, 4 Jul 2003, Czech Martin wrote:

> So far it seems to me, that emulations of nonlinear systems
> (e.g. guitar amps) are too simple minded and fumbling,
> I never heard that any manufacturer has tried it with
> Voltera-Wiener ideas. So no suprise that most emulations
> fail.

AFAIK most emulations use just simple waveshapers combined with filtering
& speaker modeling.

It is also possible to model the actual circuit. I've done this for Korg
MS-20 filter (http://www.hut.fi/~ajhuovil/ms20/ for a VST plugin) and
earlier for a guitar preamp (http://www.hut.fi/~ajhuovil/tube/ has a doc).

Tube power amplifier modeling is still pretty much black magic since
the load is inductive (transformer) and the system has several inputs:
grid, screen and plate voltage (which is inductive). The output depends on
all of those. When you add push-pull, you double the number of inputs,
although it might be possible to consider the sides as exact mirrors. Add
global feedback (presence control) and the system gets even more
complicated.

Antti

Give a man a fire, and he'll be warm that day,
Set him alight and he'll be warm for the rest of his life