On 2014-06-18, STEFFAN DIEDRICHSEN wrote:
Actually, it’s not rocket science to model a baxandall or those Treble/Mid/bass networks. A straight forward approach is modified nodal analysis, which gives you a model, that preserves the passivity of the filter network.
Obviously. If it's passive, it's passive, and that's the end of it.Except that when you have a transistor at the beginning and the end of such a network, the whole ain't passive anymore, and neither of those transistors behaves anywhere near like an ideal component, either. Certainly not after you do anything interesting with the circuit, which pretty much always involves torturing it beyond its linear range.
There is such a thing as easily analysed passive LTI beauty. But that's not what we're trying to model. If it was, the problem would already be solved and we wouldn't be talking about this multiple decades into the digital era. No, what we really want are efficient and faithful computational models of nice sounding legacy circuits, *when they're already on the rack*.
That's then not nice at all. Obviously you *can* painstakingly model even that, and achieve perfect results, but there's always the cost constraint: nobody's going to pay you for the years of lab time it takes to characterize such circuits perfectly, not to mention that sinking multiple gigaflops in your humble monophonic plugin ain't exactly going to win you mass appeal. Then, when you try to optimize things...well, there is no general theory of how to do that either, is there?
-- Sampo Syreeni, aka decoy - de...@iki.fi, http://decoy.iki.fi/front +358-40-3255353, 025E D175 ABE5 027C 9494 EEB0 E090 8BA9 0509 85C2
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