this figure (figure 3 in the paper) illustrates the analog topology. it is not a direct description of a DSP structure.
section 2 of the paper precisely concerns the classic problem of discretizing the integrator and differentiator blocks.
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first, approximation by trapezoidal rule using a delay element. the corresponding DFT2 blocks are illustrated in figure 4.
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you can stop there (the âclassicâ solution), or continue reading on how to solve the resulting system to eliminate the delay loop (the ânew and improvedâ method, which is more efficient and stable under modulation.)
also important to look at section 2.3. this discusses the nonlinearities introduced by optocoupling, which are really important to the sound of the vactrol LPG. these elements are not shown in the basic block diagram, cannot really be captured by the DFT2 model, and they complicate the delay-free model considerably.
if you just want to plug something into gen~ right away, proceed to equations (25) and (26), and at least skim the control path section if you want it to âfeelâ like a vactrol as well as sound like one.
