It appears that it should be possible to compute the "optimum" filter placements for a parametric equalizer such as the BFD ... let me brainstorm a bit here ... 1) When we measure the base response using SpectraPlus, we can save this overlay as a text file in the overlay directory .. if one looks at that, its just a text file with frequencies and db levels (which can be imported into any graphing program including Excel). 2) Now if I can describe the filter as an equation based on the "bandwidth", "center freq" and "gain", then its just a matter of picking these optimally to flatten the response as far as possible, right ? Does anyone offhand know the equation that describes the filter ? Looking at the BFD manual it appears that the filter can be described by some combination of exponential functions .. Once this equation is prescribed, it should be simple to write a program that optimally picks "n" filters to minimize some objective function (e.g. minimize the max deviation in the 20-100Hz range) .. that way we could choose both the number of filters we wish to use and their optimum description (due to filter interactions, I doubt if this is a problem that can be solved sequentially) ... more stuff to work on !