On Tue, Apr 10, 2018 at 10:13:17AM -0700, Fernando Lopez-Lezcano wrote: > I actually should go back to my original approach (more complicated) for 1st > order, which was to derive a 4x4 matrix of filters (which would be 8x8 for > the 2nd order mic).
Not necessarily a good idea. The problem with blindly inverting a matrix (in the F-domain, for each bin of an FFT) is that it will produce some result no matter what you throw at it. And of course, convolving the measurements with the resulting matrix will always produce a result that looks perfect. So you basically have no sanity checks at all. Of the tens of calibrations I've seen that were done that way (for tetrahedrals, eigenmics and others) there has been only *one* that actually made sense. All the others were just inverting measurement errors, or trying to correct things for which there is no sensible remedy, like the Zoom's built-in mic array. Regularisation can help, if it's done correctly. That means doing the inversion using SVD with careful adjustment of the singular values (depending on frequency), and not by just adding an arbitrary constant to the denominator of 1/x for very low or high frequencies as advocated in some publications. Ciao, -- FA _______________________________________________ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound - unsubscribe here, edit account or options, view archives and so on.
