Thanks Fons for you help,
> As you say the matrix inversion amounts to > > H1 = Hi / D (1) > H2 = -Hc / D (2) > > with D = Hi^2 - Hc^2 > > What you write makes me think you are trying to regularise > this by replacing D by something like > > E + (1 - E) * D > > ?? Not exactly: I was trying to add the regularization parameter to D, so that Dregul = Hi^2 - Hc^2 + E with 0 <= E <= 1 > > Then setting E = 1 would mean > > H1 = Hi > H2 = -Hc > > and since Hi ~= Hc at VLF, H1 + H2 will be near zero, > removing the mono bass. > > But this is the wrong way to regularise such an inversion. > The Hi,Hc matrix is very ill-conditioned at VLF, but it > still has rank 1, not 0. So you need to regularise only > in one dimension. > > Starting from (1),(2) we have > > H1 + H2 = (Hi - Hc) / D = 1 / (Hi + Hc) (3) > H1 - H2 = (Hi + Hc) / D = 1 / (Hi - Hc) (4) > > There is no problem with (3) when Hi ~= Hc, only > with (4), so only that one needs regularisation. > Well, that was my mistake: I was dumbly trying to regularize both inversions with the same E value. If I understand well, H1 and H2 (or H1+H2 and H1-H2) have to be calculated independently, with different regularization parameter values (E(w) being frequency-dependent "alla Farina" to account for ill-conditioning in VLF or "notches" in the HRFT). > Which means that H1 + H2 (the mono response) can just > be (3), with no loss of bass at all. Dub lovers say thanks! Best, FM _______________________________________________ Sursound mailing list [email protected] https://mail.music.vt.edu/mailman/listinfo/sursound
