Hi Jens, Thanks for your reply.
> The lower end is limited by the radial filter gain that the user chooses. The radial filters are not the same like with SMAs, but they are very similar so that the limitations are the same. > > 0th and 1st order are available for all frequencies. > 2nd order approx. above 200 Hz > 3rd order approx. above 500 Hz > etc. It's the 'etc' I'm interested in... The gain required at LF increases by 6 * order dB for each octave going down, which in turn means that for a given maximum gain the LF limit goes up with order. Which makes me wonder if for order > 4 anything useful actually remains. > I cannot comment on calibration requirements because we did calibrate > the array… (Nor did we measure how well it was calibrated out-of-the-box.). Does the 'nor' mean you did _not_ calibrate it ? > I don’t actually think that there are any special requirements. There are. The required gain (at LF) means that small differences in capsule sensitivity are amplified as well, and this distorts the resulting polar pattern. The simplest possible example would be a first order component X being produced from the difference of two omni capsule signals A and B, so X = (A - B) * (1 + j (F0 / F)) where F0 will depend on the distance between the capsules. Now if A has actually 1 dB more gain the difference signal becomes 1.12 * A - B = (A - B) + (0.12 * A) The second term, amplified by the filter for low F, will add an omni component to X. So the maximum gain that can be used depends not only on how much noise can be tolerated, but also on the calibration accuracy (and long term stability) of the capsule gains. Ciao, -- FA _______________________________________________ Sursound mailing list [email protected] https://mail.music.vt.edu/mailman/listinfo/sursound - unsubscribe here, edit account or options, view archives and so on.
