On 17 Jan 2011, at 09:20, Jörn Nettingsmeier wrote: > On 01/17/2011 02:51 PM, Ronald C.F. Antony wrote: >> Well, four cardioids at 90 deg. angles could be used to create both >> two fig8 signals at 90deg from each other, plus an omni by summing >> all four. So wouldn't that already be more or less account for >> horizontal-only B-format? > > it would, but so would three, so why waste one?
Easy: because there is a mic with four of them stacked, precisely aligned in 90 degree angles. There is no such mic with three capsules at 120 degree angles. So the three mic solution would require custom mounting, allow for easy misalignment, etc. If anyone can convince them to do one of these mics with three capsules at 120 degree, it would be a different story. Also the fig8 is easier to do just in a mixer with a phase flip and sum of two signals IIRC. With fewer signals involved in the fig8 part, it might have better impulse preservation and that might help localization; however, that's just speculation on my part. The main reason is simply that this is a mic that can be bought off the shelf that seems to ave what it takes and costs well under $1k including cables and shipping. Ronald PS: thanks for the plot and the math. Might be useful in the future. > i've played around a bit with gnuplot (hope the attachment makes it through): > three cardioids at 120° sum up to a perfect omni, and also to figures of > eight (only one given here, for clarity. > (note i had to cheat a bit with the last two functions, because in polar > plotting, there's no concept of an "inverted polarity" lobe, instead r is > negative, which means that both halves of the eight are congruent on the > positive side). -------------- next part -------------- A non-text attachment was scrubbed... Name: attachment.png Type: image/png Size: 64360 bytes Desc: not available URL: <https://mail.music.vt.edu/mailman/private/sursound/attachments/20110117/f586d8ca/attachment.png> _______________________________________________ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
