On Tue, Apr 14, 2015 at 07:29:48AM +0100, Dave Malham wrote: > Sounds interesting! I think I'll leave a member of the BLaH gang and/or > Fons to answer the calibration question, but as for the name, since it's a > bunch of shotguns bunched together, how about 'Gat" as in short for Gatling > > On 13 April 2015 at 16:23, umashankar manthravadi <[email protected]> > wrote: > > > I am planning to do an experiment and want some suggestions. > > I plan to build an eight channel microphone using short shotgun capsules > > they should be considered 2nd order directivity) I can design an octahedral > > frame to support them. overall it will make a 12 cm radius sphere, but the > > capsules will be on a 20-25 mm radius sphere. I can easily design to drive > > an eight channel a to d like the 8 pre. > > how should I go about calibrating the microphone? the eight A-format > > signals can be decoded to first order with height plus 2nd order > > horizontal, I guess.
To get full 2nd order you need 9 channels. It may be possible to get 2nd order horizontal (at the expense of vertical) by biasing the directions towards horizontal rather than using a perfect octaheder. But I see a more serious problem. Shotgun mics work by integrating pressure over their lenght. That means that the effective radius (the one that determines phase/time differences between capsule signals) will be around half the physical one. And that is rather large, it means that any linear A/B matrixing will start to break down around 2 kHz. Anyway, how to calibrate such a thing and get the best out of it is difficult to say without first studying a set of measurements. Ciao, -- FA A world of exhaustive, reliable metadata would be an utopia. It's also a pipe-dream, founded on self-delusion, nerd hubris and hysterically inflated market opportunities. (Cory Doctorow) _______________________________________________ Sursound mailing list [email protected] https://mail.music.vt.edu/mailman/listinfo/sursound - unsubscribe here, edit account or options, view archives and so on.
