Actually, directly on axis of one of the capsules may be the worst direction for a tetrahedral array. While it's true that otherwise you are slightly off-axis for a given capsule, with whatever coloration that might cause, I believe the non-coincidence problems of the complete array overwhelm this effect. When pointing directly at one capsule, the distance to each of the other three is the same, thus the peaks and notches caused by phase differences all line up at the same frequency and become one bigger peak or notch. When a source comes in between two capsules, the distances in the array don't match so the peaks and notches spread out in frequency and help to smooth each other out a bit. Of course, the calibration filters for tetrahedral mics attempt to correct for this effect, but those filters more closely match the diffuse field average of all directions than the more extreme results in the direction of one capsule.
David McGriffy VVAudio On Tue, Sep 11, 2018 at 8:21 AM James Mastracco <acoustic...@verizon.net> wrote: > I've love to see pictures of the chapel and the mic placement. > > JM > > > Hi Folks > > > Is it better to align performers to capsule axis, to get the best > > frequency, and noise performance from those directions, then rotate the > b-format encode afterwards? > > > I am recording at Union Chapel, with tetrahedral mics, and spot > microphones. > > The final output will be stereo and HOA. > > I usually just position tetra mics as normal (upside down and > > end-fire), but it occurred to me that it may be better to align the > > capsules to performers (where possible). > > All performers will be spread out horizontally on an equilateral > > triangle, with the main tetra on a corner. > > The main decode will be stereo, but I want to capture the acoustic of > the place, and do a HOA mix. > > > > Best > > > Steve > > _______________________________________________ > > 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. > > > > -- > Best regards, > James mailto:acoustic...@verizon.net > > _______________________________________________ > 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. > -------------- next part -------------- An HTML attachment was scrubbed... URL: <https://mail.music.vt.edu/mailman/private/sursound/attachments/20180911/114add24/attachment.html> _______________________________________________ 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.
