Curt Olson asked me to compare the omni-directal and cardioid positions on the multi-pattern NT2000 mics in the parallel boundary rig pictured here. I've quickly made a 3 minute mp3 test recording of clock positions in an arch ~2 feet around the front of the rig. These are not perfectly positioned stations!
It seems to me that treble centricity is one of the key factors we are trying to accommodate with these rigs and capsule orientations.
When the capsules are facing forward and there's a barrier creating 1/2 omni patterns on both sides, the tonal gradation goes from 0 to 90 (from front-center to hard left/right) with 0 being the brightest and 90 degrees being the darkest. (Of course, the field extends further behind and get progressingly darker due both to the polar pattern and the ears providing more baffling as well.) The same 0-90 spread should occur with the cardioid pattern except with more tonal contrast going from 0-90.
The creation of a uniform spectrum across the front of the stereo is different from human hearing. Some prefer the Pseudo Sass's "3/4" positions in which articulated left and right "centers" are created, but this also differs slightly from human hearing because sounds coming in directly from hard left and hard right are the brightest to our ears. So, If I prefer the stereo field to have an illusion of a spectrally symmetrical "vista" across the front with no darker middle, I should like somehing about using the cardioid pattern,.. but someone else go first! Feel free to chop up the mp3 so its easier to compare. Rob D.