Len, I have thought a lot about this while playing around with virtual microphone patterns from the Tetramic. It has the potential to be an excellent tool for exploring these questions given the appropriate decoding tools. This is one area in particular where the virtual pattern synthesis capabilities of an ambisonic microphone system like the Tetramic makes possible things we cannot otherwise achieve or test easily.
Can you point me to any B-format tools which can do the following?
1) Specify a changing polar response which varies between any two first order patterns, smoothly by frequency.
2) Specify a changing frequency response which varies between two user specified curves, an on-axis response and a 180-degree off-axis response, varying smoothly by angle of incidence.
Those tools would be a huge help in answering the questions I’m posing here by providing the ability to hear these things in real-world situations by isolating the differences to only these issues without such a wide range of other complications. It won't make the Tetramic a practical answer for the particular microphone array application I described earlier, but it would definitely provide a way of getting real-world answers to these conceptual questions and is likely to have other real-world recording applications.
Glad to hear some new things are in the works at Core Sound in regards to the Tetramic. As a longtime Tetramic user, here are two basic issues I urge you to address to make the Tetramic more user friendly:
1) VVMic for TetraMic (and VVTetraVST) needs the ability to do basic A-format channel-matching gain adjustment in the standalone application. This is a basic, critical A-level function. The user should be able to input test tone files made during a particular session for mic-preamp level calibration, determine the gain offset between each of the 4 files, and adjust for that in the application immediately prior to the A-format conversion. To do so it would simply require a signal level offset detector and individual A-format channel gain controls. The user should not be required to first import A-format test tone files to an editor, determine the gain offsets between channels, then import the audio A-format files, apply the calculated gain adjustments to them and export the files with those changes before being able to do an A-format conversion on them.
2) A small, single-box power supply eliminating the need for the four separate power supply boxes and the mess of cabling. It should have the option of either battery or P48 powering, with a 6pin mini-xlr input and a single mulit-pin output with various breakout cable options to suit various recorder inputs (XLR, ¼” TRS, unbalanced 1/8” TS plugs, etc).
[edit- Okay, after typing the bit above I just checked the Coresound site and it looks like you are providing some additional powering options with the new PPA3 and PPAc options. The PPA3 effectively addresses simpler P48 powering. What is still needed is a simple single-box battery supply, allowing any 4channel recorder to be used regardless of phantom powering. That would make Tetramic>battery-box>Tascam Dr2d (4ch via two 1/8” inputs) the smallest/simplest ambisonic recording system available.]