On March 11, 2025 at 6:50:11 PM, matthewsewell via groups.io (matthew@...) wrote:
If you do this with a dual diaphragm with a single backplate, does that mean you can only do figure 8 and (if you cut the charge to one diaphragm) cardioid?
If the microphone works in Cardioid, it will work in Omni too (assuming you have two metallized diaphragms); just short the two diaphragms together.?
If the front diaphragm is at +60 and the backplate is at 0V, disconnecting the rear diaphragm gives a 4-5dB level boost for the front diaphragm. I’ve heard that called “true cardioid” although I do not know the origin of the term.
To make Figure 8, polarize the rear diaphragm at -60VDC (equal amplitude but opposite polarity to the front diaphragm rail). Pull signal from the backplate. No coupling capacitor is needed, unless the capsule leaks DC.
You could make intermediate patterns too, via a pot on the rear diaphragm’s voltage rail. +60V would be omni. +20V would be wide cardioid. 0V is Cardioid. -20V is hypercardioid. -60V is Fig8.?
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matt.
