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Ambisonic microphone with RK12 capsules
Old 18th September 2018
Here for the gear

Ambisonic microphone with RK12 capsules

I am about to build an ambisonic microphone from a DIY project, the capsules are 14mm cardioids in tetrahedral array, but was curious if I could replace them with 34mm LDC RK-12 or RK-47 like capsules? Are they suitable for far field recording also?

Old 21st September 2018
Gear Maniac
szegedin's Avatar
I think what people will tell you is that a larger diaphragm capsule will give you "colored off axis response," meaning that frequency response by position around the axis will be very uneven. If you're in a dead sounding studio and the sound source is right in front of you, that's not an issue. But in an ambisonic mic, you are definitely going to be getting the same signal from one capsule at 0 degrees on the mic, and three others at other angles, and it is definitely going to be a huge problem. To get the ambisonic effect, you want to get exactly the same signal into each mic, just with the expected variation in loudness and delay.

On the other hand, it's always good to run these experiments in the name of science, and see what happens. You could buy four of those cheap 34mm caps and fire it up, see what happens, report back to us. But you will get better results with the flattest, fastest SDC you can get. Good luck.
Old 21st September 2018
Here for the gear

Thanks szegedin,
isn't off-axis coloration solved by placing the mic capsules in 90 degrees position from each other (tetrahedral array) as they are cardioid - two pointed upward and two rotated 90 degrees around the vertical axis and pointing downward to get a full sphere.
Aren't SDCs also prone to off axis coloration besides they are cardioids?
How to get the same signal into each mic besides loudnes and delay factors as there are also frequency filterings happening from the room reflections (if the sound is recorded in a room for example)? Isn't this solved by calibration and creating A2B matrices?
For the SDCs I do like to experiment with Primo's EM200 14mm capsules also, if I find perfectly matched ofcourse...
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