is it possible to make a directional mic out of an omni?

Hey all;

I've got a couple mic elements that are omnidirectional. It would be better for me if they were directional (like a cardioid or something). How do they make the directional pattern? Is it something in the electronics, the casing, or the element itself? Is it possible to make the omni uni?

Thanks

The directional capsules are different, they have a soundpath on the backside, where the omnidirectional ones have only a tiny capillary hole for air pressure changes. It is possible to convert an omni to directional by making an acoustical lens in front out of a bundle of plastic straws, John Woodgate had posted some pic not so long ago. You could also use a parabolic reflector with the mike mounted in the focus point. Another possibility is to electrically combine the signal of several capsules in form of a phased array. This is usually defined with the capsules equidistant in a line. Also you can make a nice stereo-mike this way with 9 or 13 capsules. I do not know how to calculate the positions and damping factors though, but I think K. Aylward has some software to do this, it should be similar for sound and antennas.

Following up on Rich's comments, you might want to Google for "Shotgun Microphone" if you are looking for super directionality and don't mind fiddling a bit. There used to be perennial articles in Popular Electronics and the like back in the '60s about how to build your own, but it all boiled down to just what Rich says: A pipe with holes in the sides. It won't be small, but it will be directional! You used to see these on TV shows where the host would point it at a member of the audience to pick up one voice from a crowded room.

However, most small "unidirectional" mics are nowhere near this directional. They are simply cardioids: The response pattern looks like a figure 8 with the front lobe bigger than the back. Also note that the more directional a mic is, the more dips and peaks in its frequency response. If you are using it for music recording, it's often better to use an omni up close instead.

Best regards,

Bob Masta dqatechATdaqartaDOTcom D A Q A R T A Data AcQuisition And Real-Time Analysis

OK Thanks for the info guys. I guess I'll just leave it the way it is.

better

they