best mic for a home-made parabola?

[goodkid1]

We are presently using a 13 inch painted aluminum wok top with a standard Radio Shack omni-directional lavalier mic ($25), for a student project. Kids screaming, dogs barking and jets taking off give very strong signal ...but normal low level human speech is weak, with or w/o background noise. Is there a better inexpensive mic to suit our applications, i.e. designed both to pick up human speech and decrease background noise? Remembering we get good amplification with unwanted sounds already, would a "pro" made dish help? Does more acurate focal length testing enter into the equation? Please give both a mic type and an actual make and model if you have the knowledge. Opinions based on general knowledge have got us little good results. Does anyone out there work intimately with parabola mics? Thanks

 

[crazydoc]

You might do better with a frisbee or one of those round sleds.

Just kidding. First, do you have the mic at the presumed focus of the approximately parabolic wok? This is probably not relevant, but since the focus of a parabola is for parallel rays (coming from infinity) you might back the mic out an inch or so - even more if your sound source is closer than 8 or 10 feet away.

If you need to determine the focal point, assuming the wok's surface is approximately spherical, find the radius of that sphere and half it for the focal distance.

 

[darrin_h2000]

Sounds like a shotgun mic...they have them at best buy for like 50 bucks...I have a nice AT one I got at a pawn broker...but it will have the tightest cardioid pattern for the money.

 

[goodkid1]

parabola mic

Focal length seems to be focused correctly. As to 2nd post, are you sure I want a shotgun mic? The sound will be coming from as steep an angle as 75 degrees estimated from the dish edges. Doesn't that call for an omni? Or does the fact that the sound is focused to a tight spot negate the need for an omni?