 path edu!crabappl edu!bb3 andrew edu!new sei edu!ci ohio-state edu!pacif mp ohio-state edu!zaphod mp ohio-state edu!howland reston an net!noc net!uunet!new larc nasa gov!grissom larc nasa gov!kludg from kludg grissom larc nasa gov scott dorsei newsgroup sci electron subject re pressur zone microphon date 27 apr 1993 17 13 04 gmt organ nasa langlei research center reptil farm line 43 distribut messag-id 1rjpj0inno78 rave larc nasa gov refer 1rjobdinnk1s crcni1 unl nntp-post-host grissom larc nasa gov in articl 1rjobdinnk1s crcni1 unl mpaul unl marxhausen paul write rememb commerci mike pzm label pressur zone microphon start show read articl engin journal describ principl involv all physic practicl standpoint author's built prototyp small soni laveli mike laid larg aluminum disk in demonstr present audio engin impress peopl bug bui yup difficult anywai build choir mike wide coverag i've good luck small electret mike element digi-kei - limit-bandwidth peakei unit buck spec'd 20khz bit flatter respons the panason cartridg bad spectacular the distanc mike open flat plate kind critic i'm debat mount side put open shade 2mm plate mount open point plate small clearanc dissect unit bui radio shack thought? don't mount side call crown compani patent pzm construct thing you determin correct space emper nois sourc spectrum analyz design panason cartridg tune caviti front electret element increas high frequenc respons go alter resist caviti entranc crown nice book subject short mathemat there's jae articl year still applic lot better bui cheap radio shack model phil rastoczni's modif clean balanc output phil's mod repost regular basi --scott 