Hello, I'm a student looking to build an impedance tube setup and need some expert knowledge on the microphones. For those unfamiliar with impedance tube they basically setup a standing wave along the length of the tube and the pressure is measured at various locations which in turn allows you to calculate the acoustic impedance at the sample end. I am currently using very cheap microphones (<$10) as a quick mock up and they are proving quite unreliable. My budget would preferably be in the few hundred dollar range, the less the better For this application: -the smaller the width the better (ie 1/2" or 1/4") -unidirectional, the only pressure I'm interested in is from the plane waves at the surface of the tube. -I am using measurement equipment that has a maximum input voltage of +-7 V @ 50 ohms, so I'm not sure which power system to use. Currently with the cheap electret mics, I am just using a simple op amp pre-amplifier. Can I get away with not having a high voltage phantom power setup? -Flat frequency response is not so important as I will be measuring relative changes at specific frequencies. My biggest need is for them to be highly repeatable so to have very small changes with temperature and a linear response with amplitude. Could you suggest any microphones that you have used or know of that could perform this task well? Thanks for your time!