Thanks SAS,
……………with the selector switch for microphone impedance it should not be too big a deal to equip helmets or headsets with the ability to switch between the two.....or so it would seem anyway.
It’s not so much impedance that’s the problem, it’s aircraft Audio Boxes and aircraft wiring. ‘Traditional’ military aircraft use Dynamic Mics, which don’t require an energising voltage to work. Your old Chinook/Huey helmet (no doubt you have one) is an example. On the other hand, ‘civil’ aircraft use ‘Carbon Equivalent’ mics which is a hangover from the 1930s - I kid you not. Carbon mics were rubbish; and needed a voltage to work, supplied from the Audio Boxes. To improve matters this voltage was hi-jacked and used to power amplifiers integral to the replacement ‘Carbon Equivalent’ mics.
Have you nodded off yet? It’s all boring stuff, other than why the US Navy has spent loads of money changing something that wasn’t broke.
If you’re really excited about this there’s an article on Mic history here
http://www.defensedailynetwork.com/c...le=1101asd.htm
and Part 2
http://www.defensedailynetwork.com/c...le=1201asd.htm