What impedance is best for what aircraft??

[bb in ca]

What's the scoop on impedance with microphones?

I've been flying for quite a few years and have used many different headsets and several different helmets with no noticeable problem on many different helicopter types.

I'm now looking to buy yet another headset and was wondering what impedance is best and why?

I typically fly S61, S76 and AS350 types.

Cheers,
bb

[500e]

Try this link
www.headsetservices.com/faq/index.html :suspect:

[rotornut]

Also, avoid electret condenser mikes in helicopters - they don't last in that environnment.

[soggyboxers]

bb,

It depends entirely on the aircraft intercom fit. Even within the same fleet these may be very different. For example, some of the S76s I have flown have had DIN plugs, others have standard NATO plugs, but have been either high or low impedance. I currently fly in S76A++s with low impedance systems and S76C+s with high impedance systems. Ideally you should get a headset with switchable impedance, such as some David Clarks; or changeable microphones, such as BOSE.

[Gomer Pylot]

Ideally, they should all be standard and use regular GA headsets and U174 plugs. Every helicopter I've ever seen in the US is set up this way, but it's possible to use whatever avionics the owner wants, so you may have to check each aircraft and see what you get. It has nothing to do with the model, it's just how each individual aircraft got set up.

[md 600 driver]

soggyboxers
whats the model no of your switchable impedence bose headsets ive been trying for ages to get some but they keep aying they dont make them only fixed ones

[soggyboxers]

md 600 driver,

The Bose X helicopter model has the option of different impedance microphones (and changeable plugs as well if you're flying French and American helicopters). You simply unscrew one microphone unit and replace it with another. The extra microphones are quite expensive (but cheaper than having 2 headsets). You can get them from places like Sporty's or Marv Golden, though it may take a phone call to make sure you get the 2 microphones. David Clarke just have an impedance switch on their H10-66.

[kersmash]

can somebody please confirm...that you need a low impedence mic for the 412 and a high impedence mic for the AW139???thanx

[Outwest]

The mic impedance that you require depends on the avionics fit in the particular a/c.

One 412 may have a low impedance system while another may have high.

Most new a/c come factory supplied with high impedance, however I was surprised to hear from a friend that the 225 he is flying is low impedance.....