Hankal wrote:
: Have you ever had a problem with squelch noise when you use two different makes
: of headsets.
: When my buddy who has a Lightspeed flies with me I get a lot of noise and I
: have to ask him to use my other Avcom.

As I mentioned before, check to make sure that it's not just the
headsets. There's a significant difference between these common noise
problems:

1. "Single Squelch Noise" Different headset sensitivites make setting the
squelch impossible. One headset breaks squelch too easily and the other
poor fool has to holler in his headset to get the squelch to break.
Solution is to get matching headset mic sensitivites or intercom with
multiple squelch triggers.

2. "Mic gain mismatch" Somewhat like #1, but slightly different. This
one shows up as one person having to yell into his mic *after* the squelch
is already open. Solution is to adjust mic gain (some headsets allow
this), and/or get intercom with separate mic circuits for each position.
When a mic triggers a squelch break, only that mic is turned on.

3. "Noise-cancelling mic" Headsets use a "differential" microphone that
relies on the proximity of the mic to the mouth to work. The common-mode
cabin noise enters roughly equally on each side of the mic boom, but the
person speaking is louder on one physical side than the other. The mic is
supposed to pick up on this differential-mode signal, but reject the
common-mode ambient noise. Unfortuately, some headsets simply have poorer
noise rejection qualities than others. Usually, there's nothing that can
be done with this, except using a different headset.

I have gone around on this one myself, having gone through #1 and
#2. I'm currently at #3 (but with a much nicer intercom than before) and
looking to get another headset. The irony is that my cheap FlightLine
HS-60B passive $100 headset has the best mic in the bunch. A DRE-6000 ANR
has the worst mic, letting in huge amounts of cabin noise when the person
wearing it speaks. The Lightspeed 15k, 20k, 25xl have mic performance
somewhere in the middle, but with the 25xl having the worst noise
performance.

Anyway, that's what I've found out over the past year or so of
fiddling with my plane and headsets. Between the poor mic and lousy
high-frequency attenuation, I'm not shelling out the bucks for a high-end
Lightspeed. I have tried and did like the QFR cross-country though. You
should see if you can isolate what kind of noise you've got before you go
fixing things that aren't broken.

-Cory

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