y Please read these instructions carefully and completely
before using the headset.
y Make these instructions easily accessible to all users at all
times. Always include these instructions when passing
the headset on to third parties.
y During flight operation, do not use the headset for
telephone calls.
y With the NoiseGard active noise compensation switched
on, typical aircraft sounds (for example, those from
engines, propellers, warning alarms, etc.) may sound
different to you. Before operating any aircraft, make sure
that, with NoiseGard switched on, you can hear and
recognize these sounds. Set the volume to safe levels that
do not interfere with your ability to hear informational
sounds and warning alarms.
y The headset is capable of producing sound pressure levels
exceeding 85 dB(A). In many countries 85 dB(A) is the
maximum legally permissible level for continuous noise
exposure during the working day. Exposure to sounds of
higher volume levels or for longer durations can
permanently damage your hearing!
y Never repair or attempt to repair a defective headset
yourself. Contact your Sennheiser agent or the
Sennheiser Service Department.
y Only replace those parts of the headset whose
replacement is described in this manual. All other parts of
the headset must be replaced by your Sennheiser agent.
y Protect the headset from humidity. Use only a slightly
damp cloth to clean the headset. For information on how
to clean the headset, contact your Sennheiser agent.
2
Safety instructions for batteries
If abused or misused, batteries may leak and, in extreme
cases, may even present an explosion and fire hazard.
Sennheiser does not accept any liability for damage arising
from abuse or misuse.
Keep batteries out of
reach and out of
sight of children.
Do not heat or throw
into fire.
Remove batteries
when the device is
not used for
extended periods of
time.
Do not solder.Do not short-circuit.
Observe correct
polarity.
Switch off battery
powered devices when
not in use.
Dispose of exhausted
batteries at special
collection points or
return them to your
specialist dealer.
Do not mutilate or
dismantle.
Do not pack charged
batteries loose –
danger of shorting
out – fire hazard.
Do not mix old or
used batteries with
new ones. Do not mix
batteries of different
types or brands.
Do not attempt
to recharge
non-rechargeable
batteries.
IAlways remove flat or
exhausted batteries
from the device
immediately.
3
Intended use of the headset
Intended use includes:
y having read these instructions, especially the chapter
“Important safety instructions” on page 2,
y using the headset within the operating conditions and
limitations described in this instruction manual.
Improper use means using the headset other than as
described in these instructions, or under operating
conditions which differ from those described herein.
Delivery includes
Delivery of the HMEC 250 headset includes:
1 HMEC 250 headset
1 soft case
1 cable clip
2 MZW 46 wind and pop shields
1 audio-in cable for mobile telephones, length 0.6 m,
with two 2.5 mm jack plugs
1 audio-in cable for additional audio players, length 0.6 m,
with two 3.5 mm jack plugs
2 AAA size batteries
1 instruction manual
4
The HMEC 250 headset
The HMEC 250 headset with NoiseGard 2.0 active noise
compensation features closed, dynamic, circumaural stereo
headphones. The HMEC 250 is a headset for general aviation
use.
NoiseGard 2.0
The NoiseGard 2.0 active noise compensation system is
based on the principle of cancelling out sound using “antisound” (phase-inverted sound). Tiny microphones pick up
low-frequency ambient noise (up to 1 kHz) near the ear. The
NoiseGard 2.0 electronics use this noise to generate a sound
wave which is the exact opposite (i.e.: at the same level but
polarity reversed – 180° out-of-phase), the result is that the
polarity reversed signal cancels most of the outside noise.
Fail safe operation
When the batteries are completely discharged, the
NoiseGard 2.0 active noise compensation automatically
switches off. RT traffic (e.g. ATC) and intercom will still be
heard through the headphones.
Peak level protection
The peak level protection safeguards your ears from volume
peaks above 110 dB.
5
TalkThrough function
The TalkThrough function allows you to communicate with
the people around you while wearing the headset. The
NoiseGard 2.0 active noise compensation and the peak level
protection remain unaffected by the TalkThrough function
and help to protect your hearing.
Additional features
y Outstanding transmission quality for clear
communications
y Good passive attenuation of ambient noise
y Foldable design for space-saving storage and
transportation
y Noise-compensating boom microphone ensures excellent
speech transmission
y Flexible microphone boom
y Separate left and right channel volume control
y Excellent comfort resulting from soft ear pads and
headband padding
y Audio-input facility for external audio sources, such as
mobile phones, MP3 players
6
Operating elements
쐋
Headset
Microphone sensitivity control
Headphone cable
Microphone boom
Earpads
Headband
Battery compartment (on both sides)