• Please read this instruction manual carefully and
completely before using the headset.
• Make these this instruction manual easily accessible to all
users at all times.
Always include this instruction manual when passing the
headset on to third parties.
• During flight operation, do not use the headset for
telephone calls.
• 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 critical sounds,
especially warning alarms and sounds resulting from
malfunction.
• The headset is capable of producing sound pressure levels
exceeding 85
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.
• Never repair or attempt to repair a defective headset
yourself. Contact your Sennheiser partner or the
Sennheiser Service Department.
• Only replace those parts of the headset whose
replacement is described in this instruction manual. All
other parts of the headset must be replaced by your
Sennheiser partner.
• Protect the headset from wetness. Use only a slightly
damp cloth to clean the headset. For information on how
to clean the headset, contact your Sennheiser partner.
dB(A). In many countries 85 dB(A) is the
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 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.
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.
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 attempt
to recharge
non-rechargeable
batteries.
Always remove flat or
exhausted batteries
from the device
immediately.
3
Intended use of the headset
Intended use includes:
• having read this instruction manual, especially the
chapter
• 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 this instruction manual, or under operating
conditions which differ from those described herein.
“Important safety instructions” on page 2,
Delivery includes
Delivery of the HMEC 250 headset includes:
1 HMEC 250 headset
1soft case
1 HZC 08 cable clip
2 Wind and pop shields for MZW 46
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, NoiseGard
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.
TalkThrough function (TT)
The TalkThrough function allows you to communicate with
the people around you while wearing the headset. The
NoiseGard active noise compensation and the peak level
protection remain unaffected by the TalkThrough function
and help to protect your hearing.
TM
5
Additional features
• Outstanding transmission quality for clear communications
• Good passive attenuation of ambient noise
• Foldable design for space-saving storage and transportation