Sennheiser HMEC 250 - 05-10 User manual

HMEC 250
Headset for
general aviation
Instruction manual

1
Contents
Important safety instructions ...................................................2
Delivery includes ..........................................................................4
The HMEC 250 headset ...............................................................5
Operating elements .....................................................................7
Putting the headset into operation .........................................8
Inserting the batteries .......................................................... 8
Connecting the headset ........................................................ 8
Connecting a mobile telephone .......................................... 9
Connecting an additional audio player ........................... 10
Adjusting the microphone sensitivity ............................ 11
Switching between mono and stereo mode .................. 11
Using the headset .................................................................... 12
Attaching the cable clip ..................................................... 12
Adjusting the headset ....................................................... 12
Adjusting the microphone boom ..................................... 13
Adjusting the volume ........................................................ 13
Switching the TalkThrough function on/off .................. 14
Adjusting the volume of the TalkThrough function .... 14
Switching NoiseGard on/off ............................................. 15
Replacing the batteries ..................................................... 16
Folding up the headset ............................................................ 17
Care and maintenance ............................................................. 18
Replacing the ear pads ...................................................... 18
Replacing the wind shield ................................................. 19
Specifications ............................................................................ 20
Manufacturer declarations ..................................................... 22

2
Important safety instructions
• 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 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.
• 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.

3
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.
Observe correct
polarity.
Do not heat or
throw into fire.
Switch off battery
powered devices when
not in use.
Remove batteries
when the device
is not used for
extended periods
of time.
Dispose of exhausted
batteries at special
collection points or
return them to your
specialist dealer.
Do not solder. Do not short-circuit.
Do not mutilate or
dismantle.
Do not attempt
to recharge
non-rechargeable
batteries.
Do not pack charged
batteries loose –
danger of shorting
out – fire hazard.
Always remove flat or
exhausted batteries
from the device
immediately.
Do not mix old or
used batteries with
new ones. Do not
mix batteries of
different types
or brands.

4
Intended use of the headset
Intended use includes:
• having read this instruction manual, especially the
chapter “Important safety instructions” on page 2,
• 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.
Delivery includes
Delivery of the HMEC 250 headset includes:
1 HMEC 250 headset
1softcase
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

5
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 2.0TM
The NoiseGard 2.0 active noise compensation system is
based on the principle of cancelling out sound using “anti-
sound” (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.

6
Additional features
• Outstanding transmission quality for clear communi-
cations
• Good passive attenuation of ambient noise
• Foldable design for space-saving storage and transpor-
tation
• Noise-compensating boom microphone ensures excellent
speech transmission
• Flexible microphone boom
• Separate left and right channel volume control
•Excellentcomfortresultingfrom soft ear pads and head-
band padding
• Audio-input facility for external audio sources, such as
mobile phones, MP3 players

7
Operating elements
Headset
Microphone sensitivity control
Headset cable
Microphone boom
Ear pads, ergonomic
Headband
Battery compartment (on both sides)
Operating control integrated
in the headset
TT VOLUME + button (Talk Through)
ON/OFF button (NoiseGard)
TT VOLUME – button (Talk Through)
TALK THROUGH button (on/off)
LED (status display)
Operating control integrated in the cable
Cable with microphone plug,
5.25 mm jack plug
Cable with headphone plug,
¼” (6.35 mm) jack plug
3.5 mm jack socket for connecting an
additional audio player (3-pin)
2.5 mm jack socket for connecting a
mobile telephone (3-pin)
Mono/stereo switch
Separate left and right channel
slide volume controls



쐋








햴




8
LED indications
Meanings of the LED :
Putting the headset into operation
Inserting the batteries
Insert the batteries into the battery compartments on the
left and right ear cups as follows:
왘Open the battery compartment by pushing the catch
and open the cover.
왘Insert the AAA size battery as shown.
왘Close the battery compartment . The battery compart-
ment cover locks into place with an audible click.
Connecting the headset
The headset’s operating control features two cables with
one jack plug each.
왘Connect the headset to the corresponding sockets of your
intercom.

LED Meaning
red NoiseGard is switched on
green TalkThrough is switched on
flashing Batteries are almost flat


Connector for connection to the
¼” (6.35 mm) jack plug headphone output
5.25 mm jack plug microphone input

9
Connecting a mobile telephone
The 2.5 mm jack socket allows you to connect a mobile
telephone. For this purpose, the NoiseGard active noise
compensation must be switched on and the microphone
connector must be connected to the aircraft intercom.
Asuitable adapter for your mobile telephone with 2.5 mm
jack socket is available from your specialist dealer.
왘Connect the audio cable to the 2.5 mm jack socket (3-pin)
on the operating control and to the corresponding jack
socket on your mobile telephone (4-pin).
You can adjust the volume of the mobile telephone via
the headset’s operating control. However, the functions
of the mobile telephone cannot be controlled via the
headset’s operating control.
왘Switch NoiseGard on (see “Switching NoiseGard on/off”
on page 15).
Audio from the mobile telephone and from the intercom
are heard simultaneously through the headset.
왘Operate your mobile telephone as usual and observe the
manufacturers instructions.


DANGER! Danger of accident due to reduced
attention!
Making telephone calls or operating the
mobile telephone limits your attention and
may cause accidents.
왘During flight operation, do not use the
headset for telephone calls!
For the latest list of compatible mobile telephones,
please refer to the „Professional Audio“ >
„Aviation Headsets“ section on our website at
www.sennheiser.com.


10
Connecting an additional audio player
The 3.5 mm jack socket allows you to connect an
additional audio player (e.g. MP3 player).
왘Connect the audio cable to the 3.5 mm jack socket
on the operating control and to the corresponding jack
socket on your audio player.
왘Switch NoiseGard on (see “Switching NoiseGard on/off”
on page 15).
Audio from the additional audio source and from the
intercom are heard simultaneously through the headset.
왘Operate the connected audio player as usual and observe
the manufacturers instructions.

DANGER! Danger of accident due to reduced
attention!
Listening to music or operating an audio
player limits your attention and may cause
accidents.
왘During flight operation, do not use the
headset for listening to additional audio
sources!
Hearing damage due to high volumes!
This headset is capable of producing high
sound pressure levels. Higher volumes or
longer durations can damage your hearing!
왘Set the volume to a medium level. Make
sure that you can hear critical
environmental sounds and warning
alarms!


11
Adjusting the microphone sensitivity
The microphone sensitivity has been factory preset to
80 mV/Pa.
To change the input sensitivity of the microphone:
왘Use a suitable slotted screwdriver.
왘Turn the microphone sensitivity control as shown.
Switching between mono and stereo mode
The mono/stereo switch  allows you to switch between
mono and stereo mode, depending on the intercom system.
Set the mono/stereo switch  to the desired position:
– mono
– stereo



12
Using the headset
Attaching the cable clip
The cable clip allows you to attach the headset cable to
your clothing so that the cable doesn’t hinder or distract
you.
Guide the headset cable through the cable clip as
shown.
Attach the cable clip to your clothing.
Adjusting the headset
Wear the headset so that
– the microphone boom is on the left side of the
mouth (see right/left labeling on the headband joints)
and
– the headband runs over the top of your head.
Adjust the length of the headband so that
– your ears are completely inside the ear pads ,
– you feel even, gentle pressure around your ears,
– a snug fit of the headband on the head is ensured.
In this way, optimum transmission quality, good noise
attenuation and best possible comfort is ensured.
To ensure sufficient noise attenuation, final adjustment is
best made in a noisy environment.


쐋



13
Adjusting the microphone boom
Bend the microphone boom so that the microphone is
placed at the corner of the mouth. Maintain a distance of
approx. 2 cm between microphone and mouth.
Adjusting the volume
You can adjust the volume directly on the intercom or via
the operating control integrated into the headset cable.
To adjust the volume for the left or right channel:
Slide one of the two volume controls 
– upwards to increase the volume or
– downwards to reduce the volume.
쐋
CAUTION! Hearing damage due to high volume
levels!
The headset is capable of producing high
sound pressure levels. Higher volumes or
longer durations can damage your hearing!
Adjust the volume to a medium level.
Make sure that you can hear critical
environmental sounds and warning
alarms.


14
Switching the TalkThrough function on/off
The HMEC 250 provides excellent attenuation of ambient
noise. In order to allow you to communicate undisturbed
with the people around you while wearing the headset,
the HMEC 250 features a TalkThrough function.
Press the TALK THROUGH button to switch the
TalkThrough function on or off.
When the TalkThrough function is switched on, the LED 
lights up green.
Adjusting the volume of the TalkThrough function
To increase the volume of the TalkThrough function:
Press the TT VOLUME + button .
To reduce the volume of the TalkThrough function:
Press the TT VOLUME – button .


햴
If you change the volume with the TalkThrough
function switched on, the new volume setting is
saved and will be used as the default the next time
the TalkThrough function is activated.

15
Switching NoiseGard on/off
To switch the NoiseGard active noise compensation on or off:
Press the ON/OFF button for approx. one second.
When NoiseGard is switched on:
–theLED lights up red and
– you can listen to music and make telephone calls at the
same time.
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.



16
Replacing the batteries
When the batteries are almost flat, the LED flashes. When
the batteries are completely discharged, NoiseGard
automatically switches off (fail safe operation). Replace the
batteries or the rechargeable batteries as follows:
Open the battery compartment by pushing the catch
and open the cover.
Remove the battery.
Insert a new AAA size battery as shown.
Close the battery compartment . The battery
compartment cover locks into place with an audible click.

Always replace the two batteries at the same time.

Remove the batteries from the battery
compartments if the headset will not be used for
extended periods of time.

17
Folding up the headset
For space-saving transportation, the headset can be folded
up in different ways:
To fold up the headphones as flat as possible:
Rotate the ear cups by 90° and turn the microphone
boom flat as shown.
To fold up the headphones as compact as possible:
Fold the ear cups in as shown.
For safe transportation of the headset, use the supplied soft
case and fold the headset as follows:
Rotate the ear cups by 90°.
Turn the microphone boom flat as shown.
Pull out the right ear cup and then fold it in.
Place the headset flat into the soft case as shown.
The two AAA size batteries can be inserted into the two
straps at the side of the soft case.
The accessories can be transported in the cover of the soft
case:
– audio cable (two 3.5 mm jack plugs) 
– audio cable (two 2.5 mm jack plugs) 
–windandpopshields



18
Care and maintenance
Use a soft, slightly damp cloth to clean the headset from
time to time.
Replacing the ear pads
You can replace the ear pads. Spare ear pads are available as
accessories.
Grasp the edge of the ear pad and peel it up and away
from the ear cup.
CAUTION! Liquids can damage the electronics of the
headset!
Liquids entering the housing of the
headset can cause a short-circuit and
damage the electronics.
Only use a soft, slightly damp cloth to
clean the headset. Do not use any
solvents or cleansing agents.

Accessories are available from your Sennheiser
partner. A list of suitable accessories can be found
on our website at
www.sennheiser.com > „Service & Support“.
When removing the ear pads, it might be that a
black plastic ring remains on the ear cup. Remove
this ring before attaching the new ear pads.

19
Attach the ear pad so that the side with the thicker
padding points downwards as shown.
Press the new ear pad onto the ear cup until it clicks
audibly into place. Repeat for the other ear cup.
Replacing the wind shield
You can replace the wind shield. The HMEC 250 is supplied
with a spare wind shield.
Carefully pull the wind shield from the microphone.
Slide-on the new wind shield  and ensure that it fits
securely over the microphone.


