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		 Instructions for use   
					Headset   
					HMEC 300   
					HMEC 302   
					HMEC 305   
					HMEC 305-C   
					HMEC 306   
					HMEC 322   
					HMEC 400   
					HMDC 322   
					™ 
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				The HMEC300, HMEC302, HMEC305,HMEC305-C, HMEC306, HMEC322, HMEC400   
					and HMDC322 are pilot headsetswith closed earprotectorheadphonesand NoiseGard™   
					active noise compensation for use in helicopters, propeller and turboprop aircraft.   
					Safety tips   
					• 
					With the NoiseGard™ active noise compensation turned 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™   
					turned 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.   
					• 
					• 
					• 
					Do not attempt to repair the headset yourself. If problems occur, contact your   
					Sennheiser agent for assistance.   
					Only replace parts of the headset whose replacement is described in this manual.   
					All other parts of the headset must be replaced by your Sennheiser agent.   
					Do not immerse the headset in water! For information on how to clean the headset,   
					contact your Sennheiser agent.   
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				Headset features   
					HMEC 300 NoiseGard™ headset   
					• 
					• 
					• 
					New active headset with effective attenuation of external noise across the entire   
					frequency spectrum due to NoiseGard™ active noise compensation   
					NoiseGard™ active noise compensation provides clear communications even in the   
					noisiest environment   
					Excellent comfort due to very low weight, soft ear cushions and padded headband   
					as well as best possible freedom of movement due to unilateral connecting cable   
					• 
					• 
					• 
					Foldable headband for easy and space-saving storage   
					Clear communications due to MKE 45-1 electret microphone with adjustable sensitivity   
					Microphone can be easily positioned and worn on either left or right side due to   
					flexible microphone boom with quick-fixing device   
					• 
					• 
					• 
					• 
					Optimum radio reception due to headphone systems with wide frequency response   
					Integrated volume control   
					Adaption to the aircraft intercom system via Mono/Stereo switch   
					With the NoiseGard™ active noise compensation turned off, the headset can be   
					used as a conventional headset   
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				• 
					Power supply for NoiseGard™ is provided via on-board power supply system,   
					cigarette lighter socket or battery pack   
					• 
					• 
					Fail safe operation in case of power failure   
					Supply voltage for the NoiseGard™ system is processed by the in-line electronics in   
					the connecting cable   
					• 
					Made in Germany, two-year warranty   
					Product variants   
					HMEC 302 NoiseGard™ headset   
					The HMEC 302 differs from the HMEC 300 in the following features:   
					• 
					Connection of microphone and NoiseGard™ electronics via PJ-068 plug   
					HMEC 305 NoiseGard™ headset   
					The HMEC 305 differs from the HMEC 300 in the following features:   
					• 
					• 
					No Mono/Stereo switch   
					Connection of headphones, microphone and NoiseGard™ electronics to the on-board   
					power supply system (12–35 V DC) via XLR-5 plug   
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				HMEC 305-C NoiseGard™ headset   
					The HMEC 305-C differs from the HMEC 300 in the following features:   
					• 
					• 
					No Mono/Stereo switch   
					Connection of headphones and microphone via XLR-5 plug   
					HMEC 306 NoiseGard™ headset   
					The HMEC 306 differs from the HMEC 300 in the following features:   
					• 
					Connection of headphones, microphone and NoiseGard™ electronics to the on-board   
					power supply system (12–35V DC) via 6-pin Redel plug   
					HMEC 322 NoiseGard™ headset   
					The HMEC 322 differs from the HMEC 300 in the following features:   
					• 
					• 
					• 
					No Mono/Stereo switch   
					Coiled cable   
					Connection of headphones and microphone via U-174/U jack plug to a high impedance   
					interface in the helicopter   
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				HMEC 400 NoiseGard™ headset   
					The HMEC 400 differs from the HMEC 300 in the following features:   
					• 
					• 
					• 
					Stylish silver design   
					Leatherette ear cushions   
					Headband padding can be buttoned   
					HMDC 322 NoiseGard™ headset   
					The HMDC 322 differs from the HMEC 300 in the following features:   
					• 
					• 
					• 
					• 
					No Mono/Stereo switch   
					Coiled cable   
					M-87/AIC dynamic microphone and low impedance headphones   
					Connection of headphones and microphone via U-174/U jack plug to a low impedance   
					interface in the helicopter   
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				Delivery includes   
					HMEC 300, HMEC 305-C, HMEC 322, HMEC 400 and HMDC 322 headsets   
					• 
					• 
					• 
					• 
					• 
					Headset   
					3-pin XLR socket for aircraft panel mounting (power supply via the on-board system)   
					Padded carry and storage bag with shoulder strap for headset and accessories   
					Wind screen for microphone (except HMDC 322)   
					MZQ 2002-1 Cable clip (Cat. No. 44740)   
					HMEC 302, HMEC 305 and HMEC 306 headsets   
					• 
					• 
					• 
					• 
					Headset   
					Padded carry and storage bag with shoulder strap for headset and accessories   
					Wind screen for microphone   
					MZQ 2002-1 Cable clip (Cat. No. 44740)   
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				Recommended accessories   
					Replaceable gel ear cushions (Cat. No. 83140)   
					BP-03 battery pack (except for HMEC 302, HMEC 305 and HMEC 306)   
					Battery pack with XLR-3 socket for powering the NoiseGard™ electronics of the HMEC 300,   
					HMEC 305-C, HMEC 322, HMEC 400 and HMDC 322 headsets. Four 1.5 V AA size   
					alkaline manganese batteries (IEC LR 6) ensure approx. 15 hours of reliable operation   
					(batteries are not included in the delivery). Length of connecting cable: 0.9 m.   
					Adapter cables (except for HMEC 302, HMEC 305 and HMEC 306)   
					Sennheiseroffersspecialadaptercablesforconnecting the NoiseGard™electronicsofthe   
					HMEC 300, HMEC 305-C, HMEC 322, HMEC 400 and HMDC 322 headsets to the on-   
					board power supply via the cigarette lighter socket:   
					ACX-1   
					ACX-2   
					• 
					• 
					ACX-1 adapter cable for powering one headset via the cigarette lighter socket   
					ACX-2 adapter cable for powering two headsets via the cigarette lighter socket   
					The adapter cables are also available with a right-angled jack plug featuring a 7.5 A fuse   
					and a green LED operation indicator:   
					• 
					• 
					ACX-11 adapter cable for powering one headset via the cigarette lighter socket   
					ACX-11   
					ACX-22   
					ACX-22 adapter cable for powering two headsets via the cigarette lighter socket   
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				Connecting the headsets   
					Connecting cables for headsets   
					HMEC 300 and HMEC 400 headsets:   
					1 
					1/4” (6.35 mm) stereo jack plug for connecting the headphones   
					1 PJ-068 jack plug for connecting the microphone   
					1 XLR-3 plug for connecting the power supply for the NoiseGard™ electronics   
					Connecting cable for   
					HMEC 300 and HMEC 400   
					HMEC 302 headset:   
					1 /4” (6.35 mm) stereo jack plug for connecting the headphones   
					1 PJ-068 jack plug for connecting the microphone and the power supply for the   
					NoiseGard™ electronics   
					Connecting cable for   
					HMEC 302   
					HMEC 305 headset:   
					1 XLR-5 plug for connecting the headphones, the microphone and the power supply for   
					the NoiseGard™ electronics   
					Connecting cable for   
					HMEC 305   
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				HMEC 305-C headset:   
					1 XLR-5 plug for connecting the headphones and the microphone   
					1 XLR-3 plug for connecting the power supply for the NoiseGard™ electronics   
					Connecting cable for   
					HMEC 305-C   
					HMEC 306 headset:   
					1 6-pin Redel plug for connecting the headphones, the microphone and the power   
					supply for the NoiseGard™ electronics   
					Connecting cable for   
					HMEC 306   
					HMEC 322 and HMDC 322 headsets:   
					1 U-174/U jack plug for connecting the headphones and the microphone   
					1 XLR-3 plug for connecting the power supply for the NoiseGard™ electronics   
					Connecting cable for   
					HMEC 322 and HMDC 322   
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				Powering options   
					There are three options for powering the NoiseGard™ active noise compensation:   
					1. Connection to the on-board system (12–35 V DC)   
					2. Connection to the BP-03 battery pack   
					(accessory, except for HMEC 302, HMEC 305 and HMEC 306)   
					3. Connection to the cigarette ligther socket (12–35 V DC) via adapter cable   
					(accessory, except for HMEC 302, HMEC 305 and HMEC 306)   
					The supply voltage for the NoiseGard™ system is processed by the in-line electronics in   
					the connecting cable.   
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				1. Connecting the headset to the on-board system   
					The NoiseGard™ electronics can be connected to on-board power supply systems with   
					operating voltages between 12–35 V DC.   
					Danger of short circuit!   
					Before turning on NoiseGard™, ensure that the on-board power supply system is   
					protected by a 1 A fuse.   
					Power supply for   
					NoiseGard™   
					The HMEC 300, HMEC 305-C, HMEC 322, HMEC 400 and HMDC 322 headsets are   
					supplied with an XLR-3 socket for panel mounting in the aircraft. The XLR-3 socket must   
					be mounted by a technician qualified to perform this type of installation.   
					Ground   
					Do not connect!   
					XLR-3 socket for HMEC 300, HMEC 305-C,   
					HMEC 322, HMEC 400 and HMDC 322   
					headsets   
					HMEC 300 and HMEC 400 headsets:   
					Ǡ 
					Connect the 1/4” (6.35 mm) stereo jack plug for the headphones and the PJ-068 jack   
					plug for the microphone to the corresponding jack sockets of your intercom.   
					Ǡ 
					Connect the XLR-3 plug to the XLR-3 socket.   
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				Headset HMEC 302:   
					Ǡ 
					Connect the 1/4” (6.35 mm) stereo jack plug for the headphones and the PJ-068 jack   
					plug for the microphone to the corresponding jack sockets of your intercom.   
					HMEC 305 headset:   
					Connect the XLR-5 plug to the aircraft’s XLR-5 socket.   
					Ǡ 
					Headset HMEC 305-C:   
					Ǡ 
					Connect the XLR-5 plug for the headphones and the microphone to the aircraft’s   
					XLR-5 socket.   
					Ǡ 
					Connect the XLR-3 plug to the XLR-3 socket.   
					HMEC 306 headset:   
					Connect the 6-pin Redel plug to the corresponding socket in the aircraft.   
					Ǡ 
					HMEC 322 and HMDC 322 headsets:   
					Ǡ 
					Connect the U-174/U jack plug for the headphones and the microphone to the   
					U-174/U socket of your intercom.   
					Ǡ 
					Connect the XLR-3 plug to the XLR-3 socket.   
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				2. Connecting the headset to the battery pack   
					(except HMEC 302, HMEC 305 and HMEC 306)   
					The NoiseGard™ electronics of the HMEC 300, HMEC 305-C, HMEC 322, HMEC 400 and   
					HMDC 322 headsets can also be powered via the BP-03 battery pack (ꢀ ‘Recommended   
					accessories’). The battery pack can be operated either on standard or rechargeable   
					batteries (not included in the delivery). However, to ensure a longer operating time, we   
					would recommend using standard AA size alkaline manganese batteries (IEC LR6). If   
					operated on rechargeable batteries, the operating time will be reduced to approx. 3   
					hours.   
					Inserting / replacing the the batteries   
					Ǡ 
					Ǡ 
					Open the cover of the battery compartment.   
					Insert four AA size alkaline-manganese batteries (IEC LR6). Observe correct polarity   
					when inserting the batteries.   
					Ǡ 
					Close the cover of the battery compartment.   
					LED operation and battery status indication   
					The battery pack has two control LEDs.   
					Green LED:   
					Red LED:   
					The battery pack is turned on and the battery capacity is sufficient.   
					The batteries are low. Replace the batteries.   
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				Connecting the headset, turning on the battery pack   
					Ǡ 
					Connect the XLR-3 plug of the headset connecting cable to the XLR-3 socket on the   
					connecting cable of the battery pack.   
					Ǡ 
					HMEC 300 and HMEC 400 headsets: Connect the 1/4” (6.35 mm) stereo jack plug   
					forthe headphonesand the PJ-068 jackplug forthe microphone to the corresponding   
					jack sockets of your intercom.   
					HMEC 305-C headset: Connect the XLR-5 plug for the headphones and the   
					microphone to the aircraft’s XLR-5 socket.   
					HMEC 322 and HMDC 322 headsets: Connect the U-174/U jack plug for the   
					headphones and the microphone to the U-174/U socket of your intercom.   
					Ǡ 
					Turn on the battery pack by setting the ON/OFF switch to ON. The green LED power   
					indicator lights up.   
					Note:   
					When using the battery pack, the ON/OFF switch integrated into the headset   
					connecting cable is out of operation.   
					Attaching the battery pack to clothing   
					The battery pack can be attached to clothing by means of the supplied attachment clip,   
					Velcro tape is also supplied.   
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				3. Connecting the headset via a cigarette lighter adapter cable   
					(except HMEC 302, HMEC 305 and HMEC 306)   
					Sennheiseroffersspecialadaptercableswith XLR-3 socket forconnecting the NoiseGard™   
					electronics of the HMEC 300, HMEC 305-C, HMEC 322, HMEC 400 and HMDC 322   
					headsets to the on-board power supply via the cigarette lighter socket:   
					• 
					• 
					ACX-1 adapter cable for powering one headset via the cigarette lighter socket   
					ACX-2 adapter cable for powering two headsets via the cigarette lighter socket   
					ACX-1   
					ACX-2   
					The adapter cables are also available with a right-angled jack plug featuring a 7.5 A fuse   
					and a green LED operation indicator:   
					• 
					• 
					ACX-11 adapter cable for powering one headset via the cigarette lighter socket   
					ACX-22 adapter cable for powering two headsets via the cigarette lighter socket   
					ACX-11   
					ACX-22   
					Connecting the headset   
					Ǡ 
					Connect the XLR-3 plug of the headset connecting cable to the XLR-3 socket of the   
					adapter cable.   
					Ǡ 
					Connect the plug or right-angled jack plug ofthe adaptercable to the cigarette lighter   
					socket.   
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				Preparing the headsets for use   
					Adjusting the headband   
					For good noise attenuation and best possible comfort, the headband has to be adjusted   
					to properly fit your head:   
					Ǡ 
					Ǡ 
					Wear the headset so that the headband runs over the top of your head.   
					Adjust the length of the headband so that   
					• your ears are completely inside the ear cushions,   
					• you feel even, gentle pressure around your ears,   
					• a snug fit is ensured.   
					Note:   
					Make sure not to squeeze any connecting cable when adjusting the headband.   
					Squeezing can damage the connecting cables.   
					Ǡ 
					Ǡ 
					Turn on the NoiseGard™ active noise compensation by setting the ON/OFF switch   
					to ON (ꢀ “Turning NoiseGard™ on/off”).   
					Final adjustment is best made in a noisy environment.   
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				Positioning the microphone   
					Relocating the microphone boom   
					The microphone boom can be worn on either side of the mouth.   
					Ǡ 
					Ǡ 
					Ǡ 
					Loosen the quick-fixing device.   
					Rotate the microphone boom by 180°.   
					Tighten the quick-fixing device.   
					Positioning the microphone towards the corner of the mouth   
					The HMEC 300, HMEC 302, HMEC 305, HMEC 305-C, HMEC 306, HMEC 322 and   
					HMEC 400 headsets feature a flexible 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.   
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				For positioning the microphone of the HMDC 322 headset, proceed as follows:   
					Ǡ 
					Adjust the length of the microphone boom so that the microphone is placed at the   
					corner of the mouth. To do so, loosen the quick-fixing device and adjust the   
					microphone boom in length.   
					Ǡ 
					Ǡ 
					Pull the middle part of the microphone boom towards the mouth so that the   
					distance between microphone and mouth is approx. 2 cm.   
					Tilt the microphone for final positioning.   
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				Additional information for helicopter use of the HMEC 322 headset   
					The polarity of the microphone connection in helicopters is not standardized. If the   
					microphone of your headset does not work with the existing polarity, you can reverse the   
					polarity on the headset by simply rotating the microphone module. To do so, please   
					proceed as follows:   
					1. Pull the wind screen from the microphone.   
					2. Loosen the screws by approx. half a turn.   
					3. Pull the microphone module from the boom-arm.   
					4. Rotate the microphone module by 180°.   
					5. Put the rotated microphone module back into the boom-arm.   
					6. Now tighten the screws from the other side.   
					7. Slide the windscreen over the microphone.   
					Rotating the microphone module does not change its acoustic properties. Due to its noise-   
					compensating pick-up pattern, the microphone can be used from either side.   
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				Using the headsets   
					Turning NoiseGard™ on/off   
					With the NoiseGard™ active noise compensation turned off, the headset can be used as   
					a conventional headset.   
					Turn on the NoiseGard™ active noise compensation by setting the ON/OFF switch to ON.   
					When using the BP-03 battery pack, set the NoiseGard™ ON/OFF switch to ON and use   
					the ON/OFF switch on the battery pack.   
					Mono/Stereo selection (except HMEC 305, HMEC 305-C, HMEC 322 and   
					HMDC 322)   
					In general, you’ll receive a mono sound source so that the Mono/Stereo switch can remain   
					set to “Mono”. When using a stereo intercom system, set the Mono/Stereo switch to   
					“Stereo”.   
					Adjusting the volume   
					Exposure to loud sounds can cause hearing damage!   
					Set the volume control to a medium value. Make sure that you can hear critical sounds   
					such as warning alarms.   
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				Mic Gain Adjustment   
					Adjusting the microphone gain   
					According to JTSO approval C58a, the microphone output voltage has to be factory-   
					preset to 400 mV. If this output voltage is too high or too low for your intercom system,   
					it can easily be re-adjusted on the microphone. To do so, use a small slotted screwdriver   
					and turn the ”Mic Gain Adjustment” screw (see illustration on the left) until you reach the   
					desired setting.   
					Attaching the cable clip   
					The headphone cable can be fixed by means of the cable clip. Guide the headphone cable   
					through the metal cable clip as shown in the illustration on the left. Attach the cable clip   
					to your clothing and then loop the cable through the clip so that the headphone cable   
					doesn‘t disturb you.   
					Folding up the headphones   
					For easy and space-saving transportation, the earcups can be folded up and tucked   
					between the headband.   
					Unfold the headphones by grasping both earcups and pulling them down and away from   
					the headband.   
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				Spare parts   
					The following spare parts are available from your Sennheiser agent:   
					• 
					• 
					• 
					• 
					• 
					Wind screen for MKE 45-1 electret microphone   
					Ear cushions   
					Headband padding   
					Cable clip   
					Carry and storage bag with shoulder strap   
					Replacing the wind screen   
					If the wind screen for the electret microphone shows signs of wear such as tears or holes,   
					replace the wind screen. Pull the wind screen from the microphone. Gently slide-on the   
					new wind screen and ensure that it fits securely over the microphone.   
					Replacing the ear cushions   
					Replace the ear cushions if they are damaged. Grasp behind the ear cushions and pull   
					them up and away from the earcups. Slide the new ear cushions onto the earcups.   
					For best results replace the ear cushions after 100 hours of use or two years.   
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				Replacing the headband padding   
					Replace the headband padding if it is damaged.   
					Ǡ 
					Pull the Ziploc type fastening strips of the headband padding apart and remove the   
					worn headband padding.   
					Ǡ 
					Ǡ 
					Put the new headband padding around the headband.   
					Pull the two edges of the headband padding together so that the fastening strips   
					slightly overlap.   
					Ǡ 
					Join the fastening strips.   
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				In case of difficulty   
					If problems occur that are not listed in the below table, please contact your Sennheiser   
					agent.   
					Problem   
					Possible cause and what to do   
					Clear communication but no   
					active noise compensation   
					The NoiseGard™ electronics are turned off.   
					Ǡ 
					Check to see if the ON/OFF switch is set to ON.   
					The XLR-3 plug has been pulled out of the power source.   
					Check to see if the XLR-3 plug is correctly connected to the power source.   
					If aircraft powered: The aircraft fuse is defective.   
					Check the aircraft fuse.   
					If battery powered (except HMEC 302, HMEC 305 and HMEC 306): The batteries are low.   
					Ǡ 
					Ǡ 
					Ǡ 
					Check to see if the green LED on the battery pack is lit. If the red LED is lit, replace   
					the batteries.   
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				Problem   
					Possible cause and what to do   
					Active noise compensation but   
					very low volume communication   
					The volume control is set too low.   
					Ǡ 
					Check the volume setting of the headset.   
					The headphone connection has been pulled out (except HMEC 305, HMEC 305-C and   
					HMEC 306).   
					Ǡ 
					Check to see if the headphone jack plug is correctly connected.   
					Active noise compensation but   
					reduced intelligibility   
					The microphone connection has been pulled out (except HMEC 305, HMEC 305-C and   
					HMEC 306).   
					Ǡ 
					Check to see if the microphone jack plug is correctly connected.   
					You are using a stereo intercom system but the headset is set to mono operation.   
					Set the Mono/Stereo switch to ‘Stereo’.   
					You are receiving a mono source but the headset is set to stereo operation.   
					Set the Mono/Stereo switch to ‘Mono’.   
					Communications in one ear only   
					(only HMEC 300, HMEC 302,   
					HMEC 306 and HMEC 306)   
					Ǡ 
					Ǡ 
					Re-adjust the output voltage on the microphone.   
					Microphone output voltage set   
					too high or too low   
					Ǡ 
					To do so, use a small slotted screwdriver and turn the “Mic Gain Adjustment” screw   
					(see illustration on page 133) until you reach the desired setting.   
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				Valuable information on NoiseGard™   
					The NoiseGard™ principle   
					One of the greatest stress factors today is noise. Research has shown that noise affects   
					the nervous system, and can cause tiredness, poor concentration, irritability and tension.   
					Of even greater concern is the permanent damage to hearing that can result from noise   
					at high levels.   
					This problem concerns pilots in particular. Cockpit noise amounts to about 80 dB(A) in jets   
					and to 90 up to 97 dB(A) in turboprops. During takeoff and landing, the noise level is even   
					higher. To be able to understand radio traffic in spite of the noisy environment, the ATC   
					signal level must be set to at least 95 dB(A). Permanent hearing loss caused by the   
					continuous noise in aircrafts is the reason why many pilots became prematurely disabled   
					or lost their pilot´s license.   
					Circumaural communication headsets provide noise attenuating properties and are   
					commonly used to address this problem. However, the noise attenuation of these   
					headsets is uneven. High frequencies are reduced considerably, but low frequency wind   
					and engine noise, the most prominent noise in manyoftoday'saircrafts, isattenuated very   
					little.   
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				In response to these problems, Sennheiser has developed an active noise compensation   
					system – NoiseGard™ – which, combined with a high-quality passive hearing protector,   
					provides consistent noise attenuation over the entire audio range. The overall noise level   
					is reduced so that the radio volume can be turned down but enough noise still remains   
					for the pilot to safely monitor the aircraft engines.   
					A 
					NoiseGard™ active noise compensation is achieved by generating a signal identical in   
					sound pressure level but exactly reversed in phase to the noise signal, the effect being that   
					the out-of-phase signal cancels most of the noise signal.   
					Active noise compensation isaccomplished in the following manner:Each earcup includes   
					a microphone, a feedback control circuit, and a transducer to reproduce both the   
					communication and the noise cancelling signal. The feedback control microphones sense   
					the total sound pressure within each earcup resulting from both the desired radio signal   
					from the receiver and the undesired noise that has come through the earcup. The   
					microphone signal is amplified and the radio signal is subtracted from it. The remaining   
					signal (noise) is then filtered and inverted and the radio signal is added back in. Eventually,   
					the entire signal is amplified and fed back to the transducer in each earcup. Since the noise   
					component ofthe signalisinverted, it cancelsthe noise signalcoming through the earcup.   
					The radio signal remains unaffected, as it was not processed through the cancellation   
					circuits.   
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				The above diagram shows noise compensation with NoiseGard™: Passive hearing   
					protectors effectively attenuate noise from the middle and upper frequency range, the   
					effect decreasing sharply in the lower range. However, active noise compensation with   
					NoiseGard™ combined with passive hearing protectors results in a reduction of noise of   
					approx. 25 dB in the 25–500 Hz frequency range. The total attenuation resulting from   
					active and passive noise compensation is about 30 dB over the entire audio range.   
					A 10 dB reduction in noise is perceived subjectively as a halving in volume. A further   
					reduction in noise of 10 dB again results in a decrease in unwanted noise by 50 % .   
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				Connector assignment   
					6 
					3 
					2 
					4 
					1 
					5 
					solder side   
					XLR-5 connector   
					Redel connector (NoiseGard™)   
					XLR-3 connector (NoiseGard™)   
					HMEC 305   
					HMEC 305-C   
					1 PowersupplyNoiseGard™(DC+) 1 Power supply NoiseGard™ (DC+) 1 Audio Hi   
					1 Audio Hi   
					2 Audio Lo / DC –   
					3 Audio Hi left   
					4 Audio Hi right   
					5 Microphone Hi   
					6 Microphone Lo   
					2 Ground   
					3 Do not connect!   
					2 Audio Lo / DC –   
					3 Microphone Hi   
					4 Microphone Lo   
					2 Audio Lo   
					3 Microphone Hi   
					4 Microphone Lo   
					5 Power supply NoiseGard™ (DC+) 5 Not assigned!   
					1 
					2 
					3 
					1 
					2 
					3 
					1 
					2 3   
					4 
					1/4” (6.35 mm) stereo jack plug   
					U174/U jack plug   
					PJ-068 jack plug   
					HMEC 302   
					HMEC 300   
					1 Audio Hi left   
					2 Audio Hi right   
					3 Audio Lo   
					1 Microphone Lo   
					2 Audio Hi   
					3 Microphone Hi   
					4 Audio Lo   
					1 PowersupplyNoiseGard™(DC+) 1 Not assigned!   
					2 Microphone Hi   
					3 Microphone Lo / DC –   
					2 Microphone Hi   
					3 Microphone Lo   
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				Technical data   
					HMEC 300   
					HMEC 302   
					HMEC 306   
					HMEC 400   
					Headphones   
					Transducer principle   
					dynamic   
					Ear coupling   
					Frequency response   
					Nominal impedance active/passive   
					circumaural, closed   
					45–15,000 Hz   
					300/150 Ω, mono   
					600/300 Ω, stereo   
					> 25 – 40 dB   
					Attenuation (active and passive)   
					Max. sound pressure level   
					Contact pressure   
					120 dB (± 5% )   
					approx. 10 N   
					Microphone incl. preamplifier   
					Transducer principle   
					Frequency response   
					Sensitivity   
					electret mic capsule, noise-compensated, MKE 45-1   
					300–5,000 Hz   
					– 
					Max. sound pressure level   
					Min. terminating impedance   
					Output voltage   
					120 dB   
					150 Ω   
					400 mV ± 3 dB at 114 dB (as per RTCA/DO 214)   
					Supply voltage   
					typ. 16 V DC (8 – 16 V DC, approx. 8 – 25 mA, as per RTCA/DO 214)   
					142   
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				HMEC 300   
					HMEC 302   
					HMEC 306   
					HMEC 400   
					General data   
					Connecting cable   
					Weight without cable   
					Power supply for NoiseGard™   
					Current consumption   
					Fuse   
					1.5 m, unilateral   
					370 g   
					12–35 V DC   
					27 mA (zero signal current), max. 80 mA   
					500 mA thermo fuse   
					Connectors   
					6.35 mm stereo jack plug 6.35 mm stereo jack plug 6-pin Redel plug for   
					6.35 mm stereo jack plug   
					for headphones,   
					PJ-068 jack plug for   
					mirophone,   
					XLR-3 for NoiseGard™   
					Mono/Stereo switch   
					for headphones,   
					PJ-068 jack plug for   
					microphone and   
					NoiseGard™   
					headphones, microphone for headphones,   
					and NoiseGard™   
					PJ-068 jack plug for   
					mirophone,   
					XLR-3 for NoiseGard™   
					Controls   
					On/off switch for NoiseGard™   
					Volume control for headphones   
					Temperature range   
					Operation   
					Storage   
					–15°C ... + 55°C   
					–55°C ... + 55°C   
					Operating time Battery pack   
					with batteries (four 1.5 V AA size alkaline-manganese batteries): approx. 15 hours   
					with rechargeable batteries: approx. 3 hours   
					143   
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				Technical data   
					HMEC 305   
					ȊHMEC 305-C   
					ȊHMEC 322   
					ȊHMDC 322   
					Headphones   
					Transducer principle   
					dynamic   
					Ear coupling   
					Frequency response   
					Nominal impedance active/passive   
					Attenuation (active and passive)   
					Max. sound pressure level   
					Contact pressure   
					circumaural, closed   
					45–15,000 Hz   
					300/150 Ω, mono   
					> 25 – 40 dB   
					120 dB (± 5% )   
					approx. 10 N   
					Ȋ 50/35 Ω, mono   
					Microphone incl. preamplifier   
					Transducer principle   
					electret mic capsule,   
					noise-compensated,   
					MKE 45-1   
					Ȋ dynamic mic capsule,   
					Ȋ noise-compensated,   
					Ȋ M-87/AIC   
					Frequency response   
					Sensitivity   
					300–5,000 Hz   
					– 
					Ȋ 500–4,000 Hz   
					Ȋ 1.8–4 µV / 74 dB at 5 Ω   
					Max. sound pressure level   
					Min. terminating impedance   
					Output voltage   
					120 dB   
					150 Ω   
					Ȋ –   
					Ȋ –   
					Ȋ –   
					Ȋ –   
					400 mV ± 3 dB at 114 dB (as per RTCA/DO 214)   
					typ. 16 V DC (8 – 16 V DC, approx. 8 – 25 mA, as per RTCA/DO 214)   
					Supply voltage   
					144   
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				HMEC 305   
					ȊHMEC 305-C   
					ȊHMEC 322   
					ȊHMDC 322   
					General data   
					Connecting cable   
					Weight without cable   
					Power supply for NoiseGard™   
					Current consumption   
					Fuse   
					1.5 m, unilateral   
					370 g   
					12–35 V DC   
					27 mA (zero signal current), max. 80 mA   
					500 mA thermo fuse   
					Ȋ coiled cable, unilateral   
					Connectors   
					XLR-5 for headphones,   
					microphone and   
					NoiseGard™   
					Ȋ XLR-5 for headphones Ȋ U-174/U jack plug for headphones and microphone,   
					Ȋ and microphone.   
					Ȋ XLR-3 for NoiseGard™   
					Ȋ XLR-3 for NoiseGard™   
					Ȋ 
					Controls   
					On/off switch for NoiseGard™   
					Volume control for headphones   
					Temperature range   
					Operating time Battery pack   
					Operation   
					Storage   
					–15°C ... + 55°C   
					–55°C ... + 55°C   
					with batteries (four 1.5 V AA size alkaline-manganese batteries): approx. 15 hours   
					with rechargeable batteries: approx. 3 hours   
					145   
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				Certificate of Conformity   
					Sennheiser electronic GmbH & Co. KG declare that this device conforms to the applicable CE standards and regulations.   
					Forup-to-date information on Sennheiserproducts, you can also visit the SennheiserWeb site at “http://www.sennheiser.com”.   
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