Sennheiser HMEC 25-CA Active noise compensation with NoiseGard, Switching the power supply on/off

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HMEC 25-KA / HMEC 25-CA

A headset is comprised of two units, a headphone and a microphone. The HMEC 25-KA/-CA headset is mostly used for communication in aircraft cockpits.

￿The microphone is a high quality back-electret condenser microphone. As per ARINC it receives its operating voltage via a connector from the aircraft´s internal power supply.

￿The headphone is a Sennheiser NoiseGardsystem. This is a dynamic headphone system which, in addition to reproducing the original audio signal, electronically cancels the low frequencies of the ambient noise. This active noise compensation operates on the principle that sound and ”anti-sound“ (in phase opposition) cancel each other out. The NoiseGardcompensation circuitry in the headphone requires an extra power supply, so a battery com- partment has been integrated into the headset cable (see illustration on the right).

Clearly intelligible communication is ensured, and the pilot no longer has to turn the volume up to overcome ambient noise.

NoiseGardincreases your comfort,

but it is not a medical hearing protection!

Active noise compensation with NoiseGard

Noise compensation HMEC 25

Reduction/dB

0

10

active

passive

 

 

20

 

 

30

40

20

100

1000

10000

20000

 

 

 

Frequency/Hz

Inserting the batteries into the battery box

The NoiseGardcompensation circuitry is powered via a battery pack integrated into the headset cable. Insert two AA size batteries into the box as shown in the digram below.

Switching the power supply on/off

The on/off switch for the power supply of the compensation circuitry is at the front of the battery box.

Pilot light

An LED on the battery box indicates the battery status:

￿When the LED lights up green, the power supply for the compensation circuitry is sufficient.

￿When the LED is red, the batteries are almost flat and should be changed immediately. The NoiseGardsystem is still operational.

￿If the LED does not light up at all when the power supply is switched on, the batteries are completely flat. The headset is still operational but without the noise compensation.

The microphone is powered by the aircraft‘s internal power supply. Thus, it is independent of the batteries and always remains operational.

ON/OFF

LED

12

13

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Contents Hmec 25-CA Hmec 25-KA Schallpegel von Lärmquellen LautLeise Lärm wo begegnet er uns nicht?Kontroll-LED Geräuschkompensation mit NoiseGardEinlegen der Batterien im Speiseteil EIN- / AusschaltenKopfbügel einstellen Mikrofonarm einstellenLaut hören ? Nein Blockschaltbild Hmec 25 KA Blockschaltbild Hmec 25 CALieferumfang Quiet LoudPilot light Inserting the batteries into the battery boxSwitching the power supply on/off Active noise compensation with NoiseGardAdjusting the headband Adjusting the microphone boomVolume up? no Hmec 25-KA Block Diagram Hmec 25-CA Block DiagramBas HautLED témoin Compensation du bruit avec NoiseGardComment insérer les batteries dans le boitier piles Comment allumer ou éteindre la compensation de bruitComment ajuster le bras du microphone Pousser le volume ? NONComment ajuster l´arceau du casque Schema fonctionel Hmec 25-KA Schema fonctionel Hmec 25-CALivello di pressione acustica delle sorgenti sonore Microphone, préamplificateur inclusCaractéristiques générales Rumore Dove nonv lo incontriamo ?LED di controllo Compensazione del rumore comn NoiseGardInserimento delle pile nellalimentatore Inserimento/disinserimentoRegolazione del braccio del microfono Ascoltare ad alto volume? noRegolazione della staffa per la testa Schema a blocchi Hmec 25 KA Schema a blocchi Hmec 25 CABajo AltoConexión y desconexión Hmec 25-CA / HME 25-KACompensación de ruidos con NoiseGard Colocación de las pilas en el bloque de alimentaciónAjuste del brazo del microfono ¿Oir a alto volumen ? ¡NOAjuste de los aros del auricular Diagrama de bloques Hmec 25 KA Diagrama de bloques Hmec 25 CAZacht LuidControle LED Geluidscompensatie met NoiseGardBatterijen in het voedingsgedeelte plaatsen In-/uitschakelenHoofdbeugel instellen Microfoonarm instellenLuid luisteren ? Neen Blokschakelschema Hmec 25 KA Blokschakelschema Hmec 25 CAAlgemene specificaties Microfoon incl. voorversterker
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HMEC 25-CA specifications

The Sennheiser HMEC 25-CA is a professional-grade closed-back headset designed to deliver exceptional audio quality and comfort for users in various demanding environments, including aviation, broadcasting, and military applications. Renowned for its robust construction and advanced technology, this headset has become a trusted choice among professionals who require reliable communication and accurate audio reproduction.

One of the standout features of the HMEC 25-CA is its closed-back design, which provides excellent passive noise isolation. This characteristic is crucial for users in noisy environments, as it helps to minimize external sounds and allows for clear communication and focus on the task at hand. The comfortable ear cushions contribute to prolonged wearability, ensuring that users can remain engaged for extended periods without experiencing discomfort.

The headset is equipped with noise-canceling technology, allowing it to effectively suppress background noise while enhancing voice clarity. This feature is particularly beneficial in aviation and military scenarios where clear communication is critical. Whether communicating with a co-pilot or coordinating with team members, users can rely on the HMEC 25-CA to deliver crystal-clear audio.

Another important aspect of the HMEC 25-CA is its versatility. The headset is compatible with various communication systems, making it suitable for a wide range of applications. Additionally, its dual plug configuration ensures easy connectivity to different devices, enhancing its functionality across platforms.

The adjustable headband and rotating ear cups further improve the user experience, allowing for a personalized fit and optimal comfort. The durable construction of the headset also means it can withstand the rigors of professional use, ensuring longevity and reliability even in challenging environments.

In summary, the Sennheiser HMEC 25-CA is a top-tier headset that combines comfort, advanced noise-canceling capabilities, and versatile connectivity. Its robust design and high-quality audio performance make it a favorite among professionals who require dependable communication equipment. Whether used in aviation, broadcasting, or other critical fields, the HMEC 25-CA stands out as a reliable companion, ensuring that users can communicate effectively without compromise.