Sennheiser HMDC 27 Audio headset, NoiseGard 600/200 (ANR on/off), circumaural, dynamic microphone, hypercardioid, cable not included - 506978

Product Overview

The Sennheiser HMDC 27 is a professional circumaural broadcast headset engineered for demanding communication environments where clarity and hearing protection are non-negotiable. It features Sennheiser's NoiseGard™ Active Noise Reduction technology, which selectively reduces ambient noise by up to 15 dB at both 600 Hz and 200 Hz frequency ranges, preserving full speech intelligibility without relying on batteries. The dynamic hypercardioid microphone delivers a powerful, focused pickup pattern that cuts through background noise to deliver broadcast-quality audio transmission even in loud on-air environments. Designed for broadcast commentators, audio engineers, and ATC communications professionals, the HMDC 27 sets the standard for high-noise-environment headset performance.

Product Description

The HMDC 27 is the flagship model in Sennheiser's HMD 27 broadcast headset series, combining exceptional wearing comfort with professional-grade noise management for long shifts in live production and communications environments. The circumaural, closed-back ear cup design provides natural acoustic isolation, while Sennheiser's NoiseGard™ Active Noise Reduction adds an additional 15 dB of noise attenuation on top of passive isolation — without requiring a separate battery, as it is powered by the phantom/microphone bias voltage from the connected broadcast desk or intercom system (P12–P48 per DIN EN 61938). The split two-piece headband design relieves pressure from the sensitive fontanelle, making the headset suitable for extended wearing sessions. A conventional wide headband padding is included in the box, allowing users who prefer a single-piece headband to convert the design instantly. The dynamic hypercardioid microphone boom can be positioned on either the left or right side to accommodate different operator preferences, and one ear cup swivels for single-sided listening when monitoring ambient sound. ActiveGard® protection (switchable on/off) automatically limits audio peaks above 110 dB SPL, safeguarding hearing during unexpected signal bursts. The modular cable concept means the HMDC 27 is compatible with the full range of Sennheiser Cable 26-II series cables — with multiple connector options available separately — so the headset adapts to any broadcast desk, intercom, or communications console. Accurate, linear headphone frequency response supports critical monitoring tasks, and the rugged construction meets the demands of daily professional use.

Key Features

• NoiseGard™ Active Noise Reduction (ANR) — Reduces ambient noise by up to 15 dB at 600 Hz and 200 Hz selectable bands; powered by microphone bias voltage (no batteries required).
• Dynamic Hypercardioid Microphone — Strong, focused pickup pattern rejects off-axis noise for high-intelligibility broadcast-quality voice transmission.
• Circumaural Closed-Back Design — Passive acoustic isolation combined with ANR for comprehensive noise management in loud environments.
• ActiveGard® Hearing Protection — Switchable on/off protection automatically limits audio peaks above 110 dB SPL to safeguard the operator's hearing.
• Split Two-Piece Headband — Eliminates pressure on the sensitive fontanelle for long-session wearing comfort; includes wide padding insert for single-piece conversion.
• Reversible Microphone Boom — Microphone can be positioned on either the left or right side to suit individual operator preference.
• Swiveling Ear Cup — One ear cup swivels for single-sided monitoring when ambient awareness is needed.
• Phantom-Powered ANR — NoiseGard™ is powered via P12–P48 microphone bias voltage from the broadcast desk or intercom, eliminating the need for separate batteries.
• Modular Cable System — Compatible with Sennheiser Cable 26-II series; multiple connector options available separately to match any console or intercom.
• Accurate Linear Headphone Response — Precise, uncolored monitoring for audio engineers requiring faithful reproduction.
• Rugged Professional Construction — Built to withstand the rigors of daily use in broadcast studios, OB trucks, and ATC environments.

Typical Applications

• Broadcast commentary and sports commentary positions
• Radio and television production studios
• Outside broadcast (OB) trucks and mobile production units
• Air traffic control (ATC) and aviation communications
• Live event and concert audio engineering
• Intercom and program distribution systems
• Emergency communications and dispatch centers

Technical Specifications

Frequently Asked Questions

Q: Does the HMDC 27 require batteries for the NoiseGard ANR to work?

No. The NoiseGard™ Active Noise Reduction system is powered by the microphone bias voltage from the connected broadcast desk or intercom system (P12–P48 per DIN EN 61938), so no separate batteries are needed.

Q: What cable does the HMDC 27 use?

The HMDC 27 is sold without a cable. It is compatible with the full range of Sennheiser Cable 26-II series cables, which are available separately in multiple connector configurations to match your specific broadcast desk or intercom system.

Q: What is the difference between the 600 Hz and 200 Hz NoiseGard settings?

The two NoiseGard™ settings target different noise frequencies. The 600 Hz setting is optimized for environments with higher-frequency background noise, while the 200 Hz setting attenuates lower-frequency rumble and engine noise, making it particularly suited for ATC and aviation environments.

Q: Can the microphone boom be used on either side?

Yes. The microphone boom on the HMDC 27 is designed to be positioned on either the left or right side of the headset, accommodating individual user preference or console layout requirements.

Q: What does the split headband design mean, and can it be converted?

The split two-piece headband distributes pressure away from the sensitive fontanelle at the top of the head, which improves comfort during extended shifts. A wide headband padding insert is included in the box, which converts the two-piece split design into a conventional single-piece headband for users who prefer that style.

Q: What is ActiveGard and how does it work?

ActiveGard® is Sennheiser's switchable hearing protection feature. When activated, it automatically limits audio peaks above 110 dB SPL to protect the operator's hearing during unexpected loud signal events, such as feedback bursts or electrical interference.

Q: Is the HMDC 27 suitable for air traffic control use?

Yes. The combination of active noise reduction, a dynamic hypercardioid microphone, circumaural passive isolation, and ActiveGard® hearing protection makes the HMDC 27 well suited to ATC and other aviation communications environments.

Q: Where can I purchase the Sennheiser HMDC 27?

The Sennheiser HMDC 27 broadcast headset is available at creationnetworks.net.