Sennheiser HMD 27 Broadcast Headset, Dynamic Mic

Sennheiser HMD 27 Professional Circumaural Broadcast Headset

The Sennheiser HMD 27 (Current Article Number: 700322, Legacy: 506976) is a premium, heavy-duty closed-back circumaural (over-ear) broadcast headset designed specifically for professional commentators, sports announcers, and live event production crews.

The "D" designation within the 27-series family specifies its core hardware configuration: it features a high-output, broadcast-grade dynamic microphone capsule. This choice makes the headset incredibly robust, capable of capturing highly detailed vocal tracking without requiring external phantom power, and exceptionally resilient against loud ambient spikes common in crowded arenas and sideline reporting.

Key Acoustic and Operational Attributes

• BMD 434 Dynamic Hypercardioid Capsule: Outfitted with a high-performance dynamic microphone element optimized for maximum speech intelligibility. Its tight hypercardioid polar pattern provides excellent off-axis rejection, ensuring that background stadium roar, PA bleed-through, and nearby crowd noise are kept out of the broadcast audio feed.

• Onboard Switchable ActiveGard Limiter: Features an analog, mechanical switch-controlled ActiveGard circuit. When toggled on, it acts as an automatic safety buffer that tames unexpected incoming signal bursts over 110 dB SPL to shield the operator's hearing.

• Pressure-Free Two-Piece Split Headband: Uses an automatically opening split headband structure that spreads apart to shift pressure away from the sensitive areas of the skull. A wide, solid padding wrap is also included in the box for engineers who prefer a traditional single-band profile.

• Swiveling Ear Cup for Single-Side Monitoring: The mechanical hinge holding the ear cups allows for a brief single-sided listening configuration. Operators can flip one ear cup completely off the ear to track immediate ambient venue cues without removing the headset entirely.

• Modular Multi-Pin Connection Base: Ships from the factory with an un-cabled connector socket. This modular design interfaces with Sennheiser's Cable-II series (such as the X3K1 XLR/1/4" combo cable), allowing technicians to replace damaged lines instantly or swap connection formats in the field.

Technical Specifications Matrix

In the Box: Production Package Inventory

• 1 x Sennheiser HMD 27 Broadcast Headset (Dynamic)

• 1 x Broad Single Headband Converting Cushion

• 1 x High-Density Wind and Pop Screen

• 1 x HZS 11 Cable Attachment Anchor Clip

• 1 x Quick Start Technical Guide

• (Note: Connection cables are sold separately according to studio infrastructure needs).

Field Configuration and Customization Advice

Configuring the ActiveGard System Switch: Underneath a small plastic cover on the side of the ear cup housing sits the micro-switch toggle for the ActiveGard hearing protection circuit. If you are working a live broadcast with a high risk of unexpected signal spikes (such as sudden satellite feedback or stadium crowd audio peaks), ensure this switch is set to "ON." If you are checking pre-recorded master media or balancing tracks where uncompressed dynamic headroom is needed up to its maximum thresholds, slide the switch to "OFF."

Optimizing the Hypercardioid Boom Placement: The flexible microphone boom can be rotated 270 degrees, enabling left or right-side wear. Because the hypercardioid capsule is designed for maximum background rejection, precise placement is vital for a full vocal tone. Bend the flexible gooseneck to position the capsule roughly 2 centimeters out from the corner of your mouth. Avoid placing it directly in front of your lips to minimize low-end pop distortion caused by direct breathing blasts.