HEDD HEDDphone Reference Open-Back AMT Studio Headphones

The HEDD HEDDphone are premium open-back reference headphones built around a full-range Air Motion Transformer (AMT) rather than a conventional dynamic or planar magnetic driver. Developed for critical studio monitoring and high-resolution listening, they extend HEDD Audio’s AMT expertise from professional loudspeakers into a full-range headphone system.

At the heart of HEDDphone is the Air Motion Transformer, an electrodynamic transducer based on a folded diaphragm. Instead of moving back and forth like a conventional piston-style driver, the diaphragm folds compress and expand, forcing air between them. This architecture enables exceptionally rapid air movement and fast transient behaviour.

To adapt the AMT principle from its traditional high-frequency role to full-range headphone reproduction, HEDD developed VVT — Variable Velocity Transform technology. VVT introduces a modified diaphragm geometry in which the folds vary in both width and depth, allowing the AMT principle to operate across a much broader frequency range.

The resulting full-range AMT driver is designed to reproduce fine transient information with high precision while maintaining control from deep bass through the upper frequencies. Its architecture places particular emphasis on speed, resolution and the accurate reproduction of small dynamic changes within a recording.

The open-back construction allows the transducers to interact freely with the surrounding air and minimizes acoustic reflections inside the earcups. This contributes to a spacious presentation with clearly defined depth and separation, particularly useful when evaluating stereo placement, ambience and complex arrangements.

With a specified frequency response of 10 Hz to 49 kHz, HEDDphone extends considerably beyond the conventional audible spectrum. The combination of the full-range AMT and VVT architecture is designed to maintain detailed reproduction across this unusually broad operating range.

An impedance of 42 ohms is combined with a relatively low sensitivity of 87 dB SPL / 1 mW. While the impedance itself is moderate, the sensitivity means HEDDphone benefit from a capable headphone amplifier able to provide sufficient power and headroom, particularly for demanding studio or high-resolution listening applications.

The headphones use a dual Mini XLR cable connection, providing separate connections to the left and right earcups. This professional connection architecture also facilitates cable replacement and integration with different high-end monitoring configurations.

The HEDDphone concept builds on decades of AMT development associated with HEDD founder and engineer Klaus Heinz, whose work evolved the original Air Motion Transformer principle developed by Oskar Heil. In HEDDphone, that technology is implemented as a broadband transducer rather than being limited to a tweeter.

By combining a full-range Air Motion Transformer, VVT diaphragm geometry and open-back architecture, the HEDD HEDDphone provide an unconventional reference monitoring system for producers, engineers and demanding listeners who prioritize transient precision, spatial information and high-resolution reproduction.

Specifications

• Brand: HEDD Audio
• Model: HEDDphone
• Type: reference studio headphones
• Acoustic design: open-back
• Form factor: over-ear
• Transducer type: full-range Air Motion Transformer (AMT)
• Diaphragm technology: Variable Velocity Transform (VVT)
• Frequency response: 10 Hz – 49 kHz
• Impedance: 42 Ω
• Sensitivity: 87 dB SPL / 1 mW
• Cable connection: 2 × Mini XLR
• Cable system: dual-entry
• Signal connection: analogue
• Primary applications: critical monitoring, professional studio work and high-resolution listening