Balanced Mode Radiators (BMRs) are designed to provide wide directivity output up to the highest frequencies from a single transducer, ensuring clear intelligibility throughout the room.

Find BMRs in everything from smoke alarms to sound bars, in the most compact of applications. They’re also ideal for home theaters, computers and docking stations, where ample space is at a premium.


Described compactly, a BMR is the practical realization of the ideal acoustic radiator; a free, flat disk driven by a perfect force. This ideal radiator has flat on-axis SPL and a smooth, extended sound power response (SWL).

Unfortunately, there is no such thing as a perfect force and to drive the disk a voice coil must be added which introduces mass. A BMR balances for the effect of the added voice coil mass and recovers the ideal radiator performance.

At low frequencies the diaphragm moves as a rigid piston, but at higher frequencies the diaphragm becomes modal (modes are standing wave vibration patterns). This carefully controlled modal behavior, superimposed with the underlying piston movement, ensures that the drive unit does not ‘beam’, maintaining wide directivity up to the highest frequencies.



Flexible Placement Options

Wide directivity is achieved over full frequency range in a single driver, regardless of size, so clear intelligibility is maintained throughout the space even when the listener is significantly off-axis to the speaker. This means that people throughout the room, side-to-side, front-to-back, all have the same experience regardless of where they're seated or standing.

Better Human To Machine Interaction

Smart Speakers are a classic example of human-machine interaction. Just as weak microphone pick-up or mistranslation of the users request in the cloud will hinder that communication path, poor intelligibility or un-naturalness of the speaker’s sound character can be irritating and hinder the interaction.
The wide directivity and smooth frequency response characteristic across the whole audible range of BMR drive units ensures that at least this portion of the human-machine interaction is maintained at the highest level.

Single Speaker Amplification Channel

Covering the full range of audibility or speech with conventional speakers often requires two or more drive units (e.g. mid-bass and tweeter drive units) to adequately fill the required space. This necessitates the use of either two amplifier channels with active filtering or a single channel with a passive crossover.
A single BMR drive unit can cover the whole range avoiding detrimental cross-over components or multiple amplifier channels. If a fuller range is required a BMR can be crossed-over to a bass driver outside of the critical voice range and well away from the audibly sensitive 1 – 3kHz region dictated by most tweeters.


Wide Directivity

By utilizing carefully optimized bending wave modal behavior in the drive unit diaphragm a BMR can maintain wide directivity up to the highest frequencies, even in BMR drive units with relatively large radiating diameters where a conventional drive unit would be significantly beaming its higher frequencies into a narrow cone.

Off-Axis Speech Intelligibility

By maintaining the wide directivity from a single drive unit even to high frequencies, a BMR maximizes the intelligibility with the minimum number of sources. Of course multiple sources can be used (e.g. two or three conventional drive units), however this can cause complex interference patterns in the sound radiated into the room, phase interactions and timing smear – all of which adversely affect speech intelligibility and musical enjoyment.

Design Simplicity

Due to the full range coverage produced from a BMR drive unit, a single amplifier channel can be used, saving weight and cost, and designers are free to explore aesthetic flexibility.