These days, it’s hard not to find solid-state microphones (micro-electromechanical systems, MEMS), as they are now replacing electret microphones almost everywhere due to their small size and low cost. Although MEMS loudspeakers are not impossible, creating a miniature loudspeaker that can displace a lot of air (‘volume’) and accurately reproduce a wide range of frequencies – unlike simple piezo whistles – is much more difficult. Here a startup called xMEMS shows that it has at least partially cracked the code using… Piezo Mims Loudspeakerswith the use of Creative Coil Release in their new brand Orvana Ice In-ear monitors.
The Cowell is a full-range speaker, but its sound pressure level (SPL) is not sufficient (~111 dB at 1 kHz) for use in active noise cancellation, which is why the Aurvana Ace also includes a conventional 10mm driver. The likely successor in the form of the Cypress is a small package (6.5 x 6.3 x 1.65mm) that claims an SPL of 143dB at 20Hz, which may be able to handle IEM ANC duty on its own.
According to xMEMS, what enabled the performance of these MEMS amplifiers was the use of silicon diaphragms (plates) combined with piezo elements. These structures can be generated with a certain degree of clarity on speakers, and according to early practical tests of the Aurvana Ace, the sound quality is very good. Since the MEMS speaker with this first product is mostly dealing with high-end hardware, the overall sound reproduction is a combination of the dynamic driver, the MEMS amplifier, and the DSP magic that brings it all together, so it’s hardly a fair assessment of the technology, but it would be interesting Interesting to see where it goes from here. Who wouldn’t want to have a lightweight 1 x 1m PCB that’s a 1500W RMS level speaker, or just laptop speakers that don’t sound terrible?
Top image: XMems Cowell MEMS-based amplifier on top of the dynamic driver. (Credit: xMEMS)
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