The Taipei-based electronics maker oBravo (more accurately Stymax, although as that sounds like a treatment for conjunctivitis in horses, most people run with the oBravo name) has been quietly designing audio products for almost a decade, but it wasn’t until it showed the distinctive HAMT-1 headphone that it’s name became more well-known beyond its native Taiwan.
The HAMT-1 was one of two similar-looking headphones shown by the brand in 2014. The cheaper HRIB-1 is currently still a work-in-progress, although it’s a regular fixture on the headphone show scene, but the HAMT-1 arrived last year, and is making a lot of friends wherever it hits. The difference between the two is obvious by the initials; both hybrid designs with conventional dynamic bass units, the HRIB-1 features a ribbon tweeter, while the HAMT-1 sports a 40mm AMT tweeter. Heil’s clever Air Motion Transducer is a folded ribbon tweeter held in an array of high-performance magnets. The AMT is difficult to make (it’s inherently hand-made, takes time to construct, and requires highly-skilled workers to manufacture), which means it’s expensive, but the linearity of high-frequency sound it produces makes it worth the effort.
This tweeter sits at the acoustic centre of a 57mm cone mid-bass driver with a neodymium magnet system, making this a true coaxial design. Between them, they are claimed to deliver a frequency response from 15Hz-45kHz, although it’s worth remembering that headphones are not expected to (or, for that matter, recommended to) deliver a truly flat frequency response, so placing +/- decibel limits is worthless.