At the end of the review of the oBravo HAMT‑1 headphones last month (http://www.hifiplus.com/articles/obravo-hamt-1-headphones/), I mentioned there was a grommet set designed to tailor the bass to suit ears, tastes, and systems, but wasn’t with me at the time of writing. As we went to press, it arrived, but something else happened between then and now.
It may not be a big thing, but the grommet set shows oBravo’s commitment to design. Just as the headphones themselves come in a small aluminium flight case, so do the grommets; it’s like an executive briefcase for Barbie or Ken. The case features a lot of small, white, silicone donuts and bungs of differing thickness, and an Allen key on a jeweller’s screwdriver. You unscrew the backplate of each HAMT-1 earcup, and insert the donuts or bungs in three equally spaced ports (a fiddly job), to tune the bass response accordingly. You could conceivably use a combination of grommets and bungs, too.
However, as I said, ‘something happened’. The headphones need a lot of hours of play before they come to life. More than expected, in fact. The HAMT-1’s initially improve, then plateau for the longest time before suddenly blossoming and integrating the bass perfectly.
The grommets were not wasted, though. They now become more a condiment than a spice, adding a touch of bass to taste rather than fundamentally changing the balance. Ultimately, I preferred the balance with the mildest grommets in place, but different tastes and especially different amplification may result in a very different conclusion.
To recap, the HAMT-1 has a sound reminiscent of really good loudspeakers. But, as the bass falls into line, the headphone pulls off the smart trick of sounding like a ‘dynamic electrostatic’ loudspeaker. It has the physicality of a dynamic loudspeaker and the top‑to‑bottom detail and tonal accuracy of an electrostatic loudspeaker. Put simply – wow!