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.
The HAMT-1 is one of those ‘looks better in the flesh’ designs, although I don’t think it looks too bad in print, either. The whole package is top class; the cardboard slip-case opens out to a grey velveteen drawstring bag, emblazoned with the company’s logo. Inside that bag is a small Halliburton style aluminium case, again with the company logo inset into a discreet mirrored logo on its flank. Inside is a plush cloth (similar to Crumpler’s ‘Slip’ laptop screen and key cloth, but once again with the oBravo logo) and some foam inserts. Other case candy include a set of monocrystal headphone cables, and a mini-jack to ¼” jack adaptor. The oBravos use the same screw-in terminals used by HiFiMAN, which meant I have a set of excellent Vertere cables made for my HE-500s to compare.
The HAMT-1s themselves have that distinctive ‘Cyberman’ look most recently seen in Abyss headphones, although in oBravo’s version, the squared off headband isn’t adjustable for width. In fairness, it doesn’t need to be, as it uses its brown velvet/velour top pad to rest on the top of the listener’s head, and the arms of the ear-cups themselves are angled in. Adjustment is limited to ear-cup position, but the gimballed earcups themselves allow a lot of wiggle room. In truth, unless you are about six, are unlucky enough to be exceptionally cone-headed, or have a head the size of a basketball, the net result is comfy and doesn’t look as weird as you might expect. The brushed aluminium, the contrasting brown suede/velour head and ear pads, and the air-dried light wooden inserts (with the logo yet again) give it a surprisingly classy, and – initially at least – pleasantly aromatic, presentation. Also, while you do feel the oBravo resting on the top of your head (rather than a band across the top of your head), this is not a heavy headphone and long listening sessions are no more or less difficult than wearing a pair of Stax headphones. The ear-cups are large enough to cover most ears, but while these are closed cans, the do not massively attenuate the world beyond the headset, because there’s no feeling of being ‘clamped’. Also note, the HAMT-1 are not ‘handed’; left and right are defined by what channel cable you plug into the bottom of each ear unit.
Although the HAMT-1 comes with a mini-jack, realistically this is a headphone designed for home listening. They don’t leak sound too much, and a 56ohm impedance and 105dB sensitivity mean they are not hard to drive, but the combination of a fairly large physical appearance and the overall presentation demands high-performance domestic audio environments. Those sensitivity figures mean the HAMT-1 isn’t too amp fussy, and it’s more demanding of quality than quantity of power, however. oBravo also makes a lithium ion-powered headphone amp called, naturally, the HPA-1. While this model is not yet sold in the UK, this natural partner to the HAMT-1 ably demonstrates that a hulking great power amp masquerading as a headphone amplifier is not required to drive the HAMT-1 well. I used a Wadia 121 DAC/headphone amp, which drove the HAMT-1’s with consummate ease.
Running these headphones in, however, is mandatory, because the headphone sounds somewhat unbalanced straight out of the box. The AMT unit needs some hours to bed in, and prior to that it tends to sound recessed, and the dynamic driver for the bass tends to sound a little wild and overblown until it’s had a few hours of play-time. As a consequence, the headphone you hear when you open the box bears almost no resemblance to the one you hear a few days later. The change is one of the most significant I’ve heard from an audio component, up there with the rollercoaster of good and bad sound you get from a stone-cold and new Naim preamp. Fortunately, once the two drivers have formally introduced themselves to one another, things settle down nicely.
You can tailor the sound with an inexpensive (c. £30) optional kit, which allows you to take off the wooden back plate of the headphone and insert one of several sets of silicon grommets into the three small ports, thereby changing the tonal balance. Crazed bass-heads can mature into reflective string quartet enthusiasts without changing headphones!
Perhaps the most immediate aspect of the HAMT-1’s overall presentation is that the headphones don’t sound ‘headphone-like’ to those who think that a pejorative. A big part of that comes down to the extremely open, natural-sounding mid-range, which gives a sense a little more like a good electrostatic loudspeaker than a pair of normal closed ear ‘cans’ (an entirely appropriate term, given the design). But an even larger part of this acceptance by old-school audiophiles is the HAMT-1’s ‘scale’ like a pair of good dynamic loudspeakers. If you move from Ellie Goulding’s small-scale, well-recorded girl-with-guitar music up to something big and operatic (Opern Gala, on DG, for example), the HAMT-1 present both with the kind of physicality and size they demand. No 20-foot guitars or scrunched up orchestra pits here. That sense of scale is something few good speaker systems (whether in room or on head) can execute well, but it’s something at which the oBravo headphones excel.
There is an underlying sense of deep, powerful bass running through the HAMT-1 sound. This isn’t an artificial bass depth, and it doesn’t rumble along, turning folk into dub reggae; instead, it adds a degree of authority to the piano player’s left hand, a solid foundation to the bass player’s performance, and a sense of rootedness to drum kits. This comes across best on small-group jazz pieces; the classic ‘Cantaloupe Island’ by Herbie Hancock [Empyrean Isles, Blue Note] sees Hancock on piano, Ron Carter on bass, and Tony Williams on drums playing off one another’s rhythms, and the HAMT-1 picks up on that well, making the piece sound fresh and exciting, instead of anodyne and anaemic. This is helped by the mid and treble being able to perfectly portray Freddie Hubbard’s sublime cornet playing, and in the process helps to perfectly separate the instruments out without the album sounding too dissolute. That’s the joy of having your ear an inch or so from an AMT device.
The HAMT-1 headphones by oBravo deliver a uniquely audiophile-friendly sound, one that helps bridge the gap between the traditional audio world (that doesn’t ‘do’ headphones) and today’s buyers (who don’t ‘do’ loudspeakers). They are efficient enough not to need a brute amp and could even run from an iPhone, although it doesn’t show the HAMT-1 in the best light. Best of all though is the sound, which is at once deep and powerful, big and bold, and subtle and refined. It’s like strapping a little pair of Wilson Audio loudspeakers to your ears.
We’re not done yet, though. We’re keen to see just how much those grommets can change the tonal balance of the HAMT-1, which is a shameless excuse to hold on to a great set of headphones for another month or so!
- Type: two-way coaxial closed back headphones with AMT tweeter
- Drive Units: 40mm Air Motion Transformer (AMT) tweeter in acoustic centre of 57mm cone mid/bass with neodymium magnets
- Frequency Response: 15Hz-45KHz
- Sensibility in dB/1W/1m: 105dB
- Impedance: 56 Ohm
- Sound pressure level: 105 dB
- Supplied with: flight case, bag, monocrystal signal cables with mini-jack connector. Mini-jack to ¼” adaptor
- Weight: 543g
- Price: £1,499
Manufactured by: oBravo:
Distributed by: Absolute Sounds
Tel: +44(0)208 971 3909
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