HAMT-1 - MondoAudio
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REPRODUCING THE RECORDED ARTS
FEBRUARY 2015 -120
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PRECISIÓN
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= ENGINEERING
FROM CH
by Alan Sircom
he 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
stil a work-in-progress, although its 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 | 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 %" jack adaptor. The oBravos use the same
screw-in terminals used by HiFIMAN, which meant | have a set
of excellent Vertere cables made for my HE-500s to compare.
EQUIPMENT REVIEW
oBravo HAMT-1 headphones
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. | 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
[oi 32 ISSUE 120
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!
п 33
“VIEW / OBRAVO HAMT-1 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.
|
EQUIPMENT REVIEW / OBRAVO HAMT-1 HEADPHONES
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 Wiliams 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 HAMI-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! +
TECHNICAL SPECIFICATIONS
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/1TW/1m: 105dB
Impedance: 56 Ohm
Sound pressure level: 105 dB
Supplied with: fight case, bag, monocrystal signal cables
with mini-jack connector. Mini-jack to "4" adaptor
Weight: 543g
Price: £1,499
М
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anufactured by: oBravo:
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\C
RL: www.obravoaudio.com
Distributed by: Absolute Sounds
Tel: +44(0)208 971 3909
URL: www.absolutesounds.com
Xd 35 Issue 120
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