Velodyne CHT-12Q User manual

40 | Australian Hi-Fi40 | Australian Hi-Fi
equipment review
though it also has an equally large number
with infinite baffle enclosures! Indeed this
time around it was my turn to be surprised by
the sheer number of models Velodyne has in
its range—it’s quite incredible!
What is also incredible is that the CHT-12Q
has Velodyne’s auto-equalisation circuitry,
which automatically adapts the frequency
response of the subwoofer for best results in
your room. To use it, all you have to do is
position Velodyne’s tiny microphone at your
usual listening position, using the miniature
microphone stand that’s also supplied, and
plug the other end of the microphone lead
into the mini socket on the front panel of the
subwoofer that I mentioned earlier (which
is so much more sensible than putting the
socket on the rear, as was the case with earlier
Velodyne subwoofers!). Then—after making
sure the CHT-12Q is switched on, all you
have to do is press the ‘EQ’ button on the
remote. That’s it. In a few moments you’ll
hear the first of a series of frequency sweeps
and, after 40 seconds or so, the job is done
and you simply disconnect the microphone,
lead and microphone stand and pack them all
away for if you ever need to use them again.
I should note that you don’t have to use the
auto-tuning if you don’t want to. If you just
plug the CHT-12Q into mains power and
connect the LFE output of your AV receiver
to the LFE input on the rear panel of the
CHT-12Q, you can be up-and-running with
just a flick of the on/off switch and a push of
the volume control. However, the simplicity
of the calibration procedure is such that it
will only take a few extra minutes, so why
wouldn’t you?
Unfortunately, although the inbuilt
calibration can match the CHT-12Q to your
room, it can’t match its output to that of
your main speakers or to your AV receiver.
So you will still have to set the CHT-12Q’s
high-pass control and volume control by
ear—as you would with all other subwoofers.
If your AV receiver is a recent model and has
its own inbuilt calibration, you can use this
to aid set-up. However, note that you must
always run the CHT-12Q calibration BEFORE
you run your AV receiver’s calibration. (Also,
since most AV receivers have only a limited
calibration range, it’s still better to set up by
ear first, and then run the two automated
calibration routines.
When the Velodyne equalises itself, it does
so for the flattest response, which it then makes
available ‘au naturel’ in the Jazz/Classical
preset position. This ensures tight, clean,
extended—and perhaps most importantly—
accurate bass response, but when you’re
playing video games, or watching an action
movie, you don’t necessarily want accurate
bass, you want ‘oomph’ and excitement!
This is where the other three presets come in:
‘Movies’, ‘R&B/Rock’ and ‘Games’. The titles
are self-explanatory, but of course you can use
any setting you like, no matter what you’re
doing. If you’re playing a video game and
you think the game sounds the best when
you’re using the ‘Movies’ preset, then use the
‘Movies’ preset! There are no rules.
The CHT-12Q’s driver has a cone of
reinforced fibre that’s driven by a two-layer
copper voice coil. I measured the cone as
being 330mm in diameter overall, a little
larger than claimed by Velodyne, but the
Theile/Small diameter is 258mm, which
gives a cone area (Sd) of 523cm². The bass
reflex slot beneath measures 345×31mm.
The amplifier plate on the rear has the usual
rotary low-pass crossover filter, but it works
‘backwards’ to usual, so that the subwoofer
operates at its maximum bandwidth (120Hz)
when the control is fully counter-clockwise,
and at its minimum (40Hz) when it’s fully
clockwise. The crossover slope is 12dB/octave
(24dB/octave ultimate). The volume control is
far from conventional, being push-button(s)
rather than rotary. (However the only time I
can imagine you would use the push-buttons
is if you have mislaid the remote or let the
batteries run flat.) Below the volume control
is a two-position slider switch marked ‘Stand-
by’ and ‘Always On’ that self-evidently
Velodyne obviously intends its CHT-Q
Series subwoofers to be used in home theatre
applications. This is not mere supposition on
my part: it’s printed right there on the front
of the Owners’ Manual: ‘Remote Controlled
Home Theatre Subwoofers.’ However, proving
that you can have your cake and eat it too, I
found that I would be more than happy to use
Velodyne’s CHT-12Q in an audiophile-quality
home hi-fi system.
The Equipment
Upon opening the packaging, and placing
this relatively small subwoofer (and I mean
small—it’s only 457mm high, 381mm wide
and 495mm deep) on the floor, the very first
thing I did was remove the front grille, be-
neath which I found something surprising.
No, it wasn’t the input for a microphone—I
quite expected that. What was unexpected
was the slot at the bottom of the front panel.
I had been labouring under the impression
that all Velodyne’s subwoofers used infinite
baffle enclosures, yet here was the CHT-12Q
with a bass reflex enclosure… though I noted
when reading the specifications that Velo-
dyne obviously prefers to call it ‘slot-loaded
bass reflex.’
I was actually quite pleased about the bass
reflex port, because although infinite baffle
(sealed) subwoofers have extraordinarily
smooth and extended bass, bass reflex
subwoofers are far more efficient (because
they harness the energy from the rear of the
cone that is completely lost in an infinite
baffle design) and because I personally think
the bass from a reflex enclosure has a little
more bottom-end ‘punch’—especially on
transients—which I particularly like, and
therefore I am prepared to trade this against
a slight loss of deep bass extension. However,
when I did a quick check-up via the miracle
of the Internet, it transpired that I was
labouring under a mis-impression regarding
Velodyne using only infinite baffle, because
Velodyne actually has a very large number
of subwoofers with bass reflex enclosures…
Velodyne
CHT-12Q
Subwoofer
(DEQ-12R*)
*Velodyne Note: Outside North America, the DEQ-R is known as CHT-Q.

LAB REPORT
Readers interested in a full technical
appraisal of the performance of
the Velodyne CHT-12Q Subwoofer
should continue on and read the
LABORATORY REPORT published
on the following pages. Readers
should note that the results
mentioned in the report, tabulated
in performance charts and/or
displayed using graphs and/or
photographs should be construed
as applying only to the specific
sample tested.
Australian Hi-Fi | 41Australian Hi-Fi | 41
lowest bass of any available musical recording:
‘Big Notes’ (DMP CD-454). You have to like
Flim and the BBs, but if you do, about five
minutes into Funhouse you’ll hear a note at
5Hz.
My favourite deep bass movie is still Jurassic
Park, and I can confirm that when listening
through the Velodyne, T Rex really stomps!
Yes, Maria, the earth truly does move… but
it’s not just the depth of the bass, even with
movies that don’t have extended bass, the
Velodyne’s performance was such that it
always provided a superb foundation for car
crash scenes, explosions, special effects… all
manner of cataclysmic events. Throughout it
all, I have to say that with rare exceptions,
no matter what preset I started on, I always
gravitated back to Preset 1 when watching
movies, and most of the time, the Preset
remained on 1 even when I was listening to
music.
Conclusion
Music or movies, Velodyne’s CHT-12Q is a
great little subwoofer that will always have a
place in my heart as the subwoofer responsi-
ble for converting me to the joys of remote-
controlled subwoofing. Paul Cameron
on the top of the front panel because in my
listening room the sub sits directly below my
screen, so I would otherwise have found the
bright blue glow more than a little distracting.
However I also appreciated the fact that the
display was so large and bright when I did
want to read it, because I found it easy to read
from clear across the room, even without my
glasses!
I thought the most important test I
could make first-up was to establish whether
Velodyne’s high-tech circuitry actually made
a difference to the sound. So to evaluate
this, I first listened to the CHT-12Q set to
Jazz/Classical when it was fresh out of the
box, using the ‘factory’ setting, then without
changing anything at all, I equalised it for
my room and then listened again. Right from
the get-go, it was immediately obvious that
the sound had improved. It wasn’t, perhaps,
quite the earth-shaking difference I thought it
might be, but then again I thought the CHT-
12Q sounded very good straight ‘out-of-the-
box’ and my listening room is a particularly
subwoofer-friendly one, being of good
proportions and equipped with properly-
positioned bass absorbers.
Having established the CHT-12Q’s high-
tech credentials, the next step was to listen
to see how well it delivered its bass. I quickly
discovered that its bass response extended
further towards single-figure frequency figures
than was necessary for any of the CDs or DVDs
I have in my collection. By way of example,
one of my all-time favourite CDs, Enya’s
‘Watermark’, digs down to 27Hz, which may
come as a surprise to many of you. (Those of
you with similarly discerning musical tastes
to my own will be able to check this out by
replaying your own copy: it’s Track 10—The
Longships). Another surprise can be found
on jazz pianist Warren Bernhardt’s album
‘Reflections’ (DMP). Listen to Stone Ground
and you’ll hear a sustained synthesised note
at 23Hz! Then again, maybe the deep bass
on this disc isn’t so surprising, because DMP
also makes the disc that I understand has the
switches between signal-sensing activation
and ‘On.’ (There’s also a 240V on/off switch,
located adjacent to the fused three-pin IEC
socket.)
Velodyne provides a full set of inputs and
outputs on the CHT-12Q, with low-level L/R
inputs and L/R outputs via RCA sockets, with
the left-channel RCA input doubling as an LFE
input. High-level (speaker-level) inputs are
via banana/screw terminals. These terminals
have a fixed high-pass filter that turns over at
120Hz for the pass-through signal.
Last, but not least, there’s an IR input. This
enables you to run a wire to a remote infra-
red relay sensor, enabling you to locate the
subwoofer in a cupboard, or somewhere else
that would normally be out of range of the IR
signal from the remote.
Listening Sessions
I have always viewed remote controls for
subwoofers as superfluous to requirements,
simply because setting subwoofer volume is
usually a ‘set and forget’ operation, because
once you have correctly matched the vol-
ume against that of your main and surround
speakers, the subwoofer automatically ‘tracks’
whatever volume you set using your AV re-
ceiver, so there’s no real need to control vol-
ume remotely.
However, seeing that the CHT-12Q offers
so much more than an ordinary subwoofer, I
found the remote almost indispensable. And,
once I became accustomed to using it, I have
to admit that I found it very handy indeed,
to the point where I found myself fiddling
around with the volume far more than I ever
have with any subwoofer I have ever owned
or reviewed that didn’t have a remote control,
and finding that there were benefits in doing
so. I confess that whenever I watched a movie,
I also switched across all the presets, to make
sure I was getting the best impact from each
soundtrack… and even this switching became
more than a little ‘more-ish’. I did appreciate
the fact that you can use the remote to switch
off the rather large and rather bright display
• Auto - Eq
•Very small
•Remote control
•‘Backwards’
Lo-pass filter
Velodyne CHT-12Q Subwoofer
Brand:Velodyne
Model:CHT-12Q
Category:Subwoofer
RRP:$1,399
Warranty:Two Years
Distributor:Revolution Technologies
Address:30 Miller Street
Murarrie, QLD 4172
T:[phone]
F:[phone]
E:[email protected]
W:www.revolutiontechnologies.com.au

42 | Australian Hi-Fi42 | Australian Hi-Fi
test results
equipment review Velodyne CHT-12Q Subwoofer
Test Results
Velodyne’s CHT-12Q Subwoofer proved to
have a very flat and extended response in the
Jazz/Classical position, which is shown in
Graph 1. This trace, measured at three metres,
using pink noise as the test signal, is shown
unsmoothed (red trace) and smoothed to one-
third octave (black trace). You can see that
the frequency response extends from 30Hz
to 130Hz ±3dB. Velodyne specifies response
as 25Hz to 120Hz ±3dB, so you can see that
Newport Test Labs’ result shows the Velodyne
exceeds the specification at the high end,
and comes up only 5Hz short in the bass. Al-
though these differences between the spec and
the measurement are so small as to be com-
pletely insignificant, I should point out that
the ‘Movies’ preset boosts the low bass consid-
erably, so that using the ‘Movies’ equalisation
preset extends the bass down to 20Hz within
the ±3dB tolerance. (The lift is shown clearly
on Graph 3, and this trace is of the bass driver
only, without the contribution from the bass
reflex port.)
The second graph (Graph 2) shows the
nearfield responses of the bass driver and
the slot-shaped bass reflex port. You can see
that Velodyne’s engineers have got the port
working beautifully, with its maximum output
almost shelved between 30Hz and 50Hz. The
roll-off at high frequencies is smooth and
controlled and almost identical to the woofer
roll-off, so the re-inforcement between the
two is perfect. The roll-off below 30Hz is also
well-contoured.
Graph 3 shows the equalisation applied
by using the different presets, as well as the
differences in level between them. You can see
that if you are listening to the Jazz/Classical
preset (black trace) and switch to any of the
others, you get not only different frequency
contouring, but also a boost in output level.
Obviously the boost varies with frequency but
on average the increase is around 2.5dB. Note
that all these traces are of the bass driver only:
the contribution from the port has not been
factored in as it has been in Graph 1.
The final graph (Graph 4) shows the effect
on the frequency response of the bass driver
of using the maximum and minimum settings
of the low-pass filter. This shows exactly
what I would have expected, so Velodyne’s
specifications are spot-on. Although the port’s
output is shown on this graph, you should
note that its output has not been scaled to
compensate for the difference in radiating
area between it and the bass driver. However,
the extended horizontal scale of this graph,
compared to the other three graphs, has the
advantage of showing that the bass reflex port
does not produce any unwanted resonances
or ‘leaks’ at high frequencies. Overall, an
excellent set of results. Steve Holding
It’s important to remember that hav-
ing an onboard subwoofer calibration
system such as the one that is fitted to
Velodyne’s CHT-12Q is not a universal
panacea. If you put any subwoofer with
an automatic equaliser in a position in
the room for which it’s totally unsuited,
the circuit will be able to make the best
of it, but you’d be far better advised to
first find the position in the room where
the subwoofer sounds the best, and then
use the circuitry to make a good thing
even better.
The two main culprits that affect the
response of any subwoofer are room
modes (eigentones) and room load-
ing. Let’s look at loading first. If you sus-
pended an EQ-equipped subwoofer in
the middle of your room, well clear of any
boundaries, the computer would quickly
work out that this was a terrible position
and would dial in maximum low bass
boost. This means the internal amplifier
would likely be working flat-out
all the time, with the result that dynamics
would suffer. Obviously, in a real situation,
the subwoofer will at least be sitting on
the floor, so the low bass will be helped
along by being close to one boundary.
However, if you move an EQ-equipped
subwoofer close to a wall, so it’s interact-
ing with two boundaries, it will deliver even
more bass as a result, so less equalisation
would be required and the internal am-
plifier would have to work less hard. If you
place the subwoofer in a corner, where it
would ‘see’ three boundaries, the com-
puter would then very likely be able to at-
tenuate volume at low frequencies, rather
than boost it, which would have the effect
of freeing up amplifier power, and increas-
ing dynamic ability.
As for eigentones, they’re what result
when low frequencies interact with the phys-
ical dimensions of your room,so they’re very
difficult to eliminate—or even modify—with-
out resorting to moving walls and raising
ceilings.
The best way of dealing with them is to
use multiple subwoofers (at least two,
but ideally four!) but since this solu-
tion doesn’t appeal to many people
for reasons of both cost and aesthet-
ics, the next best option is to position
the subwoofer where you don’t excite
any.The only way to do this is by putting
the subwoofer in all the places you’d
like it to go, and choosing the position
where it sounds the best, and this is the
technique you’ll need to use with all
subwoofers, no matter whether they’re
equipped with auto-equalisation cir-
cuits or not.
Location, Location, Location