Hardware Autopsy
and ceiling to refl ect and disperse the sound
waves, audio events arrive at your ear at pre-
cisely the right moment and trick your brain
into perceiving the sounds in parts of your
room with no speakers.
Both the Yamaha and the Pioneer digital
audio projectors are thin enough to mount
on the wall, either beneath a fl at-screen tele-
vision or behind a video-projector screen.
Both systems also feature built-in software
that allows you to confi gure their speaker
arrays for a variety of room and furniture
confi gurations (using an onscreen display),
virtually eliminating the need to arrange your
furniture around your A/V system.
DAP technology is not without its critics,
who point out that the solution relies heavily
on several unknowable variables, including
room dimensions; where the digital audio
projector will be placed within the room;
and the confi guration of walls, ceilings,
furniture, and other sound-refl ecting objects
in the room. In a room with a cathedral
ceiling, for instance, it might be diffi cult to
correctly time the bounce of sound waves
off that surface. The same goes for oblong
rooms with walls that are not equidistant or
that have a large opening on one side, but
not the other.THE FUTURE OF DIGITAL
AUDIO PROJEC TORS
Believe it or not, many of the surround-
channel speakers in the home-theater
systems purchased today end up being put
back in the box, never again to see the light
of day. For many folks, the required wiring
and calibration end up being just too much
of a hassle. Pundits predict that digital audio
projectors are the answer, and they’re fore-
casting a bright future for the technology.
After all, why run wires to inconvenient sur-
round-sound speakers when you can install
one audio projector under your TV?
Besides being housed in stand-alone
units like the Pioneer and Yamaha models
discussed here, digital audio projectors
could easily be integrated into next-genera-
tion fl at-panel displays. And if the technology
catches on in either implementation, prices
should drop rapidly as economies of scale
kick in. Analysts expect $500 price tags to
be the tipping point for the technology to
achieve mainstream acceptance.
Because you don’t need a sepa-
rate amplifier, don’t need to drill holes
in your walls, and don’t need to snake
speaker cable all over the living room,
digital audio projectors should render
the spouse factor a non-issue for many
home-theater enthusiasts.r & d BREAKING DOWN TECH —PRESENT AND FUTURE
58 MA XIMUMPC OCTOBER 2005 OCTOBER 2005 MA XIMUMPC 59
White Paper: Digital Audio Projectors
EMI FILTER
EMI (electro-
magnetic
interference)
is electrical
noise—spikes
in the power
spectrum—gen-
erated by the
switching action
of the power
supply. An EMI
filter attenuates
the amount of
EMI that is re-
flected back into
the power line.INPUT CAPACITOR
Capacitors store electric-
ity to help compensate for
fluctuations in power coming
from the outlet. The input
capacitor kicks in a little extra
juice if the incoming power
dips below spec. The bigger
the capacitor, the better.FAN The fan draws
the hot air radiating
from a heatsink out
of the power-supply
enclosure. High-end
power supplies typically
have either dual fans or
one large fan (typically
12cm) to ensure your
power supply gets
maximum airflow to
maintain low temps.HEATSINKS Transistor switches provide high-frequency power to
transformers, and diodes resolve AC power to DC power. Both processes
generate heat, which—if not managed—will reduce the power supply’s
efficiency. Heatsinks increase the surface area over which heat can be
distributed and radiated, which helps keep the power supply cool.OUTPUT CAPACITOR (beneath heatsink) A power supply
must be able to react to sudden power draws from PC compo-
nents, such as when two hard drives spin up at the same time.
The output capacitor stores electricity and metes it out so that all
devices receive a steady supply of current, regardless of load.Anatomy of a Power Supply
Curiosity has killed uninitiated cats who tinkered with their PC’s power supply. These
devices retain lethal voltages, even when unplugged, so we don’t advise opening them.
Besides, we’ve safely done it for you!POWER FACTOR CORRECTION (not shown) Power factor is a measure of how efficiently electrical power is
being used, and is expressed as a value between 0 and 1. The closer the power supply comes to delivering the
ideal power factor of 1 (where 1 volt-ampere produces 1 watt), the more efficient the power supply will be and
the less strain it will place on your PC’s wiring. Power factor correction (PFC) is a process that boosts an electri-
cal device’s power factor closer to 1, using one of two techniques: passive or active. Passive PFC uses a simple
capacitor, but this technique typically increases the power factor to between just 0.75 and 0.80. Active PFC
employs a more complex circuit and is much more effective—it can increase the power factor to 0.90 or higher.ANTEC’S
NEOPOWER 480