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(( Flat hi-fi loudspeaker technology )) PPS1 - Active System PPS1- Passive System
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LoudPanel
The ideal of loudspeakers that blend perfectly into the surrounding environment has long been the ambition of all style conscious loudspeaker designers. With modern Home Cinema
systems
comprising
anything
between 5 and 8 speakers, this has never been more important.
This is the system, from one of Britain’s oldest speaker companies, that gets closest to the ideal of disappearing speakers” Stuff Magazine The traditional solution has been to use moving-coil loudspeakers. These are the speakers most of us are familiar with. A cone is attached to a ‘voice coil’ which moves in and out of a magnetic field, depending on a music signal passed through the coil. It is the compression and rarefaction of the air due to this pistonic motion that produces the sound we hear. This ‘Driver’ as it is known needs to be enclosed in a box, so the air moved is projected forward rather than just around the edges of the cone. Often several drivers (woofers and tweeters) need to be used as certain size and shape drivers produce certain ranges of frequencies and more than one is required to produce a full frequency response. After nearly a century of engineering advances, even the most advanced box loudspeakers in the world follow these basic principles. It became clear that a different approach was needed.
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Whilst researching the effectiveness of NXT technology, Wharfedale became involved in many weird and wonderful projects, including this one by Artist Anna Hill. The base is a giant NXT transducer.
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Around 1995, Wharfedale became involved in a project with a UK government agency, researching an interesting effect that had become apparent during the testing of sound cancellation equipment in military helicopters. Sound was being produced from large, flat panels when they were ‘excited’ in a particular way. This was interesting because the soundboard, rather than moving in and out, in a piston motion, was amplifying sound from ‘bendy waves’ produced through the material. This is a similar principle to the way a piano soundboard works, amplifying the small strings to fill a concert hall with music.
“it was immediately apparent that this was indeed the answer to the loudspeaker designers quest to make the most discrete and inoffensive loudspeakers ever produced.” A new company, NXT, was formed to research commercial applications for this exciting new technology, but it was immediately apparent that this was indeed the answer to the loudspeaker designers quest to make the most discreet and inoffensive loudspeakers ever produced. Wharfedale were the first company in the world to develop a successful commercial product. and this is now the second generation of the resultant ‘LoudPanel’ range of products. They hang on the wall like pictures and weigh only a few hundred grammes. You can use any poster or print to disguise them completely, yet the sound they produce is gloriously rich and detailed.
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The nature of NXT sound LoudPanel offers a number of benefits to the
the panel and a maximum excursion of only a
listener beyond the absolute stealth of the
few microns, the resulting audio waves are
design.
entirely different in nature.
One of the key features is the ability to provide
Rather than coherent waves produced (like
consistent sound pressure levels over a wide
throwing a pebble into an otherwise still pond)
listening area. Conventional pistonic loud-
that you get from traditional drive units, the
speakers produce a very directional sound.
waves are much more complex, exciting the
Typically the dispersion varies greatly accord-
surface of the panel in numerous ways. This
ing to the frequency being produced, with big,
has the effect of virtually eliminating the inter-
low frequency waves dispersing well, but above
ference patterns that are inevitable when
around 5kHz, the sound becomes very beamy
coherent waves interact. The phase relation-
and directional, so you need to be sat with
ship between sound waves no longer has sig-
your ears directly in line with the drive units in
nificance and, perhaps the most important
order to be able to hear the full frequency spec-
consequence, the wave amplitude dos not
trum. In systems with more then one speaker,
decay logarithmically in relation to distance
these beamy mid-range and high frequencies
from the loudspeaker. Instead, a smooth linear
react with each other to create interference
decay occurs. The result is a large and consis-
patterns of sound pressure, so walking across
tent listening area, free of interference.
a room, sounds get louder and quieter with
This has its own consequence. Gone are the
very little consistency, even in the listening
days when you had to place the stereo speak-
‘sweet spot’.
ers equidistant in a triangle from the listener.
With LoudPanel, these problems simply disap-
LoudPanel can be placed anywhere, even in L-
pear. Because the sound is being produced by
shaped or irregular rooms, at different heights
longitudinal waves across the entire surface of
or orientations.
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LoudPanel technology
LoudPanel works in quite a different way from
which the panel can reproduce bass depends
conventional loudspeakers. Instead of the pis-
entirely on the size of the panel. The panel can
tonic motion that we have come to expect,
only reproduce notes with a wavelength small-
exciters bonded to the surface of a specially
er than the panel.
designed laminate panel cause it to bend and flex. This board acts rather like a piano sound-
Rather than trying to build panels which are
board and amplifies the sound to normal lis-
several meters across (although entirely possi-
tening levels.
ble) the practical solution is to supply a system complete with a discrete powered subwoofer.
Just like with a piano or such similar instru-
Because bass frequencies are essentially direc-
ment, the shape and size of the soundboard is
tionless, this can be placed anywhere in a
essential to tune the instrument, the position-
room, even behind a sofa.
ing of these exciters on the surface of a LoudPanel dictates exactly how the board
The sound produced by LoudPanels comes
responds to particular frequencies. Unlike with
from the entire surface of the board - not just
a piano, where this knowledge has been accu-
a central impulse, like that produced from a
mulated over hundreds of years, passed down
pistonic loudspeaker. This causes the
from expert to expert, the NXT system provides
LoudPanels to behave in a different way from
a computer model which can predict the ideal
conventional loudspeakers. A much wider lis-
location of exciters on a panel surface to pro-
tening area and higher ambient level are just
duce a flat and extended frequency response.
two of the advantages LoudPanels have over
The way such panels work means the extent to
traditional loudspeakers.
The wave pattern produced by conventional drive units is coherent, directional and has a rapid decay in amplitude
The wave pattern produced by an NXT driver is radically different, exhibiting a highly complex structure which eliminates interference, has a wide dispersion and shows linear amplitude decay.
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The PPS-1 LoudPanel System
The LoudPanel PPS-1 system is designed to be
speaker cable that can either be painted or
as versatile as possible, replacing conventional
papered over.
loudspeakers, which can be intrusive, with a
In addition, two peelable prints are provided
clean and discreet package that is easy to
which can be applied directly to the front sur-
install, stylish and above all, a superb sounding
face of the panels themselves. These can be
system that reproduces music and vocals with
replaced with the print or photos of your choice
unerring clarity and cohesion.
and bonded to the surface of the panel with a
Designed to be used with standard amplifiers, the
low-tack spray adhesive.
PPS-1 produces a full range stereo sound with
As well use in stereo systems, the PPS-1 sys-
two of our LoudPanels and a passive subwoofer.
tem has been widely adopted for use as rear
The Subwoofer is connected to both left and
channels in Home Theatre installations. Such
right channels, where a crossover passes the
installations are particularly sensitive to the
higher frequencies to the panels, after separat-
number of loudspeakers used, which can be
ing the bass frequencies (
