dali helicon mk2
DALI HELICON MK2
TECHNICAL WHITE PAPER
DALI ALLÉ 1
9610 NØRAGER
DENMARK
Tel. +45 96 72 11 55
Fax +45 98 55 19 40
www.dali.dk
Contents
Introduction ......................................................... 3
Brief Description of the HELICON MK2 Series ... 4
Driver Technology............................................... 4
Low Frequency Drivers ................................... 4
Midrange Drivers............................................. 6
High Frequency Drivers .................................. 6
Crossovers.......................................................... 9
Binding Posts ................................................ 10
Cabinets............................................................ 11
Grilles............................................................ 11
Base.............................................................. 12
Positioning/Use of HELICON MK2................ 12
Accessories ...................................................... 13
Packaging ......................................................... 13
Technical Specifications ................................... 14
The HELICON Series ....................................... 15
2
DALI ALLÉ 1
9610 NØRAGER
DENMARK
Tel. +45 96 72 11 55
Fax +45 98 55 19 40
www.dali.dk
Introduction
HELICON is the name of a series of
loudspeakers from DALI which has
inherited a great deal of technology
and technical features from the DALI
premium series, DALI EUPHONIA. The
second-generation HELICON speakers
are optimized for even better
performance than their predecessors.
HELICON is a location in the Greek
mountains that played a certain role in
ancient Greece. According to the
myths, it was there that the tutelary
deities (also called MUSES) for the
arts and sciences had their resort.
There were nine beautiful muses, all
daughters of the god Zeus, who,
according to the myth, appeared with
singing and music. The muses were
worshipped because of their artistic
abilities - they were the source of
inspiration. The meaning of muse can
be seen today: it is our common term
for sounds put together in a special
way: MUSIC!
Today, music is often reproduced
through a music system and ultimately
brought to life through a pair of
loudspeakers. With the HELICON MK2
speakers, DALI offers an exceptionally
high level of performance, made
possible through stunning design,
careful selection of materials and
excellent craftsmanship. All in all, a
series of loudspeakers that will satisfy
demanding music lovers or movie
enthusiasts, who appreciate excellent
sound and fine Scandinavian design.
In the following chapters you can read
about the technical principles used in
the HELICON MK2 speakers.
3
DALI ALLÉ 1
9610 NØRAGER
DENMARK
Tel. +45 96 72 11 55
Fax +45 98 55 19 40
www.dali.dk
Brief Description of the
HELICON MK2 Series
Add to that, the long term stability
requirements of the materials, which
will make it possible to enjoy the
speakers for many years to come.
When making the second generation
of a very successful and highly praised
loudspeaker series, it is difficult to
come up with a successor. Therefore,
we decided to retain the basic features
of the original HELICON speakers. But
we have still found room for
improvement:
•
•
•
•
Some of the drivers have been
co-developed
The crossovers have been
upgraded and refined
The binding posts are new
The design of the cabinet is
made more exclusive
Driver Technology
The design and development of high
performance loudspeakers requires
outstanding components. This is why
DALI designs our own drivers, which
are specifically developed to match our
design philosophies and the specific
loudspeaker in question.
There an extensive list of
specifications that a driver must fulfill
before it can be part of a high
performance speaker system. If we
take as an example the woofer for a
2½-way loudspeaker like HELICON
300 MK2; it must be able to reproduce
signals from levels bordering on the
threshold of audibility all the way up to
levels bordering on the criminally
insane. Also, it must be able to
reproduce a frequency range from 30 –
10,000 Hz – at full volume level,
without audible distortion and at a
voice coil temperature of 150°C/300°F.
In terms of acoustics, DALI drivers are
designed to be true to the recording.
The driver must not add or subtract
anything from the reproduced signal. If
there is a transient sound of a cymbal,
it must be reproduced without
compromise. Likewise, if there are
subtle details in the recording, they
must be reproduced as the artist
originally intended it.
This is why DALI speakers are
designed and developed – IN
ADMIRATION OF MUSIC.
Low Frequency Drivers
Low Loss Cones
The cone of a driver must put air in
motion to create sound waves in the
air that surround us. 100% of the
energy (music signal) that causes the
cone motion must be transformed into
sound waves – otherwise something is
lost.
DALI drivers are designed with very
stiff, lightweight cones that do not
require much energy to be put in
motion. The cones are made of paper
pulp, which is reinforced with chopped
4
DALI ALLÉ 1
9610 NØRAGER
DENMARK
Tel. +45 96 72 11 55
Fax +45 98 55 19 40
www.dali.dk
wood fibers. This gives a unique ratio
between stiffness, mass and low
internal loss in the cone geometry.
Actually, the cone is so stiff that it will
tend to resonate (add to the
reproduced sound). However, this can
be cured with a delicate amount of
coating without adding significant mass
– therefore, the cones are coated. The
chopped wood fibers are randomly
orientated which will help distribute the
energy from the voice coil in different
directions. This will also help suppress
resonances in the cone. The result is
clear, crisp undistorted sound.
Low Loss Suspension
To achieve the goal of high
performance, much more than
resonance control in the cone is
required. The rubber surround and
spider are also important components
that control cone excursion and ensure
alignment of the voice coil in the voice
coil gap. The negative effects of the
spider and the rubber surround are
that they apply counteracting forces to
the cone motion. In the HELICON MK2
drivers, a lot of effort has been put into
reducing these counteracting forces by
using a very soft rubber material and
soft, impregnated linen for the spider.
The geometry of both components is
optimized for large excursion to deliver
deep, undistorted bass. Because the
counteracting forces from the
suspensions are minimized, even
small cone movements will be
transformed into audible music
components, improving the microdynamics of the speaker system.
Class A Magnet System
Because the cone/surround/spider
assembly of a HELICON MK2
woofer/midrange driver is very easy to
put in motion, it is easy to control cone
motion by use of interacting forces
from the magnet system and the voice
coil. However, it is not a trivial task to
design a magnet system and voice coil
that together will give clean,
undistorted sound. The task becomes
even more difficult when dynamic
phenomena are considered.
In the HELICON MK2 drivers, dynamic
distortion is minimized through the use
of a T-shaped pole piece and two
oversized ferrite magnets. When the
pole piece is T-shaped, the magnetic
flux field will be tightly focused in the
voice coil gap. The magnetic field is so
powerful that it will saturate the iron
parts of the magnet system. This has
several advantages over non-saturated
iron parts:
•
•
•
The voice coil inductance is
kept constant when rocking
back and forth, leading to
constant impedance.
Modulation distortion is reduced
due to the constant impedance
of the voice coil.
Asymmetrical stray flux is
greatly reduced, resulting in a
5
DALI ALLÉ 1
9610 NØRAGER
DENMARK
Tel. +45 96 72 11 55
Fax +45 98 55 19 40
www.dali.dk
•
constant force factor within the
linear working range of the
woofer.
Modulation of the crossover
frequency will be eliminated due
to constant impedance with
cleaner midrange reproduction
as a result.
A direct outcome of the voice
coil/magnet system design described
above is lower distortion, which e.g.
can be heard as very neutral
reproduction of voices when the
woofers are working at large
excursion. Another direct outcome is
significantly improved dynamic
capabilities – still at very low distortion
levels. Often, a listener will actually
choose to play at louder volume levels
than normal, because the sound is so
clean and crisp.
The driver components are assembled
in a solid die cast aluminum chassis.
Aluminum cannot conduct magnetic
flux – therefore, it will not compromise
the magnetic field by radiating the
magnetic field in different directions.
reason is that roll-off phenomena are
well beyond the frequency range
across which the driver contributes to
the total sound. Specifically for the
HELICON 800 MK2, dual 8” woofers
and a 6½” midrange are used. The
6½” midrange driver is basically
designed according to the same
principles as the woofers. The
differences are that the suspensions,
voice coil and magnet system are
optimized for lower excursion (and a
higher lower limiting frequency). Also,
the voice coil is, of course, impedance
matched to the woofers and the hybrid
tweeter module for seamless
integration of the total speaker system.
High Frequency Drivers
In most DALI speakers, hybrid tweeter
modules consisting of a soft dome
tweeter and a ribbon tweeter are used.
This is to get the best of both worlds in
the quest for superior high frequency
reproduction. The same principle is
used in HELICON MK2.
Because of the dual magnet
configuration, the surrounding
magnetic field is also greatly reduced.
Therefore, the HELICON MK2
loudspeakers can be positioned
relatively close to a CRT TV without
distorting the TV image.
Midrange Drivers
In HELICON 300 MK2 and 400 MK2,
the 6½” drivers reproduce the
frequency range for both woofer and
midrange. This is one of the reasons
why DALI designs drivers with a large
useful frequency range. Another
The reason for not using only the
dome or the ribbon is that a dome
tweeter with a perfectly flat frequency
response up to – say 25 kHz – will not
6
DALI ALLÉ 1
9610 NØRAGER
DENMARK
Tel. +45 96 72 11 55
Fax +45 98 55 19 40
www.dali.dk
be flat when listening just slightly off
axis. Some tweeters even start to drop
off at 13 – 15 kHz, when listening off
axis. With such a design, the listeners
would have to sit precisely on axis
between the speakers to enjoy the full
spectrum of the music – which will off
cause not be the case in many normal
living environments. To make up for
this, DALI uses a ribbon tweeter which
is inherently excellent at reproducing
high frequencies – even at large off
axis angles.
compromising dynamics and power
handling.
Advantages of the hybrid tweeter
module are:
•
•
•
•
Excellent off-axis frequency
characteristics with full
frequency range.
Better integration in normal
living rooms.
Low distortion.
Larger listening area, where the
full spectrum can be enjoyed.
The soft dome tweeter and the ribbon
tweeter are bolted to a solid die cast
aluminum faceplate. The rear of the
face plate has a recess of different
depth for each of the drivers, which
aligns the acoustical centers of the
drivers. Alignment will prevent
phase/timing blur/smear, making it
possible to reproduce the cues that will
enable perception of soundstage and
imaging in music. In other words,
abrupt phase changes will not occur.
Silk Dome Tweeter
The 1” dome tweeter of the HELICON
MK2 speakers is made with a very thin
silk fabric. In fact, it is so thin and open
that one can see through it. After a
shaping process, a thin/lightweight
coating is applied to the silk. The silk
alone cannot be considered a dome
because it is so open that it cannot put
air in motion.
The ribbon is not used alone because
excursion is limited at low frequencies
– introducing distortion and seriously
7
DALI ALLÉ 1
9610 NØRAGER
DENMARK
Tel. +45 96 72 11 55
Fax +45 98 55 19 40
www.dali.dk
will be dissipated by the magnet
structure and the aluminum faceplate.
Ribbon Tweeter
The low mass of the silk/coating
assembly add almost 2 dB of
increased sensitivity compared with a
traditional dome. Going further, an
acoustic chamber behind the dome will
lower the resonance frequency to
approximately 700 Hz - two octaves
from the typical crossover frequency,
eliminating coloration of the sound.
The acoustic chamber is filled with
three pieces of felt (tuned by ear),
which optimizes coupling and airflow to
the dome. The large chamber will also
prevent air compression, when
reproducing signals with micro- and
macro dynamic content.
The ribbon tweeter is of the
magnetostatic type; a thin polymer
base is used as a diaphragm with thin
conductors of aluminum. A very
powerful magnetic field surrounds the
diaphragm.
The magnet system uses two identical
ferrite magnets to produce a very
powerful magnetic flux field, which will
surround the underhung voice coil.
Besides having a focused magnetic
field around the voice coil, double
magnets will enable use of the
speakers very close to a CRT TV
without disturbing the TV image.
To eliminate thermal compression due
to rising temperatures in the voice coil
(which will lead to higher voice coil
impedance and thereby reduced sound
pressure levels), low-viscosity
Ferrofluid (oil with magnetic particles)
is used in the voice coil gap. This will
eliminate spontaneous or continuous
voice coil temperature rise – the heat
The magnetic flux field originates from
as many as six rod magnets; three
ferrite magnets behind the diaphragm
and three neodymium magnets in front
of the diaphragm.
8
DALI ALLÉ 1
9610 NØRAGER
DENMARK
Tel. +45 96 72 11 55
Fax +45 98 55 19 40
www.dali.dk
The combination of a low mass
diaphragm with a powerful magnetic
field will make reproduction up to 28
kHz possible. But that will not make it
alone. – In front of the front
magnets/diaphragm are an aperture
grille and an acoustical lens. These are
carefully designed for wide dispersion
of the sound, so the full spectrum is
reproduced at even extreme off axis
angles in front of the speaker.
Wide dispersion is important, because:
•
•
It will give better sound in a
larger listening area.
The frequency response of the
reflected sound will be more
similar to the direct sound from
the loudspeaker.
The last point above is important,
because under normal living room
conditions, as much as 60% of the
sound heard is reflected sound (from
walls, floor and ceiling), whereas only
40% is directly heard from the
loudspeaker.
Crossovers
The basic task of the crossovers in the
HELICON MK2 speakers is to filter out
frequency content not meant to be
reproduced by the driver in question.
The desired result is achieved by a
unique combination of driver and
crossover, for a seamless blend of the
sound from two “neighboring” drivers.
The crossovers are relatively simple in
terms of the number of components
(made possible by high quality,
wideband driver design). Because of
“simple” filtering/short signal path, it is
possible to preserve as much of the
original electrical signal as possible;
9
DALI ALLÉ 1
9610 NØRAGER
DENMARK
Tel. +45 96 72 11 55
Fax +45 98 55 19 40
www.dali.dk
preserving as much musical
information as possible (contrary to
doing heavy filtering or damage control
of poor driver design, where a lot of
energy is lost in the filter).
In the DALI HELCON MK2 speakers,
the unique combination of crossovers
and drivers will form a very easy
impedance load as seen from the
amplifier. This is possible only because
certain characteristics of the drivers
and the crossovers are a perfect
match, allowing flat impedance
characteristic. Flat impedance results
in reduced distortion and increased
amplifier control as the easy
impedance load eliminates significant
amplifier distortion.
All crossover components are of a very
high quality. The woofer sections of the
crossovers have been upgraded with
even better capacitors, resulting in
even tighter bass reproduction. All
components are secured with glue and
cable ties to a black Medium Density
Fiberboard (MDF) for a highly stable
mechanical construction. Electrically,
each component is hardwired
(soldered) directly to other components
for low loss and shortest possible
signal path. The component layout is
optimized by ear to minimize
component crosstalk. As an example,
the inductors are individually
positioned away from each other and
their axes differ to avoid crosstalk
between the electrical fields
surrounding the inductors. The result is
a more clean and natural sound.
Binding Posts
The connections from the amplifier to
the crossover are made through the
binding posts. On HELICON MK2 biwiring is an option to use separate
cables for the woofer- and
midrange/tweeter section.
Alternatively, it is also possible to run
the speakers with bi-amplification,
depending on listener preferences.
The binding posts are newly developed
for increased performance. The base
of the binding posts is a laser-cut
aluminum plate screw-mounted to the
cabinet with six hex-screws. The
binding posts themselves use a large
vice grip design that will accept the
following connections:
•
•
•
Bare, uninsulated wire ends
4mm banana plugs
Spade lugs
Fine thread on the binding posts will
enable extra torque and a nice feel. On
the outer surfaces the binding posts
are covered with transparent polymer,
which will prevent contact with
conducting parts, as well as short
circuiting the amplifier(s).
10
DALI ALLÉ 1
9610 NØRAGER
DENMARK
Tel. +45 96 72 11 55
Fax +45 98 55 19 40
www.dali.dk
On the floor-standing speakers, the
binding posts are very close to the
floor, making camouflage of the cable
runs easier.
The HELICON MK2 speakers come
with jumper cables for use when the
speakers are not bi-amplified or biwired.
Cabinets
The HELICON MK2 cabinets are
beautifully crafted in real wood
veneered MDF cabinets. The veneer is
high gloss lacquered and polished for
a stunning furniture finish.
The cabinet incorporates curved side
panels and a two-layer sandwich baffle
– very similar to the construction of the
DALI EUPHONIA Series.
The drivers are screw-mounted in the
black, high gloss lacquered sandwich
baffle. The black MDF baffle is
attached to the main cabinet with
adhesive to minimize vibrational
energy from the cabinet. This
effectively isolates the drivers from
coloration caused by the cabinet walls.
The geometry of the curved side
panels makes the cabinet more rigid
and will significantly reduce standing
waves inside the enclosure. This is
due to non-parallel cabinet walls,
which significantly reduce cabinet
coloration of the sound. The curved
side panels consist of four sandwich
layers of MDF to eliminate resonance.
Internally, the cabinets are partitioned
with enclosures for each driver for two
reasons; the backpressure on the
cones from different drivers will not
load other drivers and the panels
separating the enclosure volumes
provide internal bracing of the
cabinets, suppressing resonance even
more. Because of the asymmetrical
shapes of the curved side panels,
dominant cabinet resonances are
effectively eliminated.
The floor-standing models HELICON
800 MK2 and 400 MK2 have separate
chambers for the crossovers to
minimize vibration of the crossover
components caused by extreme
internal air pressure build-up. Even it’s
a small difference, it contributes to a
more stable stoundstage and imaging.
Grilles
The grilles for the HELICON MK2
loudspeakers are made with large
asymmetrical cut-outs around the
11
DALI ALLÉ 1
9610 NØRAGER
DENMARK
Tel. +45 96 72 11 55
Fax +45 98 55 19 40
www.dali.dk
driver positions to minimize reflection
and diffraction. The grille cloth has
been chosen for maximum acoustic
transparency. Listening with minimum
loss is possible with the grilles
mounted on the speaker.
Base
The floor-standing models HELICON
800 MK2 and 400 MK2 feature an
integrated base made of solid, black,
high gloss lacquered MDF. The base
has integrated threaded inserts for
M10 spikes (standard metric thread).
HELICON 300 MK2 can be used with
the HELICON STAND, which is
available in the same finish as the
HELICON MK2 speaker cabinets. The
stand will position the speaker at the
correct height for listeners seated in
normal furniture.
Positioning/Use of HELICON
MK2
Position the HELICON MK2 speakers
at least 25cm/10” from the rear wall
with the rear of the speakers parallel
with the wall. Do not toe in the
speakers towards the listening
position, unless you are listening at
extreme off axis angles. For optimum
results, the speakers should be placed
at least 60cm/25” from side walls.
Speakers should be positioned to
avoid so-called mirror sources (direct
reflections from the loudspeaker to a
wall to the listening position). If you
have mirror sources, the effect can be
minimized e.g. by placing a plant,
tapestry or other object with an
irregular surface at some point in the
reflection’s path.
If possible, improvement can almost
always be made by experimenting with
the loudspeaker and listening
positions. Just a few
centimeters/inches can make a
difference because of different room
coupling.
For critical listening, the listener should
always be seated on the center axis
between the two loudspeakers and
with the same distance to each
speaker. In the optimal listening setup,
the distances from left speaker to right
speaker, from right speaker to the
listening position and from the listening
position to the left speaker should all
be equal, forming an equilateral
triangle.
Vertically, the optimal listening position
(ear height) is approximately 1m/40”
above the floor.
Amplifier Selection
Generally, the HELICON MK2
speakers have high sensitivity, which
does not require a powerful amplifier.
However, to exploit the full dynamic
capabilities of the speakers, a powerful
amplifier is desirable, because the
peak level of the music signal can be
many times the average power level.
12
DALI ALLÉ 1
9610 NØRAGER
DENMARK
Tel. +45 96 72 11 55
Fax +45 98 55 19 40
www.dali.dk
A high performance amplifier with a
high current power supply and low
output impedance (high damping
factor) is recommended. The
HELICON MK2 speakers are very
revealing of the equipment in the
signal path. Therefore, any
weaknesses or special characteristics
of the amplifier and source
components will be reproduced.
frequency sections to avoid tilting the
voice matching.
If the speakers are bi-amplified, use
the same type of amplifier and cables
for both the low- and high frequency
sections to avoid tilting the tonal
balance of the speaker.
For use with a single-wire cable, DALI
CONNECT jumpers are included to
connect the low- and high frequency
sections of the speaker.
Cable Selection
Select cables with neutral
characteristics to preserve the voice
matching of the speakers. If the
speakers are bi-wired, use the same
type of cable for both the low- and high
Accessories
The floor-standing models of the
HELICON MK2 range can be fitted
with M10 (metric standard thread)
spikes which are included with the
speakers.
Packaging
All HELICON MK2 speakers come in
heavy-duty cardboard packaging for
maximum protection during transport.
All speakers are packed in single
cartons – the speakers are matched
stereo pairs with respect to the grain
pattern of the real wood veneer.
13
DALI ALLÉ 1
9610 NØRAGER
DENMARK
Tel. +45 96 72 11 55
Fax +45 98 55 19 40
www.dali.dk
Technical Specifications
HELICON
800 MK2
HELICON
400 MK2
HELICON
300 MK2
31 – 27,000
31.5 – 27,000
37 – 27,000
580
3,000
13,000
(700)
3,000
13,500
3,400
13,000
89.5
4.0
3.6
113
50 - 400
Bi-wire
88.0
4.0
3.7
111
50 - 300
Bi-wire
86.0
4.0
4.3
108
50 – 200
Bi-wire
1 x 25
1 x 10 x 55
1 x 25
1 x 10 x 55
1 x 25
1 x 10 x 55
1 x 6½”
2 x 8”
28.5
> 25 / 10
112.6x30.4x53.9
44.3x12.0x21.2
42.4/93.5
2 x 6½”
32.0
> 25 / 10
102.6x26.7x50.1
40.4x10.5x19.7
32.0/70.5
1 x 6½”
34.5
> 25 / 10
43.5x20.8x40.2
17.1x8.2x15.8
10.5/23.1
Accessories
M10 spikes
DALI Connect
shunt cables
M10 spikes
DALI Connect
shunt cables
DALI Connect
shunt cables
Finishes
Real wood, high gloss lacquered Rosewood or Cherry
Frequency Range +/- 3 dB (Hz)
Crossover Frequencies (Hz)
Sensitivity 2.83V/1m (dB)
Nominal Impedance (Ohms)
Minimum Impedance (Ohms)
Maximum SPL (dB)
Recommended Amp. Power (W1)
Terminals
Soft dome2
High Frequency
Drivers (mm)
Ribbon
Midrange Driver(s)
Low Frequency Driver(s)
Bass Reflex Tuning Frequency (Hz)
Distance from Rear Wall (cm/inch)
Dimensions (H x W x D) (cm)
Dimensions (H x W x D) (inch)
Weight (kg/lbs)
All technical specifications are subject to change without notice.
1
2
RMS Watt
Silk
14
DALI ALLÉ 1
9610 NØRAGER
DENMARK
Tel. +45 96 72 11 55
Fax +45 98 55 19 40
www.dali.dk
The HELICON Series
Also available in the HELICON design are the following products. All products will be
available in updated MK2 models except for W200:
•
HELICON C200 Center Channel Speaker
•
HELICON W200 On-Wall Speaker
•
HELICON S600 Subwoofer
•
HELICON STAND for HELICON 300 and HELICON 300 MK2
Please see the DALI website at www.dali.dk or visit your authorized DALI dealer for
more information and a personal demonstration of the HELICON MK2 speakers.
15
Was this manual useful for you? yes no
Thank you for your participation!

* Your assessment is very important for improving the work of artificial intelligence, which forms the content of this project

Download PDF

advertisement