Special Forty product information sheet

Special Forty product information sheet
What’s the Special Forty?
It’s Dynaudio’s 40th anniversary speaker. The Special Forty is a classic passive two-way design: the
team in Dynaudio Labs studied the legendary techniques and technologies that make their speakers
so celebrated – and then took them back to the drawing board. The result? The ultimate compact
standmounter in its class.
What’s so special about it?
Apart from being the ultimate compact standmounter in its class? Lots of things…
The Esotar Forty tweeter
This is exclusive to the Special Forty. It’s based on our other classic Esotar designs, but has
refinements behind the scenes.
Behind the diaphragm in the magnet is a new pressure conduit – a specially shaped vent that lets us
devote more space to the rear chamber and controls how the air moves from the back of the
diaphragm into that space. The chamber itself is packed with more damping material and, in
conjunction with the pressure conduit, serves to reduce back-pressure on the rear of the tweeter
There’s an aero-coupled pressure-release outlet under the tweeter’s voice-coil. It equalises the
pressure immediately under the voice-coil with that outside to reduce any air pockets that could stop
the coil moving as it should. This reduces resonance – and manifests itself in the form of a more
detailed performance.
The Esotar Forty’s 28mm diaphragm is a classic Dynaudio soft-dome design, complete with our DSR
(Dynaudio Secret Recipe) precision coating. This coating is applied in exactly the correct places and
thicknesses to optimise high-frequency performance.
The unit is suspended in magnetic ferrofluid to increase power-handling, improve the dome’s
excursion and absorb unwanted heat and excess energy. And that, in English, means a tighter, more
controlled and more honest performance.
We’ve also taken care to extend the Esotar Forty’s frequency response… downwards. It can
comfortably reproduce frequencies down to around 1000Hz – well into the midrange. You can find
out why below.
Our best-ever 17cm woofer
The Special Forty woofer is based on Dynaudio’s classic 17W75 MSP model. This one has an
improved spider and specially optimised excursion-symmetry. Once again we’re using our
proprietary MSP (Magnesium Silicate Polymer) material: nothing else we’ve encountered so far offers
its precise combination of stiffness, stability, rigidness and damping. And unlike some other cone
materials, its properties don’t change over time.
Like all our other MSP woofers, the Special Forty’s driver is a one-piece design. You can tell by our
trademark Balance Ribs around the central dome. Making it a single structure gives us more control
over how the cone deforms as it moves, and also gives the whole area a direct connection to the
voice coil. The coil’s former is bonded directly to the back of the ring where the Balance Ribs sit –
making the dome part of the playing surface.
This is so we can extend the woofer’s frequency response upwards. It can easily handle frequencies
up to around 4000Hz.
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Seamless driver overlap
That 3000Hz overlap between the tweeter and the woofer is crucial. It means we don’t have to use
steep filters and complex circuitry to make the drivers mesh well together – after all, why manipulate
the musical signal to make the drivers gel when you can make better drivers in the first place?
Because the Special Forty’s drivers perform alike in many areas (including frequency response,
phase response, tonality, sound dispersion and on- and off-axis performance), they blend incredibly
well. We made sure to get that part right before performing any magic in the crossover.
Only after we’d nailed it did we take the crossover filter into account for fine-tuning and finematching. And what a circuit it is…
A classic Dynaudio first-order crossover
Dynaudio has used first-order crossovers for decades: we stuck to our guns even when other
manufacturers said it didn’t matter, or used higher-order designs to make their drivers work. And
that’s why for the Special Forty we’ve taken our classic designs and techniques – and then rampedup our unique Phase Alignment and Impedance Alignment technologies. Specifically selected
components handle the impedance optimisation and, because both drivers have extended frequency
ranges for even better overlap and integration, their performance borders on the mesmerising.
Advanced magnet design
The Special Forty’s drivers use some clever magnet technology. The Esotar Forty tweeter’s powerful
neodymium magnet is small, but incredibly powerful for its size. And, crucially, it’s also very light. A
powerful, lightweight magnet is extremely efficient and allows for far greater precision in the motor’s
movement than a traditional ferrite magnet would permit.
We’ve used a hybrid magnet system in the woofer. As in the tweeter, an incredibly powerful
neodymium rare-earth magnet provides the muscle – while a gentler ferrite magnet manipulates
where that energy goes. It keeps it flowing around the voice-coil, where it’s needed, resulting in
greater efficiency and control. You’ll hear it in the form of a reduction in second-harmonics – and
therefore a more accurate, more authentic reproduction of the recording.
The woofer’s magnet system also sits inside the voice-coil, rather than around it externally. Putting it
inside keeps the flux flowing more effectively around the wire, letting us use more of its power for a
given weight. It also reduces internal reflections because there’s less material for sound to bounce
off inside the driver.
Why we use aluminium voice-coils
The tweeter and woofer both use Dynaudio’s famous lightweight aluminium voice-coils. They’re
lighter than traditional copper coils, which means we can make the physical voice-coil a lot bigger –
double the diameter for any given weight, in fact – and get more windings onto the former. More
windings equals more control over the cone’s movement, which means more control over the sound
– even at high volumes and high frequencies. It also gives the driver longer excursion and better heat
dissipation. That would all be far trickier with a smaller magnet.
Better airflow
Better air movement behind and around a driver means it can do its work without having to fight
against unwanted pockets of air that would otherwise have a damping effect. The Special Forty’s
woofer and Esotar Forty tweeter both take airflow to another level. The tweeter uses new shaped
vents and larger damped chambers behind its magnet to reduce unwanted pressure build-up and
resonances, while the woofer sits in an aerodynamically optimised AirFlow Basket that reduces
internal reflections and allows increased air movement without compromising stiffness or stability.
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There’s one Special Forty model…
It goes on-sale in June 2017 for €2999.
… and it comes in two finishes
Grey Birch High Gloss
Red Birch High Gloss
We’ve always pushed the boat out when it comes to finishing our anniversary speakers, and the
Special Forty is no exception. We pushed our team to come up with something different to what
we’ve done in the past, and they took that to heart.
The Special Forty’s finishes make the very most of the Finnish birch’s striking grain – with the red
and grey stains enhancing its straight pattern in visceral fashion.
Here’s a list of the key features:
• Brand-new Esotar Forty tweeter – unique to this speaker
• Dynaudio’s best 17cm woofer yet
• Drivers have extended frequency ranges for incredible overlap and integration
• The woofer’s hybrid magnet system
• Aluminium voice-coils
• Improved airflow with the AirFlow Basket, plus shaped vents and pressure conduits
• Classic Dynaudio first-order crossover
• Two striking new finishes
Technical specifications
IEC power handling
Frequency response (+/- 3dB)
Box principle
Crossover frequency
Crossover topology
Dimensions (W x H x D)
Dimensions with feet/grille (W x H x D)
86dB (2.83V / 1m)
41Hz – 23kHz
Bass-reflex rear ported
1st order
17cm MSP cone
28mm Esotar Forty
8.1kg / 17.9lb
198 x 360 x 307mm / 7.8 x 14.2 x 12.1in
198 x 360 x 322mm / 7.8 x 14.2 x 12.7in
Grey Birch High Gloss, Red Birch High Gloss
About Dynaudio
Dynaudio was founded in 1977 in Skanderborg, Denmark. Today, Dynaudio is recognised as one of
the leading manufacturers of high quality audio systems and one of the world’s most distinguished
high-end audio companies. Dynaudio develops and manufactures dedicated audio systems for the
professional markets as well as car audio and home audio consumer loudspeaker products at the
company’s state-of-the-art facility in Denmark. Dynaudio is particularly recognised for its advanced
driver technology designed, engineered, and continuously developed in-house, and its furnituregrade, handcrafted Danish cabinetry.
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