Brochure

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We have always been
interested in magnetic
circuits, an essential ele-
ment in speaker drivers.
Having developed the
electro-magnetic technology
for the Grande Utopia EM
and the Stella Utopia EM, we came to appre-
ciate an attribute of magnetic fields that had yet
been ignored.
Besides the uniformity and intensity of the field was
a dynamic aspect over which we had no control.
Regardless of its intensity, the magnetic field
destabilizes due to additional factors: the movement
of the voice coil (Lenz’s Law) and the eddy current
passing through it, and the frequency. Consequently,
the moving part – the voice coil – moves into the
magnetic field and disturbs it, causing a variation
that results in a loss of precision. This presents a
significant obstacle to high resolution, like a shaky
hand holding a camera.
We developed new simulation software over the
course of three years, enabling us to visualize
these complex interactions, and paving the way for
the development of an extremely stable magnetic
circuit. Applying modern tools to an old solution, a
Faraday Ring, we calculated its ideal dimensions,
composition, and positioning with a recently
inconceivable precision. This effectively renders
the magnetic field immune to the position of the
voice coil, as well as to the intensity and frequency
of its current, and represents a new benchmark of
extreme definition.
NIC Neutral Inductance Circuit
Stabilizing the magnetic field
Response of a 6” midrange driver measured with the Klippel analyzer: blue curve represents the new NIC (red ring in this
cross section); red curve represents the conventional 6” midrange driver with a ferrite magnet.
Above: The variation of inductance in relation to current passing through the voice coil, varying according to the audio signal.
The NIC is perfectly stable.
Below: The variation of inductance in relation to the excursion of the voice coil. The result is spectacular.
In red, the Faraday ring on a Sopra N
°
2 woofer. Its composition,
dimensions, and positioning were optimized with computer
simulations. The impressive result achieves the best possible bass
performance and control, regardless of the voice coil’s excursion.
Our new simulation software enables us
to model a Faraday ring that combines the
best of both worlds: extreme definition with
dynamics and contrast.
Variations due to the position of the voice
coil and to the current passing through it in
a conventional circuit result in blurring.
The Faraday ring is known to improve
definition, usually at the cost of dynamics
and contrast.
Visual analogy of magnetic disturbances
The accuracy and detail
of audio reproduction
relies on the stability of
the magnetic field
Without Faraday ring
With typical Faraday ring With Focal Faraday ring