The
Electra 1000 Be series relie upon a new pure Beryllium
inverted dome tweeter generation introducing IAL
(Infinite Acoustic Loading) loading system. This
system’s goal aim to improve tweeter behaviour
in lower octaves in order to obtain optimal, unheard
of performance in critical frequencies.
One
of the main issue in that tweeter’s improvement
strategy rested on high frequency response extension
in order to comply with such recent formats as SACD
or Audio-DVD. This could be done either by adopting
a questionable « super tweeter » approach
affecting only the ultra sonic domain or by developing
a superior quality tweeter able to simultaneously
cover several octaves. It is that last mentioned,
extra-large frequency response (5 octaves from 1kHz
to more than 40kHz) sole tweeter solution that has
been retained by Focal in 2002 for Grande Utopia
Be, and was then gradually extented to other high-end
product series.
Pure Beryllium inverted dome tweeter’s choice
proved itself to be quite relevant in high frequencies
reproduction, because of its damping, rigidity and
lightness properties, allowing great transitory
and high efficiency above 40kHz response (95dB/W/m).
Despite these outstanding results, for 2005, Focal
raises up to a new challenge with the Electra 1000
Be series. The goal being to improve in the same
way the lower end of the tweeter’s spectrum
and ensure optimal response between 2000 and 4000Hz.
That range is critical because it covers the human
ear most acute sensitivity zone. Its control defines
essential parameters such as distortion ratio, linearity,
directivity and, most of all, crossover with the
midrange driver.
Infinite Acoustic Loading
This objective, was spawned, from the initial Focal
approach, by the inverted dome tweeter. Its structure
is broadly similar to a miniature woofer, allowing
optimal coupling between the coil and the inverted
dome for improved behavior in the lower spectrum.
That feature alone favors Focal loudspeakers cut-off
frequency reduction to a value between 2500 and
3000Hz while a majority of manufacturers cannot
go down under 3000Hz or 4000Hz. IAL structure retains
that defining concept and goes even further. Just
like a woofer, the all back of the cone is entirely
cleared and totally uncompressed thanks to cutting
edge mounting and architecture of the tweeter’s
peripheral. Therefore, it can be tuned with an appropriate
load, much like a woofer with the loudspeaker’s
load. That possibility opens up a all new perspective
to tune the tweeter and reach desired alignment.
Electra 1000 Be series tweeter use state-of-the-art
Infinite Acoustic Loading system (IAL), most favored
in terms of performance. A load is said to be infinite
when it’s not confined into a closed space,
in that case, there are no mechanical interactions
on the tweeter brought about by the air contained
inside; the frequency resonance is that of the loudspeaker
environment and can be subsequently reduced in significant
proportions. With IAL tweeter, our goal is to provide
a high enough, near infinite load in order for mechanical
interactions to become irrelevant. IAL tweeter
frequency resonance has been reduced to 680Hz, which
is exceptionally low and explains for the most part
IAL outstanding performance.
Early tweeter activation
IAL load decisive advantage is the cancellation
of overloading around 1kHz. Response is perfectly
flat, without any sound color altering overload
(typically between 2 and 4kHz) which requires a
high frequency filter potentially detrimental to
phase or might impose to raise the filtering frequency.
That phenomenon becomes even more substantial since
the resonance frequency usually neighbors the cut-off
frequency. The introduction of passive components
such as condenser filters generates overloading
which implies that once again a high frequency filter
is needed. What’s more, a low resonance frequency
allows mobile equipment to work under more suitable
conditions with significantly lower distorsion ratio
: distorsion is maintained to 0,6% up until 900Hz
and stays under 0,3% over the tweeter’s spectrum
which is, once again, a decisive advantage. That
new overall performance abled us to make great progress
: cut-off frequency has been lowered to 2000Hz (compare
to 2800Hz for 25th Anniversary Edition Electra Be)
while distorsion ratios have been maintained extremely
low and resonance has been totally cancelled.
This cut-off frequency reduction (around 30%) is
entirely consistent with Focal’s approach.
Above 2000Hz, a 6-1/2" (16.5cm) midrange driver,
even with a W cone, does not function in its optimal
linearity zone. Also, directivity, wich is directly
proportional to the woofer’s dome diameter
and the frequency is greatly impacted if the filtering
frequency is low. With IAL, an important midrange
portion is no more dispersed by a woofer which emitting
diameter limits dynamic capability, but by an extremely
light and rigid dome with sharper accelerations.
To the listener the resulting effect is an extremely
light sensation all over midrange with great richness
in details and better dynamic due to the dome’s
lightness.
