International Speaker User Manual

Evolution² Evolution²
Evolution²
12
THE DRIVE UNITS
THE BASS DRIVERS
The bass driver(s) incorporates a new design of cone utilising our own Kevlar bi-weave process. Kevlar has immense
longitudinal strength and is used in many structures where high strength and light weight are key attributes. Kevlar can
be found liberally used in Formula 1 racing cars, aeroplanes, boats, spacecraft, skis and even golf clubs.
These fibre bundles are woven and impregnated with special bonding resins that are subsequently pressure formed
and heat cured. The resulting material is stiff, rigid and exhibits very low levels of internal resonance. Consequently,
energy losses in the cone transfer mechanism are very low.
Similarly, lateral voice coil strength is very high. We use a combination of half hard aluminium and resin bonded glass
fibre. This, in turn, contributes towards some of the lowest distortion figures ever seen in conventional drivers. The dust
cap/cover is of the same material as the cone.
The bass drivers operate only over the low frequency range. They are only used over their true pistonic range. The cone
is terminated with a conventional large half roll of synthetic butyl rubber with excellent inherent damping qualities.
A high performance traditional ferrite magnet system is used. Motional noise can be a problem with high output bass
systems. We address this by moving air through vents in the voice coil. The magnet system is also fully vented
throughout.
THE BASS MIDRANGE DRIVERS (Evo-30,40,50)
In any system featuring a cone bass/mid driver, performance and dispersion in the upper midrange band is critical, and
even more so when (as in our Evo 30 and 40 models) the midrange driver is crossing over to a dome tweeter,even one
with as wide and well maintained a response as our Evo dome tweeters.
By using a very low mass ultra stiff Kevlar cone in our bass/midrange drivers we provide virtually loss-less energy
transfer from the coil ensuring good impulse and dynamic response times. This, combined with a carefully developed
cone profile and a precisely shaped central coil cap projection, allows the higher bass and midrange frequencies to
provide not just extension but also wide dispersion at the bass unit's upper crossover point. The result is a seamless
crossover transition to the tweeter without the compromised off-axis performance usually associated with most 2 way
designs.
13
THE 5Omm SOFT DOME MIDRANGE (Evo-50)
Derived from our flagship ‘Airedale Heritage’ loudspeaker, we have designed a series of dome mid-range
units which are exclusively used in our high-end loudspeaker products. Although costly to produce, the
benefits of a using a dome mid-range – particularly one with such as wide bandwidth as our own – are
lower distortion through this region, better integration throughout the frequency spectrum and an
extremely wide dispersion - all contributing to a very relaxed, natural presentation.
Because each driver in a multi-way system covers a smaller bandwidth, dynamic range and transient
response are hugely improved. Often this is at the cost of frequency integration but when our unique
dome technology is deployed, integration between upper and lower drive units is virtually seamless.
THE 25mm 1” SOFT DOME TWEETER
The highest frequencies are handled by a soft dome driver. Our extensive research has proven these are
a better choice than the metallic based domes that typically add their own character to the treble.
A feature of the tweeters, as with the mids, is wide dispersion and very low distortion, again typically
less than 1% at 100dB at 1 metre. The unit features a high flux neodymium magnet structure,
producing a typical efficiency of 93dB 1W@1m. This unit has a frequency response extending far
beyond audible frequencies to around 45kHz.
THE CROSSOVER AND WIRING
High quality OFC cable is used in each loudspeaker for internal wiring. High quality resin fibreglass
printed circuit boards are used throughout, and all connections are made to audiophile standards.
All inductors used are perfect layering wound and bonded and use large gauge wire for very low
insertion loss.
All capacitors used are either, low loss, low ERC polypropylene or high quality audio grade reversible
electrolytics.
Evo SignatureV3A.indd 12-13 30/09/2008 09:18:16