Evolution Technologies EVO8 - Manual (Page 11)

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Evolution²
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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 (Evo² 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 Evo² 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 Evo² dome tweeters.
By using a very low mass ultra stiff Kevlar cone in our bass/midrange drivers we pro-
vide virtually loss-less energy transfer from the coil ensuring good impulse and dynam-
ic response times. This, combined with a carefully developed cone profile and a pre-
cisely shaped central coil cap projection, allows the higher bass and midrange fre-
quencies 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.
THE 5Omm SOFT DOME MIDRANGE (Evo²-50)
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.
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