Tech Notes

maintained even at high volume levels.
Unusually, these main drivers are deployed in a wide-bandwidth role to cover the vast
majority of the audible frequency spectrum, rolling off towards very low and very high
frequencies. The drive unit design, together with the inert nature of the Aurora’s housing –
stiff, well-braced, naturally sound-absorbent bamboo with strategically placed damping
material – enables a flat frequency response from around 60Hz to 8kHz. Avoiding the need
for a crossover to hand over from one drive unit to another at critical frequencies enables
excellent phase response through the midrange.
These are the only drive units, however. Two 28mm silk-dome tweeters, one at each side,
cover frequencies from 8kHz to 35kHz. As the treble region is considered to begin at around
5kHz, and the limits of human hearing extend to about 20kHz, the Aurora’s high-frequency
drivers behave more like super-tweeters than traditional tweeters. With a simple first-order
crossover for the smoothest-possible transition and a shallow waveguide to provide time-
alignment, these tweeters not only deliver high-frequency sounds such as cymbals but are
also critical to the Aurora’s spacious soundstage.
Two further drivers – a pair of rectangular passive bass radiators – fire downwards from the
underside of the cabinet. The diaphragm used by these drivers is formed from a composite
of carbon, iron and ethylene-vinyl acetate, a well-damped material enabling the correct
resonant frequency to be obtained from a diaphragm of appropriate thickness. This is
combined with a self-centring, double-ribbed rubber surround, negating the need for a
basket.
The net result is a seamlessly coherent performance with silky-smooth frequency response,
an out-of-the box soundstage and bass that delves far deeper than most all-in-one systems
can muster.
Left: Three of the four main drivers and one
tweeter are visible in this image, within their
bamboo enclosure. The Aurora’s outer
enclosure, with its distinctive bamboo fins, sits
over the top of this.