Loudspeakers

Hi-Fi News' readers will be very familiar with Purifi's range of Class D amplifier modules, including the superb Eigentakt solution used in recent T+A and NAD products [HFN May '22 and Oct '22, respectively] but the company's expertise also extends into loudspeaker driver development. All three moving-coil drivers used in the Stella Xtreme are sourced from Purifi (which also supplies detailed 'plug 'n play' cabinet and crossover application notes) but it's the two PTT6.5X04 bass/mid units that are arguably of most interest here. The deep magnet, voice coil and suspension design of this 165mm driver work in tandem with the 'Neutral Surrounds' to deliver what Purifi claims is a driver 'that truly cracks the extended-stroke code'.

Its aim was to exceed the bass performance of a large-cone/short-stroke driver using a smaller cone – thereby extending its reach into the midrange – and far longer throw. Purifi used computer-modelling to predict the ideal cone and surround geometry, the latter disconcertingly irregular on first acquaintance. While this surround promises to reduce mechanical distortion without constraining motion it also works with the suspension spider to prevent the voice coil position from modulating the motor's force factor. All this is key in achieving low IM and harmonic distortion. PM