The Wharfedale EVO4 Series, developed concurrently with the flagship Elysian project, benefits from the same extensive R&D processes. Much engineering and technology is shared between these speakers and the family resemblance is obvious, from the substantial cabinets with their curved sides to the driver array. With prices starting at £449 per pair, the EVO4 Series sits between the existing Diamond 11 Series and Wharfedale’s forthcoming, flagship Elysian speakers. The initial stereo range comprises two standmount speakers (EVO4.1, £449, and 4.2, £599, below), two floorstanders (EVO4.3, £999, and 4.4, £1,199).
Developed from the Air Motion Transformer (AMT) high-frequency unit created for Elysian, EVO4’s tweeter has a large, pleated, lightweight diaphragm that’s driven across its surface by rows of magnets. The pleats in the diaphragm contract and expand under the influence of the musical drive, squeezing the air between them to form the desired waveform. To match to the AMT treble unit, Wharfedale has developed a dome midrange driver with wide bandwidth, assisted by the incorporation of a damped rear chamber. This unit is used by all the three-way EVO4 speakers – every model bar the two-way EVO4.1.
The soft fabric dome, damped with a plasticiser coating, is vented aperiodically into a specially shaped rear chamber that is profiled to scatter and absorb rear energy from the dome. This results in a linear response from 800Hz to 5kHz. Thanks to a high-flux magnet, the EVO4 midrange dome also has a high efficiency, ideally matched to that of the AMT treble unit, both units also claim wide dispersion which is a good thing.
The EVO4 Series’ bass drivers utilise the advanced, low-distortion motor system developed for the Elysian bass units, married to a woven Kevlar cone fitted with a low-loss rubber surround. Wharfedale’s engineers have been working with Kevlar – an exceptionally strong yet lightweight aramid fibre, ideally suited to speaker diaphragms that was formerly very popular at B&W – for two decades. The drivers’ output is combined via a computer-modelled crossover network that has been developed over hundreds of hours of listening tests. Crossover components feature high-grade polypropylene capacitors and laminated silicon-iron and air core inductors, laid out to avoid electro- magnetic interference.
Beneath the wood veneer on the EVO4 cabinets is a sandwich of woods of different densities, designed to reduce panel resonance to below audibility. The baffle’s radiused edges smooth the flow of sonic energy around the cabinet, helping to integrate the drivers’ output with the room acoustics.
Speaking about the development of the EVO4 Series, Peter Comeau – Wharfedale’s Director of Acoustic Design – said: “Other than some inventive names for ‘fancy’ cone materials, it might seem that little has changed in moving coil loudspeakers over the past 50 years. That’s why it’s refreshing to work with the advanced motor systems we’ve incorporated into the EVO4 Series, along with our version of a dome midrange and an AMT treble unit that has grown out of our research for the Elysian project..”