Wharfedales attractive EVO 4.1 bookshelf speakers offer quality sound as a standalone stereo pair, or as front speakers in a surround sound system. AMT The Wharfedale EVO 4.1 bookshelf speaker uses a specially designed AMT (Air Motion Transformer) transducer for its own silky smooth high-frequency reproduction. Kevlar Woofer Artificial and accurate bass reproduction is perfected by the EVO 4.1s bi-directional woven Kevlar cone 5" woofer. Kevlar is a material that is naturally self-damping to reduce and disperse resonances to almost negligible levels. Optimised Crossover Network The output of the tweeter and woofer is carefully combined by a thoroughly researched crossover developed using Wharfedales Computer Aided Optimisation technology. Each crossover is carefully evaluated using a wide range of music, focusing on the lifelike reproduction of voices and instruments alongside the dynamics of the musical performance.