RCF ART 735-A MK4 Powered Speaker. In its class, the ART 735-A MK4 is a singular speaker. The 3.0" voice coil neodymium compression driver with a titanium dome gives exceptional vocal clarity and sound projection. Neodymium 15" woofer provides a precise, deep low frequency control and an incredibly linear response. Modern assembly technologies are used to create the transducers. The DSP that manages crossover, equalisation, phase control, soft limiting, and speaker safeguards controls the 1400 watt amplifier.