Our goal in designing the D26 was to create a driver with high efficiency and first break-up frequencies, while using well established diaphragm materials with a proven track record for stability and reliability.
It features an anodised aluminium diaphragm, formed by a unique fabrication technique, into a profile optimised by computer finite element techniques to give an exceptional first break-up frequency above 44 kHz.
A radially polarised magnet system, comprising eight segments of high energy Neodymium Iron Boron material, is employed to maximise the flux through the voice coil while having an intrinsically low stray field, essential if the driver is to be used anywhere near a cathode ray tube (CRT) video monitor or the inductive components of a crossover. Finite element optimisation has again been used to make sure that the flux goes where it should resulting in an astonishing 2.4T in the gap!
An edge wound aluminium voice coil ensures the best match between the aluminium diaphragm and gap flux. Magnetic fluids are well established as a method of stabilising the voice coil temperature; however, the flux of the D26 is high enough to rip the magnetic particles out of suspension in conventional fluids. Vivid Audio has worked in co-operation with Ferrotec Corporation (USA) to formulate a fluid capable of withstanding the extreme conditions that exist in D26.
Our policy of ensuring that resonant effects are kept well out of the relevant frequency band applies not only to the high end but also to the fundamental resonance. Pressure from the rear of the diaphragm must be allowed to escape if this frequency is to remain sufficiently low. A tapered hole in the centre of the pole piece smoothly couples the diaphragm to a fibre damped, exponentially tapered tube which has an acoustic performance identical to that of an ideal enclosure, being completely free of resonance or reflection.
Reaction forces are inevitably experienced by the magnet structure of any driver when a signal current passes through the voice coil. On its own, the magnet motion would contribute little to the overall sound field but when coupled to the horn absorber and enclosure, the combination can possess structural resonant modes which fall in-band. In order to prevent these being a problem, the tube and magnet assembly is isolated by compliant O-rings and in a similar way, the complete driver and horn assembly is isolated from the enclosure.