In keeping with the dome drivers in the rest of the Vivid range, the C125 has an anodised aluminium alloy cone designed with the help of computer modal analysis to give the highest break-up frequency ensuring pistonic behaviour throughout the reproduced bandwidth.
Use of a large central dome helps to reduce the front cavity volume minimising the perturbations to the sound field from the higher frequency units.
Thermal management in the C125 begins with the use of
a short coil in a long magnetic gap. The increase in magnet
volume and the weight of the accompanying steelwork is
the price paid for the superlative thermal performance
which results from surrounding the 50mm diameter copper
ribbon coil with cold steel throughout its range of linear
travel. The generous thickness of high purity steel
surrounding the coil also keeps the gap flux consistent
along the whole of its length.
While the primary function of the chassis is to accurately locate the cone and coil assembly and suspensions to the magnet assembly, it also plays a vital part in the conduction and dissipation of heat from the motor system. The struts, while being slender in width, have a considerable depth and follow a parabolic area law to maximise their heat sinking action closest to the magnet assembly.
Where so many traditional driver chassis have taken the form of a metal cone with punched holes to 'let the sound out', C125 was designed from the outset to minimise the restriction of the emerging rear wave. To this end, the twelve struts of the die cast aluminium chassis have a width of just 3mm resulting in an open area in excess of 90%.
As a further step towards freeing the rearward wave from unnecessary obstruction, a radially polarised magnet assembly provides the highest level of flux from the smallest overall cross-section. A topology that also keeps stray fields to a minimum without the bulky screening cans often found in most video compatible loudspeaker systems.
Again respecting the often-ignored significance of resonances behind the cone, even the voice coil former is unique in being heavily perforated to avoid the usual resonant combination of the cavity behind the dust dome and the hole in the magnet normally added to allow undamped motion at low frequencies.
Floating Driver Units
In all Vivid loudspeaker systems the C125 driver 'floats' on set of silicone O-rings, ensuring chassis vibration is not transferred to the cabinet resulting in higher levels of acoustic purity. But this would be impossible using a conventional flange mounting system with a ring of bolts visible at the front so instead the weight of the magnet system is transferred to a rear support which is either shared by a second identical driver or by a single rear mounted bolt.