The second part of the motor-unit equation is the plinth system, a structure that must deal with the practical questions of accommodating and levelling the platter and arm, as well as dealing with internal and external sources of vibration. The compact nature of the drive system itself means that the plinth needs to be no bigger than the platter, while GPA’s experience with composite structures and mechanical resonance means that the actual shape and construction of the plinth offer a previously impossible range of options. They have chosen to create a double skin structure, it’s complex shape moulded in carbon-fibre and accurately integrating all the hard-points necessary for mounting the external elements and drive. This includes a six-bolt fixing for the alloy outrigger arm-board, located near the deck’s centre of gravity. The precision machined alloy plate that supports the arm simply slides in horizontally before fixing, allowing the ‘table to support tonearms of any length or type, pivoted or parallel tracking, although only one at a time. Alloy? Yes, alloy. Real engineering is about the appropriate use of materials rather than profligate expenditure. The specially selected aluminium serves its purpose perfectly, so why bother with a complex and more costly composite solution of dubious merit?
The void between the two outer skins is filled with a polymer damping compound creating an incredibly rigid, dimensionally accurate, stable and inert structure, representing the second layer in the ‘table’s defence against both internal and external mechanical resonance. Second? Yes. The first is the oil-bath which is an effective damper for resonance generated within the dynamic elements of the bearing itself. Bolting the bearing sleeve, well and stationary parts of the motor directly to the plinth creates an effective sink for residual energy, which will otherwise simply circulate within the structure.
GPA have eschewed any form of external suspension, instead preferring to rely on users investing in a proper support, an area of course in which the company cut its audio teeth.