Unique Nested Platter
It may be a surprise to some but a big source of noise in a turntable is the platter itself!
No bearing is perfect, even with ultra fine tolerances; the bearing must still have clearance for rotation.
This tolerance creates vibration when a bearing is required to support a platter spinning at 33 or 45 or 78RPM.
The spinning mass then precesses or "wobbles" and creates modes of vibration at a range of frequencies.
One of these modes is an up and down bobbing motion in the audible range.
This creates interrelationships with the chassis and highlights the need to place the mounting feet at an optimal position. (see Chassis Design)
Other modes a platter generates are twisting modes. The energy transmitted to the platter from a belt or direct drive are also interacting.
Using three motors to drive a platter would add vibration sources and transmission paths.
Belts are also too weak to prevent platter wobble from this perspective.
The Nested Platter
The nested platter design of the Caliburn allows for superior isolation from external and internal resonant modes of vibration that have been shown by FEA modelling to be at the surface of the platter in the critical area adjacent to the record.
In contrast other platters exhibit significant audible vibrations through the bass and midrange which can be characterized by audio terms such as "dark", "bright", "muddy", "analytical" etc.
These modes of vibration have been reduced by clever design and shape optimization as well as choice of materials.
The Vibration diagrams (click the + below to view) are from msc software NASTRAN FEA, and illustrate how we can see problem resonances. Using Shape Optimisation we move these out of the audible band into areas which can be more effectively controlled.
Vacuum Hold Down
The platter is designed for vacuum hold down and uses a washable ultrathin (0.30mm) layer of damping material under the LP to prevent dust impregnation.
We have built a database of properties and measurements which now allows us to "virtually" model any platter design and determine the sonic signature by matching it to similar signatures from prior listening tests.
The Audiophile Result
The audiophile result is an incredibly low noise floor and the ability of the platter to release every last nuance of recorded information without adding additional artefacts. You will be shocked!