The Galibier Bearing
In over two decades of development and refinement, we haven’t been able to improve on the basic design.
It’s a simple, well executed design and manufactured to aerospace tolerances.
Features and benefits:
- Tolerances so fine, that individual matching must be performed.
- Precision machining to air-bearing tolerances. An over-sized shaft (.800″ / 20mm diameter) may be overkill to run a turntable with, but thick shaft's rigidity facilitates higher precision during the machining process.
- Oil reservoir/chamber. A central section of the bearing serves to damp stray bearing vibrations – slight as they may be. Think of a plucked violin string whose maximum travel is at its midpoint.
- Massive brass housing machined from 1.5″ (38mm) stock – contributes to vibration and heat dissipation.
- Replaceable Delrin thrust plate.
- Ceramic thrust ball for long life and low noise. None of the “exotics” we’ve tried have convinced us to change this element.
Frequently Asked Questions
Lubrication has been a source of much obfuscation, propagated in part by certain Scottish turntable manufacturers.
Realize that from a petroleum engineering perspective, there is very little demand on the oil, and less so, with a close tolerance bearing like the Galibier.
What about setting belt height, with respect to platter stability (rocking)?
You’ll read much about the geometric superiority of inverted bearings, as well as optimizing the height where the belt rides on the platter. The idea is to create greater dynamic stability (less platter "wobble"), and the theory is solid.
If you're not familiar with the concept, visualize the tightrope walker's balance beam. The pole lowers the walker's center of gravity, as well as increasing his moment of inertia, and therefore resistance to losing his balance.
Lowering the center of gravity of a platter doesn't require an inverted bearing however, and we've certainly taken the physics into account in the design of our platter, our non-inverted (right side up?) bearing, and the ride height of our drive belts.
An inverted bearing may allow you to ever so slightly drop the platter's center of gravity a bit more than a non-inverted one, but like anything else, there are other variables at play, such as lubrication and thrust bearing materials.
Back to the belt ...
Strategically positioning where the belt "pulls" on the vertical axis of the bearing theoretically contributes to this dynamic stability.
At the end of the day, we've found that holding extremely tight manufacturing tolerances renders these design considerations to be insignificant, which is to say that focusing on execution is key, irrespective of bearing architecture.
In our experiments, we've attempted to upset the dynamic stability of our platter by varying the height of the belt across the entire height of the platter, and we have not been able to measure or hear any difference.
Our take? If a bearing is well executed, then there's no significant difference in architecture.
Similarly, and contrary to internet "wisdom" varying the motor pod position has no effect on speed stability.
What kind of oil should be used in the bearing?
The short answer is low viscosity oils with no detergents, and which don't leave deposits.
Lower precision bearings require thicker oil (or even grease) to attempt to compensate for their inherent instability.
We have been specifying thin, air tool oil for over two decades. It is readily available, inexpensive, and satisfies all performance criteria.
Some basic guidelines (if you want to experiment):
- Stay away from detergent additives.
- Match the oil viscosity to the tolerances of the bearing (high quality bearing = thin oil).
- Additives like colloidal graphite (what makes the Linn and Merrill oil black) are acceptable but unnecessary.
Lubrication Goal #1: protect the bearing from mechanical and thermal stress. No oil you’d consider would fail this test.
Lubrication Goal #2: provide mechanical stability (via viscosity). This is a non-issue with Galibiers, due to their air bearing tolerances, but lesser turntables have been known to benefit from thick oils, and even bicycle grease!
Lubrication Goal #3: do no harm. This is where staying away from oils with detergents, as well as the opposite – those which may leave a varnish/deposit over time comes into play. Again, air tool oil is designed to these requirements.
Can I experiment with lubrication?
Sure! Just follow the basic guidelines mentioned above, and realize that while there are guiding principles, there are no absolutes, because any mechanical drive system is an interactive system.
Changing any one of these variables will affect what you hear. Have fun!
- The motor and its controller – how quickly it responds to the dynamic demands placed on it.
- The drive type (belt, idler, direct).
- For belt drives, their compliance (rubber vs. stiff belts)
- Platter mass
- Bearing tolerance