Stability: Our integrated bearing and platter design incorporates the geometric advantages of an inverted bearing while retaining all of the lubrication advantages of a conventional bearing.
The belt pulls at a point midway between the bearing journals (the contact surfaces of the bearing). This line of pull is close to the platter's center of gravity. This geometry confers dynamic stability to the bearing and platter that is experienced as pitch stability in the music.
Large (.800") diameter spindle: Thicker stock deflects less during the machining process, resulting in the high machining precision necessary for the fine tolerances we specify.
Precision machining-to air-bearing tolerances: Further contributes to dynamic stability.
Oil reservoir: The lubricant capacity is 8.5 cc. Most of the oil occupies the reservoir which serves two functions:
- Damping stray vibrations entering or leaving the bearing.
- Cooling, as vibrational energy is converted into heat, the increased volume of oil circulates and dissipates the heat into the bearing housing.
Massive brass housing: Contributes to vibration and heat dissipation. The bearing housing is machined from 1.5" diameter brass stock.
Replaceable delrin thrust plate and hardened steel ball: For long life and user replacement in the highly unlikely event that this should become necessary. Since the wearing part (thrust plate) is user replaceable, this will be the last bearing you will ever need to purchase.
Threaded holein the bearing case bottom: For alternate means of electrical grounding.
Frequently Asked Questions
What kind of oil should be used in the bearing?
The short answer is that low viscosity oils are ideal for use in a Galibier bearing. Thick oils have the effect of suppressing dynamic contrast, pace, rhythm, and timing. We find this unacceptable in a product with high aspirations.
Lubrication has been a source of much obfuscation, propagated in part by certain Scottish turntable companies. Much time has been spent discussing this question on several analog equipment lists and several lubrication engineers weighed in on the subject. Ultimately, everyone had their own prejudices but certain principles arose from the conversation:
- Additives like colloidal graphite (what makes the Linn and Merrill oil black) are acceptable but unnecessary
- Stay away from detergent additives
- Match the oil viscosity to the tolerances of the bearing
Goal #1 - Protect the Bearing from Mechanical and Thermal Stress.
With respect to temperature stability, one needs to consider the application and how over-engineered even the least sophisticated of these products is for use in a turntable bearing.
Heat in a turntable bearing, from a petroleum engineering perspective is virtually non-existent. The massive bearing housing and large sump capacity (8.5cc) further minimizes stress on the oil.
During our early experimentation with bearing thrust surface materials, we observed that a Galibier bearing takes about 4 hours to warm up. This further demonstrated to us how little thermal stress is placed on the oil.
Goal #2 - Mechanical Stability/Viscosity
A bearing requires lubrication with some minimum degree of viscosity in order to remain geometrically stable. If the lubrication is too thin for the bearing's clearance, you will experience rocking which will manifest itself in speed instability.
Frequently, higher viscosity oils (think of STP motor oil additive) are used to bring loose or worn bearings back into spec - once again matching the viscosity to the bearing clearance.
On one analog list, a user of a VPI TNT reported great success by packing the bearing with lightweight bicycle grease. Others have reported success by using grease in the bearings of EMT's and Garrard 401's.
With the extremely fine tolerances in our bearings, you will have great difficulty getting even 50 weight oil to pass through the clearances. Don't even consider trying to get bicycle grease to pass through these fine tolerances.
Goal #3 - The Music
Now that we've addressed the health of the bearing as well as ensuring that it is stable (doesn't rock), our focus can return to the end-game which is the music.
Realize that any mechanical drive system is a resonant system.
We can tune this system optimally by recognizing its components and varying one or more of them
- Motor, its torque and mechanical moment of inertia
- The controller circuit - how quickly it responds to the dynamic demands placed on it.
- The drive interface and its compliance.
- Platter mass.
- Bearing tolerance.
Changing any one of these variables will affect what you hear (especially as far as timing is concerned), and not necessarily for the better.