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In the Forum: Analog Playback
In the Thread: Ultimate Turntable
Post Subject: Fluid viscocity/tensionPosted by Paul S on: 3/17/2008
When I was a kid we had a "Fluid Drive" Dodge that used oil rather than gears or friction plates as a torque converter. But I suspect fluid viscocity and film strength would need to be kept very consistent for the sort of speed accuracy one needs for a TT. As far as I know, viscocity is always +/- affected by temperature and load conditions, even multi-vis, and if this is true then there would have to be an effective way or ways to counter this in the "drive/float" TT application.
I think both lower speeds and tighter tolerances help the viscous platter bearing scenario, along with the fact that there is the drive motor, too, and the oil is merely offering resistance there. But in either case it might help to use some sort of sensor controlled heater.
Of course we aren't crunching fluid mechanics numbers, but I wonder, practically speaking, about the potential accuracy available from fluid drive in the home (as opposed to the lab). If do-able, fluid drive would likely cure cogging or read-and-react type effects. This might even allow the "transparent use of a speed servo to control the fluid driver. I am not sure about moving fluids as high/low pass filters, but fluid in motion might be different than "static" fluid in these terms.
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