Constructing the perfect record player is perhaps foremost on the list of challenges to humanity. It is possible to cure many types of cancer right now, but building a turntable to satisfy the audiophile community remains a potentially unattainable goal. Nevertheless, we strive.
At present, turntables are driven by electric motors* directly, by belts or idler wheels <link>. All, of course, have their pros and cons, direct drive is torquey and robust but noisy. Belt drive is quiet but less torquey and prone to belt wear. Idler drive adds radial load to the main bearing and is also subject to degradation of the wheel.
My solution is a fluid coupling. Such couplings are "free from vibration and noises" <link> and very much baked technology. In fact the torque converter <link> from a standard automatic car transmission is an excellent example of a very high capacity variable fluid coupling that can be had for the price of a round of drinks <link>.
Now, imagine the electric motor drives a mini** torque converter. The motor starts under minimal load (good for minimizing current spikes) and accelerates the fluid using the impeller. The fluid cycles through the turbine imparting torque, the fluid is recycled through a stator to complete a loop. This is lovely, because the torque converter performs as a torque multiplier when input and output are mismatched. The output is coupled to the platter upon which the record is to be rotated. Speed control should be monitored optically from the edge of the platter, provision for multiple playback speeds can be achieved using a mini** automatic gearbox.
There, a low-noise contribution to the world of record players. If anything, this will foster new warring factions within the audiophille community, which I understand, is the point. It has many advantageous features: zero vibration, robustness, inconvenience, expense, complexity.
Sadly there are downsides, the hydraulic torque converter is extremely robust and totally suited to manipulation by DJ types, and the fluid will have to be changed every 100,000 miles.
*and the problems begin... bearing noise, electrical noise from commutation in DC motors or variable current in AC motors.
**You could also go full car size, why compromise?-- bs0u0155, Sep 24 2019 Inspiration Super-quiet_20Turntable_20motor [bs0u0155, Sep 24 2019] Fluid Couplings https://www.coalhan...com/fluid-coupling/ [bs0u0155, Sep 24 2019] Turntable Drive Types https://www.vinylsp...types-of-turntables [bs0u0155, Sep 24 2019] Torque Converters https://en.wikipedi...ki/Torque_converter [bs0u0155, Sep 24 2019] Quietest place on Earth https://www.atlasob...-labs-quiet-chamberOrfield Laboratories [Frankx, Sep 24 2019] Interesting. The Wikipedia article says that "[U]nder extreme conditions, ballooning will cause the converter housing to rupture, resulting in the violent dispersal of hot oil and metal fragments over a wide area" - a feature normally found only on Rolls Royce turbofan engines.-- MaxwellBuchanan, Sep 24 2019 Thanks. Yes, this would be quiet. Prototype Competition: quietest HiFi turntable.
Maybe here: Orfield Laboratories anechoic chamber [link]-- Frankx, Sep 24 2019 Surely the solution is to have the turntable mounted on a bearing-mounted flywheel with a mass of, say, 10-20tons (and as large a radius as can be accommodated).
The whole thing could be brought up to 33 1/3rd RPM using, for instance, a Nissan Micra lying on its side with one rear wheel pressed against the rim of the flywheel. It should take less than a couple of minutes to get up to speed, if you make the right gear changes. Then use a green lever to move the Micra an inch or so and turn the engine off, leaving the flywheel to coast.
Unless you're using a very heavy tone arm, the turntable should maintain its speed, to within a tiny fraction of an RPM, throughout a complete double album.-- MaxwellBuchanan, Sep 24 2019 Yup [MB], that’ll do it. Can’t see any downside.-- Frankx, Sep 24 2019 We suggest a solution in which a horizontally-mounted hydraulic torque converter is supplied with energy by means of a single long driveshaft from a Pelton Wheel or Scotch Turbine, incorporating a heavy, damped flywheel to eliminate speed variations and driven from a simple constant-head water supply, the water being returned to the header pond after use by a Newcomen engine sited some distance away to prevent sound or vibration interfering with the audio quality.
With a large enough header pond, the pumping engine can be run only when the turntable is not in use.
<later>
This is of course an ideal application for custard as the energy transfer medium in the viscous coupling; since it will absorb energy during the operation of the system, the final act after a session of serious listening would be to open the drain valve and enjoy a nourishing and tasty bowl of hot custard. What could possibly go wrong ?-- 8th of 7, Sep 24 2019 I believe a Borg Warner transmission might be called for.-- Frankx, Sep 26 2019 Magnificent.
<Awards [Frankx] notional croissant/>
We have a special offer on Assimilation at the moment ... are you interested in joining the Borg Collective ... ?-- 8th of 7, Sep 26 2019 Ah... thanks 8th.
I’m more of the Groucho Marx “...any club...” philosophy.-- Frankx, Sep 26 2019 Is there a Sanity Clause ?-- 8th of 7, Sep 26 2019 random, halfbakery