h a l f b a k e r yThis ain't rocket surgery.
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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?
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-chamber
Orfield Laboratories [Frankx, Sep 24 2019]
[link]
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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. |
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Thanks. Yes, this would be quiet. Prototype
Competition: quietest HiFi turntable. |
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Maybe here: Orfield Laboratories anechoic
chamber [link] |
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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). |
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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. |
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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. |
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Yup [MB], that’ll do it. Can’t see any downside. |
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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. |
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With a large enough header pond, the pumping engine can be run only when the turntable is not in use. |
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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 ? |
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I believe a Borg Warner transmission might be called for. |
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<Awards [Frankx] notional croissant/> |
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We have a special offer on Assimilation at the moment ... are you interested in joining the Borg Collective ... ? |
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I’m more of the Groucho Marx “...any club...”
philosophy. |
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Is there a Sanity Clause ? |
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