Turntable Motors
 

Brian wrote:

I somehow feel that aero engines and turntable motors have
as much in common as seed drills and oil drilling rigs.

Seed drills don't rotate AFAIK.

Aircraft turbines and turntable motors are multipole drivers
used in situations where vibration management is crucial,
and noise is an annoyance. Vibration analysis is similar, in
that there are stators and rotors, each with a number of
poles, and forces upon them that vary depending on their
relative positions, which change as they rotate. Car engines
have multiple cylinders and in some respects demand similar
consideration, including the option for sprung and damped
mountings. I mentioned the possibility of using a different
numbers of blades through a turbine because the option to
use a different number of rotor and stator elements, with a
non-integer ratio, in an electric motor would result in
quite different vibration characteristics, because peak
forces wouldn't coincide.

Design engineers are generally not witless, but rather make
informed decisions, in these cases about how much vibration
is worth eradicating, and how much can be managed. They may
be misinformed, of course, about market requirements, and
constrained by the cost and availability of parts and
materials, but engineering is engineering, and vibration
analysis is pretty well understood.

Seems to me that this particular turntable occupies a niche
in which functional simplicity is considered a key feature.
If it sounded bad I could understand the criticism. You
can't spoil the ship for a ha'porth of tar if the sheep is
of a variety that doesn't need tarring. OTOH, you won't
satisfy a buyer who judges a sheep on the quality of its
tarwork.

I remember being rather impressed by those Phillips belt
drive turntables in the 70s. They worked very well.
However, there are a couple of very old Technics decks
still running in certain broadcasters studios with very
good rumble and induced field figures. So I agree it
should be better the more it costs.
Having said that i have an SL5 with an Ortofon cart that
sounds very nice, still.

Vertically integrated mainstream manufacturers can make
their own optimised motors and/or electronic controllers
cheaply and not sell them to anyone else. They're the ones
to go to if you want a mainstream product. Niche products
from small manufacturers are more likely to be quirky and
unreliable, or horribly expensive.

It really should not as its a cheap direct drive with a
servo parallel arm!

Does that mean the cartridge isn't floating? If so, and
rigid mounting to a common ground makes the whole caboodle
shake in unison, then the shaking won't matter much, maybe.

Ian

Turntable Motors
 

tony sayer wrote:

Did you see that prog on Rolls Royce aero engines the
other nite?,very
very impressive!. Its prolly still on iplayer...

Watch out, Arny's a spy.

Worth watching just for the blade containment test, I
thought. Must have been heartbreaking for the poor welder.

Remember the RB211? The one with carbon fan blades that
failed the chicken test. AFAIR, RR's recovery was assisted
by the state. Now they have those very impressive inflated
composite sandwiches that Arny's not supposed to know about.

That Boeing Dreamliner has alarmingly floppy wings, I
thought. Good for decoupling vibration perhaps, but those
huge engines droop so close to the runway it looks like they
could easily suck up something harder and heavier than a
chicken. Hopefully they learned from the Concorde disaster.

These days, although British engineers are highly regarded,
there aren't many British manufacturers to employ them. When
Forgemasters recently had their state loan stopped, they
were instead encouraged to sell themselves abroad to raise
the cash. I don't necessarily mind that in itself, but it
doesn't fit well with the kind of patriotism that is
demanded of us for football, wars, and repaying the
"national" debt, whatever that is, and whoever we owe it to.

"British engineering" seems such a quaint concept now. If
the turntable in question is actually of British design and
manufacture, then hats off to 'em for heroically paddling
against the current, even if they do shake a bit.

Ian

Turntable Motors
 

"Ian Iveson" wrote in
message news:vdvZn.183542$Hs4.127292@hurricane

tony sayer wrote:

Did you see that prog on Rolls Royce aero engines the
other nite?,very
very impressive!. Its prolly still on iplayer...

Watch out, Arny's a spy.

Correct connection at one degree of separation: My father made his name as
an expert toolmaker during WW2 as part of the team that started up
production of Rolls Royce Merlin aircraft engines at Packard Motor Car
Company, here in Detroit. RR sent detailed plans for the engine but nada
about how to tool up or assemble it. My dad helped "spy out" those little
details.

For his efforts my father was given a journeyman's credentials without ever
serving an apprenticeship, which of course was a very valuable reward at the
time.