In article , RJH
wrote:

"Dave Plowman" wrote in message

Assuming it goes round at the right speed, the only other thing might
be external magnetic fields generated, in the main, by the
transformer. Hence the toroidal which has a low field. But if you
haven't got any audible induction from the PS, you should be ok.

--

Why is it so difficult/expensive to achieve a steady sustained motor
speed? There's quite a body of measured evidence that suggests
variations between PSUs, and this points to 2 things - average and
sustained speed.

There will be variations in 'drag' as the details of the music change. This
tends to act to slow down the turntable. However this effect should be
quite small. Also, with a belt drive turntable I'd assume that - if it was
correctly built in the first place - that the main factors that determine
how much effect you get are;

1) elastic behaviour of drive belt.

2) elastic behaviour of the turntable suspension to torque variations.

i.e. I would hope the motor and its PSU would have little effect.

I'd be interested to see measurements of this, though, as it would be easy
to measure givin test tonebursts. So far as I can recall, no-one has
published measurements of this.

If it's not difficult why do people spend so much money on things like
Lingos, Origin Live PSUs etc?

Because the magazines tell them how good they are?

Perhaps because the original motor is poor?

Can avoid mains variation induced pitch alterations?

They simply 'like them'?

No idea, really. :-) For all I know, the motors used in some turntables
are so poor that this really matters... However I'd be inclined to worry
about choosing such a motor in the first place if this is the reason.

I do (of course!) accept that placebo effects arise in all matters hifi,
but things like pitch and stability are quite easy to listen for - so
there must be some truth in these exotic PSUs?! I've never noticed noise
from a power supply but I can hear differences in stability (say a
decaying piano note) - even on quite expensive turntables.

Do you mean wow/flutter, or do you mean dynamic changes due to drag? If so,
how are you establishing this as the cause?

Slainte,

Jim

--
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