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Buddha
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Turntable physics conundrum.

Aloha,

I've been playing with my motor orientation (... ...) on my Michell turntable for nigh on 23 years, and still have a slight conundrum.

I use the motor mounted "front left" instead of "rear left" and think it sounds better that way, but I can't quite wrap my brain around some of the reasons I have heard for it.

Music Hall is fond of claiming that front left motor mounting is superior, saying of it:

struts
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Re: Turntable physics conundrum.

Doesn't seem strange to me, but maybe I'm being simplistic.

The cartridge 'measures' the groove in a plane (roughly) perpendicular to the arm, from the cartridge's point-of-view the axis of the arm itself is just the 'direction of travel'. So if you vibrate the platter in the plane perpendicular to the arm (as the belt does if it is pulling in that plane) it is bound to affect the signal more than if you vibrate the platter in an axis parallel to that of the arm.

Now of course the arm's axis changes as it traces the record, but by my theory the best results should be had when the motor-spindle-to-platter-spindle axis is closest to the arm's axis for the greatest amount of time.

Buddha
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Re: Turntable physics conundrum.

I'm with ya, "push/pull" (left front) seems better than "side to side" (left rear) for motor vibration.

I can't find any literature, though.

Buddha
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Re: Turntable physics conundrum.

I also wonder how big a part of the Empire turntable allure this factor may be.

Jan Vigne
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Re: Turntable physics conundrum.

I'd say you need to heat up the oil, you've got enough red herrings in there to start a fish fry.


Quote:
In electronic signals, like an EKG, the smallest effect on the signal is seen when the
JohnMichael
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Re: Turntable physics conundrum.

Here is an interesting link from the Funk Firm.

http://www.thefunkfirm.co.uk/PL2.htm

Jan Vigne
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Re: Turntable physics conundrum.

I'm a bit surprised by Funk's claim to a patent on the Vector drive. The three pulley (two slaves), one belt system was used on the original VPI TNT and, if I remember correctly, the HW19 IV, years ago. That system has been replaced in the VPI line by the inverted bearing system that does away with the conventional bearing well and shaft.

I wonder what part of the VPI system was changed in order to acquire a patent on the Vector drive.

dcstep
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Re: Turntable physics conundrum.

Seems to me that all mechanical drives have some compromise fault that they'll need ot compensate for.

How about a magnetic drive? I can't imagine that hasn't been tried. You could use a motor in direct drive position, but driving a disc of magnets that would drive a similar disc of magnets in the platter, but without touching. Given enough magnetic power and a high quality motor, it seems like that'd be a great solution.

Dave

Buddha
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Re: Turntable physics conundrum.

It seems like we've been kind of been tere for a long time.

With many DD tables the platter is actually megnetically coupled to the stator of the motor, making it like you mention.

Zman9001
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Re: Turntable physics conundrum.


Quote:
It seems like we've been kind of been tere for a long time.

With many DD tables the platter is actually megnetically coupled to the stator of the motor, making it like you mention.

hmm. actually the platter would be mechanically coupled to the rotor which is magnetically coupled to the stator. i dont personally know of a TT where the platter itself is magnetically coupled to the motor stator but it certainly could exist.

Buddha
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Re: Turntable physics conundrum.


Quote:

Quote:
It seems like we've been kind of been tere for a long time.

With many DD tables the platter is actually megnetically coupled to the stator of the motor, making it like you mention.

hmm. actually the platter would be mechanically coupled to the rotor which is magnetically coupled to the stator. i dont personally know of a TT where the platter itself is magnetically coupled to the motor stator but it certainly could exist.

Right you are.

As I think about this more, perhaps the recent enthusism for rim drive is because tables like the VPI have the bearing point of pressure on the left middle (pulling,) and with the rim drive, that changes to right middle (pushing) - more in line with the axis of the arm/cartridge.

Idle(r) talk.

Jan Vigne
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Re: Turntable physics conundrum.

If you didn't have me on "ignore", you'd see the push/pull issue belongs in the fish fry along with your other ideas that have nothing to do with the matter at hand.

What matters is pull-release-pull-release-pull-release, etc. Depending on the bearing type, it's either the pull of the motor on the standing bearing shaft or the cogging of the motor or both (along with issues such as stylus drag).

Didn't you read JM's link to the Funk Firm's pages?

Are you ignoring everything and everyone now?

rvance
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Re: Turntable physics conundrum.


Quote:

What matters is pull-release-pull-release-pull-release, etc.

What really matters is the love and respect two people share in a committed relationship to heighten the experience of intimacy.

Jan Vigne
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Re: Turntable physics conundrum.


Quote:
What really matters is the love and respect two people share in a committed relationship to heighten the experience of intimacy.

Not while you're playing LP's for chrissake!!! You're going to have to turn the disc over sooner or later unless you have an old BeeSeR changer. And I hope you don't plan your intimate experiences around the sound of the stylus reaching the end of a side and going "schlumph ... schlumph ... schlumph ... schlumph ... schlumph ... schlumph ... " while you finish.

Buddha
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Re: Turntable physics conundrum.


Quote:

Quote:

What matters is pull-release-pull-release-pull-release, etc.

What really matters is the love and respect two people share in a committed relationship to heighten the experience of intimacy.

Did you ever hear King Missile's "Gary and Melissa?"

Fortuitously, I happen to have it on vinyl.

As to the subject, it's a sort of "thinking where the point of friction is" rather than the source of the energy to spin the platter thing.

It would be that point where the transmission of vibration would be the greatest.

Incidentally: You'll notice where VPI put the motor on their newest table, which they claim is their best sounding yet.

Front, left.

I hope Harry does an interview about deciding between belt and rim drive systems and his motor location. Even cooler would be if he makes another rim drive adapter; but the engine is quite close to the platter, so maybe not.

I think that new VPI is gonna be my next table...some day!

Well, that, or an Empire to play with. More in budget.

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