RE: High friction bearing for low mass table- sounds nuts to me.

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Posted by berlinta on January 29, 2008 at 02:28:07

In Reply to: High friction bearing for low mass table- sounds nuts to me. posted by jsm on January 28, 2008 at 18:04:19:

Hi Joe,
If stylus drag was constant, I could follow your argument. But it's not and the motor working against a constant STEADY drag, be it due to an eddy current brake or a high friction bearing, will continuously "feed" a lot of energy into the system to make up for these losses. The small and constantly varying losses due to stylus drag become less significant since they are modulating the slow turntable speed at high frequencies and the combination of motor torque and drag forms a low pass filter. The combination of a low torque motor and a high mass platter(with minimal friction bearing) forms a low pass too, but once slowed down it takes the system longer to get up to nominal speed and you're certainly encountering an "overshoot" due to the large platter mass/inertia. The speed will fluctuate around the nominal value at a low frequency .
Same for too much torque and a given platter mass, but no friction losses(damping). Speed variations are now of higher frequency.
So you could look at bearing friction as a damping device for higher frequency speed variations(flutter).
Lastly, most motors produce less vibrations when working against a defined load.

Best,

Frank

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Follow Ups Full Thread

Topic - Ayre DPS turntable - Comments by Hansen/Silberman - restock 21:24:58 01/27/08 (12)

RE: Ayre DPS turntable - Comments by Hansen/Silberman - Davy-pie 13:32:39 01/29/08 (0)

RE: Ayre DPS turntable - Comments by Hansen/Silberman - restock 13:48:29 02/01/08 (0)

A clarification from Hansen - Charles Hansen 10:21:43 01/28/08 (4)

Thank you for the thorough clarification! - restock 12:00:21 01/28/08 (2)

RE: could not find your contact information or and email address for Ayre - Charles Hansen 20:27:19 01/28/08 (1)

RE: could not find your contact information or and email address for Ayre - ejlif 21:19:42 01/28/08 (0)

RE: could not find your contact information or and email address for Ayre - Charles Hansen 19:43:14 01/29/08 (0)

A clarification, indeed! Which is just what is needed to... - Neil49 10:43:41 01/28/08 (0)

RE: Ayre DPS turntable - Comments by Hansen/Silberman - berlinta 04:56:45 01/28/08 (3)

High friction bearing for low mass table- sounds nuts to me. - jsm 18:04:19 01/28/08 (1)

RE: High friction bearing for low mass table- sounds nuts to me. - berlinta 02:28:07 01/29/08 (0)

RE: Ayre DPS turntable - Comments by Hansen/Silberman - restock 08:54:05 01/28/08 (0)

RE: Ayre DPS turntable - Comments by Hansen/Silberman - DevilDawgMom 21:37:42 01/27/08 (1)

Thanks!! - restock 21:52:51 01/27/08 (0)

Follow Ups

RE: High friction bearing for low mass table- sounds nuts to me. - berlinta 02:28:07 01/29/08 (0)

RE: High friction bearing for low mass table- sounds nuts to me.

87.230.33.55

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