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Hurst motor rumble?

I have an HW19-IV with the stand alone motor.
When I drop the stylus onto a stationary object next to the platter, there is rumble as soon as the motor is turned on. Turn it off, the rumble goes away.

I removed the drive belt and tried again. No rumble. This means the noise is not coming through the platform on which everything sits.

Next, drive belt still disconnected,I dropped the stylus and spun the platter by hand. No rumble. (The bearing appears to me to be tight and well lubed so I don't think the noise can stem from disaligning of the platter bearing by the pressure of the belt.)

It seems obvious that the noise is coming from the motor through the drive belt to the platter. I am using a standard Hurst 600 rpm motor.

I always thought, apparently erroneously, that the drive belt itself damped motor noise. If any of you has a belt drive turntable, I would like to know what happens when you perform the aforementioned test. You need deep bass and may have to turn up the gain.
Can anyone verify that a "quieter" motor might reduce or even eliminate this rumble?
Has anyone done actual measurements of this effect and what are they?
rpfef

Showing 2 responses by mofimadness

mofimadness's avatar
mofimadness
4,938 posts
 
I'm confused. Why would you even "drop the stylus onto a stationary object next to the platter"? Unless you are cleaning the stylus and if you are you should mute the preamp.

Then you say to perform the test "you need deep bass". So are you actually playing a record? Nothing in your post states that this happens when you are actually playing a record?

If this doesn't happen when a record is playing, what difference does it make? Granted, it would probably drive me crazy too, but if it doesn't happen with normal use, let it go.

I just tried this on my custom HW-19 and it doesn't do it, but again I'm not sure that I completely understand?
mofimadness's avatar
mofimadness
4,938 posts
 
I know that VPI is now using a custom made 600rpm motor.
Still from Hurst, but not available from Hurst directly as a
replacement, you have to order it from VPI. I've read that it
is supposeably better, (not sure in what regards). You
could contact VPI and ask them.
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