So Weird- No Stylus Contact Woofer Pumping with Hana ML and Elac PPA-2

Yeah, @mitchellcp you said this in an earlier post - "Woofer pumping is tied to rotation speed, the pumping is faster at 45 than 33 also spinning the platter by hand will excite the woofers."

When you were spinning by hand, was the turntable power on?

Also, when you tried 33 and 45 did you turn anything off in between? I ask because @lewm talked about turning on and off equipment can yield different results with the oscillation idea.

Not sure this below is representative, but it is interesting:

I managed to reproduce woofer pumping, with my old Dual 701/V15III (direct drive) unplugged from wall power, the platter on or off, and just having the stylus near the motor housing and spinning the housing or platter by hand. More pronounced with the platter off. I can go real slow and get real slow woofer pumping, or faster and get fast woofer pumping. Move the stylus further away and no pumping. I had to turn the gain almost to full to see anything though; increasing the gain on the phono stage increased the extension of the pumping (makes sense).

I also reproduced this, but it was much more mild woofer movement, with my old Technics SL-D20 (also direct drive), again unplugged from wall power and just spinning the platter by hand.

@ejb14 

When you were spinning by hand, was the turntable power on?

No, when the power is on you have two choices, 33 or 45.

Powered items were amp and pre amp.

It’s kind of reproduced except mine needs a record or synthetic mat or both.

My oscillation hypothesis is officially in the toilet, if the frequency of the woofer pumping is equal to the TT rpms.  Over and out.

most likely this TT/Phone inputs w/o a grounding wire between them, so it is sensitive to 33 1/3 electro-magnetic  radiation.

@byang12  I’m confused, could you restate that?