Turntable Causes Speaker Cones To Excessively Move Rapidly

OP

Please explain what VTA at 0.5 means?

Perhaps tell us how you set/aligned the overhang and two null points.

IOW, is your cartridge aligned properly.

remember, anti-skate to zero when setting tracking force, then add just a little anti-skate

Technics 1200G Owners:

Using the dials on the Tonearm, how accurate are the tonearm's dials to reality?

i.e. I found my SME 3009 II, both the tracking force and anti-skate were very accurate, while most other arms, the settings on the dials were inaccurate.

I had the same problem. My turntable was a Clearaudio Performance DC, Charisma MM cart, Pass Labs phono amp, T+A 3100HV integrated amp and Wilson Audio Alexia speakers. The culprit was the Pass Labs phono amp. My Manley Chinook phono stage did not do this. I removed the Pass Labs amp and used the phono stage in the T+A. Not only did it eliminate the woofer throbbing, it sounded great. 

@dman777 

It is super freaky, right?!?!

I recently got some new speakers that I leave the grills off.  I mostly stream and when I played some records a couple weeks ago I jumped up and raised the tonearm.  My old speakers have the grills on and they are very difficult to remove so I suspect this has been happening for a while.  It does not seem to cause any harm to the speakers but it sure is difficult to watch.  I did some research and got all the same stuff people are posting here.  My issue is not isolation, I solve that a while ago, I suspect mine is the mismatch between the cartridge and tonearm.  I haven't tried to resolve, just one more deterrent for records...ugh.  That's another thread as my digital sounds just as good on most albums and I am losing the desire to mess with records.  Best of luck in figuring it out.  Let us know what happens.