Why do my bass drivers shake violently listening to vinyl

@erik_squires Excellent post!!

You already have anti vibration feet designed by Technics for their new G series. The cabinet is a 4 layered construction. You DON’T NEED any springs or butcher blocks or any platforms under your turntable (these crap is for belt drives).

Technics turntable can be used by PRO near a HUGE sound system with tremendous bass response, probably 1000 times higher SPL than from your speakers.

G and GAE are top model in SL1200 series and stock feet are very well engineered, but if you want to try something else you have to check Isonoe (they are made for Technics).

Read this topic.

Unless you are not placing your turntable right on a SUB I think the problem is not the feet.

Chak, If the 1200GR is without construction or operational flaws, I quite agree with you.  If it has a construction defect, like an off-balance platter or bad bearings or something rubbing on something, then it is better to identify that problem than to put a rumble filter bandaid over it, I think. For that matter, I am guilty of suggesting other types of bandaid, so my own advice is also flawed in that way.  One would like to examine the TT in isolation.  The only thing I suggested that might help to eliminate problems in the Technics is to temporarily replace it with another known good TT, and determine whether the woofers still act up.  If that test is passed, then maybe the rumble filter is the way to go or any of various forms of enhanced TT isolation first.

Vinyl has much less bass extension the digital, limitation of the medium.
Vinyl playback equipment often has more. Not from the program. There used to be subsonic filters to cheat your way out of it but now... 
Saddle up.

That’s why there’s been some mention of the KAB rumble filter which is a well made add-on.