Subwoofer rumble issue

Yeah unfortunately you have to live with the negatives of the rumble filter is doing to the low bass, shame as that was what getting a sub woofer was all about.
Like I said the only way to totally get rid of "airborn feedback" as you found you have with the way I said to test for it, is to have the TT in another room as I did and which worked a treat, best bass ever, as my 2 x Kef B1814’s in 2 11cu ft enclosures were tuned down to 19hz fs each.

Cheers George

The airborne feedback is not the issue, it’s the structureborne feedback. That’s what the fuss over isolation is all about. Wake up and smell the coffee! ☕️

He's already proved he has air-born feedback, do the test above as in my first post, the way Ivor Tiefenbrun laid out all those many years ago,  (know who he is?)
Or sell the OP your useless car valve springs, or your magic pebbles, better still give them to him as they will end up in the bin, even better still give something constructive to these forums, instead of your constant malignant voodoo talk.
  http://www.machinadynamica.com/machina31.htm
 

Surely you must believe most other people are as backward and incapable of real progress as you. I’m considering putting you on the payroll nevertheless in view of your excellent job of getting the word out. 

LOL you guys are funny. There’s gotta be a solution that doesn’t involve moving my tt to another room. Would a different tone arm help? One that doesn’t use magnetic stabilizing? Ugh this is no fun. So strange that it developed over time too. I’ve had this set up for about a year now and it just started a month ago. I did have woofer pumping issues with my mains at first but fixed it by putting them on stands vs. the same surface at the tt. Do you think going to the Herron phono pre will help at all?