Help deciding which TT

You are experiencing acoustic feedback. There are two types, structure borne, which enters through the rack, or stand, and is transmitted through the TT suspension, and airborne, in which sound waves directly excite the plinth of the turntable.

Since you have already made a very smart move and gone to the wall shelf it might be best to try to determine if the remaining issue is structure borne or airborne.

You might try removing the record player from the wall shelf and placing a glass of water on the shelf. Play another source, CD or streaming, whatever you have, and observe the water for movement. Heavy movement will likely indicate structural issues, in which case a TT with a different plinth may help as well as putting a bicycle inner tube under the turntable. It is also possible that a high-pass filter will help, such as the one marketed by KAB. For me that is a last resort as this does have an effect on phase response in the audible range, and adds a set of interconnects, but in some instances it is a perfect cure that eliminates the problem.

If it is airborne, then you have to look at moving the turntable to a place that will excite it less. Play a CD with heavy bass and move your head where you might site the turntable. You will hear areas of greater and lesser bass accentuation. See if you can move the turntable to a place that has less bass accentuation. That will often help.

I hope that helps a bit.

Another avenue of concern is a grounding issue. If the turntable is not running, I'm wondering if feedback is the problem. Do all the grounding tricks....eliminate the 3rd pin of the sub via a cheater, reverse the plug, using an extension cord, plug the sub into an outlet at the other end of the house, etc. When you find the troll, you then can figure out how best to fix it. Let us know....

I'd recommend waiting one year till new Technics DD. It may be sold at your price range hopefully.

Thank you everyone for your ideas.

It's an odd thing.

As I mentioned, just having the needle dropped on a stationary record and turning up the volume level is enough to kick in the rumble. The room is perfectly silent while doing these test.

What's interesting is that I can actually dial the volume up louder when the patter is spinning and music is playing.

If I turn up the volume with the tonearm in it's resting place, I get zero rumble/woofer flapping. I use a zero dust to clean my stylus. If I lower the stylus onto the zero dust, and then increase the volume I also get no rumble/woofer flapping.

The subwoofer is connected to my Anthem MRX HT receiver via LFE connector. No issues with digital sources of course. My phono preamp is a Rega Mini Fono A2D.

I created a custom grounding wire awhile back that connects the bearing well on the Rega to the Mini Fono A2D. I found that it eliminated some HUM I get in the Winter when the air is very dry. Connecting and disconnecting the wire makes zero difference.

If the issue is a grounding problem, it seems like the source is the tonearm itself. The RP1 doesn't have a separate ground wire for the arm. It's supposedly grounded through the RCA connector.

It is acoustic feedback from the sub into the turntable body...bearing...platter...stylus. Put a slab of granite under the TT on the wall shelf.