Help deciding which TT

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.

"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."

You should only use 1 LFE connection. If you connect IC's to the LFE out on your HT preamp, the other end should go to the line level input on your sub, not the LFE input. Try that first.

You may also want to try lowering the gain on your phono preamp, as well as checking the gain on the channel you are plugging it into. A lot of theatre processors have that ability. Also, I'm assuming that you are using the analog connections on your phono pre, and not the USB option.

"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."

I have a 30lb two inch thick slab of Maple between the wall shelf and the Rega. The rega sits on top of four Herbies tenderfeet instead of it's normal three stock feet.

The Martin Logan Grotto i subwoofer is the only thing connected to the LFE output on the receiver. The phono preamp is connected to the receivers analog (AUX) input. The only time I've ever used the USB is to connect the preamp to a computer for recording.

I don't think the Rega Mini Fono has the ability to lower the gain on the analog connections. I think the gain control only works with the usb port.

"I don't think the Rega Mini Fono has the ability to lower the gain on the analog connections. I think the gain control only works with the usb port."

You can sometimes control each input on a HT preamp individually. I keep coming back to this gain issue because 5.5 MV seems pretty high. I haven't uses a MM cart in years, so I guess that could be normal for them. The highest output cart I can remember having is a DV 10x5 at 2.5 MV, and you needed to set the phono pre on MM to use it.

Maybe try fooling with the xover on the sub. See if you can set it to have a limit on how low it will go. It may be having a difficult time with really low notes, and that distortion is somehow effecting the system. Also, it wouldn't be a bad idea to try connecting the sub normally, without using the lfe, and any other type of EQ/Room Control processing.