Tube Phonostage Causing Rumble and Noises

@mulveling 

I’d love to say I’m an acoustic genius, but I figured out it was a standing wave because every time I went to look at the turntable to figure out what was going on, the sound would rapidly fade (and my heart would start beating way too fast, which I figured out was relevant later).

A very Heisenberg’s cat situation.  I’d look and the sound would go away.

Eventually it dawned on me that my body was breaking up the wave.  Did a little trial and error and then tests to confirm.

The weird heart rate is a classic symptom of intense subsonics, which I knew from working in a haunted house when I was a teenager.

This whole OP issue is odd.

@davetheoilguy - the Frog is relatively high compliance for a moving coil and favours arm's on the lower end of effective mass range, so if there is a problem, it's more likely to be in matching of the arm and cartridge than the cartridge per se.

The phono stage is fine. It sounds like the subwoofer is way too sensitive. I would disconnect the sub and any crossovers and see how things run. Remember, records always produce a little rumble. If all is back to normal you have a subwoofer problem, if not than you will have to start eliminating units one at a time. Other sources do not produce a lot of very low frequency garbage like a record does and may not excite the problem. 

@yoyoyaya 

The 3D printed tonearm is one of the Van den Hul recommended tone arms for the Frog Gold and vice versa.  In fact, they market together.  The mass of the 12 inch dual pivot is 12.5g.  They sound wonderful together.

Also note that the problem (as stated above) reproduced with the cartridge on the Esoteric Grandioso with its TA-9D tonearm which is a radically different design.

And there is no fault invovled, except the odd acoustics of my room and my tendency to listen at high volume.  I suspect any sensitive cartridge would have had feedback.