Why are my woofers pumping?

Back home, some more testing on main system:

Audiotomb suggested an arm bearing test. I set the SME V so that the arm floats, zero weight and zero anti-skate, can I lift it with a light feather? Yes. Movement is vertical, not slanted? Yes. Can I drop a 1 cm square piece of paper on the top of the cart, and the arm sinks? Yes. Can I blow the arm vertical and lateral? Yes. Can I  wiggle the arm base, is there any slack? No. Conclusion: arm bearings probably OK.

Stingreen - support is a heavy stone rack, but sure, I can try a wedge.

Atmasphere - I guess you mean that there could be a turntable issue even if the pumping is more evident on some LPs than others. I have ordered the tool to tighten the bearing shaft/housing on the Hanss, but have not received it yet. So I have no way to check directly. Come to think of it, I could try to find some DSD recordings made with the same cart and arm, on the VPI HW19 player that I used before - this should clarify the issue. If it is a turntable issue, I shouldn't have pumping on recordings from the VPI - right? (But my inner audiophile says: if things were that simple...)

I would grease the platter bearing and see if that makes a difference. If it helps, I would consider replacement of the bearing unless grease is an acceptable lubricant.

The fact that its happening in time with the rotation of the platter (as you stated earlier) points to the platter bearing.

Yes - or simply, the vinyl groove noise...

Testing DSD recordings made by the same cart-arm combo on a different player, the VPI HW19, some years ago. Not quite the same, since the recording was made with the Lyra titan i cart, not the Atlas. Yet they have the same compliance and should behave fairly equal.

Is there woofer pumping? Yes some. A bit less? Maybe, not sure yet. The jury is out.

Listening to my older recordings, I hear a poorer recording and flatter, more restricted sound than with my current Tascam DA-3000 recordings (and direct vinyl playback). Not strange, these recordings were made by the little Korg MR-1, punching above its class, but still limited, with single ended connections while I now go balanced, to the Tascam. My general impression is: when I went from standard DSD recording (Korg MR-1) to double speed DSD (Tascam DA-3000) I clearly got better sound and more bass. But maybe a bit more woofer pumping too? I am not sure. I will have to check this out.

Conclusion so far - maybe, just, live with it, until the next cart change.
Facts:
- Pumping carried over to the secondary system - clearly not amp or speaker dependent (digital LP recordings).
- Arm bearing, turntable, drive, belts etc - no indication of misbehaviour
- Maybe the leeway in the Hanss bearing plays a role, I will know soon when I get the tool to tighten it (i doubt it makes much of a diff, based on testing so far) - including: if the Hanss misbehaves, why do I see pumping also on my VPI HW19 recordings - ?
- Getting a balanced filter seems difficult. E g the KAB single ended filter would need an extra box. This combo (or cludge) would probably not be good for sound quality, compared to direct balanced.
- I suspect that a rumble filter, properly installed (in the phono stage) might help my sound.
- I see woofer pumping clealry before or between the music tracks on the LP, with the stylus in the groove. This goes on more or less, depending on the LP. The pumping is clearly related to the revolution of the record, it repeats once per cycle.
- When the music is playing and the stylus in working within the music track, I don’t see much pumping. I suspect that this is because the woofer is now in the grip of the musical energetic vibrations.
- However, it may be that the woofers are still made to "work" down below in ways not optimal to the sound. In simple terms, more stress, less peace. Not sure.
- I have a feeling that woofer pumping is related to more listening fatigue. But I am not sure. Testing different records, I also find a bit of the opposite rule - pumping is related to good, involving sound.
- If I had serious "underlying pumping problems" with analog/vinyl, I would have selected the digital source, in my system (since digital music shows no pumping). Yet that’s not the case. Digital music sounds much poorer in my system. More harsh and flat - and not much more "peaceful". Although this may also be due to the fact that my analog chain is better than my digital chain.