Why are my woofers pumping?

The Atlas sounds real good, now, with 100 ohm loading (+1 to Atmasphere). Playing Nik Bartsch: Continuum (great sound) for example, but also older overlooked classics like Joe Walsh: No peace in the city. I love this cartridge. The woofers are energetic, yes, but I cannot see much pumping.
 
Toddc2 - this reminds me of all the tweaking I did with my VPI HW19 - every little bit helped - sand box - ceramic cones - name it. I will take you up on your kindly offer to try the filter, if the pumping persists.

krelldog - I see what you mean - and I also position my speakers quite far into the room. I think best practice is to move the whole stero system away from the wall behind the speakers but thats not very possible, in my case. Which filter did you try?

The interesting thing is: it happens at certain intervals per revolution of the record (playing silent grooves between tracks). If I turn up speed to 45, the pattern is repeated, only faster. This seems to indicate that player rumble or drive problems are NOT the main issue.

Boy, that sure sounds like a drive issue to me!

But it sounds like this is mostly solved :)   I would put a drop of oil on the platter bearing for good measure...

I think it was the KAB filter....or something similar to that.

I'm not saying its not a good product....it just didn't work for me.

@o_holter

It sounds as though your setup adjustments might have reduced some cartidge resonance. I’m thinking that was likely part of the problem.

And in answer to one of your questions, yes, sometimes subsonic noise is actually pressed right into the grooves. It can result from multiple steps of the vinyl manufacturing process. It can also result from warps but that is a problem more often associated with stable balance tonearms, such as some uni-pivots, as their tracking force changes when they traverse the warps.

So there’s many factors that can lead to woofer pumping, but only one ironclad solution: a rumble filter. It will only be a detriment to the sound if that is your expectation. For every one who claims they alter the sound, there’s probably a dozen who claim otherwise.

I own the KAB Rumble Filter and I am one of the ones that claim otherwise.  (No change in the sound!)