Speakers "pumping" with record warps - normal?

I had the same problem once, and discovered it was a very low "hum" which came from the wall power. I changed power cords and it went away.

Anything that moves your stylus/cantilever will translate to speaker movement. That's always been a factor with turntable/cartridge systems. If you can find a record clamp or weight that will take out some of the warp, it will help. Hopefully you're not using any kind of bass boost or "loudness" control in your listening. If the speakers don't exceed their linear range, or bottom out: there shouldn't be any damage to the system. With regard to your tonearm/cartridge resonance: 8hz is above record warp freq., and below audibility(close to the lower end of ideal). For more insight: (http://www.gcaudio.com/resources/howtos/tonearmcartridge.html) If your house is of frame construction: mounting a turntable platform to the wall is not a great idea.

What are people's thoughts on using a little bit of tonearm damping to help reduce this? I think that's onle of the reasons those trouchs/cups/whatever are built into the bearings, no?

Enjoy,
Bob

The issue I see with using tonearm dampening is that it will affect the entire frequency range. If the woofer excursions are only with warped lps I can't see subjecting the entire vinyl collection to the dampening because of a few warped lps.

I think it is important to make sure these excursions are not pushing the amp into clipping. It takes large amounts of current to move those woofers like that, even if you don't hear any sound.