HELP-woofer moves alot when playing lps

My cartridge/tonearm combo is perfect on paper and confirmed thorough a test record. Nevertheless, I would get woofer pumping on some records, but not others, which clearly indicates the problem lies with the record, not the system. This also confirms what KAB describes on its website about the subsonic/infrasonic frequencies being imparted on the recording by the disc cutting system. The KAB filter solved the problem and I never looked back. I think the argument about sound degradation is silly; you actually improve the sound by not wasting your amp power trying to amplify infrasonic frequencies and your speakers trying to reproduce them.
If by some miracle your system is free of rumble problems, God bless you, but for those with well matched carts and tonearms and no isolation problems still experiencing woofer pumping on some records, a good quality subsonic filter is the answer.

You people intrigued me. Now I want to experiment and create big bloody woofer pumping in my system. God bless me.

And what system would that be, Inna? If you call listening to records "experimenting," no wonder we intrigue you.

Isn't analog playback fun? The old adage, "Ignorance is bliss." holds true. Just like an onion, we peel back the layers just to find more layers. Cartridge alignment, cartridge tracking, VTF, VTA, suspended turntables, rigid turntables, high mass, low mass, wood floors, concrete floors, ported speakers, unported speakers, wiring, tubes, on and on. No wonder so many young people walk around with mp3 players plugged into their heads!
I love this hobby! I really do. As frustrating as it is when things go wrong, it is just as rewarding when finding a solution. It is like we each become an active participant in the music. So many good solutions to overcome the typical problems. And Audiogon provides us with a great support group when we hit a wall. There, I just wanted to say that.
I think everyone is right regarding what has been said on this page. All the different types of turntables, speakers, and electronics in-between lead to many different solutions. I experienced the woofer issue years ago too. I could even induce feedback in my system by cranking the volume. That lead me down the path of isolation and to my current turntable which I think, like many great turntables out there, provides a firm foundation for the spinning record.
I have also experienced the occasional record with built-in rumble that excites the woofers. Mostly, I do not have much of an issue because I simply do not play music at ear splitting levels like I did in the 70s and 80s. But for those that do- then solutions like a low pass filter are perfectly reasonable. For some of us purists, the idea of a filter risks missing out on some of the music. For example, an organist who uses the 16ft pedal to give his music a certain character. Or how about the cannon fire on Terlarc's pressing of the 1812 Overture. There's a test for your cartridge/tonearm. The grooves in the record make nearly a right angle turn! So hopefully, the low pass filter is needed only for those certain records with high rumble. I remember years ago playing one of my favorites, Dark Side of the Moon, cranked way up. The woofers were excited as soon as the needle was dropped into the grooves, but the most fun was watching them pump out the heartbeat. Bragging rights to those whose speakers could blow out a match. :) Of course, I'm much too mature for that now.

I had this same issue in my system....tore my hair out until someone suggested that it is some kind of RF...from airport, etc. I replaced my cables with shielded ones, and the pumping was gone. ...I'm not saying that is YOUR problem, but it was mine. ..by the way, you CAN change the mismatch of cartridge/arm by adding weight to the cartridge end of the arm.