HELP-woofer moves alot when playing lps

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.

No, that's not that, I do listen to records but don't have such damn thing.

Just got a KAB filter and installed it. Much better!!!

One thing that is for certein is that many records are often not flat, but have minor warps that cause this great displacement of the woofers due to the low frequency. It's not the problem of the table, the cart, ot the isoltaion. It IS the record and the ONLY way to solve this is to use a low pass filter. It is down 3 dB at 18 Hz and continues down at a steep 18 dB per octave from there. This is not going to cause any negative effects. And bass is in mono anyway from 140 Hz on down and the filter also removes any vertical rumble in this region.

The KAB has in fact has tightened up the bass in my system. Highly recommended!

A rolloff point at 18Hz will cause phase shift up to 180Hz- IOW, 10X the cutoff frequency. The phase shift will manifest as a loss of impact, increasing as frequency is decreased.

This might not be all that noticeable if the speaker has an LF cutoff that is significantly higher than that of the filter! Smaller speakers, where the LF noise is outside the passband of the speaker, may well be particularly susceptible to woofer motion. We run some smaller monitors here that cut off at 40Hz and have not had any troubles with them at all, FWIW

We set our preamps up with about 2Hz rolloff, even in the phono, to avoid phase shift. We avoid woofer pumping by the proper combination of cartridge compliance and effective mass in the arm.

Not uncommon for warps or other imperfections in record geometry to produce subsonic rumble To some extent. Goes with the turf with hi fi phonos. resonance frequency of cart/tonearm can exacerbate the problem with certain combos more than others.

The biggest danger of this is that subsonic rumble uses power that is no longer available for music and clipping can occur sooner, impacting sound quality and putting drivers at risk, so be careful.

BEst solution is avoid records that have this problem too much as much as possible. Get a better quality copy. High pass filters are the common solution, but that is a band aid and effects on sound are usually noticeable.

Better yet, go digital. No subsonic rumble and other vinyl snafus there! :^). Digital can be very good for not much cost these days, much more so than in the past.