HELP-woofer moves alot when playing lps


Hi-
When I play a record on my TT, I get an excessive amount of woofer movement, even when no music is playing. When I lift the arm off the record with the finger lever, the movement stops, and the phono stage is dead quiet. Its only when I drop the needle and turn it up a bit, the woofer starts to move in and out. I dont get this when playing cds, only lps. I have my system on a shelves, with the table onto and my integrated amp directly under my TT. Might this be an isolation issue? Thanks in advance.
tbromgard
Thanks for the responses. I purchased the KAB filter. I dont believe isolation is an issue-the TT is well isolated. Also, the tonearm manufacture believes cart/arm mismatch is not the issue. The arm and cart are both medium mass/compliance and should work fine togther-so I dont think that is an issue either. I really dont want to add another circuit path for the signal to run, but it seems inserting the KAB filter is my best choice. I will report the results once I rec'v the unit. Thanks all.
Tbromgard, despite claims to the contrary woofer pumping is not something that ported speakers are prone to.

My speakers are ported and go to 20 Hz. They don't pump particularly more on LP than they do on CD.

This is a common problem with arm/cartridge mismatches. Daned's comments above lead me to suspect that he has a problem with this too. If you have a heavy arm and a high compliance cartridge, you are going to get pumping. The 'effective mass' and 'mechanical resonance' of the arm/cartridge combination are the issues you want to study.

The KAB filter is one of the best out there but if you have a transparent system with bandwidth you may not like what it inevitably does. IMO/IME you are better off curing the cause rather than the symptom. Good Luck!
Transaudio, let me explain. IME, when you put any filter in the stream you can hear the effects. Well, at least I can in my system. Woofer pumping, which we cannot hear, does cause issues in higher ranges that we can hear as distortion and or nulls. I guess the easiest way to say is that we don't hear the direct effects around 20Hz but we can hear the side effects. Stop that woofer from flapping in the breeze and the bass tightens, etc. Add some filters and you also crush dynamics. Get the right filter and you get the best of both but you still give up something. Pick the compromise that works best in the system.

In my case I use a Marchand crossover and the natural roll off of my bass horns. The Marchand keeps everything below 100Hz confined to the bass horn which rolls off very quickly below 25Hz. Kind of a built-in filter.
As it happens, the Clearaudio Concept MM I purchased-broke. The needle was slowly moving to one side of the cartridge, and now is totally limp. I am going to return it as it seems to have a manufacturing defect. I purchased the Orotfon 2M Blue, which will arrive soon. Hopefully once it is installed I will not experience woofer pumping.

Thanks again for the responses.