HELP-woofer moves alot when playing lps

Dan_ed, At the very least, yes, though I don't understand what you are getting at at all. I feel like you are misunderstanding something though as there appears to be animosity on your part.

So maybe I have not been clear enough:

Woofer pumping is not a symptom of a speaker unless you are driving a small speaker well outside of it bandwidth limitations. IOW if the problem shows up on phono and not CD, its a problem with the phono and not the speaker.

Woofer pumping is a symptom of an incorrect cartridge setup, wherein the cartridge compliance combined with the effective mass of the arm causes the combination to have a mechanical resonance outside the range of about 7-12Hz.

Generally I would make it out to be too much effective mass coupled with too much compliance in the cartridge. IOW the cartridge's cantilever is moving a lot and the arm mass is not keeping up with it.

Fortunately with the Triplanar its easy to try the various and different weight setups until you find out what seems to work best with your cartridge.

So in this case to reduce the effective mass, you would put a heavier weight closer in towards the bearings of the arm and set it up for the same tracking weight. This will give the cantilever more leverage to move the counterbalance weight and so reduce deflection of the cantilever. This in turn reduces woofer pumping.

Does that make more sense??

Hi Atmasphere,
**Woofer pumping is a symptom of an incorrect cartridge setup, wherein the cartridge compliance combined with the effective mass of the arm causes the combination to have a mechanical resonance outside the range of about 7-12Hz.**

That's possible but often a compliant cartridge on a med/heavy arm won't cause pumping, even if it's resonating at 6Hz. Acoustic or mechanical feedback is a much more likely cause. Turntables on top of equipment racks, susceptible to mechanical shock, are more prone to have problems. They are likely to have problems even when there is no cu/arm mass mismatch.
Regards,

Fleib, there is another thread on this subject that is current as of this writing, that does address this issue also:

http://forum.audiogon.com/cgi-bin/fr.pl?eanlg&1315713166&&&/Cartridge-Loading-and-Compliance-Laws

Read the posts by Tonywinsc that occur on 09/13/11.

Real cart/arm mismatches are rare these days and hard to accomplish unless one is intentionally doing so. Am I one of the few guys who has the usual number of slightly warped LPs in his collection. That is THE #1 cause of woofer pumping, IME. Generally speaker, because of the way in which ported speakers gather extraneous energy to be released at that tuned frequency does allow ported speakers move more easily and to a greater degree when a warped LP is played. IMO, IME.

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.