HELP-woofer moves alot when playing lps

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!

Hi Dan_ed, I have a Triplanar too :) -and no, I'm not saying that. If set up right it handles the widest range of cartridges of any arm I've seen.

For more on this, take a look here:

http://forum.audiogon.com/cgi-bin/fr.pl?eanlg&1315713166&openflup&10&4#10

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??

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.

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.