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
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
So when Atma-sphere amps show up not working one should assume they weren't built or serviced properly?
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.