Why are my woofers pumping?


The other day, with sunlight direct from the side, I noticed that the woofers in my speakers are pumping in and out, much more than I was aware of, when the stylus is in the groove, even between tracks (no music).  I can see it, even if I don’t hear it. Why does it happen? The woofers behave normally (no pumping) with digital music, and when the stylus it lifted from the groove, so it is not the speakers, amps, preamp or phono stage. 

I’ve read that the typical reason for woofer pumping is that the cartridge / arm resonance is too low.  I tested, with my Hifi News test record, and yes, the lateral test puts the resonance at 7 hz or so – too low (but I’ve seen some doubts about the results from that test record).  It is strange, since the combo I use – Lyra Atlas cartridge and  SME V arm (on a Hanss T-30 player) is supposed to work well. I tried to strip my arm of extras, cleaned the damping trough, etc – but it did not help much.

Anyone has an idea, why it happens, or what to do about it?  


o_holter
From the A-gon opinions so far, here, such examples are not very interesting. It seems that the SME V can work OK with the Atlas, but it is not the ideal arm - ? I will look for other cart / arm combinations, when my current one runs out, and I have the money. But for now, I look for a fix.
Dear @o_holter : Seems to me that you don’t have a real problem between your SME and the Lyra cartridge in the resonance frequency, you are safe there.

What " alternatives " left other than that. Thinking " loud " some things could be stay happening:

maybe to many playing hours in that cartridge that in some way affected the cartridge suspension or stylus tip or both, only for you can be sure re-check all the tonearm/cartridge set up parameters: VTF, VTA, overhang, offset angle, etc, etc., if you have a different platter mat you can try it and see what happens, same with the use of a platter clamp and if you are not using it then try one, could exist a very low bass oscilations developed in the phono stage so browse from somewhere and make a change of phono stage only for testing, you can try too to put some kind of damping material as bluetack between the cartridge top plate and the tonearm headshell, you can damp the SME arm wand with a elastic thread around t in helicoidal way ( in the past Sumiko marketed this kind of trap to damps the arm wands and made it a great improvement always. They used a ligthly elastic material. ).

Could be another reasons that explain such behavior? could be but rigth now those are some things you have to check and see what happen.

I assume that you did not any change in your system/roo but the same as always only that you do not noted before, rigth?

Regards and enjoy the MUSIC NOT DISTORTIONS,
R.

cut off below 10hz? as invictus said that will degrades the cartridge signal and in the other side you do not know at which bass frequency is the problem, seems to me more lower than 10 hz but as you I can't say for sure.

Thanks, Raul. I will test some of your suggetions - platter mat - and report back. But like I said before, it seems very basically "physical" - it happens before eventual mechanical turntable etc problems.
@o_holter : problem is that you just noted it and could be many thing. Even that speakers can't reproduce the frequency the woofer movements are affecting the quality level performance of what you are listening.

Even a mistmatch impedances between phono stage and line stage could be ( for whatever reason. ) the source. The electronic very low bass oscilations are more frequently that what we can imagine.

You have to make several tests about because exist no rules to make a sure diagnosis about.

R.
o_holter
Thanks Cleeds, but I don't agree. Please prove the case. Why does the arm kill the cartridge?
The SME V is a terrific arm, but your woofer pumping problem simply suggests you've mounted the wrong phono cartridge to it. There's no reason to suffer such a problem, imo, and using a subsonic filter is treating the symptom rather than the disease.