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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
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cleeds
2,065 posts
 
o_holter
I am happy with everything this combo does, except that it overarches in the low region
That's rather like, "Other than that, Mrs. Lincoln, how did you like the play?"

It sounds like the cartridge compliance is just too high.
o_holter OP
541 posts
 
Thanks Cleeds, but I don't agree. Please prove the case. Why does the arm kill the cartridge?
o_holter OP
541 posts
 
Example - audio review - SME V works well with the Atlas
http://www.tonepublications.com/review/review-lyra-atlas-cartridge/

o_holter OP
541 posts
 
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.
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rauliruegas
9,123 posts
 
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.

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