Why are my woofers pumping?

Dear @o_holter : Sorry to hear that.  That happened to me twice and I remember that in a trip to Houston in a firned home place just when we wanted to listen his great audio system suddenly the stylus tip just " was not there ", by coincide was a Lyra too: Titan .

R.

Dear @o_holter : ""  But the results - so far - are more one of a kind. The Atlas pumps, the others don’t. This makes me suspect suspension wear or some other non-optimal condition in the Atlas. ""

As I said in my posts you had to test your Clavis, that could be interesting to know about and now you already know why I told tou what I told you. Fine.

R.

Dear @o_holter : Nice result you experienced with the Clavis ( that ovbiously is not even a " small " challenge for the great Atlas. ).

""" So the "subsonic overwork" of the woofers seems far less. Or mainly absent. """

Either the Clavis/Atlas compliance and weigth puts the resonance frequency in the " green " territory as you said. So, seems no trouble for that and very specific tonearm/cartridge resonance frequency issue.

I imagine that you already tested both cartridges using the SME V in static and balanced way about the VTF set up.

Your Atlas has over 1,500 hours of use that are not way higher but not way low number.
Trhough those 1,500 hours stylus tip and cartridge suspension are the ones that could starts to work outside manufacturer specs and I’m not saying that’s your case but only thinking " fully loaded voice ".

Who can tell you if any problem down there? not a single re-tipper but the manufacturer it self. maybe time to talk with J.Carr for he can take a look to your beloved Atlas.
In the mid time you can re-tip your Clavis with a re-tipper using boron cantilever and you will be surprised the Clavis improvements.

Anyway, I think you need to try JC directly.

R.

Dear @o_holter : """   compliance is similar to the Atlas so the test may not tell much........ """"

well, you have a " problem " that till today you don't know exactly the reason or reasons for it. You assumed that cartridge/tonearm resonance is the culprit but you really don't know because you just don't want to make tests as listen the same system with different cartridges ( Clavis DC. ) or with different tonearm that you can borrow from somewhere or some one.

Clavis has same compliance: so what? from where came that can't tell you nalmost nothing?

makes no sense that kind of answers from you because you need to find out ( or maybe not. ) what's happening making different kind of tests and if you don't want to do it then is better to just forgeret about as invictus005 said and try to enjoy MUSIC.

R.

Dear @o_holter : I think you own a Clavis DC too. Do you already tested with?

Characteristics are almost the same as the Atlas regarding resonance frequency calculations. 
I think you have to test it because you " think " problem is that resoannce frequency tonearm/cartridge behavior.

R.

Dear @o_holter : ""  full SS phono pre - yes, good idea. But again, I wonder, if this would solve the mystery. ""

you will know when you try it. It does not needs to be a top SS unit because is only to make some tests.

If you have the opportunity to do it then you must to do it. You can lost nothing but time consuming.

R.

Dear @o_holter : Two question, how is conformed your system speakers and its frequency response? is a passive design or active? two subwoofers or none? well more than 2 questions and other one.

I posted before that could be a good test to try to borrows a full SS phonolinepreamp instead buklbs you are using. I think you have to have that test, is a must.

R.

@o_holter : Again:

https://forum.audiogon.com/discussions/why-are-my-woofers-pumping/post?postid=1551771#1551771

With all respect to those gentlemans that insist on the KAB filter or the like please ask you: who of them owns the Atlas or even listen that kind of very high quality performance levels?

Seems to me that no one of them because they are not taking in count what really means: quality level performance at the Atlas levels- They say that with the filter they almost did not listen degradation and this just makes no sense.

R.

Dear @o_holter : According your self research looks like the rpoblem is developed by the TT and not a mistmatch between cartridge/tonearm because even at 100hz the Atlat compliance and effective mass puts the resonat frequency in a " solid " 8hz.

The cartridge is a very sensitive " microphone "/transducer and it's picking up " something that is happening somewhere in the TT.

Normally when  a some kind of resonance/vibration are exiting/coincide with the cartridge/ tonearm resonance frequency in between the pick up jumps more than make a noise.

Before you go for the filter try to " figure " what could be happens in your TT. You are the one that know it, even contact the TT manufacturer and ask for its advice.

Regards and enjoy the MUSIC NOT DISTORTIONS,
R.

@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.

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.