Why are my woofers pumping?

Back to testing.

I've brought my (quite worn)  Titan i down from the loft. And will connect it soon.

Since the Clavis creates less pumping (next to none), I would expect that the Titan comes in the middle (if the resonance theory is right). This is due to the weight differences (assuming that the 10hz compliance is much the same, maybe 21, as suggested earlier in this thread). The tonearm effective mass is 10.5g, the two screws add 1.1g (I measured), the Clavis 9.5g. This gives a 7.6 hz resonance, according to the calculator. With the heavier Titan at 10.5g, there should be a 7.4 hz resonance. And with the heaviest Atlas at 11.6g, a 7.2 hz resonance.

This fits somewhat with my results, but I wonder if the compliance of the Clavis is in fact lower. Since woofer pumping goes from visible and maybe a problem with the Atlas, to not much visible, with the Clavis.

It may be that the wear and tear on the cartridge suspension plays a role here. The Clavis has only 200 hours, the Titan maybe 2200, the Atlas 1600 (rough estimates). My audio friend Eirik remarked that he had not noticed this pumping problem earlier, in my system. Myself, I am not sure, it may have been going on as long as I've used the Atlas, only we did not look for it, or it may have become stronger over time. I remember that, as the Titan became more worn, I had some rumble and bass problems, but I am not sure if the Titan was the culprit.

So it will be interesting to reinsert it into the system and hear how it compares with the Atlas. Like I've told you, ten minutes with Clavis made me think, this is decent, even very good - and then I ached to get back to the wider and deeper soundscape of the Atlas. Pumping woofers or not. The Titan should perform in a middle zone, but closer to the Atlas.

Testing the Titan i (ca 2008 model).

To my surprise, there is little to no subsonic pumping. Much like the Clavis. Or maybe a little more. But clearly different from the Atlas. The woofers are more engaged, more vibrations, changing from Clavis to Titan - but this fits what I hear, it is fast vibrations, not pumping.

Sonically the Titan is a clear step up from the Clavis (today, also) with wider, deeper, better detail, better e g on female voices (R L Jones: Evening..). On Pink Floyd’s Echoes, the soundscape is now almost as large as with the Atlas, although still a bit more harsh, less natural, with some sibilants (I could cure some of it through adjustments).

I had expected a gradient, according to resonance theory. The Clavis should pump least, the Titan some, and the Atlas most.

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. Yet I was surprised to find no signs of pumping with the Titan - since this has been used maybe 500-800 hours longer than the Atlas, so if suspension slack, wear and tear, is the culprit, it should show up there. But no.

"what I hear, it is fast vibrations, not pumping" - this needs a clarification.

What exactly is the symptom? With a better cart - changing from Clavis to Titan - I hear / see / touch woofer behavior changes (method described above: fingers slightly touching woofers, observing, listening). The woofers are more energized, asked to do more. The better cart offers more musical information, deep energy, etc. This "normal" energizing is quite easy to observe - you hear it as you see / touch it, and it is normally a fast movement, the woofer "shivers". Mainly (not always) what you see is what you hear. Sometimes there is woofer movement not clearly linked to sound, but it follows the same main pattern and is probably not serious.

The see/touch (you dont hear it) pumping is different. It is slower, more stately, rather than quick vibrations. It follows, more or less, a "once per revolution" pattern. There is no clear relation to the music, and it is easiest to see when the stylus is in the groove between tracks. The pumping is less observable when music plays, but there is (so far) no indication that it is "turned off", it is still there, but working in the background.  

The observant reader may ask why I did not try the Clavis and the Titan before, since I had them at my loft. That would have saved us a lot of speculation in this thread. The answer is that I thought they were broken, due to many hours on the Titan, and a cantilever problem on the Clavis. But both are playable, and good enough to test for woofer pumping.

Since I am testing mainly for subsonic woofer pumping the sonic impressions may be less relevant, but the experience is clear and maybe interesting for some of you. Listening in "retrospective" to the Clavis DC, allthough it sounds good, I have two problems, one is the limited soundscape, the other is the harsh almost digital type of sound in dynamic parts of the music. But if I had known no better I would have loved this cartridge - and I did, fifteen years ago! The Titan i that I got ten years ago was clearly was a major step up, from the Clavis - and it sounds very good today also. The soundscape became much wider and bigger, more width and depth, refinement and detail. The Atlas is some steps above the Titan. The wider and deeper soundscape was present with the Titan, but the Atlas improves and tunes it better so it sounds more natural. No looking back...