Why are my woofers pumping?

My audio friend Eirik came around today and helped me tighten the housing of the spindle on the Hanss player. Luckily the needed 2.5 mm Umbraco driver was included in the set I had bought. So - what was the result? Pumping: no difference. It did not go away. Sound: maybe a tiny bit more relaxed, less tense, but this may be my imagination. Eirik brought along some fine-sounding records and we played tracks from the Mofi edition of Dylan's Another side, and from the reissued Grateful Dead Cornell 1977 box. They sounded very good, and neither he nor I could find any clear indication of too much rumble. But he did remark on the LOOKS - the visual (subsonic) pumping of the woofers especially between tracks. It does not look like that in my system, he said.

Dear Raul, thanks!

1)
The speaker system is Audiokinesis, Dream Makers in front, plus LCS speakers firing towards the roof, in the back of the fronts.
Similar to this one (but in much nicer light wood):http://www.audiokinesis.com/dream-maker-lcs.htmlThe frequency response is down to 20hz or lower in the combined system, not sure. It goes deep, that's sure.
But if speaker energy into the room etc was the main culprit, I would NOT have woofer pumping on my vinyl recordings (made when the speakers were off) - and I have!
2 Borrow full SS phono pre - yes, good idea. But again, I wonder, if this would solve the mystery. If it was related to the phono pre, the pumping should appear, depending on the volume. But it doesn't. It only appears when the needle is in the groove. More or less, depending on the vinyl record. Usually - maybe always - in EXACT repeat, each turn of the record.

The pumping pattern seems to follow its own logic, different from the normal vibrations and excitations of the woofer. As stated above, it is less obvious within than between tracks. This evidence suggests that it does indeed relate to the cart - arm match - it has too low resonance, and picks up too much down-below vinyl excitations, for some tastes, or just "good enough" for other tastes. The whole system goes deep down.

We played Pink Floyd: Meddle, the intro number, with the hammering bass, and noticed that a bit of pumping was still there, but NOT in time with the bass notes, but repeating - like before - in a once per revolution pattern.

"The highlighted noise on the LP playback, approximately 7 Hz, is absent on the CD. By the way, the very low frequency noise was present on every LP I played for this test: from new pristine vinyl to older worn LPs with more clicks and crackles."
https://www.vinylengine.com/turntable_forum/viewtopic.php?f=18&t=99388

Yes I will tell, once I find the culprit. The subsonic pumping does not occur with CDs, only vinyl. It does occur when I play digital recordings (rips) of my vinyl. Since these were made with zero speaker volume, acoustic feedback is unlikely. As I've said before, my phono preamp needs balanced out, single ended sounds far less good, so the single-ended KAB would need some kind of cludge to work. If KAB had lived next door I would of course have tried it, but it requires ship across the atlantic, tax etc - for what probably degrades the sound even if it takes away rumble.

Thank you for your patience and help my friends.

Handymann - hire an exorcist – indeed !! I played Crime of the century (Mofi version). Woofer pumping between tracks – yes, some. Much energetic woofer vibration in the loud parts of the music - yes. But it sounds great. You said the Fathom subs “didn’t like it”, what happened?

Atmasphere - the pumping seems to repeat very exactly once per revolution – yes. But why does that point to the turntable, rather than the vinyl? My suspicion is that I pick up vinyl noise. That’s why it varies between records, and why I see it also on recordings made on my former VPI turntable. And why tightening the spindle housing and oiling the spindle made no difference.

So yes, I have a main suspect, so far – the low or borderline low cart-arm-resonance, around 7 or 7.5 hz. I will have to check with a lower compliance cartridge, when I get the chance. I borrowed an Ortofon Cadenza Black a year ago. At that time I was not much aware of the pumping problem (maybe, it was less prominent), but I remember that I felt the sound was more polite, less grunt in the bass, compared to the Atlas (the data of the Cadenza, combined with the SME V, suggests a resonance around 8.5 hz).

Raul – try another phono stage - good suggestion. Maybe the “borderline problematic” resonance interacts with some other factor, like an over-eager phone stage (or some non-optimal tubes in it). I will test with my ASR Mini Basic phono stage, solid state, very decent sounding. I bought it since the Aesthetix Io was a long time gone for repair. But when the Aesthetix came back, the reaction over here was just WOW. So if the ASR pumps less, it is maybe because it is more anemic or polite. The Aesthetix is known for its explosive dynamics and it goes down real deep. I will check.

All in all, I am learning to live with the problem...enjoying the music, but also, not giving up, the mystery will be solved. Music mainly sounds great. There are no “obvious” signs of rumble. I have a suspicion that the subsonic pumping I see between tracks has a negative effect on the music, but I don’t know this. If it had been really bad I would have preferred playing digital, but I don’t.

A final observation. The pumping is more visible in the right than in the left channel (in my home system, at least – not sure about the cottage system). No idea why.

Thanks tkr - but I live in Oslo.Thinking about the problem, I thought: maybe it is related to the Telefunken NOS tubes I use in the super sensitive first gain stage of the Aesthetix Io. So I pulled it halfway out of the shelf, enough to get off the top, and swapped the two Telefunkens in the right channel for a new pair of PSVANE 12ax7. Result? No difference. The pumping is still more visible in the right than the left channel. Then I swapped the left and right phono cables leading to the Io. Again: no difference. Right channel pumps more.

I disconnected the Aesthetix Io, and connected the ASR mini basis mk2. Playing Pink Floyd Echoes once more. Result? Very similar behavior. Subsonic pumping, strongest in the right channel. Even if the ASR has far less deep grunt in the bass compared to the Aesthetix. I was surprised! Clearly, like Atmasphere said, the phono stage is off the hook. 

I am back to square one. Invictus005 was right: "There’s nothing you can do. It's normal. .. Just live with it and when the stylus wears out get something else." 

Channel imbalance in woofer pumping? No. Mystery resolved. It turns out that one of the driver tubes in the left channel amp was going bad - at first, just weaker sound (and less pumping), but after plugging in the ASR and going back and forth to the Io, the sound became clearly distorted. Failure of a brown-base 67SN7GT Made in China. Replaced with a Electric Harmonix tube. Now the channels are equal in volume, and in pumping.

Dear friends

Atmasphere, VPI - if the pumping repeats once per revolution, how do you know it is the drive / turntable, and not the record itself?

As shown above - the evidence in my case points to the vinyl. E g the pumping varies from record to record. It would not have done so, if it was due to the turntable. And a number of turntable fixes have no effect. AND vinyl recordings made on my former HW-19 turntable seems to pump the same way! The main suspect is the cart-arm combo.

I hope to test this, with a different (lower compliance) cart, in some weeks time, and will report back.

Clearthink - I do want to resolve the problem! I agree with your line of thinking - I also thought it was a two-component problem (low resonance plus something - possibly a turntable issue) - but recent testing seems to show that this is wrong. It is basically a one component problem - the resonance. I’ve tried a lot of remedies, so far. The turntable is not the main suspect. Please folks, read up on the Hanss T30 players. Not where you would look for rumble (and I have tried).

Analogluvr - good idea. I can vary the phono stage volume (it has volume controls). Basically, up to a point, the more the Aesthetix phono stage takes care of the gain, the better the sound. The sound is fine with the Einstein preamp also, but still, it is a step down (the sound is more slim, solid state, compared to the fat, organic Aesthetix). The best fit, in my system, is ca two thirds Aesthetix, one third Einstein gain, before the signal is fed to the amps.

I tested a bit - Pink Floyd: Echoes, once more - changing relative gain levels. Result: much the same woofer behavior, regardless of the phono stage / preamp mix. Like you write, maybe turning down the Aesthetix "alleviates" the problem, but this is marginal. Basic conclusion, the amount of gain phono stage vs preamp is not a decisive factor.

Once more I note that the woofer pumping varies with the LP. Example: I put on my UK original of Colloseum: Those who are about to die, expecting pumping, but there is little, despite very energetic woofer movement within the music tracks. Is there, still, a part-subsonic rumble, due to the low resonance, disturbing the sound? I don’t know, but it is not very obvious. The bass on this LP seems limited (compared to Pink Floyd Meddle, made ten years after). The problems I hear with the sound seem to relate to the treble, not the bass.

My system has "distributed" bass reproduction. It is not a full Audiokinesis "Swarm" bass system, but goes part of the way, with four speakers reproducing the bass. These can be aligned in the analog domain by positioning and other measures. This sounds better than any form of digital equalization I have heard so far. I had a Velodyne DD-18, but sold it.

It should be easy to test here on Audiogon. If you have a cart-arm combination with resonance around 7hz, you should be able to see the pumping. (Put weight of arm and cart, and cart compliance, into the vinylengine resonance calculator, and/or test with the HFN test record, lateral compliance track).

Examples of records with subsonic woofer pumping:Pink Floyd Meddle (UK orig), Rickie Lee Jones: Evening of the best day of my life, Byrds: Untitled (US orig), Byrds: The Columbia hits (Sundazed).

Thank you, vpi. I have no indication that the pumping happens only with flawed or warped records. I think your hypothesis 2) is correct, that is, first the low resonance plus a superb cart picks up subsonics, and next, the system is very resolving and sends it all to the speakers. Note, however, that even my modest cottage system was able to reproduce the pumping.

I don't have test instruments to test if the pumping is exactly in sync. I can only say that the pattern repeats ca once per revolution. This is easiest to test in the outro of a record with pumping. There is a click once per revolution when the lead-out groove meets the circular groove at the end, and I can see (and touch) the woofers pump in a regular pattern between each click. So it seems roughly in sync. Which would be the case with most records I would guess? 

Testing Jefferson Airplane Volunteers, the new 45 rpm Mofi edition. Not much clear woofer pumping in the outro. But clear in the intro, before We should be together.

The subsonic woofer pumping seems inherent in the recording itself, picked up by my cart-arm combination. It is not due to vinyl warps or turntable problems. But more, due to recording issues, engineers’ decisions. Sometimes the recording goes way low - sometimes it doesn’t.

I associate the records with pumping with "quite good sound", or even very good sound (especially in low energy music, like on Pink Floyd’s Echoes, in the subdued sections). Not "bad sound". Pumping records maybe go a bit further down in the bass, with an overall improvement factor. Even if I suspect that the pumping is not so good for the music.

It is quite bewildering - testing LPs - Elvis Costello: This year’s model - intro yes, between tracks no, outro yes. JA Volunteers mofi side 3, intro yes, between tracks some, outro some. Liz Phair: Exile side A - some, but rather little. A Parsons: I robot, Classic, intro yes, mid track yes, outro yes - with note "great sound".

More surprises: Simple Minds: New gold dream, 2016 half speed remaster - pumping - yes. Procol Harum: Home, UK orig - some.

Thanks vpi. This is my thinking as well. I will first try a different cart, and then maybe, a filter, if I get a money back option. A significant fact in all my investigations so far, is that "pumping" LPs are often very good sounding. Lean back and enjoy it.

Raul - yes, I have a somewhat worn Clavis is on my loft. I could test it. But I think the compliance is similar to the Atlas so the test may not tell much. Let me tell you, I don’t like exchanging cartridges....do I get my former adjustments back...or do I have to start from scratch, for cart adjustments.

Invictus005 please. What may be ridiculous to you may not be so, for fellow a-gon members. You seem to "know" it all - but where is your actual listening evidence? We're all in this hospital together.

Audiotomb - I already tried the feather test, and found no problem. I also contacted SME who said, basically, if you don’t notice a problem with the V, it should be fine.

Raul sensibly suggested (going the resonance path, along with invictus005 and others) - test with the Clavis DC ca 2007 model that I have on my loft (not much used, since I soon changed to a Titan).
So I’ve done it. Interesting to hear the sound of the Clavis - from back then. Quite decent.

Pumping? I am sure you’re all dying to hear the result!

First impression: less pumping, maybe only normal woofer energy.
Testing the 2016 remaster of New gold dream. And then, with even more clear result, Pink Floyd Meddle.
There is a lot of woofer energy, yes. But less, or very little, of the visual-only pumping. So the "subsonic overwork" of the woofers seems far less. Or mainly absent.

This seems to confirm the resonance problem view. There are some doubts however. First, there is the possibility that some woofer pumping is actually not a big problem - just look away from it. As was suggested early in this thread. I mean, the Atlas sounds better than the Clavis, reaching further down, more explosive dynamics, wider soundscape. After ten minutes listening to the Clavis, I want my Atlas back. Also I've noted that LPs with pumping often sound good.

 Second, I am not sure of the compliance of the Clavis - is it 12 or maybe ca 20 (due to failure to translate the Japanese 100hz rating). It weighs 2.1 g less than the Atlas, though. According to the vinylengine calculator, even a compliance of 20 is thereby enough to get me into "green" territory. This seems in line with my results. I cannot test with the HFN record since it is on loan to a friend.

Invictus005 wrote: " This has to be the most ridiculous thread on Audiogon at the moment. Everything and all of it. OP, I told you it’s a problem YOU can’t solve. Just enjoy the music. Some of these things are just part of vinyl. Many comments here have crossed the line of insanity. Seems like some people want to end up in a mental hospital?"
Let me posit this in a positive way. "Sound is good. Relax. With a good cart you get some vinyl pumping. Look away". Ok? If so, I agree. Fits my evidence, mostly.

But the thread, even if ignorant or repetetive, is not ridiculous. A large list of potential problems, regarding low rumble and woofer pumping, has been listed and described. Even if low cart-arm resonance is the main culprit in my case, the suggestions are interesting on their own, for anyone investigating low frequency vinyl problems in resolving systems.

I was maybe a bit optimistic in my last post. The thread is all over the place, yes. But so are most of the threads I’ve read on this subject. Compare this one: https://forum.audiogon.com/discussions/the-arm-cartridge-matching-myth . Halcro argues that resonance means ca nothing, others don’t agree, kirkus has a good post stating that resonance is only a rough measurement, the cart-arm-combo acts as a high-pass filter. For an even more esoteric discussion, compare this: https://forum.audiogon.com/discussions/strange-tonearm-tweak-long

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.

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.

"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...

Thanks. Trying to get in touch with Lyra.

Oh no. Worst case scenario. Trying to fasten the lead clips to the Atlas, to get it back on to the arm, something has gone wroing. Cartrudge first gave strange distorted sound, we adjusted some more, but then it just sailed across the record. Cause - no diamond. It is gone. Without any external hits, stresses etc that we can see. Maybe it just did not like this thread. Anyway it is no longer there. Atlas - caput.

Nothing so bad it isn’t some good also. I am trying to find a way out, how to repair it for a reasonable cost. This should not happen, for a moderately used (not misused) cartridge. Such things - diamonds falling off, cantilevers breaking, cantilevers or diamonds not precisely tuned - are known to happen, across cart makers. As users we hope for better quality control and follow-up when sub-optimal units have been sold.

I think we now have a very clear main suspect, not suggested by anyone in this otherwise very rich thread. That is: 1) the Atlas showed increased signs of woofer pumping, over some months. Abnormal, when comparing to the Clavis and Titan. 2) For a short period, the diamond was half-loose from the cantilever, with blurred sound. 3) Next, it broke off, from the cantilever (this happened through normal, careful handling)  All this points to a gradually increasing defect in the diamond / cantilever connection. Assuming that a potential crack or breakup can indeed give some strange bass / subsonic pumping effects at first. I am no engineer, but it seems highly possible, and fits the data in my case.

I thank you all for all suggestions in this thread. My problem of woofer pumping is 'solved'. No diamond, no pumping. No woman no cry. Maybe, it was mainly a result of usage. It has 1200 or 1300 hours use, in my estimate. I will try to fix the Atlas. But this thread is now at rest from my side, since the problem is gone.  

Update: I have got a replacement for the broken cartridge, and I am very happy with the performance.

Some testing: The new Atlas makes it clearer that the subsonic effects (and possibly, the subsonic woofer pumping once per revolution) is part of the intended sound, e g in the introduction to Pink Floyd: Echoes. It resides in the recording (or my pressing) and is not in a fault in the system, even if the resonance frequency of my arm and cart is a bit low / challenging, so everything happening down at the end of the frequency scale is picked up.

I don’t hear much rumble or other unwanted effects, just a marvellous big soundscape.

On Rickie Lee Jones The evening, I no longer see any clear subsonic woofer pumping, just a lot of energy, in the woofers, coherent with what I hear.

So it seems, especially with the new Atlas - just look away from eventual woofer pumping (as long as the woofers don’t complain), give it a go, and enjoy the superior sound.

Pink Floyd’s Echoes is known to include "subsonic" effects. Maybe once per revolution - like they later experimented with heartbeats, on Dark side...or maybe on Echoes this is a not intended side effect, who knows. I have an early second pressing of the Meddle UK original, matrix side 2 (with Echoes): "SHVL 795 B-6" "11"? "1" and handwritten "HTM". HTM means Harry T Moss cutter extraordinaire at EMI UK. I have read that subsonic effects may happen due to record warp, but I cannot find any signs of this, with my copy.

Does it sound good? You bet!

Hi mijostyn
Too light? I have not thought  that adding mass / weight to the Sme V would help. Seems that the Atlas sounds better without it. The resonance is a bit high - 7 hz ish -  using my hifi news test lp - but to get it down I would rather have to reduce the total arm and cart mass - or am i wrong? I am away now but will test your 'add two grams' proposal soon. Thanks!

One more update for all my Audiogon friends. The newly replaced Lyra Atlas cartridge sails through my stress tests without problems. I play Pink Floyd: Meddle, and the woofers react a lot, yes, but they dont over-react. The silent woofer pumping is gone.

My former Atlas, made in 2013, was used successfully over a period of several years, before it broke down, after five years - the needle saying goodbye to the cantilever, for unknown reasons. No mishandling on my side. Although the leaning of the LPs was so-so. My first cartridge became non-optimal, after long use ca 1000 hours, and it remains to be seen if the new Atlas extends the score.  

Thanks mijostyn. I like it with all kinds of music. The effect is  that I enjoy listening more. I wonder if it actually sounds slightly better than my former Atlas did when new. Possibly the low output version (Atlas SL) is even better, but I can't risk it with the Aesthetix Io phono stage, which likes the 0.56v output of the standard Atlas. 0.25 or thereabouts may be too little for the Aesthetix to sound its "robust" self. At least if using NOS tubes, like I prefer, even if I get a little more background tube noise. Lyra warns that the SL version is not for everyone, the phono stage must be up to it, or you should use a stepup. However, Aesthetix says no to using the Io with a stepup device, don't do it. I think this would destroy the purity of the design and be a waste of money. I tested with a Jensen stepup some years ago, and this confirmed their point. Tubes all the way = best sound, no doubt about it, to my ears. I think the Atlas feeding the Io is a very good match. Some have complained that the Atlas is a bit hard and harsh. Or a bit bright. I don't hear much of that. Rather, the tonal balance is spot on, meaning that the "character" of the cartridge is very hard to identify, since each LP sounds different. I am not saying the Atlas has no faults, but usually, they turn out to be faults of the LP production, or "to the limit" type production (cf Pink Floyd Meddle), or the LP itself (wear), or my turntable setup isn't 100 percent, so whenever I think I have a problem with the cartridge, it disappears on a different type of LP / music /  or with setup tuning. In all, the Atlas/Io combo works great. And the Atlas sounds better on the Hanss T30 player than I ever managed with the VPI HW19 (using the same SME V arm).  

Maybe. I did a new round of tests. The new Atlas not only sails happily along the trail without any silent woofer pumping (or mistracking), it also reproduces my stress tests cuts beautifully, including Pink Floyd Echoes and tracks from Rickie Lee Jones: The evening on my best day. Passing with flying colors. 

Hi rdk777This agrees with my own experience, especially regarding the VPI HW19 player I used before. Every little thing I could do to it, regarding the platform, feet, etc, made a change. Air (bike tires), a large bright star sand box, ceramic feet, you name it!
Now, with the maglev system of my new player, Hanss T30, it does not seem so tempting. It rests directly on my very heavy stone rack. Maybe HRS might improve things  even there. I note that Aesthetix recommends HRS feet under their boxes (like my Io phono stage).

Just a little update. Testing Pink Floyd: Echoes, with the Lyra Atlas replacement I got back in August, 2018. Could it be, that the pumping woofer syndrome is caused by wear of this cartridge? Short answer: no. The new cartridge has now run ca 1200 hours. I don’t see or hear any problems. The woofers DO show subsonic energy (they move/vibrate although I don’t hear sound), yet it is nothing like the heavy pumping I had with the 2013 Atlas.

I think the diagnosis is fairly clear here. First, this is a really wide frequency recording, especially in the opening section, and therefore, a good diagnosis tool for lowest bass performance (the treble is extended too, exceptionally life-like). Your copy of Meddle may not have this - it concerns my second press, cut by H T Moss at EMI UK). It was made to challenge your stereo.

The reason why it created woofer pumping was mainly related to the poor / worn state of my 2013 Atlas cartridge. The arm, player etc had nothing to do with it. A few months after I discovered the woofer pumping, the stylus fell off the cantilever. For no clear reason. I think it had received a bump or shock earlier - from a not so clean or dusty record - and that the woofer pumping was the result of that. It had got loose. I cannot prove any of this, but it seems the most likely explanation. Needless to say I have improved my record cleaning. Even if a record looks clean, I always use a Mofi brush before play. A little speck of dust, or a hair, can be a big hurdle for the stylus.

 

A few months before I noticed the woofer pumping with the 2013 Atlas, it was in for a check at a local service shop. Soon after I noticed the pumping, the diamond dropped from the cantilever. So it *may* be that it received some tough handling at the shop - and not from my records, even if some of them were dusty. I will never know for sure.