rumble issues - see old thread update

I originally posted this under amps
as I thought I might be experiencing clipping

looks like it's definitely turntable related and rumble from subtle record warpage is the main culprit

see my last comment on this thread

may check out with my outboard ZYX Artisian phono pre when I get it back from a friend

Hi Tom,

this is not unusual at all with ported speakers. I used to deal with this back when I had Aerial 10t's. I'm pretty sure we can rule out the Galibier bearing and table setup. :-)
That leaves the warps and off center pressings, which is something we vinyl junkies have to contend with.

I don't believe Nick uses sub-sonic filters (a very good thing, IMHO), but you are correct that this woofer dance is likely adding distortion. KAB sells a sub-sonic filter and adding that may be the lesser of two evils. It would be something to try.

I agree that you should be concerned about possible clipping, so be sure to keep the volume to reasonable levels if your amps are not up to delivering lots of current.
HI Dan

Richard Gray - my local tech and designer thought it probably is tone arm compliance - needing a little more weight

we will see where it goes from there

Hi Tom,

As you know we use the same arm, cartridge and preamp. With 8-10 different UNIverses on our arm we've never had such issues with any music, at any volume up to window shattering.

Based on that experience I question the tonearm/compliance theory (assuming your cartridge has the SB option). You can test by trying a different counterweight, positioned to give you the same VTF. That will change the eff. mass slightly, which would alter the behavior if eff. mass were the culprit. Seems doubtful to me, as I said, but it can't hurt to try.

We get only minor woofer pumping on obviously warped discs, as we should. Basically it's just the cartridge, arm, preamp and and amp reproducing the warp frequency and pushing it through to the speakers, as they should. But in our setup this never results in sonic breakup or "clipping" unless a warp's so bad the cartridge mistracks. We have exactly one LP that can cause that, a nasty pinch warp. It's our torture test for vertical tracking ability. ;-)

I suspect you have some combination of room interactions reinforcing a low frequency and/or amplifier headroom issues. Both would be volume sensitive and could lead to breakup at higher SPLs.

Just for fun, try blocking the ports on your speakers and see what that does. Try borrowing a different amp too, if you can.
Audiotomb, I responded to this on the other thread. I run the Triplanar and ZYX and have used a variety of speakers, a good number of them ported. In addition, our preamp has phono bandwidth flat to 2 Hz.

We get no pumping. IOW the bandwidth the of the preamp is not an issue; if a low frequency rolloff fixes the problem then you have a set up problem.

Remember how I commented about using different weights? With the Triplanar you can use a lighter weight further from the arm, thus increasing the effective mass, or a heavier one that is closer to the bearings, thus reducing the effective mass.

The other possibility is that all your LPs are really badly warped, but I don't buy that.

You could also have a low frequency resonance in the room that is interacting with the phono. I don't recall you mentioning the stand that the table is on- that can have a **huge** effect. We use a Sound Anchors stand that is custom built to accommodate our equipment platforms, one of which is beneath the 'table (which has no suspension). The stand is perched on a set of Aurios Pro bearings. On this set up the 'table is immune to any playback volume- I do not get pumping even at sound pressures of +105db.
"NOT UNUSUAL AT ALL WITH PORTED SPEAKERS"? where do people get this stuff? My ported speakers don't rumble at all. EVER! just clean, tight, powerfull bottom end and only when the vinyl calls for it. not even on "warped, as few as I have, albums.
I "got" this stuff from my own experience with ported speakers and preamps that don't roll off. I have sat a watched Doug's speakers do the dance. I have seen just about ever other ported speaker do this with analog. You have a different experience. I won't say anymore about this because I can't say anything nice at the moment.

All ported speaker cones oscillate when air inside the chamber is energized at the port frequency. When air is compressed at the port waves flow back into the cabinet at that frequency. Something inside has to move and the easiest thing to move is the cone.

Dan is correct, mine do oscillate (though never to the point of audible breakup or distortion, as the OP is experiencing).

There could be many reasons why you haven't seen yours oscillate and I'm glad you haven't. Your speaker ports are certainly tuned lower than mine. Your phono stage may have a built in rolloff or filter. Your line stage or amp may not go low enough. You may not have noticed. But this doesn't change the fact that they will oscillate if excited at the port frequency.

Want proof? Try YELLING into the ports at their tuned frequency. ;-)
Yes, woofer pumping with vinyl and ported speakers is a very common problem. As Doug has alluded to above, the problem may be more severe depending on the frequency at which the ports are tuned.

While a tonearm/cartridge mismatch is certainly going to create a problem, I'm always amazed at the number of posts in these threads on woofer pumping that absolutely insist it is a setup problem.

IME it is absolutely possible to have a perfect match in terms of cartridge/tonearm, along with a well setup properly isolated table and system and still have problems with woofer pumping with ported speakers.

I have a great deal of respect for Ralph (Atmasphere) and perhaps my amplification is just not up to the job and that is why I've experienced problems with woofer pumping with vinyl. But frankly, I doubt that. I'm comfortable with someone saying they have absolutely no woofer pumping with vinyl and ported speakers but feel that they may just have a little bit of luck going for them too.

When you look at reports of woofer pumping from audiophiles here and on other audio sites they are almost always coming from someone with ported speakers.

Sometimes, in the real vinyl world, unless I suppose you want to change speakers (or possibly amplification-not so sure about that one) you just have to bite the bullet and employ a high quality subsonic filter.

Those who continually denigrate a subsonic as a band-aid solution and negatively affecting sound quality are, in my experience, off base. My system is clearly not in the same league as some posters here, but does consist of a vinyl front end and phono preamp with a retail list price approaching $6,500 with the table mounted on a high quality wall mount with a custom shelf. No tonearm/cartridge mismatch issues. Without a decent subsonic filter (I've used the KAB, which is an excellent product, and my Aqvox phono preamp has a very high quality switchable subsonic filter), I have woofer pumping.

In may case, the subsonic is not in the least degrading of sound quality. In fact, I'd argue it improves sound quality. Now if I had no woofer pumping, it might be a different story, but I do and replacing my speakers or amplification is not a cost effective or justifiable solution for me. A decent subsonic filter is.
thanks everyone

I'll go through this thread with Richard

I do have multi weights for the triplaner and Richard and I are going to try this first- I also have the sb with the shim under the cartridge

Richard was over and said I definitely don't have an amp clipping issue - although some of the amps power is being robbed when feeding the low freq outbursts

there are some minor warped records that cleary set off pumping in the speakers, and some other's that it's so minor (but stil probably mucking up the low end) but probably still there

I want to get all the clarity out of my setup and maybe this is the limiting factor

as for suspension - I have the Silent Running Audio platforms and stand - and a very heavy platter - floor concrete - about as isolated as I can make it

it could be a room mode - I have a 14 by 27 room
long wall setup - at listening area - null against wall and reinforced 2 feet in. I've tamed slap echo with echo busters but no low freq suppression. CD's sound fine.
Table slightly forward of speaker ports which are 3' from back wall.

Perhaps if I placed the table closer to the wall on my seperate Billy Bags stand.

I'll try covering the speaker ports as well. Ports 2 2" at bottom of speaker. Jim Salk has not encountered this before with his speakers, then again, few owners with analog

Richard set this table up with a scope and the results are stunning other than the 'pumping' problem - which is there but only strong on high voumes and minutely warped records.

If this is truly a port / room issue then I'll have to look at placement of either the table or speakers. I'm a bit concerned that a subsonic filter might just mask a problem rather than correct.


HI Tom,

I just noticed your BAT SS amp. Yeah, I doubt you're having clipping issues if that is the amp you are using. That is the worst possible problem that can occur, but it most often doesn't. Better safe that sorry though. It seems that you're woofer dance may be no different than most. Did Jim Salk think this could be detrimental to the sound of his speakers?

If the pumping varies with volume, surely room mode interactions must be a prime suspect. My guess is that tweaking the eff. mass of the arm/cartridge may vary but will not eliminate it.

A concrete floor may dampen but it does not isolate, unless the concrete hasn't fully set and can slop around a bit. ;-) Owners of very substantial rigs on high mass stands, SRA platforms and solid concrete floors have still heard substantial improvements from adding true isolation with something like a Minus K. Not saying that would necessarily help with woofer pumping, just noting that concrete is not an isolator.
thanks guys

I'd hate to have to go to a another speaker, my friend has ported Salk's smaller

Dan_Ed - my Bat is on loan to a friend more than a few states away

Moscode 401 HR - I don't think it's clipping anymore but analog related

yes Doug volume is a culprit - increase it and more and slight warps in records.

never noticed this before, but I'm sure if things are not quite right even at lower volumes - the lower freq vail is affecting the sound.

45 rpm 180 gram blu note recordings sound fabulous
so maybe that has an effect

Room modes could be contributing. It does sound very resolving and no real flaws on cd, perhaps it sets up tone arm resonance issues. I'll try my Rives freq test and SPL if I can find them

ported speaker issue -
possibly - I'd hate to have to go to a another speaker, my friend has ported Salk's (a smaller model) and they pump all the time - he has a wood floor, not as well isolated and his speakers are close in to the back wall
sorry - floor carpet, thick pad, foundation is concrete

known as "sea meant" to the locals down here in Louisiana

diagnosis round II

Richard came over with his 'higher tech' scope

we found a little isolation issue caused by the light hollower SRA platform under the turntable - we replaced that with a 3 cm granite slab which isolated the table much more efficiently

the scope showed resonance problems in both channels around the 4-7 htz range - which Richard said were caused by a low mass arm being mated with an overly compliant cartridge. I told him that the ZYX and Triplaner often matched with great results - as many of you can attest to

we tried additional shims, counterweight options and also more and less weight to no avail
I typically run 1.75 g

he felt the high compliance of the cartridge and tonearm
combined with the highly resolving low end of the Dodd pre and Moscode amp were allowing the tonearm/cartridge resonance issues to be reproduced by the speakers

we checked the speaker baffle output and it wasn't sufficient to cause an issue

next step - Richard will bring a lower compliance cartridge to test out and see how it mates with the arm resonance wise

I'll call the various manufactures to get their input

any suggestions from others here on the arm / cartridge synergy would be very helpful


hit up an excellent website calculating resonance

I did a little research and calculations using the formula stated

check out the ZYX Universe site

that's a pic with a triplaner from their beloved US dealer Mehran

ZYX universe specs

Universe specs

horizontal 15 x 10 -6 cm/dyne
vertical 12 x 10 -6 cm/dyne

I have the SB (0.24mv) version

Triplaner specs

11 grams

resonance freq = 1000/6.28 *suare root (M*C))

for vertical 12 compliance = 13.86 hz

for horizontal 15 compliance = 12.40 hz

these are both in the ideal range stated in the gc audio article

high enough to be out of the record warp subsonic stage but low enough to be out of the musical relm (well, most music these days)

so what gives?

perhaps dampening trough needed?
Hi Tom,

I spend Sunday at Doug's and we were thinking about your issue. There were a couple of noticeable woofer excursions but I believe each could be attributed to vinyl anomalies. I think from your description your woofer pumping is much more frequent.

There are obvious differences between speakers. Driver suspension, crossovers, internal box pressures, etc. The Salks may simply be use drivers with different mechanical properties and parameters. The fact that your friend also has Salk's and they pump as well is telling us something. I do remember my 10t being susceptible to woofer pumping with vinyl. A local brick and mortar guy once told me "Perhaps it is time to put the covers back on and quit watching them." This was after he was satisfied no damage was being done. He's an experienced Linn-ey. Don't rule this out as possibly the final solution. If you don't hear problems, don't go looking for them. :-)

If this is increasing with volume, Doug could be on to right track. It should be easy to get an idea if this is the problem. If you haven't already tried this, here is an experiment that may help show you something. Try moving your speakers farther into the room at least 4-5' from any wall, back and sides, and see if the pumping decreases.

BTW, what are the room dimensions? Sorry if you previously posted that information. It is possible to calculate room nodes and your speakers may indeed be close to one.

What is the weight of your Universe? I'm assuming you have the extra weight from the little plate.

I seriously doubt that anything you do to the tonearm will fix this without choking off the music.

I agree that the first thing you should try to ascertain is the pumping caused by airborne or mechanical anomalies. So ...

- move the speakers
- put up some kind of baffle between the TT and the speakers
- move the TT off the rack onto the floor or in another room
- check and double check your cartridge alignment
- try a different counterweight and play with location (heavier weight closer to the pivot point, or lighter counterweight placed farther from the pivot point)
- try a record clamp or periphery ring (if you can) to see if you can get a better interface between the vinyl and your platter surface

If that doesn't work then check your cartridge compliance and theoretical resonant frequency. Add something to the headshell to increase the mass of your tonearm (rebalance and reset it all, of course) and see if that alleviates anything.

In my case it was definitely caused by the arm-cartridge compliance. Switching cartridges removed the problem entirely.

Good luck,
I usually run the ZYX a little more than 1.75 grams FWIW, more like 1.85-2.0.
hi guys

just reading your insightful posts

latest update

less woofer excursion after using granite slab under table on craz rack - it eliminated or greatly reduced isolation
slightly warped records set it off, but most have much more minimal speaker pumping (I can live with if not damaging cartridge)

craz platform is floating and works great with electronics but not with turntables - I could tap it and get noise through the speakers - not now as I replaced it with 3cm granite

pumping is more pronounced on outer portion of record which fits with the warpage scenario
so I may have similar observations as what you saw at Doug's (room and port elements may add to this)

the arm is still resonating (as seen on the scope) - calculations and your experiences as well as Mehran's and Thom Mackris say this should work and it seemed to till I got a low end pre amp -the doshi

weight 1.75 ish - have the shim and adding a quarter on top of the cartridge didn't work either
I tried the mass counterbalance variations along the arm

room 15 by 27
I have system/speakers on long wall using Cardas nearfield setup
There is a dip in volume om the back wall behing the couch - increases two feet into the room
speakers 3 feet into room. CD's sound great in the room with no noticable freqency humps

haven't tried the speaker placement
do have some echo buster type iso panels I could stick between speakers and equipment

alignment is dead on as shown by scope with test records and hearing music

I have a heavy anvil I can use on the top of warped records
is the clamp more effective

the pumping at present isn't really audibly effecting the sound anymore or minimally except for warped records

Richard is also going to bring over a few other cartridges with lesser compliance and see if we can remove resonance

this may be as dan and bob suggested - live with it

I think I'm getting closer, just want to isolate this and tweak everything out of my system

enjoy music tolerate equipment ...

thanks for all the helpful insight,
much appreciated
Those resonance figures you posted are absolutely fine. This is not, IMO, a tonearm/cart resonance issue. That combination is used by many people with no issues. Now, if one is using the Universe without one of the plates, 5 grams may be too light.

I have no idea what you mean by low end preamp.

Doug's B&Ws do not pump in the least with almost every record we played. There were maybe 3 times over a 6-7 hour session that I noticed woofer excursion out of the norm. We have also mounted his Universe on my TP and had no problems.

But it sounds to me like you are getting to the issue. I think you're rack, or what is under the table, is the problem. The granite shifted the resonances up higher. I know because I also have granite under my table as the shelf for my sandbox. It sucks because it does cause smearing in the midrange. I use Stillpoints between my plinth and the granite to remove the ill effects from the granite.

FWIW, I can tap on my stand and hear it through the speakers. That proves absolutely nothing about how the table is performing, IMO. Well, unless one tends to tap their stand while they listen to music.

No offense, but who is Richard and why is he intent on proving your arm/cart match is wrong?
Great post, Dan. I agree on nearly all points (except I believe you got it just half right on the granite).


If changing your craz shelf to granite reduced the pumping then it's likely the additional mass lowered the resonance frequency and amplitudes of the shelf/table system taken as a whole. Thus less pumping.

However, as Dan noted, granite can also be problematic because its higher frequency internal resonances often introduce smearing, ringing or shouting into the audible band. Listen carefully for that. If you don't hear any, great. If you do, consider isolating the table from the granite as Dan suggested or (ideally) trying different support solutions that might lower the shelf/table system's resonance frequency without introducing ringing at higher frequencies. The Minus-K stands come to mind.

...the arm is still resonating (as seen on the scope)
Of course the arm is resonating. All arms resonate. At what frequencies? Under what conditions? What exactly are you measuring? What does it have to do with woofer pumping? The statement as posted lacks meaningful content.

...slightly warped records set it off, but most have much more minimal speaker pumping...
Good! You're building a system designed to reproduce everything that's on a record. "Everything" includes warps. If one's woofers are susceptible to pumping then on certain warps they in fact ought to pump. If they didn't, it would mean the LF signal generated by the warp was not reaching the speakers.

The solution is not to install LF filters, nor to worry about what is in fact an indication of good LF system capability. The solution is to flatten or replace warped records and perhaps to consider woofers which don't pump.

Vacuum hold-down would eliminate all but the severest warps. Center clamp + periphery ring would be next best. The Anvil may help on some records, but on others its weight can actually cause a flat record to dish upward. An adjustable clamp like Teres uses is more effective on a broad range of records. Further, each time I've heard the Anvil it also caused upper midrange smearing or glare, whereas the Teres cocobolo clamp actually reduces smearing and glare.

Sadly, there are no perfect solutions. We're just groping our way blindly from equipment toward music!


P.S. Your friend Don Ricardo seems like a man tilting at a phalanx of windmills with but one lance in his armory. ;-)
Yep, the oscillations of the craz were in my brain, but my fingers don't move as quickly as my thoughts. I tend to leave out parts. In this case, skipping ahead to the problems with granite.

Adding a suspension under a non-suspended table is not the way to go, IMO.
Oops! Dogma demolition time!

"Adding a suspension beneath a non-suspended table" is exactly what devices like the Minus K do. Chris Brady and others have found that it provides major benefits beneath even the heaviest (unsuspended) tables and is markedly superior to the best 300+ lb. unsuspended stands. My poor man's equivalent (sorbothane hemispheres between our equipment rack and the floor) also add a suspension to a suspended table.

Yes, our Teres is ultimately sitting on a compliant suspension. So was your Galibier both times you brought it down. I trust you didn't hear any softening of dynamic impacts, murky bass or other effects attributed to lightly suspended tables. The trick is to do the suspending effectively, with awareness of certain unavoidable contradictions.

A. The main reason to suspend a TT is to isolate it from floorborne vibrations.
B. The main reason NOT to suspend a TT is to allow the table's mass to resist being displaced by big transients.

These goals are self contradictory, so we address each while trying to minimize impacts on the other.

In our setup the non-moving mass of an 80 lb. TT is pretty tightly coupled to the ~300 lb. mass of our equipment rack and other gear. Except for the tiny amount of movement allowed by the Stillpoints (which do slightly diminish dynamics, as you know), we effectively have a ~380 lb. plinth to resist transient-induced displacements. So far, so good.

To avoid floorborne vibrations, this entire mass is sitting on weight-specific compliant bits to create a tuned system. The compliant layer sees all ~380 lbs. as a single mass and has a resonance frequency of < 10 Hz. If I could afford a Minus-K large enough to suspend the entire rack I could get that down to around 2 Hz.

To get a ghostly low sound floor and big dynamics too, we must suspend, but not too much. The devil's in the details.
I also have a Galibier (Stelvio) table and have had a friend's ZYX mounted on my Triplanar. We did not experience the woofer pumping you are experiencing. Your CRAZ rack is an amazing product. I wonder if it would be worth a call to Kevin; perhaps he could point you in the right direction. As an aside, my turntable sits on a GPA Monaco platform on a EquaRack. Perhaps the EquaRack product might be worth exploring.

BTW, great information on this thread.
Nope, no dogma here. I specifically included this is my opinion.

The granite was added on top of the craz, if I read Tom's post correctly. If that extra mass reduced oscillations getting to the speakers, something is moving too much. I didn't mean to point directly at the Craz, just whatever the table is sited on. But if that is the Craz, well not everything works in every application.

The Stillpoints are the limit I will go with compliance under my Gavia, and even then I know it is a compromise to the sound I could get with a braced, aluminum shelf on my sandbox. If I ever grow tired of that beautiful Dakota Mahogany granite it will be gone along with the Stillpoints. Remember, I'm coupled to a concrete sub-floor so I don't have the issues of a suspended floor. If I did I might own something other than what I now own. Suspend away if you want or need to. I don't find it necessary or desirable under my table to get a low enough noise floor.

Yes, there are things I hear in the mid and upper ranges differently in your system and mine. But down low is a different issue, and that's what where talking about here. I dont hear any down low in your system, I never have. I have to extrapolate what I think it would sound like. But I realize you do have your system tuned for a different sound than I based on our different preferences. Even as close as our systems are, they are still as different as the music we each prefer.
Agree about the Stillpoints, we both heard similar advantages/disadvantages. Like you, I'd rather not have that compliance so close to the TT. I'd ditch them too if our Salamander rack weren't so ringy (it's like your Dakota Mahogany granite, except for the good looking part!).

That's different from the sort of suspension I was referring to though. We both know people with sub-20Hz systems, very high mass tables (200+ lbs.) and concrete floors. Every one who replaced a big, high mass stand with a Minus K reported significant benefits with no loss at the bottom end. We're not talking bouncy, bouncy Linn here.

Agree there's little down low in our system vs. yours. Our speakers roll off below ~42 Hz. They can't reproduce the bottom octave no matter what we do at the source.

FWIW, our missing low end is not by choice and has little do with sonic or musical preferences. It's a function of geography and budget: we lack room for a sub and funds for full range speakers that would fit.

I'd love to try big Coincidents, which claim 20Hz without being much larger than our B&Ws. They're also easier to drive, have great crossovers and drivers (on paper anyway) and they're not ported - no woofer pumping!

That's my segue back to the topic. Sorry to Tom for threadjacking!
I just finished reading up on that device. Oh, yeah. That MinusK is a completely different league. It had better be for that price. Then again, when you look at the price of decent equipment racks it doesn't look as expensive.

If you think the Minus K is pricey (and you're correct, it's not given the price of something like an HRS rack, a Grand Prix Monaco or many lesser performing aluminum, polymer and glass monstrosities) take a look at the Halcyonics device. We're talking serious vibration control for electron microscopy and other critical scientific applications. Both devices make a Vibraplane look like a toy.
HI Richard,

Yes, I never liked the idea of air and pumps.

I did have some time this morning to scan the Halcyonics. The only issue I have with it is that it is active, however it is reported to have a faster damping time. Yes, this kind of device does put things in another league.

I also like that workstation table on the MinusK website. Change out the adjustable feet with spikes. A Billy Bags short table would also work great under one of these, so it would seem.

Employing a MinusK would probably allow me to play through the next quake in the good ol' granite state. :-)
hi guys

thanks for the further tutorials
this hs spinned into a very insightful thread

Richard is Richard Gray of the Power Company fame
he is an electronics guru and has set up a wide range of tables, arms and recognizes issues via scope, test records, etc

the Craz rack is fine - minimal suspension pads under denser surface material, titanium in the frame. It's the SRA VR platform above it that was causing the problems - these work miracles on amps, pre's, cd's etc but as we found out - the floating element is transmitting too much to the turntable

we replaced it with 3 cm granite and much lower resonance and speaker pumping. SOme in sync with the music, some not and probably in sync with the record. Sound doesn't seem to have added a shrill mid range

I also have a Billy Bags turntable stand my loricraft sits on - that sounds like some lugging I don't want to try

someone at a NOLA audiophile meeting last night suggested eccentricity in the spindle/bearing - but those Galibrier tables are built like a tank. I thought I heard the sligthest squeak the other night on a quiet passage - once a revolution. Do I need to re-oil it Dan?

low freq pre relates to it passing a lower freq signal - lower than my prior Dodd and Arc LS5.

salks ruler flat to 34 hz f3 under 29 hz f10 23 hz

I'l call Thom Mackris and Kevin at SRA for starters

I'll have to look into the record clamps
and yes I don't use the anvil but have seen records that it hurts on warpage more than helps

as Doug suggests - you get to the point where you are hearing all the eccentricities in musical reproduction

or as Richard said - compliant arm, compliant cartridge, comp pre, comp amp, etc - you are going to hear everything - warts and all

I think that if you filled the bearing all the way there should be no reason to worry about oil. There is no place for it to go. The bearing itself? Ah, no. ;-)

Got it this time. The one SRA turned out to not be a good match with the table. There is one layer peeled back, perhaps the only based on your results. BTW, have you tried the Gavia directly on the top shelf of the Craz? Heck, you could even move the Gavia to the floor since you're on a slab. Might tell you something.

I am not familiar with your amps and speakers, but it seems they are just going to move a bit with vinyl playback. Perhaps Atmasphere will have some input on this.

If things sound good, don't worry, be happy, and listen. Put the covers on if it bothers you. :-)

I was just pointed to this thread. There's too much good inforamtion to sift through at the moment, but based on the names of the posters, along with a quick scan, it looks as if you've received good advice.

I likely missed some of the finer points, but here are some thoughts.

1. Same problem with all sources?

Do you get the same pumping when playing CD? I assume this isn't the case, but it needs asking

2. Changes in stands/shelves.

This strategy seems to be pointing you in the right direction. No time to comment on the apparent disconnect of suspending an unsuspended turntable.

The key point to mention however is, that with Vibraplanes, microscope tables, etc., the entire 'table is suspended - the critical relationship between drive system and platter is still intact.

Maintaining this fixed relationship between drive system and platter/bearing is key to the success of an unsuspended design, and placing the entire assembly on an air table is consistent with the design goals.

My expereience of a Townsend Seismic Sink on my turntables was essentially a whole lot of trouble for no improvement over a *well* *implemented* sandbox design.

I've never met Sorbothene that I wanted in the same zip code as my hi-fi, but I can't profess to having tried every last permutation. Let's just say that it's the last place I'd look for answers.

3. Cartridge.

Don't rule out the cartridge, just because the Tri-Planar/Universe is a ubiquitous and compatible combination. You might have a sample that's aging differently. Mount another cartridge. You've tried enough differnt things to not want to overlook this.

4. Oil.

It wouldn't hurt to re-lube as you've been running your rig for something like 3-4 years. I don't expect any changes here.

I'll try to work through this rather long thread as time permits, but don't hesitate to call me.

Thom @ Galibier
The key point to mention however is, that with Vibraplanes, microscope tables, etc., the entire 'table is suspended - the critical relationship between drive system and platter is still intact.
Agreed, and we go even further. In our setup the entire table + system + rack are suspended as a single entity, well away from the table and drive system. All our sorbothane floor supports see is a single, rigid mass of nearly 400 lbs. This is very different from sticking it directly beneath the TT feet or something. I tried that once, just for ha-ha's, and it sucks big time.

Agree that the connections between drive system, platter, bearing, plinth, armboard, tonearm, cartridge, LP and record clamp must be as non-compliant as one's components allow. The only compliance anywhere in our vinyl setup is Stillpoints instead of spikes beneath the plinth. As anyone who's tried them knows, they do ennable a tiny degradation of transient speed and dynamics, though most feel the reduction in sound floor makes for a worthwhile tradeoff.

It's about thoughtful implementation, as always.
Hi Doug,

Thanks for the clarification on your Sorbothene implemenation, as well as the validation that locating it closer to the source component is a non-starter.

Thom @ Galibier
What I find bothersome about the MinusK, and I fully admit I have no experience with it, are the reports of these going into oscillation by something like a cd drawer opening and closing. It seems that they do dampen out and work, but I can't imagine my gear on top of something that moves when queuing a record. I suppose I'd have to see it, but it doesn't sound comforting. :-)