Why do my bass drivers shake violently listening to vinyl

Different signal from each. Vinyl putting out more bass than digital. The question is how does it sound? Is it distorted? If so, then you may have a problem. 

It sounds incredible! I'm just concerned that I may be doing damage to my speakers. 

You likely have a mismatch between cartridge compliance and cartridge/arm mass.  Do a search.

@audionoobie - Some questions:

• Do the woofers visibly pulse in and out i.e. you can see the movement
• Is the "shaking" consistent for every album
• are the albums warped, so the pulsing matches the album warps 
• is the platter free from warps
• is the bearing in good shape
• is the stylus clean and in good condition
• what kind of stylus are you using
• does your phono stage have a sub-sonic filter

Take a read of this thread
Phono-pre: subsonic filter on or off ? | Audiogon Discussion Forum  

It might give you a clue as to what is going on

Good Luck

@williewonka interesting thread before it went off topic. The KAB rumble filter was brought up. Here is an excerpt from their site which accurately describes what I am seeing:

Getting into LP's and startled at the big speaker cone movements that you're seeing? Thinking a better turntable will help? It may not! This very low frequency energy is called rumble. Much of it is actually cut into the record groove when the master disc was made. But the main source is feedback exciting the natural stylus/arm resonance between 7 and 12 hz. This produces a slow easily visible in and out motion of your woofers. If you cannot see this motion, the RF-1 will not solve your feedback problem. If you can see this motion, the RF-1 will solve your feedback problem.

• Do the woofers visibly pulse in and out i.e. you can see the movement - Yes
• Is the "shaking" consistent for every album - Yes
• are the albums warped, so the pulsing matches the album warps - No
• is the platter free from warps - Yes
• is the bearing in good shape - Brand new Technics 1210GR
• is the stylus clean and in good condition - Yes brand new AT VM760SLC
• what kind of stylus are you using
• does your phono stage have a sub-sonic filter - Not sure. It is a Herron VTPH-1. I'll have to research that.

@melm It seems my cart is a very popular choice according to the Technics SL1200 FAcebook group. Many users using this cart.

Do the woofers move when turntable is switched on with volume, but no record playing? If so, it could be a DC voltage leak going to the speakers. If so, power down and clean up that spaghetti tangle of wires, minimizing crossing of cables and certainly not letting phono cables touch other cables. Cheers,
Spencer 

@sbank No. None of that is happening. And this isn't the first time I've seen this. It happened with a completely different set of speakers and different cart, on the same table. I thought it was something particular to those other speakers. 

@audionoobie

RE:   But the main source is feedback exciting the natural stylus/arm resonance between 7 and 12 hz.

If this is the case try placing a small amount of bluetac or silly putty on the heard/arm and recalibrate the stylus down force to the recommended amount for the cartridge. This will change the overall mass, which may reduce, eliminate or exacerbate the problem. Either way you will know the cause of the problem. 

Do the bearings in the arm have any play in them?

Regards

It sounds incredible! I'm just concerned that I may be doing damage to my speakers

Rarely does a problem allow the sound to be good, much less incredible. What kind of music do you notice this with?
Some music causes this phenomenon of very active woofers. Heavy metal and hard rock is one of them . Plus your speakers have a a " 8” Carbon-Loaded Cellulose Flat-Cone Woofer with Ultra-Long-Throw Motor Assembly" according to their literature (specs) I doubt you have a problem. unless the woofer moves without being fed any signal

@williewonka how can I tell if the bearings have any play in them? Not sure what you're referring to.

@artemus_5 I noticed this any time any record is playing. It is not genre specific. And like I said, there is no discernible audio issue. Just the bass drivers going in and out like mad. 

You need a rumble filter, a low frequency filter specifically created to solve these problems with vinyl playback.

What's going on is that you are getting a strong signal below the resonance filter of the port, so there's no longer an air spring there to hold the driver back.

If you can conveniently plug the port you should try and watch again. :)

Still, you need a rumble filter to reduce the strain on your amp and speaker, and yes it's dangerous, either from excess excursion or overheating of the coils.

Of course, you may also need better isolation of your turntable. On a springy wooden floor a simple stand will not be good enough.

What arm and cartridge are you using!  Put the information in this calculator and you will get the resonance frequency number!
http://www.mh-audio.nl/Calculators/RF.html

@erik_squires Excellent post!! 

I suspected it was dangerous. The excursion or cone travel is pretty extreme and it seems to be as you said with no spring holding back the driver. 

And, yes, I have a springy wooden floor in a second floor bedroom and a cheap Pangea audio rack.

I could try plugging the port although with the Treo's they are located on the bottom. I will absolutely look into getting a rumble filter.

Thanks all!!

@yogiboy Technics SL1210GR arm and AT VM760SLC cart. 

Arm = 12 g
Cart = 8 g
Fastener Mass = .5 g (guessed)
Compliance = 10 x 10-6 cm/Dyne  

Tonearm Resonant Frequency = 11.12 Hz

Erik is 100% right. Back in the day, rumble filters were a feature on many receivers as it was often needed for the very problem you are experiencing. I had the issue myself sometimes.

Before purchasing a rumble filter, I would first see whether changing the location of your turntable in relation to the speakers has any effect on the phenomenon you are observing. Also, the addition of some isolation to the turntable base might help the problem. You might try to suspend the Technics turntable in someway. There are “feet” available for that. I would put all this ahead of adding a rumble filter in the signal path, only because the rumble filter is not without its sonic penalties. There is no free lunch in Audio. The only other thing I would add to the discussion is that someone mentioned DC voltage as the possible culprit. That is impossible since DC by definition has no frequency. Significant DC voltage delivered to the speaker voice coil could damage it, but it is not causing the piston like movements you are observing.

Per your system pics you now seem to have the TT placed in a dormer off to the side of the left speaker.

If possible try pulling the rack out of of the dormer, just temporarily, to see if the LF feedback lessens.

DeKay

All phono stages should have a rumble filter to cut off frequencies below 20hz. The result is cleaner bass and less strain on the amplifier and speakers!

8” Carbon-Loaded Cellulose Flat-Cone Woofer with Ultra-Long-Throw Motor Assembly

I copied this from the Vandersteen site . Notice " Ultra-Long-Throw" IMO, that is what you are experiencing, an ultra long throw of the wooferThat said, @erik_squires may be right about a subsonic filter. It can’t hurt but will it help? I’d take a video and send it to Vandy tech service. They should know if this is normal for that speaker
You might also do as others have suggested by pulling the TT out of the dormer. Bass may be feeding back thru the cart and thus exacerbating the bass issue

I copied this from the Vandersteen site . Notice " Ultra-Long-Throw" IMO, that is what you are experiencing, an ultra long throw of the woofer

Your opinion in this case is not actually correct. :)

The phrase "ultra-long-throw" or "long throw" have no specific meaning, but are understood to mean that the driver MAY travel further without distortion than conventional drivers of the same size. Typically, larger drivers have longer throws.  This is specified by manufacturers as Xmax, and is usually in millimeters.  So you'd read it something like this:

Xmax : 10mm (the distance the driver can travel from rest is 10mm before distortion sets in).

That doesn't mean they flap back and forth more than any other driver of the same size and output.  The symptoms from the OP are definitely being caused by excess, and inaudible, bass in the signal which could probably be replicated by jumping on the floor. :)

You don't need an "ultra-long-throw" woofer to flap back and forth, just too much rumble in a ported enclosure.

Audionoobie, welcome to vinyl. There is a lot of low frequency rubbish on records in the form of warps and irregularities in the vinyl. It can be made worse if your cartridge and arm are not matched correctly. unfortunately the flapping woofers increase distortion and waste power. Other than making sure your cartridge is appropriately matched the only other way to deal with this is a steep subsonic filter. A two way crossovers used with subwoofers will stop the flapping in your main speakers but will pass it on to the subwoofers so a subsonic filter is still necessary for the best performance. I use a very steep 8th order filter at 18 Hz. It is digital which is the best type of filter to use for this purpose.

Another way to read "ultra long throw" driver is:

This speaker will play louder before you hear distortion or compression than if it wasn't ultra-long-throw

@erik_squires

I have no real knowledge of electronics as you do. But I have been involved in using stereo systems for 60 yrs and can only speak from my observations. That said, I have seen my subwoofers pump wildly...or at least what I thought was wildly. It was much more than 10 mm. But I have never had any sound issues nor break downs. That said, Why does it still sound " incredible " according to the OP? I know what sub sonic means but I have heard it before in a system..at least thats what I thought it was. It DID go away with the subsonic filter
BTW I'm seeking answers not a fight (-:

The flopping is due to things you can't hear, and the OP should be grateful that he didn't have the volume up any higher. :)

Those signals could be in the 5-10Hz range, quite easily.  Removing them wont' make it sound less incredible. :)

I generally prefer to go from the simple to the complex, in trying to solve any problem.  Simple is to either move your turntable in your listening room or suspend it, or both.  Complex is to add a subsonic filter.  If you add a subsonic filter, then a steep slope at a frequency below 20Hz is desireable, but 24db/octave is to be preferred over 18db/octave, because of phase anomalies that may affect upper frequencies. (6db/octave is also good but much too gradual for slope in this case. 12db/octave and 18db/octave are less "good" compared to 24db/octave.)  I will bet that moving the TT will solve your problem or at least ameliorate it sufficiently so as not to be a bother.

+1 erik, problem most likely subsonic 5Hz or so. Use a 24dB/octave filter, the steeper the slope the better.

@lewm

I generally prefer to go from the simple to the complex, in trying to solve any problem. Simple is to either move your turntable in your listening room or suspend it, or both. Complex is to add a subsonic filter

I agree wholeheartedly with this approach

FYI: Japanese cartridge specs are rated at 100hz not 10hz. You have to multiply by 1.7 and the resonance frequency is not 11.12 it is 8.53. That is a fine figure and will not cause the problem of woofer pumping! 

"Working" from home today so I moved the TT from within the dormer area on the Pangea shelf to outside of the dormer on a much more stable IKEA Kallax shelf. (see Audionoobie's system pics) Was pic 4, now is pic 3. 

Same problem....

Seems like I'll be looking for a rumble filter.

That's very interesting.  You mentioned you are using a 1200GR turntable.  Do you own or can you borrow a different TT, just to see if the problem is the same with a different source TT?  I am wondering whether there is some sort of defect in your 1200GR.  That seems very unlikely, given that Technics make thousands of them and have vast experience building TTs with a very low error rate, but unlikely events do occur.  If you own a stethoscope, place the bell on the plinth and listen for excessive noise; that might be an indicator of a problem. (It's also interesting that a Pangea shelf is not as stable as an IKEA product not even made to support a TT.)

Sorry noob that you had to read through all the bad advice before finally lewm helped you out. It is not the record or the turntable or arm or cartridge or anything to do with compliance or any of that. Sorry you have been so misinformed. What you are seeing is the mechanical vibration being transmitted up from the floor, rack, and shelf into the turntable. 

This happens because the signal cut into the vinyl goes through RIAA equalization that turns the lowest frequencies down 20dB. That is a lot. When playing back the phono stage has to amplify that 20dB back to sound flat. Only problem, no way of knowing what low frequency vibration is signal and what is noise. Even the tiniest vibration amplified 20dB is gonna be quite loud. Which is exactly what you are seeing. Only it is too low frequency for your speakers to reproduce audibly, but it is there and so you see it. This is the grain of truth in some of the bad advice above.

The solution lewm has in mind is to put the turntable on something more stable. There are several ways of doing this, which one will work best in your situation is hard to say. But the good news is these are tried and true simple and easy and cheap to do.

Easiest/cheapest will probably be Nobsound springs. Put the correct number of springs under each footer, will be a big improvement and might just solve your problem in one fell swoop. For $30. If not no worries they will be an improvement for sure you just might need to go further.

A nice thick butcher block shelf works well. Another one is to build a sand box. Anything the right size you can fill with an inch or two of sand. Mix the sand with just enough mineral oil to eliminate dust, pack it down, put the butcher block on top, turntable on top of that. Nobsound between butcher block and turntable. Premium isolation for cheap.

Any one or two of these will probably do the trick, and not just eliminate your woofer pumping but improve sound quality a lot in the process.

I have posted this many times already but I will do it again.  I tried everything MC and other describe here, nothing worked on my VPI Prime.  I tried it on a 4 inch thick maple platform, I bolted a shelf to the wall, I moved the TT all over the room, tried isolation cones, etc.

Out of desperation, I bought the KAB filter and it was the best decision I made.  The filter is stuffed with audiophile grade parts and it does its job without altering the sound.  I run mine through a processor loop on my preamp so it is only used when I play vinyl.   Do yourself a big favor and get the KAB rumble filter.  I believe it is around $179.00.

Thanks @stereo5 I think that is the route I will go down. For my own understanding, is this a turntable feedback loop? The low frequencies being put out by the speaker are traveling along the floor, into the rack, picked up and amplified by the cartridge and phono pre and sent back out the speakers further exacerbating the issue?

I really appreciate everyone's responses. This has been a big help....

+3 On The KAB rumble filter.

@audionoobie re:

@williewonka how can I tell if the bearings have any play in them? Not sure what you’re referring to.

Simply hold the arm between thumb and finger and gently push/pull the arm - if there is play you will feel a slight movement or feel a clicking

This is not common, but can occur - if this is the case the beerings need adjusting (if possible)

Regards

@erik_squires Excellent post!!

You already have anti vibration feet designed by Technics for their new G series. The cabinet is a 4 layered construction. You DON’T NEED any springs or butcher blocks or any platforms under your turntable (these crap is for belt drives).

Technics turntable can be used by PRO near a HUGE sound system with tremendous bass response, probably 1000 times higher SPL than from your speakers.

G and GAE are top model in SL1200 series and stock feet are very well engineered, but if you want to try something else you have to check Isonoe (they are made for Technics).

Read this topic.

Unless you are not placing your turntable right on a SUB I think the problem is not the feet.

Chak, If the 1200GR is without construction or operational flaws, I quite agree with you.  If it has a construction defect, like an off-balance platter or bad bearings or something rubbing on something, then it is better to identify that problem than to put a rumble filter bandaid over it, I think. For that matter, I am guilty of suggesting other types of bandaid, so my own advice is also flawed in that way.  One would like to examine the TT in isolation.  The only thing I suggested that might help to eliminate problems in the Technics is to temporarily replace it with another known good TT, and determine whether the woofers still act up.  If that test is passed, then maybe the rumble filter is the way to go or any of various forms of enhanced TT isolation first.

Vinyl has much less bass extension the digital, limitation of the medium.
Vinyl playback equipment often has more. Not from the program. There used to be subsonic filters to cheat your way out of it but now... 
Saddle up.

That’s why there’s been some mention of the KAB rumble filter which is a well made add-on.

A rumble filter will definitely eliminate woofer flutter. But it will do nothing to improve sound quality. Springs, sand box, etc will definitely improve sound quality, and also in most cases eliminate woofer pumping. You can spend your time and money on improvements, or fixes. 

The low frequencies being put out by the speaker are traveling along the floor, into the rack, picked up and amplified by the cartridge and phono pre and sent back out the speakers further exacerbating the issue?

No. That is different. There are two main forms of vibration to deal with, both vibrations but completely different in effect. Your original question is about subsonic vibration. Speakers can't audibly output, you can't hear it, you're concerned with something you can see but not hear. 

Then there are vibrations from speakers in the audible frequency range you can hear. This range of vibration will smear detail and color instrumental timbre making individual instruments sound less distinctive. Putting speakers on springs like Nobsound will greatly improve this. As will putting the turntable on springs. They will not eliminate the large amplitude low frequency pumping you are seeing. They will however greatly improve clarity, detail, dynamics, imaging, etc.

This is why I recommend the things I do. Springs, mass, etc work together to solve both problems. Solve. Eliminate. Not patch over with a band-aid. While simultaneously improving sound quality. None of which you get with a filter.

@audionoobie
I kindly ask that you post your solution after you get this problem solved. I'm just curious

As a long shot remove the dustcover!

I have a TT and cart combo that will blow a normal sub 80 hz < but with servo plate amps and servo correction, it’s a tame, deep, very clear bass signal to 25 hz. I’ve always used a spring suspension and gummy puffers for isolation.. A heavy ply plinth, rubber line and spring load the bottom with springs or an inner tube. I use Thoren TD124s and Russco.

The main speakers can’t pump because the bass is cut from 280< and from 100-300hz are bass columns. My system CAN’T pump!! You can throw the TT in the middle of the room... Servo is pretty cool.. ;-)

I use up to 6 12" OB HE drivers. Maybe 100 watts to each driver @ 8 ohms. 100hz < no TT problems..:-)

Regards

Millercarbon, so far you have been totally and completely off base twice in this thread. The OPs problem has nothing to do with the turntable's location. Isolating it will do absolutely nothing. If there is a cartridge mismatch improving that will help otherwise his system is appropriately amplifying the signal that the cartridge is picking up. With smaller woofers this causes excess movement. Next. Stopping that excess movement results in a large improvement in sound quality because of the marked decrease in several forms of distortion. It also results in greater headroom because power is not being wasted. The improvement a subsonic filter will make will be far in excess of any problems it might cause. 
@lewm, subsonic filters are not complicated issues in the digital world, you just program one in. I know this rubs you the wrong way but personally I do not like being stuck in the past. Digital reproduction has advantages that can not be matched in the analog world and the advantages outweigh the disadvantages. I am dead certain you would agree if you could hear it in action. 

I agree with those who say before you do anything, try another turntable in your system at the same location. Whether or not you get the woofer excursion with the second table will determine what to do next. Before you can solve your problem, you have to know what the problem is.

You either need a better turntable with a much better bearing or a very good rumble/subsonic filter on your amplifier.

The OP is experiencing an undamped medium mass arm with a too-compliant cartridge in combination with vented speakers. A stiffer suspension cart, sealed box speakers, a viscous damped arm…any will stop excess sub-bass from causing woofer oscillation. Eric Squires explained how driving a vented speaker below its cutoff frequency is part of the picture, and Yogiboy provided a calculator for arm/ cartridge resonance. Getting reliable data for that from manufacturers specs…good luck! The results speak for themselves. IF OP’s preamp has a processor loop or tape monitor then a high pass filter is the simplest solution but beware unwanted loss of subtle quality cues if the HPF isn’t as good as your excellent Herron phonostage. Maybe they can add an HPF to their circuit??

One of the problems with a ported speaker is that below the port resonance the woofer is literally floating in the breeze with nothing to stop it(unlike a closed box where the compression of the air brakes the driver). If there is a low frequency resonance the driver can go in and out totally uncontrollably which can damage a driver. A poorly matched arm/cartridge resonance can be a source of this kind of low frequency energy. Look at controlling this resonance and/or use a rumble filter.