Subwoofer Isolation, what do you think...

I just got this big honking subwoofer, a DD-18 Velodyne. I've a ceramic tile over concrete floor. I also have a nice turntable in close proximity to the only WAF approved site for the big honker. Anyone have any feeling for if the adjustable feet that came with the DD-18 are enough or should I replace them with cones or something else? I always use the sub even with the vinyl as it adds so much depth to everything. I can't say my turntable's stand is very good, it isn't but I'm working on finding something good (and affordable!). I am concerned though with this big thing so close... maybe within four feet.
Thanks People!
The problems you may experience are more likely to be with airborne vibrations. I don't think that you will benefit much from further floor isolation under your sub. Your turntable, perhaps. Generally it is best to place your turntable (and other components) in a spot in your room which has a bass null or at least a neutral zone to minimize the effect of airborne vibs.
I agree with Newbee about not isolating under your sub.
Also agree about turntable location.

If you would prefer upscale feet for your sub, then there are a number of choices. They can be of benefit in reducing unwanted vibrational effects in the sub.

Disclaimer: I work for a company which produces Audiopoints, a vibration management foot system.
I had a 2" thick piece of limestone cut and then used spikes for the sub onto the stone. Tightened up the low end response; ie, cleaner sounding, not muddy any longer.
I had the same problems with my Velodyne FSR1800X Subwoofer next to my Projector stand shaking the pj. I tried Aurio 1.2's first and then went to Aurio Pro's to Decouple my Subwoofer from my tile floor. I also went through that same process to float my 17lb projector to take it to the next level. I am going to do a shootout with my Sistrum SP-4 stand under the subwoofer again which tightened up my sub considerably in the next month once I stabilize the changes in my system. I use 2 sistrum full racks for my video and audio system.
I can't say I've a problem but I'm more wondering what other's do, if anything, to their subs in this situation. The built-in leveling feet are great and make a solid mount but...
Oh Yeah get a 25lb bag of #6 (I bought #7.5 instead because that is what the gun shop had in stock and it works also)lead shot and throw the bag on your sub with whatever isolation you choise it will tighen up the bass more by adding mass to the top of the sub cabinet. Especially with an 18" subwoofer cabinet!
Look into Sistrum stands for the subwoofer. It will isolate it beautifully and improve it sound.

I believe that you may have misinterpreted Newbee's post. He was not discussing whether to isolate or couple the subwoofer. He was suggesting that air-borne vibration was the major issue in Sailfishben's system and that he should attend to that at the turntable. Newbee also suggests that Sailfishben try decoupling the turntable so it is shielded from the vibration from the subwoofer. Maybe Newbee can clarify.

I would say that sending more of the subwoofer's vibration and energy into the floor through rigid coupling is not the best method to control that vibration because the vibration will travel through the floor towards the other equipment in the system and have negative sonic effects. If the other equipment is also rigidly coupled to the floor the vibration will have a direct path into the equipment through the supports. A rigid coupler (whether it be a point, a spike, a slab of stone or wood, etc.) does not have the ability to send vibration in only one direction (out of the component). By virtue of its rigidity it allows vibration to travel in BOTH directions - also up INTO the component.

Best Regards,

Barry Kohan

Disclaimer: I am a manufacturer of vibration control products.
WAF factors dictate putting a 25lb bag-o-shot on top of our beautiful piano gloss black BIG HONKER will only land me in the doghouse so thats out. This thing weighs in at 120lbs... it ain't moving. Hell, if it was only a bit bigger I could use it later when I go to the big room. Kidding aside it seems like you all are telling me to stabilize the turntable first with a good rack etc. Besides the Sistrum's who's got the best price to performance rack? I only need it to be about 25" high. I'd only hold the phono amp along with the turntable so the longer IC run was to the processor, is that how to do it? Seems like starting with a decent rack or stand at an affordable (cheap?) rate then later adding another product to it fits in with my budgetary restraints.
Thanks people!
Barry from Bright Star... will your NODES support the 120lbs of weight?
Barry, are you suggesting that tons of solid concrete floor(which is directly coupled to the Earth's surface) does not have enough mass to dissipate energy from a subwoofer?

And if you think it does not, then how much amplitude is that several ton solid concrete floor going to generate, when driven by an 18" subwoofer(via the cabinet and spikes, and damped by the entire mass of the planet)? And at what frequencies?

Is not a device like an Audiopoint or Sistrum Platform, which is designed to sink the wideband airborne vibrations to the concrete floor(where they can be dissipated), a better option in this case? After all, they are situated as locally as humanly possible(directly impinging on the cabinet underside, and then directly touching the concrete floor below).

Are you saying that your products can outperform the energy dissipation properties of a massive concrete slab sitting on the entire mass of the Earth itself? Or would it be better to let the natural energy dissipation properties of the Earth do it?

You know, that the neutral connections of your electricity wiring(which feeds all the power to your audio system) is attached to an earth ground that easily and hungrily soaks up all that power running your gear(including the sub), and has the capacity to soak up much much more.

According to the 2nd Law of Thermodynamics, ALL ENERGY(not just electrical) seeks the ground state via the path of least resistance. Certainly you realize this, yet you promote the interruption of this "path of least resistance" in all your designs, preferring instead to substitute a smaller piece of "earth", or a very small bit of flexible material(subject to very easy overload, which reflects all it cannot absorb back into the nearest boundary - the component, as the Zener Viscoelastic model tells us) to do the job.

We obviously differ on the most efficient methods used to manage the vibrational energies present with audio equipment.

I agree that a "very live and flexing floor" could lead to difficulties, but the floor is being driven by airborne vibrations(sound pressure waves) primarily, and only much less-so by the bottom of the speaker cabinet. Our suggestion for those cases would be to address the issues with the unstable floor, and not to interfere with the performance of the audio system that sits on it. This may not be as easy as buying small pieces of rubber and putting it under the speaker, but it is much more effective in curing the problems of an unstable floor. A flexing wood floor is much like an acoustic guitar(which I custom build in my spare time). There is a direct coupling of the strings to the top via the bridge. If the top of the guitar is responsive(flexible), it will produce strong amplitudes of sound vibrations with wide frequency response. If the top of the guitar is overbraced and stiff, it will be "dead" because it cannot move with any significant amplitude, even when driven, and since in the case of the guitar, there is no route to ground, the vibrations basically remain primarily in the strings(although some vibrations are damped in the wood mass) and dissipate there in the classic air-damped string decay pattern.

In my home situation, I have to deal with a typical suspended wood floor all the time. When playing at 105db peaks, I have no problems with vibrations "re-entering" my system from floorborne vibrations. I situate my equipment near the wall that has the foundation under the edge of the floor, which is a node, and doesn't get into large amplitudes. I also have concrete piers under the center of the floor, to keep it from going into any noticable amplitudes by terminating the center of the area of peak oscillation amplitude(the center). This "center node" is at my listening position, and doubles the frequency and halves the amplitudes of any previous(unsupported) floorborne vibrations. This simple form of bracing can control the development of any significant amplitudes that may be driven by either airborne sound-pressure vibration or speaker-bottom driven vibration, because since it is more difficult now to drive the floor into oscillation, the easiest path becomes routing to the earth.

Maybe not everyone can do this, and maybe most don't want to be bothered to do it. In these cases, it is easier for them to compromise, and typically that is what is done. In most construction, the structure is of sufficient rigidity to bear out this concept, and certainly concrete floors are.
Since Barry asked for some clarity about my post.....

My focus was on the effect of airborne vibrations. I think TWL appreciated my intent. But I'm not sure that I can totally agree with (or perhaps appreciate) all of the discussion since my post.

TWL discusses amplitude. This is one of the few times that word has been raised, that I can recall, even though I have felt for some time that it was the purposefully missing link in these discussions about vibrational control devises. I applaude him for this. However, at the same time, for that exact reason, I must wonder about the effectiveness of providing a "drain" path as a method of reducing the effect of airborne vibrations.

From my point of view the major effect of airborne vibrations has already taken place before these vibrations can even be drained. You might be able to reduce a resonance frequency in one of the TT systems components, at least in theory, but would its amplitude be sufficient to cause further damage without the reduction? And, since all matter resonates at some frequency, I might be as concerned that the "damping" or "draining" materiel used might start resonating itself and thereby feed back vibrations into the devise we are trying to protect. FWIW I just don't think there is a universal solution to vibration control. I favor a combination of isolation and drain path within the system supports (not the underlying floor), just makes sense to me.

Re the comments on the sub on the floor. I think the amplitude of any vib's which can pass thru the concrete would be so low as to have no effect on the type of coupling the speaker has with the floor. A case could be made for stiff coupling, especially if it is sitting on carpet. However, with this heavy a sub and its frequency band width I'm not sure how any specific coupling would affect its sound. But, FWIW, I would probably put it on spikes or cones, just to feel better. :-)

Barry, question for you...

In another post you advocated placing a speaker in a "sand box" - I'm not familar with your product, but I have this impression of a tall speaker sitting on a plinth in a sand box waiting for some minor displacement to cause a compression in the sand along one of the plinth edges and the speaker tipping over. What am I missing?
Hi Sailfishben,

Each large size IsoNode foot can support a maximum of 10.5 pounds. They are normally sold in sets of four and the set can hold a maximum of 42 pounds. If the component or speaker exceeds that weight, additional IsoNode feet can be put in place underneath so that the load weight can be supported properly. We generally do not recommend that the user be at the maximum load for optimum performance. I would recommend that 14 - 15 large size IsoNode feet be used under a 120 pound speaker.

Best Regards,

Newbee, I agree that there are some things which cannot be fully prevented from happening in most stereo listening environments, short of placing the equipment out of the listening environment, and of course at least the speakers must be in the listening environment.

Our intent at Starsound is not to attempt to prevent or eliminate 100% of the vibration issues, because it really cannot be done. The whole listening environment is strongly charged with high SPL soundwaves which definitely will have effects.

What we do is to try to employ designs which we feel(and our factory testing and listening tests) reduce the negative sonic effects of this vibration. And I know that Barry approaches the same issue with different ideas, and that is great. We like Barry, and he is a good mfr with a good record, and some good ideas. He's a forward thinker, and an innovator. We like to think of ourselves in a similar way, too. It is just that our ideas on how to do things differs, and that is why we have different companies and different products.

Returning to your questions/comments about the initial impacts and effects of the soundwaves on the components before any of our products can affect the situation, you are absolutely correct. Our system, and most other systems that I can think of, actually require the soundwave vibrations to be propagating in the component before anything can be done with them, at least for a short duration and path. Since the environment is as it is, it is inevitable that this will occur. The better systems deal with it quickly.

What is done after the initial impact of the soundwaves on the component is then the issue, isn't it? It amounts to 2 major schools of thought, local damping, and energy transmission. Each will attempt to make sure that the initial impact of soundwaves is the only event that makes an effect on the sound. Methods will vary, based on the maker's ideas on how it should be done. Basicallyt the idea to attenuate the effects on the equipment by either damping it at the component, or making a path for the the energy to exit rapidly, so that it is not reflected back into the component(causing a phase-shifted re-occurrence of the initial event).

What I feel causes confusion is that both methods do work. Local damping works, and energy transmission works. In fact, they are really tied together, if you think about it. The results will be based on how well the system is designed and implemented.

However, one of the main issues that really separates the "camps" is the issue of internally generated vibrations, and those effects on the sound. We, at Starsound, want to let the internal components generate their inherent vibrations as they naturally "want" to do, and then evacuate them as quickly as possible, so that they don't come back to bite us as a phase-shifted occurrence. These devices "need" to vibrate naturally, and if they are too damped, they don't function as intended, sonically. This is borne out by anyone who has ever experimented with local damping. You can "over-do" it, and deaden the harmonic content of the sound, as well as the dynamics. Typically, local damping that is sufficient to deal with the high levels of vibration in the listening environment, also is enough to "deaden" some of the sound we want. If it is damped low enough to not "deaden" some of the sound we want to keep, then it is insufficient to deal with the high level SPL that is "pounding" into it from the airborne vibrations. This is a dilemma.

Then you come into the part where there is always some "transmission" required as part of nearly every "local damping" system, and "damping" involved in every "transmission" system, because no system damps everthing as locally as could be possible(thus it has at least some transmission to the damping site), and every "transmission" system has "damping", because it is in the nature of materials to have some kind of damping effects, and the eventual destination of the vibrations in a "transmission" system is the earth, where the vibrations are "fully damped" in the ground. It is a matter of how things are done, and where the damping occurs.

Then there is another method which uses some transmission with a relatively local high mass, which attempts to replicate the effects of earth ground with a box of some kind of high mass product. Then they use transmission type products to transmit the vibrations from the chassis to the high mass, where it is hopefully damped.

When we were faced with this dilemma 16 years ago, before "transmission" types of vibration management systems were around(or were inaccurately called "isolation" systems, mechanical diodes, etc), we decided that some "out of the box" type of thinking was required. We needed to look at other ways to deal with vibration that could allow us to escape from the dilemma. We felt that if the vibrations could be sent rapidly away to be damped by nature at another location, our job could be accomplished without impeding the natural resonances produced by the things that need to vibrate to sound right. It took some work. Our result initially was Audiopoints. This was our first product, and it defined our "Resonance Energy Transfer" concept. Basically, this is a system of materials and geometries that reduces Coulomb's Friction in the exit pathway, and allows rapid enough exit for the vibrations. If the pathway is not fast enough, it will not operate as intended, which is why the other "brass cones" are not in the same league, and which is why our products should not be mixed in with other devices which could negate the speeds of our exit paths. Of course, over the 16 year history of this product(since 1989), it has validated our concept, and everything we ever expected from it. Then after 10 more years of research and development, the goal of improving the Audiopoint performance through the introduction of the Sistrum Platform happened in 2000. Since then, the Sistrum Platform has been an award-winning product and always in contention for the best vibration management product available at any price. So, there is no doubt that this concept works extremely well.

But, not everybody wants this kind of system, and not everybody prefers it over local damping, so we have a diverse market of products from many manufacturers who sell different concepts and different products to satisfy the different market needs.

No, none of them are perfect, and there are still many horizons to conquer regarding this issue. With people like ourselves, Barry, and others working on it, I'm sure that we will see even further advances in this field.
Hi Newbee,

Thank you for your clarification.

Yes, it is critical that the support that is under the component not add its own negative contribution. That is why the choice of materials is very important. I do not recommend using materials that tend to ring (metal, stone, glass, etc) or are known to be significantly resonant (wood, acrylic, plastic, etc) as they will impart those qualities on to the signal that is flowing through the component.

If a damping device is used to control vibration it should absorb as much vibration out of the component as possible without subsequently releasing it back into the component. The more well designed the device is the more able it will be able to achieve that goal.

The "sandbox" you asked about (and which is widely discussed on many internet forums) is our Big Rock platform. The Big Rock was created by me in 1985 and I was granted a patent on the design in 1993. When the Big Rock is set up according to our easy to follow instructions the Plinth (top plate) upon which the component or speaker rests does not flex or deflect in reaction to speaker's movement. It is held firmly in place so that Doppler shift is minimized. If a person does not follow our set up instructions properly or does not use the leveling tool that we supply with the Big Rock it might be possible for the speaker to not be supported as well as it should be. We always recommend contacting us directly if a person has a set up questions.

We do have laboratory measurements that show the improvemnets to a speaker's performance when used with our products. Those interested may view the measurements here:


I have also posted an extensive discussion of vibration control as it pertains to loudspeakers at this Audiogon thread:


Your comment about air-borne vibration that is affecting the component is well considered. If the air-borne vibration is allowed to affect the signal that is flowing through the component, how can "draining" it after the fact return the signal to its previous, pristine state? The same would hold true for internally-generated vibration.

Best Regards,

I understand a 25lb of shot on top of a gloss black sub is not WAF compatible but it can put placed on the sub when listening only. I thought my 105lb velodyne was well built enought but the top is still less than 1" thick and not brased enough. Bob at suggested this, but he dresses up the bag with a dress black sock slipped over it (make sure not to use a goldtoe sock)

For your turntable isolation post on the analog forum to get the best feedback.
I can't believe the great information and knowledge I've be able to learn from with my original question. This 'forum' thing is truly incredible place to find out answers to things. I say that with all sincerity. I'm even going to dig out some of my big 'deep-drop' leads we use for big groupers and snappers 1000' feet down and just see what effect that has substituting that for Cytocycle's 'bag-o-shot'. Once my turntable is stabilized better I'll compare the hard feet (spike-type) to those 'nodes and see what I come up with... meanwhile tight lines and keep those round things spinnin