Subwoofer Isolation, what do you think...

Hi TWL,

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?