Why Does A Concrete Floor/Spiked Metal Rack...

suck all the warmth and life out of my system?

I have been thoroughly dissatisfied with my hi-fi system for the good part of a year now and I have been unable to until recently to put my finger on the problem. In a nutshell, almost every CD I would play would sound bright and harsh and bass light. The top end and upper midrange would completely overwhelm the bottom end. I have experimented with all sorts of tweaks and in particular various isolation devices, and although I was able to achieve minor changes to the tone the overall top end brightness and lack of bass was still evident.

I was enjoying (as best as I could given the problem!) a listening session and wracking my brain (for the ten millionth time) for ideas on how to make my system work better, when it suddenly dawned on me that I had these small plastic/hard rubber? cups that might be ideal to place under the rack spikes as a last ditch attempt to solve the brightness issue. With the music still playing I carefully tilted the rack enough to slip the cups under each spike on the four corners of the rack, thus de-coupling the rack from the concrete floor. They were a perfect fit and the effect was both immediate and DRAMATIC. The system was for the first time tonally balanced, the bass response increased, the sound stage widened, the noise floor dropped, there was greater depth, increased clarity, and most importantly the brightness and harshness had completely disappeared!

I was firmly of the belief that audio racks should be coupled to the floor for stability and assist with the reduction of floor vibration eminating from the floor. My rack is a rigid design composed of tubular steel and every cavity is filled with sand in order to reduce any possible ringing. The rack is supported by four large adjustable screw in spikes which penetrate the carpet and couple the rack to the concrete floor beneath. The components are supported on MDF shelving. What I discovered this weekend is that this rack/floor interface was completely sucking the life out of the system. Upper midrange and top end frequencies were being accentuated at the expense of the lower mid range and bottom end, thus producing the fatiguing brightness and harshness.

Can anybody explain to me in laymans terms why this occurs?
I'd like to take a stab at your question. But I am not an expert by any means.

Keep in mind that the goal is not only to keep vibrations from the floor from entering the rack, but more importantly the goal is to provide an expedient exit path for all air-borne vibrations that the components and rack have already captured.

When properly done, a concrete floor is said to be an excellent conduit for transfering vibrations away from your rack. I did not think this to be so, but one expert in this area, (who may have more knowledge on this subject than any other) made this statement. Much to my surprise as I assumed a wood sub-flooring system was the preferred foundation.

For others to better assist, you might consider listing all of your equipment and accessories.

As for the rack, you are using MDF shelving which is not a very good material for this applicaton. You also are using vibration dampening sand in your hollow tubes. Perhaps, solid rods would work better?

You also may be using inferior engineered spikes, cones, or points. In addition, you do not mention using any spikes, cones, or points of any kind under each component or speakers.

In other words, you have to properly execute the vibration handling methodology you choose.

I'm not saying you haven't, but as with everything else, there is a right way and wrong way to accomplish this goal.

If, per chance, one has improperly executed this strategy, then one cannot expect miracles where the points makes contact with the concrete.

Although I am skeptical about the need for exceptional vibration isolation/suppression for well-designed audio equipment, I can offer a few thoughts about vibration isolation.

In my business (testing of missile inertial guidance systems) for some tests vibration must be minimized. Our test stations, where the GS is mounted, are set on top of 3000 pound granite slabs, which are resting on pilings that are driven about 60 feet into the ground. These "piers" are isolated from the building.

Over the years we have learned that this type of construction is almost always effective, but occasionally is not. There is no way to tell before you build the pier. You build it, and then you test it. At our facility we have a room with five of these piers in a row. Four of them are fine, but one has so much vibration that sensitive optical measurements can't be done. I'm told that this type of pier can pick up ground vibration from trains passing a mile away.

Accordingly, I surmise that while a concrete slab is usually vibration-free, this cannot be guaranteed.
I agree with both of the above.

It's not just any concrete floor/spiked metal rack. It's your floor and your spiked metal rack. They have an interaction with your component which is not properly engineered. The first thing that I would do is get the sand out of it.In a coupled system, deadening the ringing is not the goal. Letting it vibrate is the goal. If it is truly well coupled and properly designed, the ringing is passing the vibrations to mechanical earth ground. Then try steel or hardwood shelves instead of MDF. And make sure that your CD player is on good audiopoints, so that the rack isn't defeated by the lack of good coupling at the start.

There is one other possibility, which we can't assess if we don't know what your CD player is. That possibility is that the CD player/cables combo may have a naturally overbearing bright sound, and that the rubber de-couplers actually created a condition that allowed colorations to be introduced that sounded more apparent in the bass.

I realize that may sound funny, but we all know that sometimes when an upgrade is made, it reveals shortcomings in some other part of the system. Perhaps the rack is functioning well, and thus revealed some other problems. I can't say for sure that this is the case, but it may be. Maybe now you are hearing what your CD player/cable combo is really doing.

If you want to fill the stand with something, use the Micro Bearing Fill from Sistrum. This is designed to enhance the performance of a tubular rack that is coupled, and not fight against it like sand does.

Those are my initial thoughts on the subject.
I would think it is a resonance problem. Your room with your stand is just messing with the electronics via some high frequency vibration. As you found out, just changing one thing in this chain will stop the problem.
You might experiment with different solutions similar to the one you have used, but may be more elegant.
I personally would try some sorbothane hemispheres in there.
Or even size 8 or 10 rubber bottle stoppers from a place like American Science and Surplus.
In layman terms, the order of execution might not be correct.

In some circumstances, totally isolating the system can cause it to sound sterile. However, I am not sure this is the case since the rack/component interaction hasn't been properly described. Although, you do seem to try to kill vibration with your application of sand and mdf boards. I think this is more relevant than the rack/floor interaction.

Also, generally, in applying draining and deadening techniques to system, one wants to drain vibration from component to something that is "dead". You seem to have this backwards. And, this seem to lessen the effect your rack/floor interaction has on your system's sound.

Lastly, as the rubber cup is under the rack now, vibration is not drained as expediently as when the rack's spikes are directly touching the bare floor. This ought to slow down the velocity of vibration traveling in your rack if there is any significant vibration still moving around. I don't think this is very relevant since you got the sand and mdf applied to your rack.
Thank you for your responses. I think TWL may be on to something with regard to removing the sand from the rack. The only changes I have made to my system in the past twelve months have been to fill the rack with sand and upgrade my amplifier from older model Plinius pre/power separates to a Plinius 8200 MKII integrated. Up until then my system sounded just fine. The interesting thing is that I did not hear my older amp on a filled rack as I had sold it prior to filling the rack, and I have not heard my new amp on an unfilled rack as I had filled the rack prior to bringing the new amp home! I believe it is time to experiment futher. I'll keep you posted.
Here is my two cents worth and probably nobody will agree with me. The MDF is very good for shelving, and the sand fill is also a step in the right direction. You want to eliminate vibration from the rack and your components. The only thing that should be spiked to the floor is your speakers and adding a good solid base, spikes and weight to them is helpful. Vibration kills dynamics and details IMHO.

I have known a local designer in New Jersey who has shown me the light on this subject and proven it to me many many times so if you wnat to email me, I will pass along what I have learned so far.

Happy Listening.
Gawd! As much as I appreciate all the help I'm now completely confused?? It took me the good part of a day to fill the stand as there are four uprights and sixteen cross supports each with only two very small filling holes, one at each end, and each hole needed to be adequately plugged to prevent the sand from leaking out. Now it will not take anywhere near as long to empty, but I do not wish to go through all that rigmarole again if emptying does not provide the desired result. Regardless of whether it is correctly set up or not, my system seems to be working, so maybe I should just leave well alone?
Yes a bird in the hand is worth two in the bush.
Stop now if it is ok!!!
Just think if you mess with it and then it REALLY SUCKS!!!
But if you just HAVE too... good luck!
At the risk of stating the obvious, why not just set your system up on a less rigid/damped rack/table to see if the difference in sound warrants removing the sand ?
Years ago, when a certain Scottish t-table ruled the world, many people were setting them up on simple TV dinner type table stands !! The concept was that a simple rigid stand provided less intrusive detrimental effects than a large mass loaded one.
When in doubt ... try it out !
There are merits in both methods of isolation. Mass loading works in some instances, and lossy decoupling in others. The bottom line is if you like what you're hearing don't fret about it.. just enjoy your system.
You now have stored and impeded the exit of resonant energy when you added the sand to your rack..You have a conflict of mechanics within the rack itself. You say the rack is designed to couple and then you filled it with dampening material. One will work better without the other! The fill material mentioned by TWL was chosen to aid in the retreval of resonant energy, and with coupling, the noise now has a point of exit. I am a total coupler, no dampening allowed in my system..This concept is hard to accept. This concept takes much time and effort to implement. This concept I feel brings me closer to the truth of the music..Tom
I guess I should have pointed out in the beginning that I live in New Zealand. While I would very much like to try out some of the devices suggested they are not available here. I have found NZ sources for Black Diamond Racing Cones and Polycrystal Cones. The BDR Cones I am able to audition before purchase but the PC Cones I would have to source from another city. Any comments on the effectiveness of these devices? The PC Cones are twice the price of the BDR Cones, are they twice as effective?
Changing one thing will not eliminate the problem.Changing one thing will only mask and fail to eliminate the inherent problem. The root cause of the problem still exists. Dampening is another storage medium. Tom
NZ has earthquakes that are of low intensity but more frequent than anywhere else on earth. How near to Rotorua (SP?) are you?
Other end of the country. Rotorua is in the central North Island, I live towards the bottom of the South Island. As for NZ having earthquakes of low intensity, there was a 7.4 quake in the lower South Island a couple of weeks back. Luckily the epicentre was well away from human settlement, but it scared the bejesus out of a lot of people, me included!
O.K. I emptied the sand from my rack as Twl suggested, removed the cups from beneath the spikes and now my system sounds thin, bass light and has a metallic ring to the sound. I should have followed my instincts and left well alone!
Unhalfbricking...As you may have guessed, I spent some time in NZ as a child, and still have the right to reactivate NZ citizenship. You have a great country.

I think that the worst NZ quake some years ago was near you in Dunedin. Seismic activity at a very low level is frequent which is fortunate because it relieves stresses and minimizes occurrence of big damaging quakes. Much earthquake research is done in NZ, which surprises most people because well publicized big ones are so rare.

If you have any of that super fine pumice sand near you, try that as a damping medium in hollow tubular legs of you stand.
Unhalfbricking, sorry I made you go through the trouble of that. I really expected it to help. Perhaps there are some other issues that we're not aware of.
Unhalfbricking, I don't think anybody suggested you continue using the same hollow rods once you emptied the sand. I suggested earlier that you replace the hollowed rods with solid steel rods. Others suggested you substitute the sand with micro-fill from StarSound Technologies. Either should be a vast improvement over the hollow rods.

In addition, I do not believe you gave any indication aside from the mdf and sand-filled tubes as to who made your rack and how it is put together. It's entirely possible that your rack's engineering is all wrong for what you are trying to accomplish.

Not to mention that you still have not indicated whether or not you have points under your components and speakers and if so who makes those as well. One should never assume that all products are created equal, even if they appear simple looking on the surface.

Contrary to what others above have said, properly coupling or grounding your components, rack, and speakers to the flooring system is rather easy. So long as you do it right.

But taking only a half-serious approach to this task or any other for that matter, one should not expect anything more than half-serious results at best.

It really needs to be all or nothing if you desire the improvements others rave about.

I feel Stehno is correct, coupling is very revealing of the whole system. For coupling to work properly it must be carried thru the entire system..No dampening no energy storage. It is like a direct coupled amplfier no capacitive storage no blurr or smear. Hold on though when properly and totally implemented into your system coupling, will reveal all within. Then from there it can be another journey all together different.. Tom
Just an odd thought, but has anyone thought of hermetically sealing hollow tube stand components, and pressurizing them? This is a not-uncommon way of making such a tube more stucturally rigid.
Should we pressurise the tubes with air or nitrogen? I am sure that the choice of gas will affect the sound also! Seriously, pressurising the tubes won't change the rigidity of the structure, but will add to the mass (slightly) due to the added gas.
impep_whatever...Yes, the pressure will stiffen up the tubes by prestressing the steel. I think that high performance racing bicycles have pressurized frames. It permits the use of lighter tubing, and for those bikes every ounce counts.

By the way, use nitrogen. Nitrogen is a byproduct of oxygen production (they distil liquid air) so it is inherently a completely dry gas, and quite inexpensive because you get lots of it when you make liquid oxygen. Co2 would work also. The main thing is don't use air because the oxygen could cause corrosion.
If you were to cyro the support rods and the internal conductors and the Micro Bearing fill and the shelves and the Audiopoints you would be coupled even more closely to the music....Align the molecules. The most direct coupled high speed resonance transfer device this would surely be..Would the addition of sorbothane or rubber make it slower or faster or just totally destroy the whole high speed connection?....Tom

Give it up.
Yah, you tell'em Dave!
So you think I was kidding about the cryo'd materials for a rack. The most efficient means of energy transfer and the preservation of the musical event is what I strive for in all my components.Tom

No, I think you are dead serious. However, I do not live in a perfect world (one in which one mechanical system is always the end all).

There have been numerous threads (another one recently over @ AA) in which for some reason spiking to a solid slab cement floor does not offer decent results with the particular systems. Perhaps something to do with the gear/room as such a vibration drainage system generally works well in these types of configurations. Again, it's not a perfect world.

To think that cryoing the spikes (in these setups) would solve the problem is unsound thinking, IMO.

Think the recent AA tread is about heavy speakers (not a rack), but with that system, as well, soft footers pretty much solved the problems.

Soft footers don't work with any of my current gear, but if they sound better in a another system then that is what it is all about.
Dekay spikes or spiked platforms have always worked for me and my friends who have dis-similar equipement but the same floor material...concrete. Because some may have a poor experience when they add a new device to their system does not mean that they added the wrong device.Could it be this new device or technology is more revealing of the existing system flaws?This has been my personal experience many times in the last few years. Yes we heard the difference but what was the cause and the effect? It is very difficult to identify the root cause. I agree it is not a perfect world or even a perfect hi-fi, we can have neither. All, any of us out there can do, is try to convey our experience as best can be described. Much may be lost in the description or in the reading. The implementation of the experience for one person can hardly be duplicated by another, especially over the net. Thank you..Tom
Face it, most racks such as Target and such that uses hollow tubing and a mixture of materials from metal to wood to plastic is not going to "drain" anything but the life from the music. Those kinds of racks are designed to be filled with sand to minimize unwanted resonance and mechanical vibration. The rubber footing further reduces vibration in this kind of set up.

If you want to drain vibration, first make sure you got the right rack ie. Sistrum then worry about the right spike that further enhances vibration draining. Otherwise, the spike is only good for isolating the rack from the earth.
IMO, Theaudiotweak and Viggen are both right on the money.

Theaudiotweak mentions some of the many variables that come into play which reminds me what one very knowledgeable individual said not too long ago regarding this hobby:

"The best thing one can spend on their system is time."

Ain't that the truth?

Oops, it is more correct to say vibration is "altered" not "minimized" in my thread above. Only resonance is minimized.
Eldartford, a little knowledge is a dangerous thing. I don't know about bicyclists using pressurized tube frames, but I bet you that if they are, they are using helium as the gas and that is what is making the frame lighter, through bouyancy. Again, seriously, one doesn't "pre-stress" tubes with gas pressure. Also, CO2 would not be a good gas to pressurise the tube, since the pressure necesary to have any effect on the structural stiffness of the tube would cause the CO2 to solidify, even at room temperature! BTW, make sure that you completely dry the inside of the tube before introducing the CO2. CO2 and water make a nice corrosive atmosphere. At least it is not an explosive atmosphere.

salut, Bob P.
inpepinnovations@aol.com..You are right about the CO2, (a careless afterthought on my part) but wrong about internal pressurization stiffening up a structure. There are many examples. I picked the bike example because it somewhat resembles the tubes we are talking about. Blimps, Atlas ICBMs, and children's inflatable toys are others that come to mind. Heliocopter rotor blades are pressurized, but this is mostly done so that the pressure can be monitored for evidence of cracks.

Of course pressurisation stiffens structures that are inherently non-rigid, vinyl and other plastics. Metal tubes are much more rigid and pressurising them to make them more rigid would be impractical, i.e. pressure would have to be higher than the capability of the tube to hold.

BTW, that is the only reason that helicopter blades are pressurised, to detect cracks - see how much those suckers flex?

maybe we could pressurise the interiour of vinyl discs to increase their rigidity and affect their resonance also. (tongue firmly in cheek).

Salut, BoP.
Of course it would benefit "proper" frame stiffness to design the frame correctly in first place - w/ sufficient skin thickness and diameter of tube based on specific requirements, plus use of stength members. Many variables invloved...is it possible the best sounding structure is actually no structure?
inpepinnovations@aol.com...Sure, chopper rotor blades flex: that's why cracks are such a concern.

The Atlas ICBM structure is aluminum, not vinyl. It is kept pressurized at all times.

Yes, depending on the wall thickness of the tube, fairly high pressure would be necessary. But the stiffening effect will come into play long before risk of tube explosion.

Actually, I am not a big fan of super rigid TT mounts. I prefer isolation. If you are lucky enough to have a completely non-vibrating floor, I guess that coupling would work just as well. (But who is that lucky?)
Eldartford, that is why I also don't couple to the floor with a rigid stand. I suspend (isolate) the turntable from the ceiling with 4 small gauge wires holding a MDF shelf. No footfall worries nor vibration through the building structure, since the wires do not respond to nor conduct those frequencies.
I make no claims that this set-up is better than stands, coupled or isolated, but it is as good sounding as any other system that I have heard (albeit it has been a long time since I have heard another TT set-up).
BTW, again, the Atlas ICBM structure is pressurised for other reasons than structural rigidity and if I told you that reason, I would have to kill you after! :-)

Salut, Bob P.
inpepinnovations@aol.com...I guess your system is like a rigid rack except that you are coupled to the ceiling instead of the floor. If you are in a one floor building, this will avoid problems with people walking around your listening room. If you lived in an apartment house you would be at the mercy of the folks upstairs. Isolation would be provided if you replaced the wires with bungee cords, but that would introduce many new and interesting problems!

It was always said that Atlas pressurization was for structural reasons. The design is about 50 years old so I can't imagine that there is anything classified about it.
You rocket scientists crack me up! :)

Seriously thought, inpepinnovations with your shelf suspended by cables hanging from the ceiling, how are you able to provide an exit path for the air-borne vibrations captured as well as those generated internally?

Sure no vibrations from the housing structure can intrude (hypothetically), but neither can they escape for those vibrations that WILL be captured.

Stehno...Cables to the ceiling provide a rigid path to structure: it's just that the structure is rafters instead of joists. Either one could be stable or vibrating.

Airborne vibration, which I find to be my only significant problem, is absorbed by the mass of an isolated turntable/base. If the mass is high enough it won't be moved by the vibration. The isolation alternative is more practical IMHO because it does not require a floor (or ceiling) with no vibration.
Furthermore, Stehno, any vibrations in the rafters are attenuated through the wires, much more so than they would be through a more resonating structure such as a support on the floor or on the wall.
Eldartford's remarks concerning airborne vibrations are dead on IMHO.
BTW, vibrations are not conducted anywhere, they are absorbed and turned into heat at rates which vary according to the mass and natural resonance of the structure. Coupling in effect adds to the mass of the object coupled, which aids in the absorption of the vibrations.
Trapped, internally generated electro-mechanical resonance as well as airborne resonance, loss of efficiency and no fast way out. As I see it..Tom
All forms of energy seek the ground state via the fastest route possible. Vibrational energy WILL seek ground, and it CAN be transferred there. Some vibrations CAN be dissipated as heat in certain materials, but that is definitely NOT the only way that vibration can be dealt with.

According to the Zener visco-elastic model, any energy which can not be visco-elastically dissipated, will be reflected or transmitted into the nearest adjoining surface. This threshold is easily reached at the vibration levels we are dealing with in the audio environment, with the materials typically used as "absorbers". Changing mass merely "tunes" the transmitted vibration frequencies. Going to very high mass increases the Coulomb's Friction to point where it will not be moved easily at the amplitudes encountered, and that is the direction that the heavy stone stands aim for. However, it is just as resistant to transmitting the energy away from the equipment, as it is into it - so airborne vibration is not dealt with at the equipment level with that type of stand.

Without question, a properly designed stand which provides a well-engineered vibration evacuation path that conforms to the laws of physics is the best route to take, because it will allow all forms of vibration to seek mechanical earth ground, no matter what the source of the vibration is. The only exception is the movement of the earth which will affect any system that is not an "active" control system.

Also, if your floor has a problem with not being stable, it is not a "fix" to compromise your racking system performance to try to compensate for an unstable floor. Fix the floor. Then let your properly designed racking system do its job.
TWL, that is a fancy way of stating the Law of Entropy. Most of the time the "easiest" way for the energy to be dissipated is through absorption as heat. When the vibrations are being so-called transmitted through a structure that simply means that they are being allowed to set the structure into vibration so that ultimately the "receiver" mass absorbs it. The source of first vibrating member continues to vibrate and the amplitude has not been diminished at all by conducting out the vibration. Mass (either through direct application to the offending structure or rigid coupling to a large mass)is best way to absorb vibrations.
Some of us here have been proponents of this technology for some time now. The end results are tremendous.Nice to hear from another source..Tom
Seismic vibration will easily "outpower" any airborne or component-induced vibration. Not that the latter two are totally unimportant, but (continuous) sesimic vibration in range 0-35 Hz), sufficiently powerful to move an entire building, can move the component (and the rack) effortlessly. In the frequency spectrum that is the most critical to the sound - i.e., resonant freqs (8-12 Hz) of tonearm, cartridge, laser assembly, others - seismic frequencies have far more "power density" - if you will - than the airborne or component-induced contributions. My story/sticking to it.
Geoffkait, I agree that seismic movements will "outpower" any of the typical airborne vibrations in an audio system. However, short of a laboratory type active platform, there is nothing that an audio rack can do about that. No little rubber blocks or grommets are going to absorb and dissipate the energy that is moving your entire building around. They are going to move your rack, no matter what the rack construction is.

The airborne vibrations, however, can be more easily and successfully addressed by the equipment rack.
I totally agree with Geoffkait. If you couple your rack to your house, then vibrations from the house will be transmitted to your rack. Cones and spikes are not one way devices! If you live within 5 miles of rail tracks, interstates, airports, industrial areas, construction sites or any road that carries truck traffic then your house is being excited (vibrated) by low frequency energy. Research by Gran Prix Audio, the makers of high end racks, indicates that this structural transmitted vibrations is several orders of magnitude higher than both energy transmitted through the air from the speaker or a components' interally generated vibration.

For my specific house and system decoupling is the way to go. I'm floating my entire rack with Aurios Pro devices (the rack is on 3.5" of maple which rest upon the Aurios). Other people living in different locations with different housing structures may have other solutions to the coupling/decoupling question. It's not a one size fits all issue.

One of the observations by Gran Prix Audio is that deep bass from loudspeakers is a major source of vibration being fed back into an equipment rack. It makes me wonder if people with systems that don't produce deep bass (say sub 40Hz) at high levels would have less need to decouple their equipment racks?
I think a company such as Sistrum has addressed the directionality of cones/spike. I think it is safe to say most of the mechanical vibration is drained in the direction to the point of the spike.

As for seismic vibrations, that is a physical vibration where its effect on stereo equipment is minimized when attached to solid matter rather than a soft one. Seismic waves will travel right through solid matter. If I remember correctly, seismic waves causes most damage their P and S waves are slowed down and impeded from completing their waves.