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  3. 1064803157

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?
unhalfbricking

Showing 5 responses by stehno

stehno
1,453 posts
 
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.

-IMO
stehno
1,453 posts
 
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.

-IMO
stehno
1,453 posts
 
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?

-IMO
stehno
1,453 posts
 
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.

-IMO
stehno
1,453 posts
 
If the isolation and dampening methodology really worked, then why does my chest thump and my car's inside rearview mirror vibrate like crazy at a stoplight when some nut 3 cars behind me has his subwoofer blasting?

Perhaps this is a poor illustration, but I would think that if there were any positive attributes associated with the isolation and dampening methodolgy, then my radial tires filled with air, my leather seats, my closed windows, carpeted interior, and rubber surround for my windshield would do the job. Not to mention the other guy's radial tires filled with air, etc..

-IMO
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