2. misc-audio
  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
eldartford
4,262 posts
 
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.
twl
3,251 posts
 
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.
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
theaudiotweak
2,797 posts
 
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
eldartford
4,262 posts
 
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.
More to discover