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Well, this thread prompted me to try a bit of experimentatio ... Photon46
Yep photon46, exactly why all the shelves my gear rests on i ... Albertporter
I put this point, but nowone responded, so i will ask again. ... David12
David12, i wonder to what degree the golden section ratio re ... Photon46
Yes. snake oil. cheap snake oil (in this case, free), but ... rmaez@
Your moniker seems to indicate that you work for boulder amp ... Albertporter
Wood = okay but ceramic (pumice) foot sanding stone material ... Cdc
Dumb question time for all you resonance control affictionad ... Newbee
The last time i replied to a similar post it never made it p ... Rotarius
Rotarius...could you please elaberate... are you saying sor ... 883dave
Or suffer yourself and plow through the article, it's heavy ... Cdc
Cdc, fwiw my question is probably not relevant as i was mixi ... Newbee
I use hockey pucks and they work just fine. Mitch4t
cryo'd? :) Tvad
Tvad, i purchased a box of the pucks from a supplier in minn ... Mitch4t
883dave, i am going to try and explain what an isolator real ... Rotarius
Sorry, rotarius. i would agree with you except that many of ... Dan_ed
Try herbie's tenderfeet. Nonoise
I just tried the cardas myrtle wood blocks under amp (pass l ... Ozzy
Dan_ed, i never said you would end up liking an isolated com ... Rotarius
Rotarius, fair warning! nasty wars have already been fough ... Newbee
Fair enough, rotarius. i understand your point. best, dan ... Dan_ed
Hello newbee..nice to see you here all these years..the foll ... Theaudiotweak
oh crap! we don't need more po'd folks. our hobby is all ... Rotarius
I own some teak blocks i cut from cheese trays (local goodwi ... Elizabeth
Rotarius... thanks for explaining...makes sense. i use an ... 883dave
Hi tom, i agree with your thought. as the world turns so to ... Newbee
There are so called "magnetic isolation" tables bu ... Herman
Remember newton's first law? the thing is if anything is vi ... Stevecham
Newbee, i agree. i should've been more clear, how about this ... Cdc
Rotarius, your explanation makes sense. however in the case ... Cdc
Cdc - ".....you're trying to get rid of vibrations in t ... Newbee
Cdc, yes the air borne vibrations is another component that ... Rotarius
Why wouldn't those magnetic levitaton devices be the ultimat ... Woodburger
Newbee, by rigidly coupling the CVDP to and appropriate damping shelf and stand the vibrations would never be there to begin with. Quoting the "Bad Vibes" article:
This, then, is the most practical solution for a good supporting platform: Employ specific materials and geometry that increase the platform's stiffness:weight ratio so that the improved rigidity raises the resonant frequency
Hence my "infinitely stiff / infinitely light" pumice material.
2) By rigid coupling you are reducing the number of vibration modes in the entire stero component system. This makes it easier to tune the system tahn if each component is singing at it's own frequency. Soft rubber dampers have the oposite effect.
Again quoting the article:
A rudimentary version of the traditional damped suspension is formed when elastomer materials such as Navcom or Sorbothane are used to support a heavy preamp or amplifier, either directly or with an intervening platform. These elastomer pucks can be quite effective at isolating moderate amplitudes of vibration ranging from the upper bass and above, and will generally have a fairly predictable performance throughout this range of frequencies when used with a wide range of gear. Also, a broad band of vibrations generated within the component is partially damped by these compliant materials. Unfortunately, their damping and isolation ability is not only ineffective at very low-level vibrations of any frequency, but is essentially transparent to all amplitudes of very low frequencies, acting basically like rigid coupling rather than an isolator in response to vibrations lower than the natural resonance of the suspension.
For many systems using rubberlike pucks, the resonant frequency ranges from approximately 10Hz to 20Hz or higher depending on the actual compliant material, how it is shaped, and the load it bears. So even though the peak displacement at resonance will be reduced, vibrations below resonance will either pass right on through or be amplified. In practice, many such suspensions have relatively high resonant points, so this amplification will often extend into the lower audio band. For example, a system formed by typical rubber pads or pucks supporting a moderately heavy steel plate will have a vertical resonance of around 15Hz or so. Its related resonant displacement is fairly well controlled, yet the zone of amplification actually extends from approximately 3Hz up to around 25Hz---above which isolation finally begins. This scenario can contribute to the subjective impression of a "mushy," "soft," or "boomy" bass response, even as the suspension reduces the amount of transmitted vibrations from the midbass on up, and partially damps the component-generated vibrations.
Unfortunately, this limitation of certain elastomer supports is often misconstrued as "over-damping," even when describing its effect with amps and preamps, and has led to the unfortunate condemnation by some of any sort of damping at all. Actually, this negative subjective effect, reported when elastomer supports are used in some systems, stems from the amplification of the suspension's relatively high resonant frequency intruding into the lower audio band (the opposite of damping).
Paradoxically, systems that emphasize the bass can sometimes sound rolled-off in the treble as well, although this is usually a psychoacoustic effect rather than a genuine rolloff. In any event, this example highlights the danger in drawing cause-and-effect conclusions about subjective experiences in audio without trying to tie them back to real physical principles. The positive sonic effects of elastomers are almost entirely due to their damping and isolating qualities; when properly applied, elastomers can result in a significant reduction of vibrations from the upper bass on up.
Incidentally, several equipment supports or footers now on the market combine a degree of rigidity with a measured amount of damping, without being overly compliant. These devices seem particularly well suited for connecting components to a platform already isolated by a suspension. (See my Townshend/Vibraplane review elsewhere in this issue for some examples.)
The ideal stand as I gather would be:
1) completely rigid and operate as a single unit. Bad vibes article "Minimize the relative motion between different elements that comprise a system"
2) resonant frequencies would be pushed as HIGH as possible so vibration's amplitudes are as LOW as possible. Bad Vibes article:
"lowest natural frequency will be the most dominant". Minimum resonant frequency = maximum amplitude".
"Reduction in frequency leads to an increase in dispalcement...resulting in a "noisier" less stable
"The lower the resonant frequency of a platform, the less desirable-the associated increase in amplitude will cause more serious ringing that damping can only partially reduce." So using sorbothane actually INCREASES ringing which damping can only partially reduce.
"Enough damping should be applied" BUT ITS PURPOSE IS TO "further lower the displacement of resonances" not increase it.
As I understand it, sorbothane has
1)high amplitude as in actual dimensional dispalcement
2) soft material with numerous, complex. vibration modes.
So maybe we just disagree on everything.
Cdc (System | Threads | Answers | This Thread)
Rotarius: because isolating will 1) increase the number of ... Cdc
Cdc, 1) even if you rigidly couple all components in your ... Rotarius
Rotarius i agree with the vibes article that: "the goal ... Cdc
Cdc, fwiw, you are probably correct. i doubt that we will ag ... Newbee
Excellent point newbee, i will begin design on a moon shield ... Herman
Hi newbee i'm not going there. i will not put on the facade ... Cdc
cdc, i just wanted to add one more thing, those conclusions ... Rotarius
Another vote for herbie's tenderfeet, which are low cost, an ... Listener57