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Component isolation

Let’s say you’re going to add isolation feet to a component with no moving parts, such as a preamp, phono stage, DAC, amp, tuner, etc. 

Which one is most critical to the extent would get your attention first? 
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geoffkait's avatar
geoffkait
23,365 posts
 

kingbarbuda14 posts03-17-2019 9:40pm**Leaving to ask what would be the incremental benefit of *any* expensive vibration resolution solutions.

>>>>>Generally, the two determining factors for isolation device performance are resonant frequency Fr of the iso device and number of directions of isolation (degrees of freedom). Thus, the spring rate of the spring should be as low as possible for a given weight of the component. Very Stiff Springs 🏋🏻‍♂️ must obviously be used under very heavy amps, speakers and turntables, otherwise the component will topple over due to insufficient lateral support.

As I already pointed out a Fr of 5 Hz will result in transmission of 90% of vibrations with frequency of 10 Hz, whereas if the Fr can be reduced to 2 Hz the percentage of transmission for 10 Hz vibration can be reduced to 50%. The low pass filter characteristics of mass on spring isolators provide very low transmissibility for frequencies greater than 20 Hz. But obviously there’s an incentive for trying to achieve very low Fr. My Nimbus Sub Hertz Platform was the first audiophile iso stand to provide six degree of freedom isolation. By contrast, most audiophile iso stands provide one or two directions of isolation, the vertical direction 🔝 and horizontal plane 🔛.

There are six directions of motion for any object, including three rotational directions around the x,y, z axes, respectively. Forces in rotational directions are usually caused by Earth crust motion that is analogous to shaking out a carpet or a wave 🌊 passing under a boat 🚣‍♀️.Thus, the ideal vibration isolator addresses all 6 directions. But the more directions addressed by an isolator the greater the complexity and cost, generally speaking. A combination of mass-on-spring isolators and roller bearing assemblies can provide isolation in most of the six directions, for example.

There are additional factors involved in effective vibration isolation, such as method of mounting the component on the top plate of the iso stand, method of mounting the iso stand on the floor or rack, and method of reducing “residual vibration” on the top plate of the iso stand. The geometry of the spring or airspring is yet another variable. A bicycle 🚲inner tube, for example, has a very non-ideal geometry. And the airspring used in my Nimbus Sub Hertz Platform had ideal geometry, whereas the air bladders used in some iso devices are not at all ideal geometry-wise.
jburidan
803 posts
 
The room is full of vibrations -- that’s what sound is. So, I’m not a true believer in vibration control, mostly because there’s no such thing IMHO. Tube dampers will make a difference with microphonic tubes. And you want something to stabilize your turntable from external shocks. But other than that, it's a waste of money.
geoffkait's avatar
geoffkait
23,365 posts
 
millercarbon419 posts03-17-2019 7:25pm
geoffkait-
“If I could explain it to the average dude they wouldn’t have given me the Nobel prize.”


Oddly enough, no Nobel Prize winner ever said that.

>>>>Really?

“Hell, if I could explain it to the average person, it wouldn’t have been worth the Nobel prize.”
>>>>>Duh! 😳
michaelgreenaudio's avatar
michaelgreenaudio
1,019 posts
 

Kind of a fun thread for me, cause while posts are going up I am also on my split screen walking people through tuning their components in real time.

mg

bdp24's avatar
bdp24
9,788 posts
 

Doug Sax had the best method of determining the transparency of any given piece of equipment---the bypass test. He would compare a live feed from his studio with the sound of the same signal passing through the device being evaluated. Any difference between the sound of the two was the component adding it’s own sound to the signal---aka distortion. The idea of high fidelity is to minimize that difference. Hi-fi components aren’t musical instruments, they reproduce them. The sound of musical instruments and voices contain timbres and textures; a hi-fi system should have none of it’s own. In fact, the less it has, the better able is it to reproduce that of instruments and voices.

It’s a very old dilemma: Do you want your system to reproduce the sound contained in recordings---whatever that sound may be, or do you want it to create sound you "like", regardless of the sound contained in recordings? J. Gordon Holt, the pioneer of subjective reviewing, argued for the former and against the latter. Harry Pearson’s standard was what he called, as we all know, the absolute sound---the sound of acoustic instruments in a real space, like a concert hall, cathedral, or even recording studio. But that construct relies upon the assumption of recordings containing such sound, waiting only for it to be reproduced. Very few recordings contain pure acoustic sound in a real space (in Pop music, virtually none do), yet Harry and his believers continue(d) to evaluate components based on their ability to create sound like that heard in those real spaces.

That is not so different from Amar Bose designing a loudspeaker that mimicked the 11% direct / 89% reflected sound heard in concert halls. That is imo an inherently flawed concept (recordings made in those spaces contain the direct and reflected sound; to play them back on the Bose 901 doubles the effect. For Bose’s concept to work, recordings would need to be made in an anechoic chamber). So imo is the notion of a hi-fi system itself being approached as a musical instrument, "tuned" to one’s liking. Minimizing the sound added by the system, on the other hand, is a noble pursuit. A hi-fi system (and perhaps I ;-) should not editorialize. The sound of the listening room is itself, of course, part of the system. Perhaps the largest part, along with the recordings. Minimizing the deleterious contributions of the listening room is imo the biggest challenge facing music listeners.

Guitarists who play in more than one tuning often have multiple guitars on stage, one (or more) for each tuning. They don’t play one guitar, retuning it for different songs. I find it hard to believe many here have any desire to re-"tune" their system for each recording they want to listen to. Am I mistaken? Don’t most of us want a system that makes ALL recordings sound as much like what we think music does (or perhaps should)?

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