Racquetball isolation platform perfection

Undertow,
good story & good reminder that (if possible) not having the rack in between the speakers is ideal. Thanx for taking the trouble to provide all the system pix links.
FYI, I did *not* forget that having the rack off to the side would greatly help. In this thread Chashas1 also stated this. For me (& for many others) this is not possible at this time for a multitude of reasons that I will not mention here. I could possibily get around to doing this the next time I'm on a cable shopping spree.

This is not a substitute for good isolation, but trust me it helps just as much as the room acoustics themselves sometimes.

That's right! Your post was slightly OT but much appreciated all the same. I think that not having the rack in the middle, as you stated already, helps a lot with soundstaging. We were talking about isolation here. I'm sure that, since much of the energy is concentrated in the center, as stated by you, moving the rack out of there can be very helpful.

04-24-09: Halcro
Problem is Bombay, that you simply don't understand the physics and acoustics involved in translating 'impact-induced' sound transmission with either Structure-Bourne or Air-Bourne Sound transmission

The problem Halcro is that you cannot seem to comprehend that my knocking test is pre-empting the situation by mechanically exciting the resonances in the rack/shelf/plith/platter. In real-life, this would happen when the walls flex with the music or when there is a foot-fall or the roof shakes due to high wind, etc. Rather than induce the resonances that way, I cut thru the chase & mechanically excited these resonances w/ my knocking test. Yeah, the knocking is a worst-case scenario as the impacts are direct & probably excessive. That's OK as I believe that taking a variable to the extreme is a good way to test the what-if scenario.
It's very simple & I believe does not need any scientific study or equations like you demanded in an earlier post.
Impact-induced sound is exciting resonances just like structure-borne & air-borne sound with the impact-induced sound being a worst-case scenario. why are you having so much difficulty correlating the two w/o the walking stick of scientific equations???

Impact-induced sound is exciting resonances just like structure-borne & air-borne sound with the impact-induced sound being a worst-case scenario. why are you having so much difficulty correlating the two w/o the walking stick of scientific equations???

Bombay, there are only 2 forms of acoustic feedback applicable to audio reproduction.
Air-Bourne sound transmission and Structure-Bourne sound transmission.
Please read the attached link which has diagrams to explain the two.
http://www.avguide.com/forums/sound-transmission
Unless you are inclined to sit listening whilst a friend or relative raps on your shelves and/or turntable, Impact-induced sound transmission is not a consideration in normal audio reproduction.
To validate your testing of Impact-induced sound transmission as it applies to the regular two forms of sound transmission one needs to provide conclusive and repeatable scientific tests which demonstrate a quantifiable link between the three?
To my knowledge, there does not exist any scientific evidence which establishes a direct correlation between Impact-induced sound transmission and the other two?
Without this information, all your assumptions and knuckle rapping are about as useless as your dismissal of the role of science and physics in audio?

Without this information, all your assumptions and knuckle rapping are about as useless as your dismissal of the role of science and physics in audio?
Halcro

I never dismissed science & physics in audio! you have misconstrued my words & minced them to mean whatever you thought. In earlier posts in this thread I was talking about the physics of rotational machines with Chashas1. Did you gloss over those posts?? Obviously I know better than to simply dismiss science & physics in audio. What I said was that I did not believe that there was a need for scientific formulae for this particular test. Read my post(s) again.
Thanx for the link - I'll read it.

Unless you are inclined to sit listening whilst a friend or relative raps on your shelves and/or turntable, Impact-induced sound transmission is not a consideration in normal audio reproduction

I agree with you that it's not considered normal to have a friend knock on your rack while listening. Let me re-iterate (for the nth time) my objective of my test - I want to see if the rack/shelf/plinth resonance is excited will I be able to hear it. I really do not care how the resonance is excited just that once it's excited I want to kill it off. Also, material's resonance is only 1 freq no matter how it is excited - knocking, air-borne, structure-borne. So, I knock on the various components & check if there is an adverse sonic effect of this. If there is, I trace it & work on dissipating the resonance. Once I'm satisfied, then, I can be reasonably sure that if resonances are excited via air-borne or structure borne transmissions (as cited in the link you provided), I will not hear them.
You can do this test by actually inducing air-borne &/or structure-borne sound xmission; it's easier, more expedient & gives the same results (afterall the objective is to try to excite resonances) if one knocks on various materials & sees if they need work damping-wise &/or isolation-wise.

Bombay,
Structure-Bourne and Air-Bourne sound transmissions into materials are vastly different to those transmissions excited by Impact.
Why can't you understand this?
There is no scientific correlation between the three yet you continue to assume and state that the resonances excited by impact are just an 'exaggeration' of the other two.
As Clint Eastwood famously said.....'A man's gotta know his limitations'......and you would do well to stick to subjective comments and leave science to those who have something to contribute?