Racquetball isolation platform perfection

"I'd like somebody to explain why this is not a good test."
"I don't have any evidence at the time of writing this post so you are free to dis-regard my post re. the knuckle rapping test & carry on w/ your life.
I'm afraid that I do not have scientific evidence, etc for every tweak that I do. If I were a man who did every tweak only after I found scientific evidence I would most likely not be in this hobby."

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 and as you say, you don't really care?
Yet you now want us to tell you why your 'rapping' test is irrelevant?
Just go ahead and enjoy yourself....but for heavens sake spare us your attempted pseudo scientific justifications?

Thanks, I am delighted to be forgiven and dismissed all in one paragraph.
I would say, or rather ask, one thing, Bomby, in looking at your system, couldn't most of your problem in needing further isolation be eliminated by removing your source from between your speakers?

p.s. and again, sorry, but you are just plain wrong--a good wall shelf will have less of a sonic signature than the tweeks you have been suggesting. and quit beating on your equipment, you're proving nothing...

Bombaywalla
If you hit yourself in the head with a hammer do you feel it? If I hit your turntable or stand holding your turntable do you think its gonna feel it and your gonna hear it thru the speakers? OF COURSE! However if I hit the wall across the room with the hammer now will your turntable feel it, will it amplify thru the speakers?

This was my point use the source of speakers to induce some kinda airborne or vibration in the room structure, not smacking it with your hand, this is a totally different induced action. I mean of course if you tap on your turntable with a pen you will hear the ticking thru your cartridge and amplify it with the speakers, but are your speakers that are not physcially touching even with heavy bass making the same "Knuckle Rapping" sound thru your system? No because unless you are literally bouncing your woofers into your turntable stand to physcially contact it like you are with your hand your really proving nothing right?

04-24-09: Chashas1
Thanks, I am delighted to be forgiven and dismissed all in one paragraph.

glad you noticed & ack it!

good wall shelf will have less of a sonic signature than the tweeks you have been suggesting

I never denied that. All I said was that a wall-shelf also has a sonic signature. It might be less, it might be more. Read my post again! Man, you REALLY need reading glasses & your comprehension skills are pretty poor - you repeatedly keep miscontruing my words & then apologize in your next post! What a guy.....

quit beating on your equipment, you're proving nothing...

well, that's your opinion. You hold onto that. I don't see any evidence as yet that my test is fallacious. I might not have proved it in scientific terms but that does not mean it's wrong. Not everything in audio has a scientific backing & that does not mean that it's not right or that won't work in audio.

for heavens sake spare us your attempted pseudo scientific justifications

dude, you are in a pseudo-scientific explained hobby! if you didn't know that, now you do! More than half the things that you believe in audio are pseudo-scientific, psycho-acoustic, etc! While my test might have a scientific background but it does not mean that it's wrong or won't give you an idea of isolation. Just because it's not proved does not mean that it's disproved.

I hit your turntable or stand holding your turntable do you think its gonna feel it and your gonna hear it thru the speakers? OF COURSE!

No, Undertow, if the rack & TT is built well then you will NOT! That's the point I'm trying to make.
If you know a friend/dealer/acquaintance try this on some well-built rack like a Mapleshade Samson, Grand Prix Monaco, HRS. The knocking does not get thru to the speakers. Also try this with a well-built TT like a Micro-Seiki, HRX, Rockport, Goldmund. Again, the knocking does not get thru even when you knock on the platter. The top-end racks & TTs are made with far more inert material than the less expensive units but (& this is reason to tweak & DIY upgrade) with some work in the right areas it is possible to (significantly) improve the less expensive units. That's precisely what Timtim was doing & sharing & that's where I was going too.

the source of speakers to induce some kinda airborne or vibration in the room structure....
....but are your speakers that are not physcially touching even with heavy bass making the same "Knuckle Rapping" sound thru your system?

thanks for the clarification. I didn't understand what you were trying to say the 1st time around.
I agree, this is another good test - get the speakers to flex the sheet-rock walls & see if that couples into the rack & gets picked up.
This would again highlight how well (or not) the rack is decoupled to the floor & how well it is damped.
When the walls flex they induce resonances in the rack & these travel to the TT & get picked up.
Another test that I have used is to jump on the floor near my listening chair which a worst-case scenario of foot-falls or running across the room. If you have children this is definitely happening while you are listening. Again, this induces resonances in the rack that get/do not get picked up.
What my knocking test did was simply bypass all these resonance inducing mechanizms & get directly into inducing the resonances in the rack by knocking on it. The idea is to induce the resonance - flex the walls with the speakers & get that to couple into the rack or knock on it. Yeah, the knocking might be an extreme case but it does give you an idea what's happening. Taking variable to the extreme is often (not always) a good way to check out a "what-if" idea.