Racquetball isolation platform perfection

The racquetball platform dates back to around 1980, I use to make them using pieces of slate I bought from a company that made pool tables. This works even better than plywood but I have no idea what it would cost today. I recently made one with a large maple cutting board and it worked well. What we always did was to deflate the racquetball by making cuts in it as it was too bouncy otherwise.

Thanks Tim. Sounds good. I will try it.

Stanwal : Thanks for your input. I'm a little leery of using anything heavier for my platform material. Here's why: I have some lead weight bags from a dive shop, and tried weighting down the source sitting on the racquetball platform I made. No amount of weight I tried improved anything, but it did take away dynamics and make the bass more bloated. It may just be that my system found that lucky " perfect spot " exactly as I have it, or it could be that the birch plywood is acting as a constrained layer shelf itself and killing some of the vibrations before they get to the racquetballs. Ginko themselves use a lightweight plexi material.
I will however buy a few more racquetballs and make some small slices in them to see exactly how that works. At that point though, there are no more air bladders, just absorbtive material. I'll report back..

I made something similar under my turntable. Basically my TT sits on a butcher block, then I put 9 squash balls under that, then there's another butcher block floating in a sand box. I didn't route out any cups for them though.

Try the squash balls instead of racquetballs. They flatten down quite a bit more and do not bounce (squash balls are essentially dead). Here's a picture where you can sort of make them out:

http://cgim.audiogon.com/i/vs/i/f/1231696007.jpg

Here's a link to the balls I used:
http://www.amazon.com/Prince-Squash-Single-Double-Yellow/dp/B001H0G1AA/ref=sr_1_43?ie=UTF8&s=sporting-goods&qid=1232559985&sr=1-43

Enjoy,
Bob

Hi Bob,
I considered using different balls, but after doing some research online, I found where a university science and engineering class did a research study on the properties of racquetballs. While this covered literally EVERY property imagineable, it was especially interesting when they studied what happens when a racquetball compresses or bounces. They found, and proved with some sort of seismic looking computer readouts, that the bouncing or compressing is converted almost entirely to heat ..... This is exactly what you want any isolation or coupling system to do ... Convert energy to a non interfering form of energy. This is probably why Gingko has such success with their products. I've tried several different isolation materials ( wood, lead, ect ) and all of them killed my system's dynamics and inner detail.
Just some food for thought.

I was thinking of doing the same thing but was thinking hand balls or squash balls since they are much denser than raquetballs. I was thinking of getting a slap of plexiglass (like gingko uses) and using a hole saw to cut the holes so that the balls would sit stationary. I am glad someone else has tried this and it works. nice

good discussion guys & perfect timing for me! :-) I am in the midst of making a tweak to my TT isolation platform! I've had a sandbox with a "floating" top-plate under TT for the last many yrs but recently felt (after reading some threads on another forum) that I could do even better.
I'm now thinking of isolating the rack shelf from the rack using 3 brass cones. Then, isolating the sandbox from the shelf using another set of 3 brass cones & finally isolating the "floating" top-plate from the sand in the sandbox using large bubbles bubble-wrap.
What do you guys think??

I was also thinking of racquetballs & squashballs - I felt that the racquetballs would be too bouncy hence might not be effective in damping but I'm happy to read from Timtim that they convert all kinetic energy to heat. Timtim, can you please provide the link to that article? thanx!

04-21-09: Emorrisiv
I was thinking of doing the same thing but was thinking hand balls or squash balls since they are much denser than raquetballs.

I *think* that in this case denser would be worse, no? The denser the material, the higher the coupling & the worse the isolation. Racquetballs might be better as they are more full of air - less coupling??

This is fun.

"I *think* that in this case denser would be worse, no? The denser the material, the higher the coupling & the worse the isolation. Racquetballs might be better as they are more full of air - less coupling??"

Could be. I would never claim to be a expert on this subject. Happily it is cheap and easy to experiment with any of these balls, since they all have virtually the same OD and should fit the DIY cloud platform.

Keep the conversation coming.I for one can't learn enough about the couple/Decoupling topic and the hobby in general.

e

Keep the conversation coming.I for one can't learn enough about the couple/Decoupling topic and the hobby in general.

OK! :-)
here goes:-
last night I did an isolation test (the idea was provided by a vinyl-phile from overseas) wherein I switched on my electronics, set the volume to that level I normally listen to, put a LP that I did not care about on the platter & set the stylus onto that LP. NOTE: the TT motor was NOT spinning. I did not want the platter spinning; all I wanted was the system to be 'live' i.e. the stylus to be in "picking up" mode.
Then, I started an extensive knuckle rapping test - rapped on the rack, rapped on the shelf the TT was on, rapped on the plinth, rapped on the motor, rapped on the LP far away from the stylus, rapped on the LP very close to the stylus.
Each time I rapped, I listen to the output from the speakers - could I hear the my knuckles rapping thru the speaker outputs?
Yes, I could when I rapped on the sandbox on which the TT sat, on the plinth & on the LP. :-(
The volume was not loud at all & the freq was on the low side. I did not have a SpecAn or a o'scope but I'm *guessing* that the freq was in the 100-200Hz range.
I got some more isolation work to do......

Bombaywalla,
Can you provide any scientific study or evidence, any physical or acoustic principles or formulae which correlates the 'knuckle rapping test' with the behaviour of 'real-world' acoustical feedback?
I see many audiophiles who place great importance on this dubious 'test' and have seen no evidence of its relevance in scientific terms?

04-22-09: Halcro
Bombaywalla,
Can you provide any scientific study or evidence, any physical or acoustic principles or formulae which correlates the 'knuckle rapping test' with the behaviour of 'real-world' acoustical feedback?

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. Many things that we obsess on in audio have not or cannot (due to our inability to measure the exact parameter) be explained. And, of course, there are many other things in audio that do have a scientific background.
So, if you are the kind of person who wants evidence before even considering a tweak, then, the test I suggested is not for you.
My rational for the test was that knuckle rapping manually & forcibly excited the resonances in the rack, shelf, sandbox, plinth, platter. These resonances could very possibly be excited during the course of vinyl playback, couple to the TT, be picked up by the sensitive cartridge & be heard thru the louspeaker. I do not know how loud the music would have to get or how much vibration would have to couple into the rack for these resonances to be excited but, intuitively, the harder one would have to rap on the rack/shelf/plinth/sandbox the louder the music would have to be for the resonances to be excited & for them to be coupled to the cartridge & heard thru the loudspeakers. Again, intuitively, harder the knuckle rapping in order to hear it thru the loudspeaker, the better the TT isolation. The goal is to get to the point where none of the knuckle rapping is heard thru the loudspeaker & apparently, from talking to a few people, this is possible.
From the viewpoint of available commercial TT products, I can see this in the implementation of the top-of-the-line offerings from brands like Goldmund, Rockport, Basis, VPI, Teres & Continuum.

Knuckle rapping and raquetballs are sooo 80's....
I thought I was reading a back issue of Audio.
Come on, guys, progress a little, will ya?

LOL!!! most of my gear is from either the 70s or 80s so I guess I'm just a retro kind of guy.Some people also call this old age.
I guess I will just sit back in my mid century Danish chair and sip some more single malt while I rap my knuckles on the table.

e

04-23-09: Chashas1
Knuckle rapping and raquetballs are sooo 80's....
I thought I was reading a back issue of Audio.
Come on, guys, progress a little, will ya?

you are like Wall Street that thought since they were in 2008 (modern times, the time of information age, etc, etc) they could we-write the fundamentals of finance. You can see where that has brought us today.
You want "progress" for the sake of progress even if it brings hardly anything new to the matter on hand. IMO, that's not progress; it's B.S.
The turntable design has not changed in multiple decades only the quality of materials have. The same old fundamentals apply to its proper design & functioning & I believe the same old tests apply to testing its isolation.
And, I think that you are simply being an antogonist (with a zero contribution to this thread)!

Well, sorry bomby, but you are clearly wrong in asserting that turntable design hasn't changed. You must be locked in some time warp.
I'm not meaning to be an antogonist, sorry, but rapping a table has nothing to do with how it will sound. Fremer used to do that long ago, and has now wised up.
And as for your balls, if you like what they do, fine. I had a friend in the early 80's using those, and tennis balls.
Good luck.

04-23-09: Chashas1
Well, sorry bomby, but you are clearly wrong in asserting that turntable design hasn't changed. You must be locked in some time warp.

I'm afraid I differ in this from you. I still say the fundamentals that are used to design a TT have not changed. A TT is a rotation machine & all the physics that apply to rotating machines applies to the TT during its design phase. Yes, the materials used in the TT design have changed over time but the fundamentals have not changed. That's what I wrote in my prev post & that's what I'm writing again.
I'm confident that I'm not in a time-warp but I do think that you are under a mistaken impression.

but rapping a table has nothing to do with how it will sound.

I NEVER said that I knuckle rapped my TT to find out how it would sound. You made this up!
Read my original post again!

And as for your balls, if you like what they do, fine. I had a friend in the early 80's using those, and tennis balls.

Man, you really need reading glasses! I'm not the one using balls! Yeah, I thought about using them but ended up never using them. You need to read the whole thread again & figure out who's been writing what before you make allegations.

I'm not meaning to be an antogonist, sorry

OK. thanks for clarifying.

04-23-09: Chashas1
Knuckle rapping and raquetballs are sooo 80's....
I thought I was reading a back issue of Audio.
Come on, guys, progress a little, will ya?

hey Chashas1 maybe you want to tell these words to fine folks at Ginko Audio (who make TT isolation platforms using raquetballs) & to all the users who have bought these isolation platforms & are having remarkable success with them!
http://www.gingkoaudio.com/cloud9.html
http://www.gingkoaudio.com/cloud10.html
http://www.gingkoaudio.com/cloud12.html
http://www.gingkoaudio.com/minicloud.html

(or, maybe you will write back & tell us that these isolation platforms don't work because they are "sooo 80s"??)

Okay, so here is what I want to know… knuckle rapping cannot be very well proven to tell you anything with a turntable isolation. However my suggestion is this, first anything physically "Knocking" on something attached to your cartridge will most likely feedback the sound thru your speakers..

However are your speakers playing in the room doing it self induced via airborne or not? In otherwords here is what the real freaks can do to test this, go and buy a 50 or 100 ft roll of 12 dollar 16 gauge speaker wire from Rat shack or wherever… Take your primary speakers out of the room leaving your whole system in place ready to "Rumble" turntable and all…

With these speakers now out of your room, put a cheap pair of speakers or a boom box in place of those speakers…This has to be on ANOTHER system or Boom box source.

Hook up your primary speakers back to your amps in that room still with your turntable as the source using the long speaker wires across the house.

Now Play the boom box totally on a separate system while your Vinyl rig is on and needle down just not playing an album so that your primary speakers you hooked up now on your main system across the house is not playing a signal… Remember your whole primary system is up and running just as if you were in the room with it playing music, however the music is coming from another system not the same one your evaluating the sound from your turntable on. Go and see in the other room if your primary speakers are actually picking up any noise from the cartridge…during this totally separate system playing.

Can you hear the music coming thru your primary speakers hooked to the turntable that is not playing anything in the other room? Can you hear any "Thuds" or "Knuckle" knocking type sounds? If no then this is just physical forced wives tales about the knuckle rap test… If you hear music however like if your cartridge is a microphone? Well this is probably the real feedback, and best thing is to put a like Isolation box around your turntable like I have using some basic acoustic wall foam in a nice little wall structure to just absorb the reflections. Not sure if you will ever get rid of sound like this just because your turntable base is inert to all vibrations or not, I am sure it will help, but feedback would still obviously go back into the cartridge unless your turntable is in another room from your speakers playing entirely. I am interested in the results if someone tries this!

Also results of before and after "Ginko Cloud" or Solid maple platform would be good, so lets say you do hear all this noise on your primary speakers that the turntable is picking up in the other room, does putting it on the cloud or maple stand eliminate or help it? Oh and still without a record on the player playing I am sure this could be a good test then turning on your motor as well to see what happens further.

04-23-09: Undertow
Okay, so here is what I want to know… knuckle rapping cannot be very well proven to tell you anything with a turntable isolation.

Undertow, why not??

first anything physically "Knocking" on something attached to your cartridge will most likely feedback the sound thru your speakers..

not necessarily. if the TT isolation is good any knocking that excites any resonances should get dissipated (if your rack is damped, etc) or decoupled (if you have brass cones, roller-blocks, squash balls, etc) from the TT thereby disallowing it to get to the TT in the 1st place.
(I think the only place where this would not hold is if you knock on the LP itself when the stylus is in the groove).

However are your speakers playing in the room doing it self induced via airborne or not?

The knocking is not creating any significant air pressure changes to modulate the drivers & the speaker terminals are connected to the amp. The amp is on during this test thus the primary input signal feed to the speakers is an electrical feed from the amp output.
so, how are the speaker drivers modulating via airborne if one is knocking on the rack/shelf/plinth, etc??

Sorry, Bomby, didn't mean to misconstrue your words.
--I believe turntable design has truly changed through the years. Yes, it's still a rotational platter, yet, the ways to make it spin are everchanging.
--To all you table rappers out there, stop it. It proves nothing. Plus, I'd hate to have you damage your cartridge.
--To all Gingko owners or diy-ers of balls, your product and method can be fine, but not always, not for every situation and product. There are many ways to isolate--cones, points, balls, tubes, sandboxes, air, wood cubes, etc. Many will do a great job of isolating, and of giving support. Not all will "sound" great in a given situation. You may isolate the hell out of your item, but what if it does something to the sound as well? something not good?
--My opening glib comment was just that, these things have been going on for years--years! But I would never be a buzzkill for someone who's taking the interest to try and improve their system. We all start somewhere. For a lot of us it was the 80's.
--Apologies to Bomby.
--I know it's fun to experiment, but why not just use a wallmount if you're trying to isolate something? If that can't do it then you are in serious need of a solution.

Hey Chashas1,
thanx for the clarification & apologies.
Looks like agree to disagree on TT fundamentals. That's fine with me as we each are entitled to our own opinions.

To all you table rappers out there, stop it. It proves nothing.

I'd like somebody to explain why this is not a good test. Right now those who oppose it are saying "this is not a good test because we say so". I'd like some explanation better than that. I claim that knocking on the rack/shelf/plinth/sandbox, etc excites resonances & one can hear thru one's speakers how well these resonances have been damped before the cartridge picks them up.

Sure every tweak has its sonic signature & that applies to the wall-shelf as well! Your words seem to imply that the wall-shelf has no sonic signature but that's not true. I think that all the tweakers are fully aware that when they undertake a tweak it might not work out & that their effort might be wasted. Goes w/ the territory.

Many times having a wall-shelf is simply not possible for a myriad of reasons - looks too ugly, studs too far away, spouse will not allow it, not enough space, etc, etc. So, the wall-shelf cannot be a panacea for many. Certainly you do not think that these people are sunk???

Looks like we need to part ways on this isolation idea as you certainly subscribe to some other idea(s). That's fine with me.

"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.

Bombaywalla
Heres a pretty simple story… A friend of mine had a huge big screen, and his rack between the speakers.. Fairly large room, all wood floors, kid that would run around time to time etc… Now I said first the location of all his gear was just bad, not even center totally off center due to the big screen in the middle, and cables all over yada yada… You could hear anything picked up thru his table unless directly placed on the floor coupling it to obviously the ultimate surface in the entire room to dissipate the floor.. Sounded good right on the floor with some cushion footers! However this is not practical nor safe, so realistically a new idea had to come out of it..

First off we had pretty hi end gear, and cables going which it sounded good but not great. So my idea was he had a wall to the right of the whole thing he could move this stuff too, however with obstacles, first cable lengths, and second french doors going to another area in the house.

So long story short I did a quick cheap test.. We moved all the gear to this wall, now easily 12 to 15 foot from any speaker resonance or drivers firing, the room was plenty wide to not even have to overlap the gear over the soundstage or be in front of the path of the speaker at all on that side. Well so now stuff is moved, bought some super cheap Rat shack speaker cables, like 16 and 14 gauge for about 18 bucks 100 foot…

I knew I was not happy running 15 plus foot speaker cables vs. the 4 ft expensive cables we had already been using when the system was in the middle.. But anyway doubled up the rat shack wire to give a little better current carrying from the amp to the speakers. Bottom line, this configuration blew away anything possible having the turntable or system in general between the speakers!! Cheap cables or not made no difference at the incredble results especially now the turntable sound was exhibiting…

Nothing made this table have an issue now, techno, super heavy metal, clean and smooth as water. Its simple, either overbuild to a ridiculous degree of racks and isolation in the middle of your speakers, or take the table across the room or out of it all together!

Put the table and system on the sidewall if possible, the other plus to this is kiling off all that reflection and soundstage your losing with the gear between them. Also I suggest that leaving the amp in the middle of the speakers for short quality cables is good, and taking long interconnects to the preamp on the side of the room, you will have excellent results… Of course ultimately it is better to have XLR balanced connection from your preamp source to the amp or amps between the speakers, but in most cases if your not going to far like 12 or 13 feet it can work fine..

I do not suggest however running super long interconnects to your turntable from the phono amp, this could create some kind loss or very high capacitance. That’s why I suggest moving the entire heart of the system from between the speakers in the first place.

By the way if you note the best systems in general do not have any source gear between the speakers due to several reasons, one of them being thats the spot where the most energy is focused many times in a given room. See several links below for examples, its probably the most overlooked simple tweak of all time! Of course you need the space, thats why conventionally everybody just goes and sticks their gear in the center as its just the way they normally think about a system or see it. links below to the best and brightest. This is not a substitute for good isolation, but trust me it helps just as much as the room acoustics themselves sometimes.

http://forum.audiogon.com/cgi-bin/fr.pl?vaslt&1188907858

http://forum.audiogon.com/cgi-bin/fr.pl?vaslt&1065030431

http://forum.audiogon.com/cgi-bin/fr.pl?vaslt&1140365841

http://forum.audiogon.com/cgi-bin/fr.pl?vaslt&1169058049

http://forum.audiogon.com/cgi-bin/fr.pl?vaslt&1104944182

http://forum.audiogon.com/cgi-bin/fr.pl?vaslt&1170194197

http://forum.audiogon.com/cgi-bin/fr.pl?vaslt&1123210106

http://forum.audiogon.com/cgi-bin/fr.pl?vaslt&1094159192

http://forum.audiogon.com/cgi-bin/fr.pl?vaslt&1090183709

http://forum.audiogon.com/cgi-bin/fr.pl?vaslt&1065609917

http://forum.audiogon.com/cgi-bin/fr.pl?vaslt&1022712214

http://forum.audiogon.com/cgi-bin/fr.pl?vaslt&1036349020

http://forum.audiogon.com/cgi-bin/fr.pl?vaslt&1069279142

     

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?

Structure-Bourne and Air-Bourne sound transmissions into materials are vastly different to those transmissions excited by Impact

WTF cares if they are different mechanizms of sound transmission. The net effect on the gear, rack, TT is the same - resonances in the gear, rack, TT are excited.
Why can't YOU understand that I'm NOT concerned with how the resonances are excited. I'm merely concerned with exciting resonances & dealing with dissipating them.
When I want to differentiate amongst the different mechanizms of sound propagation I'll ask you. Right now I'm concerned with exciting resonances & dealing with them appropriately. Understand???

[quote]There is no scientific correlation between the three[/quote]
you have said this a few times now. Where have you read this? Do you have any evidence of this? Or, is this your conjecture??

and you would do well to stick to subjective comments and leave science to those who have something to contribute

You would do equally well by NOT counting yourself amongst those who have any scientific knowledge to contribute. I read the posts thru the link you provided earlier. The manner in which you have dealt with the subject is total a joke! It's totally risible - it's half-assed, hand-waving & you hide behind

but there are many more issues involved and it is infinitely more complex than my basic description

!

Halcroman, the great science contributor using language the following language in his treatise of structure-borne, air-borne sound transmission:

Also the frequencies that are happily carried by one material may be UNHAPPY in another material

happy frequencies & unhappy frequencies.... soooo scientific, Halcroman!

This is why turntable manufacturers laminate dissimilar materials to form their platters so that various frequencies are prevented from ‘jumping over’.

yes, more scientific verbage - frequencies are jumping over.......just like the cow jumped over the moon!

With this knowledge, it is easy to see that the long-wavelength frequencies in the wall are not HAPPY to travel in the thin metal brackets which are attached to it

more talk about unhappy frequencies....
Boy, by this time in your treatise on the subject, I'm feeling like I'm being taught by an authority on the subject.

the shelf being DENSER than the bracket, will scoff at the minute high-frequencies it sees

Oh boy, the shelf is now getting an attitude! It's scoffing at some unhappy frequency that wants to come into the shelf. Very scientific, Halcroman!

Of course if you really want ULTIMATE decoupling, placing some rubber or neoprene between the bracket and wall is even better

Alright! Now we have come to *the* ULTIMATE solution. This is it, guys, look no further - if you want to decouple to the best ability that mankind knows none other than *the* Halcroman has written it (pretty much like the statement we read sometime back that Al Gore invented the Internet).

However the physics and acoustics are undeniably on the side of mounting the turntable off the wall and NOT on a floor mounted stand

The final line in the treatise on the subject - according to Halcro it is UNDENIABLE at this point that a TT should be mounted on the wall. The crap that you have written in the lines before the final statement is a whole bunch of hand-waving, obvious statements that anyone can find in a textbook covering acoustics such as F. Alton Everest & many others. There is no logical progression thru the obvious statements you have written & you conclude UNDENIABLY that TTs should be wall-mounted. You MUST have terribly flunked logic in the GRE (if you even went to grad school).
Halcro, you are a joke when try to toot your trumpet & try to call yourself a man of science. Just hide your face & crawl back in your shell.

Bomby, you have a great chance to learn here, but you are too busy arguing with everyone, i think you will soon start arguing even with yourself. You've had several good knowledgable people give you advice, and you cannot stop to see it. Stop chasing your tail.
I kept checking the thread because I thought you were so funny, now I leave it because I am sad for you.

Chashas1,
Please don't be sad for me & please don't pity me - I know when I've shut my mind to new knowledge, when I've opened my mind, when I'm upset at somebody & when I'm agreeable with somebody.
I don't like tooting my own horn & I don't like patting myself on the back. I bring this here only because I believe that it's needed now - Look at my 100s of posts since I joined A'gon & see how many times you can find when I actually got into a fight w/ somebody. You'll find that you can count these instances on 1 hand & you'll also see that it wasn't me who started the fight - it was provoked by the other party.
I'll say this about myself - I'm a pretty agreeable chap & DISLIKE VERY MUCH getting into a fight. I've got an open mind & have NO PROBLEM even a newbie teach me. I DO NOT KNOW everything there is to know about audio. I've never claimed it nor will I.
However, both you, Chashas1 & Halcro have come into this thread with great belligerence & with a great air of superiority & with harsh words for me esp. Halcro. His words have been demeaning & condescending. He has always written his posts in an off-hand dismissing manner. And I take serious offence to this method of treating another A'gon member who happens to be in good standing. There are many other ways to make your point without rubbing the other person the wrong way. Neither of you had the humility to do so. Obviously, you got the fight you were looking for.

While I understand that there are sound transmissions via air-borne & structure-borne, I also realize that these transmissions are doing mainly 1 thing when they come in contact with the rack, shelf, TT plint, TT platter, etc & that is excite resonances.
If the objective is to excite resonances - and, this IS my intention - then there is more than 1 way to do so. I'm sure that you will agree with me on this (there is usually more than 1 way to "skin the cat" as the proverb goes). Thus, knocking on the above mentioned components is 1 method to excite these resonances. These resonances are impact-induced, agreed. The resonances in real-life might not be impact-induced, also agree. However, if you cut thru the chase, what is air-borne & structure-borne sound transmissions doing to the audio gear?? It is principally exciting resonances in those materials.
What is impact-induced sound xmission doing? Also exciting the same resonances!
You will agree with me that a material's resonance frequency is only 1 particular frequency whether it is excited air-borne or structure-borne or impact-induced. Thus, the simple, easy method of using impact-induced sound xmission to debug where one is lacking adequate should be just fine to resolve the issue.
Then, in real-life when these resonances are excited in whichever way that Halcro & you deem correct, the listener can be quite sure that the effects will be minimized.
I believe that both Halcro & you have failed to see this. Both of you have been stuck with the notion that since sound transmissions are only 2 types, one simply cannot debug the issue any other way! You KNOW that's simply NOT correct. The other thing is at this point where I am testing isolation, I believe that I am not concerned with HOW sound transmits to the rack, shelf, plint, platter; what I am concerned with is that somehow the resonances are excited. Both Halcro & you have failed to realize this & keep going on & on about air-borne & structure-borne.
I will NOT believe for a minute that the resonance frequency for air-borne & structure-borne sound xmissions is a different frequency from that for impact-induced. I believe that it just cannot be - once a material resonants it resonants at it's 1 resonance frequency. Thus, for the purposes of debugging the isolation issue, it does not matter how the resonant freq got excited; merely that it got excited.

Both you & Halcro have been pretty demeaning in your posts in this thread & have provided zero knowledge & suggestions on how to actually debug the isolation issues. Atleast Undertow had a much better attitude - he suggested an experiment, shared a story about his friend, trolled the A'gon website & provided links to people's systems as examples for us to look at. Both you & Halcro did nothing of this sort, except waltz into this thread with a great deal of arrogance & an air of superiority. Anybody would take offence to that!

Above is my last attempt to explain where I was coming from. It's very likely that it will still not sink in with you. If that's the case, so be it. I know that I tried. Good day to you, Chashas1 & Halcro.

Oh ... my ... lord. Have you ever crapped all over my well intentioned thread with your eggshell egos and childish need to get the last word in.
Regardless, I have now placed the same isolation under my 70lb integrated, and have heard even more good things, regardless of what generation you may think I am stuck in ... LOL

My sincere apologies to you Timtim. I assure you that is was NOT my intention. Way up in this thread, Emorrisiv wrote "keep it coming" in that he wanted to have a dialogue re. isolation, etc & I posted with very good intentions. Since then I'm afraid that we hijacked your thread. I think that the thread is badly scarred but we might be able to limp back to your intentions for this thread (I hope).

Good to read that you've had very good luck w/ your isolation technique w/ your integrated. I believe that the technique you are using is sound & will yield good results.

Well, it's not really a big deal. At least you guys stayed civil for the most part ..LOL
I just hate to have a thread written off as useless, when the original tweak has done so much good in my system.
So let me throw out a few more thoughts: While there is a TON of BS hype in the world of audio tweak advertising, Gingko has labratory results to back up their cloud platforms. They even have shown real time vibration comparison results on HUGE screens at national A/V events. Take a look at their website for real world experiments with empirical data to prove it.
I think we "audiophiles" sometimes keep looking for the next great thing, when in truth it's already been tried, proven to be successful, and passed over in our over zealousness. The platform under my Lexicon is literally night and day, by a huge margin, and with ZERO psychoacoustic mentality muddling things. Yes ... I have done blind listening comparisons with my family and friends, even if they did think it excessive .. LOL

Anybody ever try gel packs?

Timtim, I am glad you like the results you achieved, especially for the dollars invested. Just remember, since you've touted the Gingko results, raquetballs are not Gingko balls. Sometimes we diy-ers get pretty close, sometimes not. If you ever get to hear a comparison in your system let me know.

Racquetballs turn vibrational energy into heat VERY well. Those who know this are listening with a grin :-)

Way to go Timtim. I have not tried the DYI cloud yet, but I am trying to get the materials to do it. I did pickup a set of the Dmotto bearing stands and they work great,and were not expensive at all. I won them here on audiogon.
Meanwhile I am still searching for the plexiglass. I see that it can be ordered online but I would like to find it local shop. Do you have any photos of your design? I would love to see it.

As for all the arguing, it gets very boring to read.You guys lost me quickly.I really couldn't keep the logical order of the discussion from the boring scientific boasting and the even more boring rants and personal attacks.
This hobby like all hobbies creates children from adults and then loses the fun factor.

My apology to Timtim if I was the impetus for starting the whole mess. I have been intrigued by the Cloud and thought that it could be duplicated in a DIY project and was happy to read someone had done it.Keep up the good work.

e

This started off as a very good thread.
I would encourage audiophiles to try these.

I have implemented 5 black racquetballs placed on Vibrapods as the suspension for my custom dual Plinth VPI with Triplanar arm and Zyx cartridge. The balls fit perfectly into the VPI holes that are already cut into most VPI bases.

This is the best isolation system I have ever found, and I have tried quite a few by different manufacturers over the last 30 years.

It has zero vibration\sound coming through the suspension, and great dynamics as well.

If interested, please take a look on my "System" page, or email..

Have fun..

Joe