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11-25-2013 Post does not mapped to Knowledge Tree
N-set
Gdansk, Poland
Posts 617
Joined on 01-07-2006

Post #: 26
Post ID: 20304
Reply to: 20303
Em-bedding
fiogf49gjkf0d
Paul, I've been definitely looking at the DIY CNC "market" for ideas!! Esp. regarding the frame construction.
The problem is that they are happy once all the frame resonances go to 3-5Hz, so they use
a lot of mass loading. Here, my airsprings resonate there, so I want to have the resonances higher up.
Changing sand+shots for perlite and additional bracing +/- gave me that.

The   reason I'm lazy with steel-slate interface is that I do not have acoustic systems and listen
on headphones. So there is no acoustic feedback to tame, only footfalls and building vibrations.
I'll go more into that interface once I have the proper listeting environment and the table is embedded in
acoustic field.

Cheers,
N-set



Cheers,
Jarek
STACORE
11-26-2013 Post does not mapped to Knowledge Tree
N-set
Gdansk, Poland
Posts 617
Joined on 01-07-2006

Post #: 27
Post ID: 20310
Reply to: 20304
TT stand ass-embly
fiogf49gjkf0d
Below are some pics of the final TT stand assembly. Visually it turned out
better than I thought (although width/heighth proportions are ugly due to space constraints).
The pneumatically suspended top is on it's place, with the
120kg slate slab on it. It does respond very nicely to excitations,
like a suspension of a luxurious car. Now I'm making initial tests for
leakages under the load and hope to put the TT soon and then everything
will be clear: have I lost 9 months and $$$$ or does it work?

MastorackTT1.JPG

MastorackTT2.JPG

MastorackTTframe1.JPG




Cheers,
Jarek
STACORE
11-26-2013 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 10,160
Joined on 05-28-2004

Post #: 28
Post ID: 20311
Reply to: 20310
Very nice but it is just a beginning.
fiogf49gjkf0d
Yes, it looks not particularly sexy but it I was made to fit and it is for sure very functional. You shall not worry about attractiveness as when I pile up on this thing TT and whatever else will be located on it then it will have completely different look and fell. My experience suggest that is a few month this thing will be coved with CD boxes in multiple layer, so you will not be seeing the thing. I am not sure you did not made a shelf or two at the bottom of the thing as the empty space looks a bit conspicuous. I presume that you have plans for it. Anyhow, I think shelves under the bottom will make the assembly more solid.

Yes, those pneumatic feet are marvelous. BTW, there are some of them with built in highs adjustment, including the auto-adjustments. I did look at them years back and they were quite expensive around $1000 for a set of 4. You need a small compressor to power this thing, get the smallest you can get but able to do 80-120pci.

The most important question how will it sound. For sure as the DIY project it is wonderful; the direct impact to sound is totally different matter. In some cases those type of tables do not have sonic effect, in some they do. It would be depending from many indigents, including type of your TT, what it will be sitting on, location in the room, type of speakers you use and many other things. I do not think that you will be able to get the direct relation between new TT and sound. I think the new table is a good based that clear some concerns and upon which it is sensible to built up your sound.


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
11-26-2013 Post does not mapped to Knowledge Tree
N-set
Gdansk, Poland
Posts 617
Joined on 01-07-2006

Post #: 29
Post ID: 20314
Reply to: 20311
Inner Cage
fiogf49gjkf0d
Romy, there will be an inner cage for electronics inside the TT stand:

MastrorackInnerCage.JPG

This is a sand+shot filled steel frame topped with the same vulcanic slate as the TT stand.
I tried to put the cage a la RixRax but it did not work
(the picture&explanations are here: http://goodsoundclub.com/Forums/ShowPost.aspx?PageIndex=1&postID=19738#19738)
The plan is to decouple the inner cage from the floor via the leveling bearing feet I posted few posts up.
I wanted to put it also on the air springs but the center of gravity is too high I think.

As for the visuals, it's not that bad as the pics may suggest. Actually the ugly proportions and not-so-high-end
frame execution are quite nicely compensated by the material choices: hypnotizing Italian slate,
beautifully machined spikes, black anodized spring covers and mat powder coated steel.
All the pneumatic cabling is almost invisible. It is not a typical high-end furniture but neither a rough industrial one.
I guess I caught some interesting balance here.

 Romy the Cat wrote:

I think the new table is a good based that clear some concerns and upon which it is sensible to built up your sound.


This has been my goal with the project, you've summed it up really nicely!

Cheers,
N-set





Cheers,
Jarek
STACORE
11-26-2013 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 10,160
Joined on 05-28-2004

Post #: 30
Post ID: 20316
Reply to: 20314
Very nice.
fiogf49gjkf0d
Ah, I see, you have an insert that goes into the belly on the rack and that do not touch the main frame. Very slick and very inelegant.  Juts to ice the cake I would provision 4 hooks atop of the insert that would allow you to hang the insert to the air-suspended platform in case you find it worthy.  Anyhow, all together it looks like you built a good rack.  The insulting part of all of it that if you throw bike’s inner-tubes under a plywood board then it would produces a similar sonic result. It will not be as sexy  and as elegant though…


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
11-26-2013 Post does not mapped to Knowledge Tree
N-set
Gdansk, Poland
Posts 617
Joined on 01-07-2006

Post #: 31
Post ID: 20318
Reply to: 20316
Slick inelegance
fiogf49gjkf0d
 Romy the Cat wrote:
Very slick and very inelegant.


Hahaha, thank you Romy Smile

 Romy the Cat wrote:
Juts to ice the cake I would provision 4 hooks atop of the insert that would allow you to hang the insert to the air-suspended platform in case you find it worthy.


Oh no, it's something I'm quite afraid of after version 1 of my rack I reported earlier. I'd have a big mass pendulum atached to the TT platform.
The springs would have to counter not only the floor/air movement but also the movement of the insert. As this is my 1st design, I feel much safer separating TT platform and the insert which will go on it's own roller bearings.

 Romy the Cat wrote:
The insulting part of all of it that if you throw bike’s inner-tubes under a plywood board then it would produces a similar sonic result. It will not be as sexy  and as elegant though…


Add to that marbles in egg holders and you have a real 6 axis decouplers, lightyears better than any audiopedofile $$$ spikes/cones/stillponts/HRS etc. Thank you Bary Diament for enlightning writings:
http://www.barrydiamentaudio.com/vibration.htm



Cheers,
Jarek
STACORE
11-26-2013 Post does not mapped to Knowledge Tree
Paul S
San Diego, California, USA
Posts 2,658
Joined on 10-12-2006

Post #: 32
Post ID: 20320
Reply to: 20318
Bike's Innertube?
fiogf49gjkf0d
Well, I hate to think N-Set's efforts equate functionally with such a "basic" solution. For a while I had my CD transport sitting on a wood platform that was "decoupled" by several blue rubber handballs that were stopped from rotating and interfaced by plastic sockets I found in the plumbing section of the local big box. At some point I ran a kind of A/B listening comparison and wound up abandoning this "isolation" platform in favor of sitting the platform/transport directly on carpeted floor near the wall. Reflecting, I think the handballs were too tall, with the particular accompanying movement that implies.


Best regards,
Paul S
11-26-2013 Post does not mapped to Knowledge Tree
N-set
Gdansk, Poland
Posts 617
Joined on 01-07-2006

Post #: 33
Post ID: 20321
Reply to: 20318
Ball bearing
fiogf49gjkf0d
 N-set wrote:
Add to that marbles in egg holders and you have a real 6 axis decouplers, lightyears better than any audiopedofile $$$ spikes/cones/stillponts/HRS etc. Thank you Bary Diament for enlightning writings:
http://www.barrydiamentaudio.com/vibration.htm


I'm actually thinking on how to add ball bearings below the air springs to have 6 axis decoupling. Here is my latest and most reasonable idea:

Lozysko12.jpg



Cheers,
Jarek
STACORE
11-27-2013 Post does not mapped to Knowledge Tree
N-set
Gdansk, Poland
Posts 617
Joined on 01-07-2006

Post #: 34
Post ID: 20322
Reply to: 20320
Why people buy Vibraplanes?
fiogf49gjkf0d
 Paul S wrote:
Well, I hate to think N-Set's efforts equate functionally with such a "basic" solution.


In general of course I agree, Romy&Paul! But there are few niuances, although how importnat sound-wise I do not know.
First, Vibraplane & alike (incl. my clone) have damping reservoirs, so a fair comparison would be a tire connected to a
damping reservoir. Second, and this is more in the wishfull thinking cathegory, those horribly expensive industrial springs are supposed
to be engineered specifically for LF vibrations, so my expectation is they *should* work better (lower fres, higher internal damping,
higher durability, etc), but I've never seen any test of a, say, SLM mount vs. a bike tire...Would be fun if someone done it!
 Third, with independent springs I can level the platform, and this is probably the biggest functional
advantage over a bike tire Wink

Cheers,
N-set




Cheers,
Jarek
STACORE
11-30-2013 Post does not mapped to Knowledge Tree
N-set
Gdansk, Poland
Posts 617
Joined on 01-07-2006

Post #: 35
Post ID: 20325
Reply to: 20297
Steel-slate interface
fiogf49gjkf0d
 N-set wrote:
I'm looking for a nice material to interface between the steel frame and the slate top
as a contrained layer--would be a sin to loos such an occasion for constr. lay. damping.
After some research, Sorbothane seems unsuitable as it leaks and looses it's properties under the load.
Rubber some claim "deadens" the sound whatever it means. Any ideas?


I think I've finally intelectually worked out a solution for the steel frame-slate interface. No rubber, leather, sorbothane, raw meat etc
but roller bearings, ideally under each slate slab:
Lozysko15_2.jpg

Bottom rests on the steel frame, top glued to the slate, now I can experiment with whatever between the bearing and the steel/slate. The main decoupling and damping is there.

This came to me after reading a lot of Barry Diament writings: 
http://forums.stevehoffman.tv/threads/attention-barry-diament-and-other-speaker-isolation-gurus.154013/
Apparently the mental mistake I've been making was that I intnded to put the bearings below the air springs, while
Barry advocates the other way around for whatever reason.
For me more logical was rollers first than springs but what do I know about audio vibration controll?
Anyway, the idea is now to put the rack insert on the airsprings too, not on the berings and fuck potential
stability issues---the daughter is quite grown up now, the insert is in the rack's belly,
the visitors who would run full speed into the rack aren't welcome anyway, so with a bit of care it should work ok.
All this vibration cotroll is just a plain pain in the ass...just like ground loops.
Cheers,
N-set



Cheers,
Jarek
STACORE
12-01-2013 Post does not mapped to Knowledge Tree
Jorge
Austin TX
Posts 141
Joined on 10-17-2010

Post #: 36
Post ID: 20326
Reply to: 20325
Roller Bearings color the sound too
fiogf49gjkf0d
I had been using Aurios roller bearings under my Cd transport for a long time, Every time I changed a transport I would immediately put them under, and they always helped: Untill I got the Forsell transport.  When I first brought it into my listening room it was sooo heavy I just put it on a side rack and compared to the transport I had at the time head to head,  needless to say the Forsell aboslutely killed the other transport (CEC TL1)  so I finally took the TL1 out and put in the Forsell with the Aurios on the bottom: It sounded the same as the TL1 !!!
Took them off and the great sound was back!
I tried again the CEC TL1 without the Aurios and it didnt change that much.
Now I have the Aurios on the DAC... It gives it a bit more clarity.... maybe?

I use sand isolation for my rack now.
12-01-2013 Post does not mapped to Knowledge Tree
N-set
Gdansk, Poland
Posts 617
Joined on 01-07-2006

Post #: 37
Post ID: 20327
Reply to: 20326
Aurios
fiogf49gjkf0d
Jorge, do you have any picture of those Aurios? Do they have two caps to hold the ball or one?
If two, did you attach the upper one firmly to the component or simply put it on it, using weight?
How would you describe the negative sound change?

Is Forsell still in business? I'm trying to find their webpage to see if the transport has its own suspension.

As for the sand I'm very-very sceptical about it. I still have it in the vertical
colums of th TT stand and they vibrate like a fucking gelly when knuckled.
Sand solidifies and creates a perfect "bridge" for ULF vibrations. The added mass lowers the resonance but also
lowers the damping at the same time. I'm conteplaiting taking the pain and exchanging
the sand for a foundry perlite ore, which  my welders have put in the horizontal braces. Seems
to work better...at least with a knuckle test.
 



Cheers,
Jarek
STACORE
12-01-2013 Post does not mapped to Knowledge Tree
Jorge
Austin TX
Posts 141
Joined on 10-17-2010

Post #: 38
Post ID: 20328
Reply to: 20327
Aurios bis
fiogf49gjkf0d
I will get some pics for you in the afternoon,  I put another bearing on a hole they have and that is what supperts the equipment on top.

The sound becomes airy and transparent, but looses dynamics and tone.


http://drforsell.com/home.htm


12-01-2013 Post does not mapped to Knowledge Tree
N-set
Gdansk, Poland
Posts 617
Joined on 01-07-2006

Post #: 39
Post ID: 20329
Reply to: 20328
Implementation
fiogf49gjkf0d
Ok, 2 thoughts:

1) Forsell seems to have some air suspension for the CD platter.
I don't know in which axis/axes it works but if in the same as the
rollers (lateral motion+torsion) then there is a potential for a trouble
with a double compliance system.

2) You mentioned the transport is heavy. What is the transport bottom plate the
bearing balls worked against? The balls may have micro-dented the bottom plate
(very easy to imagine e.g. with a powder-coated steel) and the bearing instead
of isolating started coupling.

I plan to experiment with 25-30HRC hardened steel, working surfaces micropolished and
thread coupled to the steel & slate. But this comes after I get used to the TT on a new stand.





Cheers,
Jarek
STACORE
12-01-2013 Post does not mapped to Knowledge Tree
Paul S
San Diego, California, USA
Posts 2,658
Joined on 10-12-2006

Post #: 40
Post ID: 20330
Reply to: 20327
Sand vs. Sand
fiogf49gjkf0d
There are lots of different types of "sand", including various sizes and shapes of the aggregates, not to mention the constituent materials, themselves. I thought that in most cases the idea of in-frame sand is to quench/diffuse "ringing", not ULF. Of course ULF has to be dealt with incrementally, usually by limiting and "tuning" infrastructure travel rather than trying to eliminate it entirely.  In this case, the resonant modes might become more "complex" but still effectively better damped than a given "un-treated" spike or spikes that may result from - for instance -  tightening screws "too tightly" or too strictly limiting travel in any one mode.  Conversely, too much may be lost through simple entropy when damping is over done.

Any "pearlite" I am aware of is pretty damn light! Anyway. it seems like any frame filler should somehow "wick" away and diffuse the usual steel frame "skin" noises, but that same sand (or, whatever...) would be +/- useless for ULF (of course...).

Regarding decoupling the transports, my own Accustic Arts transport already has special built-in "feet" that - apparently - decouple/isolate the machinery well enough on their own; certainly the carefully-located stock unit sounds better than when I "double up" by adding a decoupling platform. My own (self-suspended) Sota TT is similar, but not the same. It sounds its best when mounted on a +/- "ridged" platform, but much closer attention needs to be paid to every aspect of the platform.


Best regards,
Paul S
12-01-2013 Post does not mapped to Knowledge Tree
N-set
Gdansk, Poland
Posts 617
Joined on 01-07-2006

Post #: 41
Post ID: 20331
Reply to: 20330
Sand context
fiogf49gjkf0d
Paul, I can olny speak within my context and with no audio tests, only knuckling.
I use pure silca sand in 3 granulations (2 of them fine unfortunately), mixed with steel shots.

Of course the sand is there to quench the steel ringing. But while achieving this very nicely
(I hear zero ringing, only deep, bell-like "thunk") it adds something: lowers the construction
resonances and makes them less damped (the effect of the added mass). In my case I clearly feel
gelly-like subsonic vibrations, lasting >1s !!! Now everything depends on the context how the support is used.
For electroncs I'd not care much with <5Hz.
But I have the air springs resting on the columns with ~3-5Hz fres. The frame with its own ULF vibrations in that range instead of
providing a solid support for the springs adds them additional very hard work. You see what I mean? I'd prefer to have frame resonances
somewhere higher, 10-15Hz region where the speings start to work efficiently.

Perlite: yes, it's very light. I have it now in the upper table holding the springs. When knuckled at some points
it does have a faint ringing in the 2-3kHz region, barely audible also through the slate (!),
so the perlite is not so effective but I needed some additional kilos to be saved here.
In the horizontal braces I have a third material: perlite ore. This is unexpanded perlite, denser than the expanded one but
lighter than the sand (1.1g/cm3 vs ~1.6g/cm3). It seems to work nicely where it is: the initial knuckle tone is higher but lasts shorter (feels dumber
vs organic with the sand), there is some LF vibration but not so pronouced and I do not feel much of a subsonic one.
I'm thinking of buying a simple guitar piezo and looking at the resonances instead of shooting in the darkness.






Cheers,
Jarek
STACORE
12-02-2013 Post does not mapped to Knowledge Tree
N-set
Gdansk, Poland
Posts 617
Joined on 01-07-2006

Post #: 42
Post ID: 20332
Reply to: 20331
Hmm...
fiogf49gjkf0d
I think I've slowly started to understand the behavior of my rack.
A very approximate calculation shows that in my case I should have the profile fundamentals around 20Hz, so
perhaps what I take as subsonic vibrations are actually 20Hz, poorely damped due to the added sand mass.
 I've ordered a dirt-cheap guitar piezo and try checking that. The wooden floor I have seem to have the resonances
+/- in the region of the frame (hope my piezo experiments will shed some light on that too): stepping hard close to the frame excites it.
I've followed the mass principle with my mastodont frame hoping big mass=small displacement with a given excitation,
but mass lowers the frame frequencies and looks like I've come close to the floor resonances?

Paul, you seem to have some experience in construction engineering. Does it all make sense to you?

Another random fucktor are the spikes: they look fantastic and they fantastically couple floor vibrations to the frame.
I will try 7cm round feet instead of the spikes to see what happens.

Cheers,
N-set






Cheers,
Jarek
STACORE
12-02-2013 Post does not mapped to Knowledge Tree
Paul S
San Diego, California, USA
Posts 2,658
Joined on 10-12-2006

Post #: 43
Post ID: 20333
Reply to: 20332
Floor Resonances
fiogf49gjkf0d
N-set, you may remember that from the beginning I encouraged you to try a wall mount, for all the reasons you have just cited, and this approach seems even more obvious if the walls are concrete/masonry vs. floor joists and sheet subflooring, not to mention open joist bays.  A stethoscope will tell you broadly about noise in the frame, but it will take spectral analysis to narrow it down. A cheap pick-up should work, but you will probably have to figure out and write a curve for it, if it will do <20 Hz in the first place. The idea with spikes is not to couple directly to a wood floor system but to couple directly to an effective interface between the rack and the wooden floor system; that's why I suggested you try felt. Various band pass "breaks" like bladders, etc. should help with 20 Hz, but (of course) they may result in other mostly ULF motion(s). Naturally you are only ultimately concerned with output from the device or devices that sit on the rack. I can tell you that long-span floor joists often have very persistent vibration, both primary and modal, so good luck coupling to a wooden floor system. It is generally better near the walls as far as primary resonance, but all bets are off for cavity and modal resonances.

Best regards,
Paul S
12-02-2013 Post does not mapped to Knowledge Tree
rowuk


Germany
Posts 454
Joined on 07-05-2012

Post #: 44
Post ID: 20334
Reply to: 20332
The best pickup - is a pickup
fiogf49gjkf0d
Hi N,
I just use my turntable, arm and cartridge to measure the effects of vibrations. Don't turn the platter on, drop the cartridge into a groove and your phono corrector output will tell you everything that you need to know - as it would happen during playback. You can even locate the position of least destructive resonance by moving the turntable around until you are happy.

Just plug the phono corrector into a PC and you will have a very effective source for spectral analysis.

I am very suspicious of digital sources that are microphonic. There is simply no need for a DAC to be sensitive to airborne vibrations. I would suspect that cables would have to be hundreds of times more "sensitive" and no one uses lead shot or sand there............... 

Although, I might just try.......


Whenever I feel blue, I start breathing again.
12-02-2013 Post does not mapped to Knowledge Tree
N-set
Gdansk, Poland
Posts 617
Joined on 01-07-2006

Post #: 45
Post ID: 20335
Reply to: 20334
Spike pickup
fiogf49gjkf0d
Paul, I hear you clearly re wall mount. Well...I have chosen the hard way an occasion to have one, +/- universal solution I could "copy&paste"
if I change location.  Go through that hell and have it done once and forever.
I even ask my daughter to put this mastodont on my grave when I die. Not so much as a symbol of my biggest
achievement but rather something that shortened my life Smile

I'm not sure I was clear with the spikes. I see them on 100% of all "high-end" racks  (but never-ever on e.g. optical tables, where nano-vibrations can ruin everything) and I've "smartly" decided to follow the crowd,
semi-backed up by the fact that they are also used as a simple antivibration mounts in industry. What escaped me is that
I've approched the subject from the ass: in the case of vibrating machinery, what is on the mounts is vibrating and we want
to decouple that from the floor. And there the spikes can work as they provide some angular and torsional freedome of motion
Here of course is to the opposite: floor is vibrating and we want to decouple the rack form the floor.
By achievieng super high pressure the spikes are tightly coupled to the floor and I believe happily transmitt everything.
A nonsense "solution" in other words. That's why I'd like to try a wide feet with a big area, low pressure contact to see how they behave,
if there is any difference at all. The felt idea sounds ok, but felt gets compressed and has to be exchanged from time to time
and I dont want to do that with a 300-400kg mastodont.

As for the bladders that break the vibration path, let me repeat: I don't want the support rack to add them additional work by its
own resonances, magnifying the floor modes. I start to believe that a better strategy than mine would have been a lightweight, rigid frame, topped with baldders and a high mass, not a high mass frame. Well, I can always get rid of all the profile filling and will end up probably with a pretty rigid
frame, given the sizes of my profiles.

Rowuk, of course I do what you describe!! This is how I learn e.g. the vibrational spectrum of my neighbour's waching machine. But I wanted
a cheap solution to check every frame member. For 10Eu I don't expect much, but hope it to have some output below 20Hz. I don't need
the exact amplitudes of the modes, only a very rough guide: the lowest present modes must be the fundamental and should be attacked first.

Cheers,
N-set








Cheers,
Jarek
STACORE
12-02-2013 Post does not mapped to Knowledge Tree
Paul S
San Diego, California, USA
Posts 2,658
Joined on 10-12-2006

Post #: 46
Post ID: 20336
Reply to: 20335
Re: curve
fiogf49gjkf0d

The primary mode may not be the lowest present mode, but it will only be apparent if the pick-up's own curve is known over the desired frequency band.

As for spikes, I see no reason to use them on a suspended wood floor, but in any case the idea is to get the frame itself down to "one mode" if you can, and then deal with that one mode by going back and forth between targeting the dominant mode directly and spreading it out, backed up by listening, of course.  If felt on broader contacting feet works to reduce the transmission of floor-generated/borne noises, then...  Yes, the cartridge-on-an-LP method is very effective at amplifying noise that affects the stylus under those "static" conditions.

Again, you might gain something by fastening the rack to adjacent walls and adjusting the tension and/or damping of those connections. In any case, you'll want to prevent swaying of a TT support, and likely a CD transport, as well, and it might even damp some noises that enter the frame from the floor, just like standing there and poking it with your finger.


Best regards,
Paul S

12-03-2013 Post does not mapped to Knowledge Tree
Jorge
Austin TX
Posts 141
Joined on 10-17-2010

Post #: 47
Post ID: 20337
Reply to: 20336
Sand
fiogf49gjkf0d

For some reason I cannot post pics, they wont upload to the server so I cant select them.

The way Aurios work is with 3 ball bearings rolling inside a round chanel, something like an inverted doughnut...top and bottom.
On the center they have a bolt that allows for some movement but wont let the whole contraption get dismanteled, in case, lets say, of a big hit on the side.  Each ball bearing is held in place by a thin plastic circle that hold the bearings in a triangle shape.

The main thing is they work very nice and slide sideways with a lot of ease.
There is no way they will damage the bottom plate of any piece of equipment, imho.
They couple to the shelf, with a big area and some felt, and to the equipment on top with a ball bearing: I have used a small brass cone here and heard no change.


I dont use the sand inside the posts that make up my rack,  I could, but I see no need just yet.I used pretty thick material.

Each shelf of the rack is supported by something like a sand box, with a lot of area and about one inch deep of sand, 
each shelve has its own sand box: this gets rid of a lot of vibrations.  Let say Each shelf couples to the rack via sand.
The easiest and fastest way for me to do it, was to use Plywood shelves,  I know, not my first choice.
The idea was to use them temporarily untill I ordered some Marble or Granite shelves cut to size.
I havent got around to ordering the heavy shelves...

For my TT I use a 2 inch slab of Maple, I detach it from the shelf with Sorbothane, and form the TT plinth with Brass cones.
It works pretty good and it is still sensitive to added weight on top.   If I jumpt right next to the rack I will hear a thump if the record is playing.
My listening room is made of brick and mortar with concrete floors.

12-03-2013 Post does not mapped to Knowledge Tree
N-set
Gdansk, Poland
Posts 617
Joined on 01-07-2006

Post #: 48
Post ID: 20338
Reply to: 20337
Stoned beaings
fiogf49gjkf0d
 Jorge wrote:

For some reason I cannot post pics, they wont upload to the server so I cant select them.

The way Aurios work is with 3 ball bearings rolling inside a round chanel, something like an inverted doughnut...top and bottom.
On the center they have a bolt that allows for some movement but wont let the whole contraption get dismanteled, in case, lets say, of a big hit on the side.  Each ball bearing is held in place by a thin plastic circle that hold the bearings in a triangle shape.

The main thing is they work very nice and slide sideways with a lot of ease.
There is no way they will damage the bottom plate of any piece of equipment, imho.
They couple to the shelf, with a big area and some felt, and to the equipment on top with a ball bearing: I have used a small brass cone here and heard no change.


Hard to imagine without a picture. What does the ball touch at the top? Directly the equipment or another puck? This felt below the lower puck doesn't sound right to me: one wants here very hardcoupling to the shelf to set the ball in motion with a slightest micromovement.

 Jorge wrote:

I dont use the sand inside the posts that make up my rack,  I could, but I see no need just yet.I used pretty thick material.

If you ever feel need, be carefull!

 Jorge wrote:

...
The idea was to use them temporarily untill I ordered some Marble or Granite shelves cut to size.
I havent got around to ordering the heavy shelves...


I'd avoid granite. It rings.

http://www.newport.com/Granite-Optical-Structures/139776/1033/info.aspx

Marble...maybe but a selected one. If you go through all the stone pains why don't you rescue some

vulcanic slate from n old biliard/snooker table like I did? There is  reason English snooker players moved from once traditional

marble tables to vulcanic slate (Itlian slate) ones. Better damping. And the color!! My pics don't do the justice to the stone,

it's just hypnotically beautifull, with absolutely no graveyard pretensions! Some people even think it's plastic, until they touch it.

 Jorge wrote:

For my TT I use a 2 inch slab of Maple, I detach it from the shelf with Sorbothane, and form the TT plinth with Brass cones.
It works pretty good and it is still sensitive to added weight on top.   If I jumpt right next to the rack I will hear a thump if the record is playing.
My listening room is made of brick and mortar with concrete floors.

How is sorbothane working under compression? Does it leak? Would you please share some technicalities:
which duro sorbothane, which thickness, how big mass it supports and through what area?

Cheers,
N-set




Cheers,
Jarek
STACORE
12-03-2013 Post does not mapped to Knowledge Tree
N-set
Gdansk, Poland
Posts 617
Joined on 01-07-2006

Post #: 49
Post ID: 20339
Reply to: 20336
Ad hoc fixes
fiogf49gjkf0d
 Paul S wrote:

Again, you might gain something by fastening the rack to adjacent walls and adjusting the tension and/or damping of those connections. In any case, you'll want to prevent swaying of a TT support, and likely a CD transport, as well, and it might even damp some noises that enter the frame from the floor, just like standing there and poking it with your finger.



Paul, instead of ad hoc fixes, I'd prefer to understand what's going on and find a real solution.

What I have now are low lying but long lasting frame vibrations, caused most probably by the added
mass to the profiles, esp. te sand+shot in the vertical columns. Quite counterintuitive, the sand-filled profile vibrations feel
also like higher amplitude than those filled with lighter stuff,
which should not be the case as higher mass should displace less given the same excitation.
What feels right ot me by knuckling is a middle path between light mass (perlite) and high mass (sand+shot),
achieved in the horizontal members by the perlite ore. I'm mentally preparing myself for exchanging
the sand for the perlite ore in the colums to see what happens.

Cheers,
N-set



Cheers,
Jarek
STACORE
12-04-2013 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 10,160
Joined on 05-28-2004

Post #: 50
Post ID: 20340
Reply to: 20338
Granite
fiogf49gjkf0d
 N-set wrote:
I'd avoid granite. It rings.
Granite rings?  I am not a huge fan of granite but ringing us not the character that I would attribute to granite. N-set would you care to elaborate on it and tell how did you come to the ringing observations?


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
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