Equipment isolation and vibration damping.

[Daudio]

what have you found to be the optimal "cup" for your roller bearing method? I am using furniture cups now but they are almost infuriating to work with...

 

Going for 'optimal' whether with commercial products, or having your own cups custom machined is going to involve some serious money, especialy for enough devices to outfit an audiophiles complete system.

 

I have never quite understood how the rough wood cups and imprecise marbles are able to deliver any audible performance at all, but Barry says he has heard it...

 

I looked for a middle route and found one. All my cups are acrylic moldings made for retail display purposes. They are available in an array of sizes, shapes and colors. And they are inexpensive ! I can put together a set of 3 for $10 - $15.

 

I was already a big fan of acrylic for its workability and good looks. In the application to ball and cup vibration control devices, the material is not optimal, but I think it is a good compromise. While the surface of the cast acrylic is nowhere as hard as steel, or some AL alloys, it is very smooth, which I think contributes to the performance of the system (assuming the plastic is not overloaded by too much weight, and goes into deformation).

 

These retail 'dimple blocks' do not have as shallow a cup as would be preferred, but a smaller size of the SS 'ball' (while still usable) can optimize the relationships of the curves to make the best of the situation.

 

I have my entire system, electronics and speakers, outfitted with these DIY Acrylic/Stainless Steel devices, and I clearly heard veils lift when, first the digital stuff and amp, and then the speakers and subs, were floated. No going back

 

I don't know what degree of sonic difference there is between my plastic hybrid devices, and Barry's 'Hip-Joints, and the commercial products. I hope to learn that one day, but for now I feel have achieved almost a 'Regen' level SQ improvement, for less then even that small cost.

 

Color me pleased as punch !

 

 

(P.S. the inspiration for me to do this experimentation came directly from Barry's BLOG and forum postings. Thanks BD)

[Daudio]

The machinist I chose made me sets of three at well under $50 per set. Of course, this was over a decade ago,

 

 

Barry,

 

A decade ago in an craft that is going more to the big CNC shop and less to the 'old lathe guy' kind of thing, I used to see a lot of around the 'Motor city'. Not so much anymore

 

Anyway, how many units did you buy at that > $50 per set price ?

 

 

I would not agree that changing the size of the ball will do anything significant with regard to the curve. (Well, maybe if the ball was so small, it no longer protruded from the top of the "bowl" -- but even then, I say still no significant effect in terms of resonance frequency or damping. That's basically all in the bowl.

 

OK, how's about we put some numbers to them ? What diameter are your bowls (the full negative space, not the block intersection) and bearing balls ?

 

I'll figure out my variations.

 

 

It really is an easy (and for do-it-yourselfer's an economical) way to significantly up a system's performance.

 

So true !

 

Reminds me of barrows signature: "everything matters". Attending to vibration control, contact treatment, cable dressing and routing, AC power, and such, will get the most out of whatever audio hardware one happens to have hanging around

[Daudio]

... Tungsten Carbide and Chrome Steel. I will have to check Grainger or similar if they have them in 3/8", 7/16", or 1/2" diameters. Any other known sources?

 

Mark,

 

I got 3/4", 1/2", and 3/8" SS G25* balls off of Amazon. At the time they were very reasonable. I agree with Barry that the Tungsten Carbide balls are 'a bridge too far'

 

 

* (G25 - concentricity accurate to 25 millionths of an inch) (good enough for me)

[Daudio]

That was "well under $50 per set."

I made enough for everything, including the speakers and subs. If I recall correctly, probably 12 sets.

 

Hi Barry,

 

Ok, so we're talking about less then $500 for a 'system set' (as opposed to a 'device' set of 3). Ten years ago. And access to custom machining services is variable. Unless some enterprising job shop got setup to make, a nice, simple design... (Alex, are you listening ?)

 

I spent about $200 on blocks, balls, and inner tube stuff. Some was experimental, and wasted. But I ended up with about the same quantity.

 

 

Iteration #1 uses a .96" diameter bowl that is a section of a 2" sphere. Bowl 1/8" deep at the center.

Balls are 1/2" chrome steel.

 

All right ! So you have 2.00" dia bowl, and a .500" ball. 4 to 1 curvature ratio.

 

My 'medium' size Ball Block has a 1.300" section of a sphere, and the ball is 3/8" - just enough for a nice low profile device.

 

So the DTA DIY do-hickey, is 1.30" to .375", for a 3.47 to 1 ratio.

 

That doesn't sound like a huge difference, to me And I'll bet that your upcoming 'Iteration 2' will have a larger sphere diameter bowl, right

 

Cheers,

Dave

[Daudio]

didn't you say you are using off-the-shelf acrylic "bowls"?

 

Yes, a place called 'World Plastics of Michigan'. I was very happy to discover that they were located about 5 miles from my house, but turned out they only did large fabrication there, and the factory was in Arizona. And ordering was online only.

It was more like 'wait a month+ for my order to be made', then off-the-shelf

 

 

Sorry if I wasn't clear but that is not correct. As I said, "Iteration #1 uses a .96" diameter bowl that is a section of a 2" sphere."

That's a .96" diameter bowl, not 2". Further, to look at the bowl diameter to ball diameter ratio without looking at the shape of the bowl is, in my opinion, to miss the mark entirely. As I said earlier, from my perspective, it is all in the bowl.

 

I'm not sure we're in sync with our words here.

 

Imagine you have a big steel ball that fits perfectly into the bowl, touching on all sides and on the bottom of the bowl. The size of that 'ball' would be what I call the spherical diameter (or radii). and it would be larger then the circle made by the intersection of the bowls concavity and the top surface of whatever it is carved out of (the block). The diameter of that intersection circle and the depth of the bowl in the block form a chord, and can be used to calculate the spherical diameter, but I forget the formula .

 

It is not so easy to measure the bowls spherical diameter, since there is nothing there to lay a rule on ! My bowls diameter was larger then any of my radius gauges, so I went looking for thin disks (could be washers) till I found one that fit perfectly. It was 1.3" in diameter. One could draw, and cut out, paper circles to do the same thing. I don't think tight tolerances are necessary here

 

So where you are saying 'the shape of the bowl', I think I am saying 'the spherical diameter', and I believe both boil down to the curvature of the bowl, as expressed by a diameter or radius.

 

Does that work for you ?

[Daudio]

If you place a 2" diameter spherical ball into the bowl of one of my Hip Joint roller bearings, it would fit into the bowl touching it on all surfaces.

But I wasn't thinking of spherical diameter when I described the Hip Joints. Well, perhaps this is what came to your mind when I mentioned the shape of the bowl is a section of a 2" sphere. .

 

Barry,

 

How about we call the bowls spherical diameter (size of the imaginary ball that fits into the bowl), the 'bowl curvature diameter', or just 'bowl curvature' ?

 

 

When I refer to the diameter of the bowl, I'm talking only about the top edge of the bowl. The whole Hip Joint is a 2" circle, 1/2" thick.

 

OK, so we refer to the opening of the bowl as "bowl diameter"

 

I'll only use those terms so we should be in sync Bowl curvature is the measurement I'm interested in here, to compare with the ball diameter, as I did eariler:

 

Barry's Hip-Joints = 4.0 to 1 curvature/ball ratio.

DTA DIY Ball Block = 3.5 to 1 curvature/ball ratio.

 

Do you think that 12% difference might have have a significant effect on my devices's resonance or rolloff ?

 

I wish I had a better idea of which characteristics are more important for the bowls and balls: hardness, smoothness, curvature, concentricity, or ? ??

 

 

 

(good night)

[Daudio]

This CAN be a problem for devices you need to push buttons on, this can cause the gear to move a lot if you use a shallow bowl. Think carefully about using remote control for these functions, or using a rotary control rather than push buttons.

 

John,

 

It can be quite a problem with changing cabling !!, Even with optical disks and USB sticks, if used under a PC.

 

My Mac Mini and DAC sit on the same 10" x 16" acrylic plate, which rests on 3 SS balls siting in acrylic cups. When I changed out a pair of stiff interconnects, with some softer ones (not the intent), my gear kept wanting to slide off to the side. It seems that the shelf it all sits on is not quite level ! A chunk of foam is keeping things in place until I get around to leveling the stack.

 

That quasi-frictionless feel is what tells me that I have the rollers setup properly. Not always easy to do under heavy equipment

 

 

As has been mentioned the lowest resistance is the goal, this is achieved with hard round surfaces rolling on hard smooth surfaces, so things like chrome steel etc are pretty good choices.

 

 

While I'd like to have the 'hardest' material for the bowls, as well as balls, the expense rules it out for me at this time. But I'm pretty happy and hopeful for the acrylic bowls, and acrylic in general (I can work it pretty well).

 

While its hardness compared to metal is quite low, what gives me that hope is the 'smoothness' factor. The cast parts I'm using have very, very smooth surfaces. So smooth it looks like water under surface tension. I can even use a torch to 'flame polish' edges of cut sheet, and achieve the same smoothness and gloss.

 

I have a feeling that the smooth surfaces on the bowl, ball, and suspended plate (if not the bottom of some gear) contribute to the functioning of the isolation device.

 

 

I look forward to more comments from you on vibration control for audio. Thanks for chiming in !

[Daudio]

As ringing, is acrylic a good material? I gather we'd need hardest and smoothest, but also something which does not ring too much...

 

I haven't thought too much about ringing in acrylic. I don't see the bowl blocks as really transmitting vibrations.. well.. just between the base and the contact area with the ball. Don't think there any vibrations of consequence bouncing abound inside the square and disc shapped blocks.

 

And, we are talking mostly about low frequency vibrations here.

 

Also, I have heard many good, synergistic, things about acrylic, in conjunction with vinyl, at least. As a matter of fact, I have a Teres turntable that consists of a 3" thick platter, 2 1/2" thick base, and 2" thick arm board: all made of beautiful clear acrylic. Ringing is not a problem in this Very Well Regarded turntable

 

But, it could be an issue, I suppose... Anybody else have thoughts on this ?

 

 

Very encouraging. How large can you make these?

 

I generally use blocks that are either 2" square, or 2" in diameter. The bowl curvature is the same. I bought some larger ones (3" dia), but they had the same curvature in a deeper bowl, which doesn't work out very well in practice. They are very pretty in a piano black finish, through !

 

I use 4 of the square ones for my 95 lb electrostatics (panel, xformers, base). A three way support is just too unstable for a 6' tall speaker, and 4 spread out the load better. Not easy to set up on carpet

[Daudio]

From what I've read so far:

 

Hardness: as hard as possible (if it dents or marks, the motion won't be smooth anymore, and may even introduce vibrations)

 

Smoothness: as smooth as possible

 

Curvature: as shallow as possible: you want the oscillations to be as long as possible.

 

Concentricity: eh?

 

 

Yash,

 

Be careful here, any engineer will tell you that you can NOT optimize all variables in a system

 

 

Concentricity - the accuracy of the surface as compared to a theoretically perfect sphere. Applicable to the ball and the curvature of the bowl, both.

 

With cheap G25 bearing balls readily available, I'm not worrying about that. The Tungsten Carbide balls are definitely harder, but at their cost, your facing the law of diminishing returns. Yes, people say the sound better. If you want to pay the price, be my guest. I choose to be satisfied with G25 Stainless Steel.

 

 

 

Re: Tungsten Carbide

But they're the most durable.

 

Yeah, but what are you going to do with them ? Launch them from a rail gun ??

 

 

(actually I think they may be more brittle the SS)

[Daudio]

The larger the dimension, the shallower it allows the curve to be. I think actual dimensions should vary with the components, to be able to make as large an equilateral triangle as Barry usually puts it.

 

In theory, yes, but I told you that the acrylic blocks I bought do not actually do that. Triangle ??

 

 

I checked one of my amps, and for these, something with a diameter of 4" appears better.

 

How did you arrive at that dimension ?

 

 

I have read a lot of people hearing issues when using 4 contact points: they're hard to set in the exact same plane, and the result is that one contact point always then rattles, affecting the sound negatively.

 

Yeah, maybe, but it doesn't mean much after your favorite speaker falls over and self destructs, leaving you without a good audio system !!!

 

 

I'd put them under my components, but with the less hard ones, if they dent or deform at any time, you'll need to buy new ones.

 

I don't think any of the parts we are talking about will undergo any deformation at all, in the modest service of our audio applications. With the possible exception of a severely overloaded acrylic block. Not to worry

[Daudio]

From MinusK's website (click on it to see the animation):

[ATTACH=CONFIG]19231[/ATTACH]

 

Since the Linn LP-12, and a few other audio encounters, I have disliked any kind of springs in things audio. They all have resonances, but some think thay can tame them. I have my doubts...

[Daudio]

I want the 3 largest blocks I can place so that I can host the largest and gentlest curvature inside them. Actually, I think the dimensions should be even bigger.

 

 

I think you misunderstand the bowl dimensions. You can have a 1" diameter 'bowl' in some material, but the curvature can be just about anything you want. From Hip Joints at a 2" curvature, to my acrylic blocks at 1.3", or make it 4", or 48" if you really want to go shallow. And they all can fit into that 1" circle in that little bowl block. It is just the depth at the center of the bowl that changes - and the curvature, of course.

 

I don't think making a huge 'runway' for the ball is of any value, and just wastes metal and money. The vibration isolation magic is going on in the visibly stationary bearing ball (and it's interfaces). Once these devices are setup, you don't want them wandering about

[Daudio]

The top section is spherically cupped, and the bottom section is a straight edged cup, about a 1/4" deep.

 

I will experiment with just the spherical cupped end on the bottom, with the chrome steel ball on top, and the speaker siting on top of the ball. Only problem there is that the speaker has a slightly textured finish, which is not ideal for isolation based on everything mentioned in this thread. Won't hurt to try.

 

I would keep the original 3 parts together, as the flat section is presumably smooth, where the bottom of your speakers are not, and the edges will keep the ball nicely contained.

 

I don't think it matters much whether the curved cup is on the top, or bottom. You can experiment, of course.

 

Could you post a picture or two of this device, when you get a chance ?

[Daudio]

concave optical mirrors made of glass, they are hard, have highly accurate surfaces and highly polished... I found several places on Amazon that are selling concave glass mirrors in the 35-50mm diameter sizes for $2-$3 each. You can get focal lengths from 50mm to 250mm to try different "steepness" of curves. I haven't tried these yet but I'm planning on getting several and giving them a try.

 

John,

 

Sounds interesting. Care to share some links ?

 

 

On aluminum...

 

Too bad I scrapped all my aluminiun plate and stuff, a couple of years ago.

To reduce the clutter.

Wise decision,

or not ?

 

Oh, just remembered I do have one peice left, infrequently used as a surface plate, even looks good, but long, not square

[Daudio]

Aluminium would therefore be great for the support platform which is between the component and the ball, right?

 

I don't think it is smooth or hard enough for that job.

[Daudio]

How about Teflon-coated steel?

 

How about polished steel, as in those camping mirrors that John S. recommended ?

 

Aluminium doesn't polish well, probably the softness, but anodizing does create a very nice surface on alu, but not quite as good as a polished hard metal, IMHO.

 

There is something about a Teflon coating that just doesn't sit right with me for this application, but I can't put my finger on a rational explanation.

[Daudio]

- good quality aluminum bowls made on Barry measurements,

 

Can you give us an idea of how much your custom bowls cost per set ? And about how many sets you got to get that price ?

 

TIA

[Daudio]

A good page comparing various isolation methods on the Wave Kinetics page, The Truth:

 

And a not-so-good part of that page:

 

"There are many products designed around very hard ball bearing interfaces where the theory is that the single point of contact on the bearing provides an efficient path to allow vibration to flow out of a component or speaker into the supporting structure or floor. If the impedance from the component to footer is mismatched and there is no damping in the system then vibration is reflected back into the component and can cause sonic coloration. If there is an impedance mismatch but there is damping at work, then the vibration energy can be dissipated due to the damping. Hard bearing systems attempt to match the impedances sufficiently to allow vibration to move relatively freely both from the component to the platform and from the platform to the component."

 

It gets worse in the Pro's and Con's...

[Daudio]

Understanding the phenomena, mechanisms and pros and cons of each can help in designing and implementing new ways of isolation for audio.

 

Additionally, I don't think the cup-and-ball + air-cushion is ideal, ...

 

Yes, but, misunderstanding the phenomena is not very helpful

 

 

Yash, you remind me of one of those firework pinwheels, showing sparks in all directions ! I can't keep up with all the different stuff you're coming up with. Wheeeuh !

 

I'm more interested in looking at what is, or can be, available in the here and now, and can be used to the benefit of many audio systems, modest or expensive. So, I'm going to try and focus on that goal and leave the invention of the Absolute Best Isolation Mechanism to others for the time being

 

Not that I've lost interest in which parameters in the ball and cup system seem to be more significant then others !

[Daudio]

The string is about 6 feet long, this gives a very low frequency resonance which is very effective at isolating the speakers from everything else.

 

John,

 

What does it sound like when you pluck one of them ?

 

Both when quiet and music playing ?

 

[Daudio]

Here is a simple and inexpensive implementation.

 

I founds some aluminum discs on ebay, ordered some 50mm concave mirrors...glass (or aluminum if available).

 

 

jabbr,

 

Cool !! Links please

[Daudio]

I found out by experiments that even small amount of glue would damp the sound...

Also, I am avoiding glass. Even thin 2 mm alu plates above balls/bowls are good for me, although I am going to get thicker better quality alu plates and maybe go away from bamboo completely as well.

 

I agree about avoiding glue and other squishy stuff !

 

Why avoid glass ? Possibility of fracture ?

 

I was at a local non-chain, well stocked, hardware store yesterday, and noticed some small Stainless Steel sheets (4" x 8" x .018" thick) (about 10cm x 20cm x .45mm). It was next to the brass and SS tubing, so may be from K&S.

 

I am considering buying some for the equipment underside surface. I just need to find a way to cut the sheets into smaller pieces without warping them. Still looking into SS camping mirrors, to find an inexpensive source.

[Daudio]

Do you think something like this would work for the ball and cup method

 

Surgical Steel Concave Flared Flesh Plug- Buy Jewellery

 

Lee,

 

The largest one there is only 16mm in diameter, or about 5/8", which is pretty small compared to the devices we've been talking about here.

 

The inside curvature looks pretty small and deep, requiring a larger ball to clear the top, making the ball to bowl curvature ratio very low. I don't like the look of the 'bowl' either, it looks too imprecise (low concentricity) for good performance as an isolation device.

 

I do like the double concavity through, reminds me of the underside of the Symposium Series 2 blocks.

 

Sorry, but nice try anyway !!

[Daudio]

I'll see if I can source some chrome steel balls from surplus stores online.

 

 

Try Loose Steel, Ceramic Bearing Balls Online - VXB Bearing online

[Daudio]

the choice of material may depend on preferred type of music. For example, in my system aluminum plates under speakers on a top of bearings/balls give better defined low end punch and smooth mids and works better for rock, reggae, etc. But, hard ceramic plates in the same position gives more air, transparency to more lifelike highs and works better for classic or chamber...

 

Have you thought to try the ceramic plates under the aluminum ?

 

Are the ceramic and alu plates same size as bottom of your speakers, or smaller with multiple plates ?

 

I recently changed from thin steel disks between my speaker bases(wood) and the ball bearings, to 4" square, smoothly glazed, porcelain tiles. I think they sound better, but my system has been through too many uncontrolled changes to say for sure.

 

How are you polishing your alu bowls ?