zero cost isolation

I won't pretend to understand this in all its complexity but I believe coupling is to couple two things together. Vibrations travel differently in 'high wave speed' materials than they do in 'low wave speed' materials. As such, you also get interactions when the vibrations propagate from one such material to another.

Steel for example has a very high wave speed vs that of MDF, so if you had your MDF speakers well coupled to a good amount of steel (extreme example - a solid steel post set in a concrete floor), the vibrations would be effectively 'sunk' away from the speakers at a high speed through the steel.

On the other hand going from one material to a comparatively low wave speed material such as neoprene foam, there is not a good transfer of energy due to a 'bad' impedance match. This is considered 'isolation' - when vibration transmission is reduced.

You may want to stop vibrations from the floor, going to your turntable, and so you should isolate it from the floor and table upon which it is sitting. On the other hand you might want to couple a large engine to something to sink the vibrations away from it and stop it shaking itself apart.

Hope that explains it.

 

ok, so you are "isolating " equipment to protect from external energies....but "coupling" them to dissipate energies to ground.....?

as dreftar says, a paradox!!

I think i've confused myself again!!

 

No I think you have it. What you could do I suppose is sink the vibration from your turntable to a base of steel and once it is there, convert that energy to something else such as heat or a different direction of motion. Then isolate the whole thing from the external source of vibration.

Someone who really knows their stuff may soon come along and tell me I have got it all wrong but I think thats about how it works!

 

mass will also act as an energy sink and gobble up spare vibration.....ie an engine vibrates but the vibration will not make the earth vibrate with it as the earths mass is very large so it can overcome the inertia.

the way I see it....

spikes or other point couple....

loosey materials decouple

if you have a point thats connected to a lousey material you create a drain [?]

then theres constrained damping which tries to utilize the different layers transmission speed and mass etc to remove /convert vibrational energy into heat or sideways motion.

 

You don't want to isolate a hi-fi component unless it has no vibration (which even a passive item will have)! If you do, there is no path for the vibration to escape along.

The component needs to be coupled to something that the vibration will be 'attracted' to, rather than staying in the hi-fi component.

As has been said, you then need to 'deal with the vibration, although if the fundamental resonancy is below the audible range, and/or it can't get back in to the hi-fi component, then all you need to do is isolate it from the rack, floor etc.

Now please don't ask me how you stop that vibration it getting back into the hi-fi component but I'll give you a clue. Think about an electric circuit and what is required to make those electrons flow around it (or stop them).

If I don't reply to subsequent posts, it is because I am currently only able to bring up the ZG site about once every 2-3 weeks!

 

The magnitude of external vibrations, those caused by loudspeakers, are many times greater than vibration caused by motors and transformers inside hifi kit. Given the nature of piezoelectric effect in some types of electronic component, to turn a mechanical stimulus (vibration) into a proportional voltage, any benefit will come from de-coupling. Coupling will only serve to promote piezoelectric effect.

One solution is to use compliant circuit board stand-offs or constrained layer damping on circuit boards. This addresses both external and internal sources of vibration. Otherwise, footers that de-couple or mass-spring suspensions that lower resonant frequency (typically found on turntables) are best.

 

Pete's idea has merit if still points and ceraballs are to be believed. They use a similar 1 + ballbearings to provide isolation/decoupling.

This is a different layout with a silicone/blutac layer to provide decoupling over and above the hard interface of the stillpoints.

Great idea to combine the 2 of them.

 

Having thought about this a bit Isolating is what you're trying to achieve. Isolation is to seperate one thing or things from the rest of the world.
HOW you do that, I think, is where the term decoupling has arrisen. I can't really see the relevence to isolation, the only thing that decoupling has any relevence to in hi fi (as far as I can see) is in the electronic capacitor/PSU isolation stage, purely in electronic terminology.
So to decouple a speaker is ummm, rubbish. It's a buzz word that has been invented and bastardised by Hi Fi sales people to confuse.

You want to isolate your Turntable from your speakers. You can channel the energy away from your speakers and sink it into the floor. Ideally build wooden pillars (solid metal may be better) with the speakers on spikes have the floor seperated from the pillars by a few mm. This channels the energy into the earth and you can forget about it. Do the same with the electronics so you can leap up and down in front of your turntable until your hearts content.

Of course it's not always practical to do this. So compromise by absorbing the energy with several different materials. Spikes, aluminum cones, sorbothane feet, wood, slate, granite anything that likes certain frequencies.
All IMHO of course.

 

The word decoupling appears in the engineering dictionaries I have to describe means to reduce interaction between two (or more) bodies. Interaction being mechanical or electrical. In the case of decoupling loudspeakers this is to reduce interaction between loudspeakers and electronics through piezoelectric effect and microphony.

The idea that energy will disappear or “sink†in the floor is a fallacy. Energy doesn't disappear anywhere. The best that can be done is to convert energy (in this case vibration) into another form - usually heat. Decoupling loudspeakers using lossy materials that convert or lose vibration to heat is one way to do this.

 

Why not simply isolate all equipment first of all, with blobs of blutak or silicone. (ie to stop the bass from speakers vibrating cd players etc).

Then if your still worried about internally generated vibration (cd transport etc) then tackle that with a second system. Perhaps by placing a vibration absorbing item directly onto the chassis / case of said item (bitumen damping?)

 

I find the correct grade of sorbothane to be very useful for easy and unobtrusive isolation. A great benefit is its lack of resonance compared to conventional rubber type products. Never over compress it though.

I use bitumen/dynamat in my players with good results.
I do, in theory, very much like the idea of zip locked/resealable bags of sand placed strategically and very carefully inside CD players as a way to dissipate vibrational energy as heat. Still, I have never heard a difference with this method but I like the theory behind it!!
A bag of dry play sand also has an uncanny resemblance to an illicit substance so keep it hidden!!!

 

I was trying to think of a way to utislise sand actually. It's small and fine to allow it to easily be affected by tiny vibrations.

 

Interesting ...but has digressed from the original point

On sunday I visited Davidf

we spent a considerable amount of time listening to my lash up design which again did what it said on the tin ie focused the imagining debluring the sound so that more detail could be heard .

Don't ask why as I have no concrete ideas ......

Davidf then used his lathe to produce a set of rather smaller oak cylinders with spherical recess for the ball bearing .....

These were placed in set of three beneath his speaker on the top plate of his stands .....this wrought more improvments in the same vein. With no change in the tonal balance ...just great focusing.

Davidf has kindly offered to make some sets available .at a modest cost of approx £5 per set of three plus postage to those who don't have the material ......

if theres any interest can you pm davidf directly ...... I can't make them as well as he can ...he has all the wood turning gear...

 

Cheers pete.

Yes, anyone interested in trying this idea pm me.

 

promised photo.....

the size of the these feet ....

18mm dia x18mm high with a 6mm steel ball bearing ...

 

How about a smaller wooden cup at the (so the bearing is sanwiched) top to stop your equipment wandering about?
Glad to see your having fun DavidF!

 

yep, interesting idea.......thanks

Indeed I am! .....

 

yep...though it was not something that we noticed ....

the ball bearing is only acting as a point contact rather than a roller unit.

 

Peter kindly left me with some of his prototype bearings last week while dropping off some equipment and although i cant give you any of the technical arguments that some of the posters have i can definatley say that when these are under my cdp those high chords on paul wellers guitar just seem to be so much clearer!!

Your interconnect has improved his vocals to new levels aswell peter

big Thanks

 

Cheers mate
just to say wezzo's cones are a four ball tetrahedron affair using perspex to hold the lower three together ....these are the prototype for a more advanced support.

That cable just seem to do the bizz......

I hope the pre's still singing too