Equipment isolation and vibration damping.

[YashN]

Rubber bands tend to have too high a spring constant, thus too high a resonant frequency. But there probably exist some elastic materials that would work well, it would take some experiments to find a good solution.

 

The Slinkys tend to have a good spring constant for lightweight items as is.

 

John S.

 

While reading about Tube Amp and Pre-Amp construction, and learned about a technique to isolate components called 'trampolining': the component is on a surface which is itself suspended all around its periphery just like a trampoline is like this:

[YashN]

Hi gent's I haven't read all posts but have you seen these. Maybe enough room for a ball bearing... Magnetic spring type device

 

1 PCS D48*H40 Sound Isolation amplifier CD Spikes Maglev feet HIFI audio Stand mat

 

1 PCS D48*H40 Sound Isolation amplifier CD Spikes Maglev feet HIFI audio Stand mat-in Amplifier from Consumer Electronics on Aliexpress.com | Alibaba Group

 

These look great for the price. I wonder how the mechanism is around the sides where one half slides within the other though.

[YashN]

Water might not pass seismic waves, but as we all learned back in our early swimming pool days, it transmits audible-range acoustic vibrations really well. Also, I personally have a talent for disasters with inanimate objects, so H2O in the vicinity of expensive electronics is probably a no-no for me.

 

Only one type of seismic wave is blocked by water, not both, so you need to combine this solution with a second one which deals with the other type of vibration, so the couple of isolation layers become very effective for seismic isolation. Besides, the vessel does not need to be completely filled with water, and if that's the case, you technically have 3 layers of medium transition in just the vessel containing water + air for instance. Now, what the effects are of varying these different parameters (, full or if not how full) needs to be experimented with.

 

Now, audible-range or other airborne acoustic vibrations are something else which also need to be addressed too but require other solutions nearer to the gear itself or else inside it too. One of the feet I referenced earlier in the threads and which contains several balls inside a flexible pouch address part of this issue.

[YashN]

Sam: Thank you for the extremely detailed and well explained posts. The one part you didn't address, but that Barry frequently mentions, is isolating your speakers and other components from environmental oscillations and vibrations. In fact, I think Barry suggests that it is these, rather than vibrations produced by the equipment itself, that need to be controlled. If that is true, then presumably those environmental vibrations must be large enough to move the whole house, floor, cabinet, etc. no matter how massive or heavy it is. His roller bearing approach would seem to provide effective isolation at least in the horizontal direction to such vibrations and I suppose the frequency of those vibrations would determine the extent to which inner tubes solve that problem in the vertical direction. Do you have a view on the degree to which the problem that really needs to be solved is equipment based versus environment based?

 

Both need to be addressed, and in addition, any other type of vibration like air-borne ones (even that produced by the music itself) or inside the component itself.

 

It is Townshend and not Diament who showed correlations between seismic vibration and SQ with charts in his presentation.

 

Additionally, the roller bearing approach wasn't discovered by Diament either, and neither was the air cushion: he learned these from two other people who he mentioned previously by name.

 

Diament doesn't believe that mass loading is effective but he is wrong.

 

The thing is what Towshend shows as incidence on SQ may be even more fundamental (more important), but this doesn't mean you can't mass load your speakers (as I do with stands for our bookshelf speakers) and then combine it with a ball-and-cup + air cushion arrangement (I currently only have ball-and-cup for the speakers and for a few components).

 

The frequency of vibrations in the horizontal plane has no bearing (ah ah) on the vibrations in the other planes.

[YashN]

What's better than spikes? Those bearings like Stillpoints, Aurios, etc., which move in the horizontal plane, on concave metal races with very gentle slopes, are a great advantage for high-end speakers. Instead of spikes that push the cabinets back in the direction they were pushed by the woofer cone, they simply glide a tiny bit on the bearing.

 

On the contrary, the principle of operation is such that the cabinet is supposed to move very little if at all: that's why the isolation works in the horizontal plane.

[YashN]

Barry doesn't claim to be a pioneer in vertical damping, but he did bother to explain his trials in CA on more than one occasion.

 

Not just on CA, he's been posting the same info on several forums over the years.

[YashN]

As for cabinet construction, my speakers combine a rigid front baffle and corner bracing with lossy panels which are allowed to vibrate in a controlled manner through the use of damping that absorbs these vibrations.

According to the literature available at the BBC website this allows for quick energy dissipation although when fed with a constant signal those panels do produce a reasonable amount of sound as can be seen in Sphile's measurements.

What happens to this energy when the cabinet is rigid?

Does the cabinet also ring?

Is the energy sent back to where it came from, the driver?

 

You definitely have the cabinet vibrating and the driver also does back motion.

 

I was researching open-baffle speaker construction and it was quite enlightening. A simple open-baffle has a rudimentary construction compared to a boxed speaker when it comes to all the patching that is necessary once you are considering a box.

 

You can see that from design pictures of course but a couple of things emphasized this difference: first you can check some videos of Lawrence Dickie and what design principles he used in the excellent Vivid Giya (a cabinet/boxed implementation). Second, one of the relative weaknesses of Open-Baffles are weaker bass, so there are various implementations including variations of frames to help with this.

 

Now, it so happens that for some of these solutions, the frame starts looking like an 'H' or 'N', etc... One builder was testing these designs and measuring them and he found that he had to start adding additional bracing in the frame.

 

Once he did this, he measured again, and found that he had to start adding additional stuffing/absorbing material to correct some issues.

 

All this to show that this implementation described starts veering into the area between open-baffles and boxed implementations (the latter of which an Open-Baffle designer wants to avoid), accompanied with all the 'patching'.

 

The boxed implementation complicates a lot of matters: you need a labyrinthine design in the box, stuffing material, bracing, and even then, there are still cabinet vibrations which colour the sound, not to mention the crossovers are usually also inside and subject to internal vibrations as well. On top of that, you also have to work on using diffusers and/or acoustic panels behind the speakers.

 

Open-Baffles have little of these 'patches' and 'complications'.

[YashN]

I still think Magico is king when it comes to over-the-top cabinet bracing...

 

Such convoluted designs...

[YashN]

I have Wilson's here. They weigh 100s of pounds each and are spiked to the floor. They about as close as you are going to get to the concrete speakers cabinets described above. Without a doubt they don't resonate a bit.

 

The spiking will transmit seismic vibrations to the speakers though.

[YashN]

In audio, the isolation of components is the almost unexplored frontier. As baffling as it might seem to the uninitiated, the more capable the system becomes the more influential that isolation, correct coupling and grounding becomes. That is why in my previously explained efforts with my turntable support, I have incorporated all three elements in one complex mechanism. They all have a place and a contribution to make towards the betterment of the result.

I agree, the more revealing your system, the more the subject becomes important and noticeable. However, our case of audiophilis (not a typo) is even worse than that:

 

Every time you successfully work on a weak link, the system becomes more revealing to the changes that you could subsequently perform on the new weakest link.

 

...

[YashN]

So living a few hundred yards from the San Andreas fault line, I'm pretty sure my listening pleasure will be adversely affected when "the big" one strikes; but, exactly what seismic frequences and of what magnitide are we actually trying to protect speakers and equipment from on an everyday basis?

 

Easy to try yourself, but for more info, look for Townshend's presentations and pdf where seismic isolation is mentioned.

[YashN]

Yes Euler springs are one of the few good techniques for dealing with the DC bias of the weight of objects, and a real pain to match to the load!

 

I've been thinking about building a spring/pendulum isolated DAC with the DAC board isolated inside the case, using carefully design power and signal wires so as not to mess up the isolation. That way the user gets to use whatever they want connected to the case.

 

Been thinking since last year of a suspended / ball-bearing'ed platform for my AC filter internals...

 

I would need a way to latch the platform in place when connecting and disconnecting the AC plugs, and then toggle the latch off to make the isolation effective again.

 

So far I thought of the ball-and-cup, together with rubber bands at each corners, or else I'll have to build the platform suspended from the ball-bearings from above as in my Speaker design...

[YashN]

Been thinking since last year of a suspended / ball-bearing'ed platform for my AC filter internals...

 

I would need a way to latch the platform in place when connecting and disconnecting the AC plugs, and then toggle the latch off to make the isolation effective again.

 

So far I thought of the ball-and-cup, together with rubber bands at each corners, or else I'll have to build the platform suspended from the ball-bearings from above as in my Speaker design...

 

I was thinking about this again, knowing I had seen something similar in recent times. And then it came back.

 

When I bought a Technics Direct-drive turntable, the owner of the store showed me the locking mechanism for allowing transporting the turntable home. Then, before use, this mechanism is unlocked so that the turntable can be played properly and be isolated to some extent by springs I believe.

[YashN]

True, but the point is that the system has become more revealing of the qualities on the recording. One can utilise the ever more revealing nature of the system as a tool to confirm or eliminate the viability of approaches to gaining even more of that revealing quality.

 

Wasn't really the point I was making though. What I was saying is that it can be a long chain of optimisations - seemingly unimportant changes in prior incarnations of your system may become much, more audible once you've worked on something else, and on it goes.