Vibration Isolation Info

[Primalsea]

With the recent talk about dampening and whether isolation makes a difference some people might be interested inthese links.

https://www.lord.com/products-and-solutions/vibration-and-motion-control/industrial/isolators/vibration-isolation-theory

https://www.lord.com/products-and-solutions/vibration-and-motion-control

Useful for anyone looking to DIY some vibration control for their hifi.

A bit heavy to go through in one go (I haven’t gone through all of it yet), but should help in choosing the most likely optimum solution.

[MikeMusic]

Thanks Paul

These guys are serious

[hifinutt]

Ta so much, a lot to think about and digest

[Primalsea]

If I understood it correctly what we would be looking to achieve for hifi equipment is that same sort of “bounciness” that you get with those old suspended turntables on music centres from the days of old, or washing machine gubbins.

[Yomanze]

If I understood it correctly what we would be looking to achieve for hifi equipment is that same sort of “bounciness” that you get with those old suspended turntables on music centres from the days of old, or washing machine gubbins.

My speakers move freely when pushed around, and if I give them a nudge, there's a little wobble, maybe 3Hz. It's a myth that this causes the speakers to move when being played, because they don't...

But yes, in essence you are looking for a 'spring' that oscillates below 5Hz when loaded.

[Pharos]

Have you actually measured it under transient conditions Neil?

[Yomanze]

Have you actually measured it under transient conditions Neil?

Yes, by installing 'VibSensor' on my phone, which is an accelerometer / seismometer, placing it in top of my speakers, and cranking it up.

I also used it on my floor right next to my speakers to see the effect of decoupling, needless to say, huge effect!

[Pharos]

The conflict between the desire for no fore-aft movement under transient conditions, and a decoupling from the floor to avoid transmission of energy is a hard one.

Soft suspension risks loss of the transient, and spikes will couple to the floor a lot of energy if wooden.

I'm surprised at your results Neil, but the phone on top I think questionable; against the front probably being better, and is the phone app good enough? I presume that many current mobile phones carry an accelerometer.

[Yomanze]

I was surprised too, as I have always used spikes, including a Mana rack, but the sound is now cleaner, more focus and 3D, less room boom. I can play it louder without upsetting the neighbours anymore, no loss of transients either.

I don’t really see how a 5 inch driver is going to be moving anything, and in any case my speakers sit slightly off the stand top plates and are bolted into a rear fixing.

Decoupling has been the best VFM upgrade for me yet, so just went ahead and decoupled everything.

[Clive]

I've found the idea that speakers need to be rigid coupled to prevent the loss of transients isn't the case at all. At least that's my experience with some hefty bass drivers. I have open frame (ie no baffle) 15 inch bass drivers. These cover 18Hz to 110Hz in my system. The drivers are wired in reverse polarity and face each other so the cones travel in the the same direction, not cancelling out forces.

The interesting part is that the drivers are suspended by steel wires. The drivers are free to move - totally the opposite to normal practice. I was skeptical this could work as intuitively you'd think when bass kicks in the drivers will move and wreck the leading edge of notes. The reality is that this does not happen. I can perceive no physical movement of the spiders. Bear in mind that with all the bass cancellation involved with open frame there an enormous amount of power feeding these drivers...(900W per driver - yes I use 2 stereo class d amps to power these). Even on really bass heavy material such as Kraftwerk - The Man Machine - the only movement is from the cones - [U]massive[U] excursions. The bass is easily these the best I've had and pretty much the best I've heard.

https://farm2.staticflickr.com/1746/27482080647_a5264cf745_z.jpg (https://flic.kr/p/HSuR7F)IMG_20180525_221445 (https://flic.kr/p/HSuR7F) by Clive M (https://www.flickr.com/photos/132168588@N08/), on Flickr

[Pharos]

Your results are interesting Neil, and somehow I feel that we are fed ideas without verification by the market.

My speakers weigh 77kg and are have an MDF base of 1.5" thickness. They are 20" front to back by 17", and are resting on new carpet (non foam) pile. What is your opinion on that arrangement? I have bought S/S domes to screw into the bases which were originally designed for spikes, but you can imagine 77kg on spikes into a wooden floor? I really wonder at the need for even the domes.

That arrangement is interesting Clive, but arguably the main transient power is in the harmonics, this being felt when in phase with the fundamentals. Yours remind me of the Celestion 6000 woofers, but they were bipole and not dipole like yours. I remember the Hi-Fi News write up on the ideas behind the resulting smooth bass response.

[struth]

The movement should equal out at a guess. Interesting idea

[Yomanze]

Your results are interesting Neil, and somehow I feel that we are fed ideas without verification by the market.

My speakers weigh 77kg and are have an MDF base of 1.5" thickness. They are 20" front to back by 17", and are resting on new carpet (non foam) pile. What is your opinion on that arrangement? I have bought S/S domes to screw into the bases which were originally designed for spikes, but you can imagine 77kg on spikes into a wooden floor? I really wonder at the need for even the domes.

That arrangement is interesting Clive, but arguably the main transient power is in the harmonics, this being felt when in phase with the fundamentals. Yours remind me of the Celestion 6000 woofers, but they were bipole and not dipole like yours. I remember the Hi-Fi News write up on the ideas behind the resulting smooth bass response.

You’re right, those are some heavy-ass speakers, even with the most appropriate Sorbothane I could find, 4x spheres would support 40kg, so you would need 8x under each speaker... and even then what a ballache to site.

From what I can see, perhaps the Auralex Gramma would be more appropriate, if at all...