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Equipment isolation and vibration damping.


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OK then, it wouldn't work properly otherwise. Just wondering...

I thought so, but on checking, no it's not separate isolation platforms, it is a single one although it appears from the upper surface to be two different areas.

 

The platform is, however, a spring-based isolated one.

 

It's a Technics SL-1800 direct-drive, quite similar to the original SL-1200 but with less features.

Forrest:

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OK then, it wouldn't work properly otherwise. Just wondering...

 

Apart from needing to change the tonearm + RCA cable and requiring some fluid damping, it works fine.

 

The point, to come back to the thread subject matter, was rather that if a turntable is already suspended by springs, it might not benefit from an additional vibration isolation layer.

 

This said, I have a list of a total of 19 mods or so to it that I want to do one day, including externalising the transformer from underneath the platter...

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All,

 

While I'm not this threads OP, I don't think that YashN would mind too much if I attempt to split the thread, and leave this one for more theoretical, weird devices, and SOTA issues, and my new one for more concrete "what can I put in my system now ?" concerns.

 

Here's the new thread: http://www.computeraudiophile.com/f8-general-forum/roller-type-vibration-isolation-devices-info-24991/#post440610

 

 

Keep up the great postings !!

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While I'm not this threads OP, I don't think that YashN would mind too much if I attempt to split the thread, and leave this one for more theoretical, weird devices, and SOTA issues, and my new one for more concrete "what can I put in my system now ?" concerns.

 

I'm accustomed to people having a hard time following me. :P

 

The thread's purpose is in the first post, i.e. methods of isolation.

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Hi Sam,

Pulling your leg? Do you mean regarding the name? Or something else?

No joking intended. Sorry if I wasn't clear. (The name is explained in one of the blog entries.)

 

Not sure why the contact materials would need to be different. How would the ball "know"?

As it happens, I'm using different materials since the top is either dead marble tile (smooth side against the ball) or the chassis itself (if smooth enough).

My experience as an amateur astronomer and telescope enthusiast has shown me that glass is a lot more flexible than one might think. I would not use it for audio purposes (unless I was designing transparent bells ;-).

 

Hi Barry,

 

Oh you wrote it clearly, I only had to decide whether "Hip Joints" referred to "hip joints [humor about the sound of new body parts]" or "Hip Joints [acoustic isolators]". Yes I found it after looking around. It's easy to get frantic on CA because of the @#$% no-post-editing rule.

 

My apologies, I thought I had rewritten the part about race materials. What I meant to say was only that the bearings and races couldn't all be the same material, AFAIK, because of the galling (grinding) action of similar materials against each other. But sure, top and bottom surfaces (races) can be the same like in most bearings. I originally wrote "top" and "bottom" to mean the top of the ball and the bottom of the race, i.e. contacting surfaces. That is, just the obvious operation of bearings. Sorry about that!

 

I think mass is easier to implement than vertical isolation devices as long as you have good dry sand available to fill hollow tubes in equipment stands. And I understand the utility of vertical isolation, i.e. dropping the resonant frequency or damping for components with sensitive devices. But as you know for loudspeakers the internally-generated motion is a much bigger distortion source than what is seen by other components. So in speakers the horizontal momentum summing done by bearings is many times more effective than vertical isolation.

 

For speakers I think the best approach for vertical cabinet motion is mass and a noncompliant coupling. IOW, I think the usual method of having a very heavy cabinet on top of a stiff interface (spike, bolt, etc) with the floor is effective. Beyond that one can use constrained-layer damping by placing more mass beneath the compliant layer, like heavy stone slabs separated by sorbothane. That makes the resonant frequency in the vertical axis very low and keeps amplitudes very small. Cheers

Mac Mini 2012 with 2.3 GHz i5 CPU and 16GB RAM running newest OS10.9x and Signalyst HQ Player software (occasionally JRMC), ethernet to Cisco SG100-08 GigE switch, ethernet to SOtM SMS100 Miniserver in audio room, sending via short 1/2 meter AQ Cinnamon USB to Oppo 105D, feeding balanced outputs to 2x Bel Canto S300 amps which vertically biamp ATC SCM20SL speakers, 2x Velodyne DD12+ subs. Each side is mounted vertically on 3-tiered Sound Anchor ADJ2 stands: ATC (top), amp (middle), sub (bottom), Mogami, Koala, Nordost, Mosaic cables, split at the preamp outputs with splitters. All transducers are thoroughly and lovingly time aligned for the listening position.

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It's easy to get frantic on CA because of the @#$% no-post-editing rule.

 

You can post-edit, but I think it's within a time-frame of 30 mins or less.

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Barry's observations about the size of the tube have been spot on for me. I started off with a 12" under the tt and it was great for music with very little bass. So I went back to the bike shop - no 18" so I grabbed a 16". Thought I would put the 12" under my integrated amp and the 16" under the tt. Whoops! Talk about too much bass. It was all I could hear. Now I know what bass bloat is.

 

So I put the 16" under the amp and ran my dac. Strong bass but ok. Overall a greatly enhanced sound from my dac - an inexpensive Matrix Quattro from my bedroom system - so I was very pleased.

 

New night, different bike shop, and an 18" tube now under the tt and the 16" still under the amp. Good strong tight bass. No bloat. And the rest seems full of life and energy - V M's Moondance album. Now John Martyn's Solid Air with the acoustic bass really humming, vibraphone floating on top and some tenor linking. Fantastic. The air in that sax is really coming through.

 

I've ordered some piano casters and bearings on Aliexpress so that is next.

 

A big thank you to Barry.

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Barry,

 

I understand the ringing in large plates like shelves, but wonder if that is not a big factor with smaller pieces of glass that are only passing force through, not around the plate ?

 

I'm still curious about those glass lens 'bowls' John Swenson talked about. (without links :(

 

Here is the link for the best price I can find:

 

Lens Sets

 

You want glass concave lenses. Most of them are going to be double concave, that should be fine. The first number is the diameter, the second number is the focal length (larger number = shallower)

 

Amazon sells the same lenses for twice the price.

 

Make SURE you get glass not plastic lenses. If it doesn't explicitly say glass then it is probably plastic.

 

The stainless steel mirror is:

 

Amazon.com: Coghlan's Stainless Steel Mirror: Sports & Outdoors

 

John S.

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I think mass is easier to implement than vertical isolation devices as long as you have good dry sand available to fill hollow tubes in equipment stands. And I understand the utility of vertical isolation, i.e. dropping the resonant frequency or damping for components with sensitive devices. But as you know for loudspeakers the internally-generated motion is a much bigger distortion source than what is seen by other components. So in speakers the horizontal momentum summing done by bearings is many times more effective than vertical isolation.

 

For speakers I think the best approach for vertical cabinet motion is mass and a noncompliant coupling. IOW, I think the usual method of having a very heavy cabinet on top of a stiff interface (spike, bolt, etc) with the floor is effective. Beyond that one can use constrained-layer damping by placing more mass beneath the compliant layer, like heavy stone slabs separated by sorbothane. That makes the resonant frequency in the vertical axis very low and keeps amplitudes very small. Cheers

 

What is interesting among other things in this thread, is that by asking questions, we have come to a few causes and their related compensations.

 

If you've followed the questions I asked Barry initially, I wanted to know what exactly he and others using the same implementation were aiming to resolve. There ensued some good-nature back-and-forth about the terms of isolation and damping, and heat loss etc..., in addition to a description of my own bookshelf speaker + stand arrangement.

 

So, fine with mass loading to reduce speaker cabinet vibration, but what Townshend and Barry want to do is cope with seismic vibration coming from the ground up into the components.

 

These are two different things.

 

For seismic isolation, you do not want the arrangement spiked to the floor (assuming it is a concrete surface), although spikes can be beneficial against cabinet vibrations.

 

The Townshend presentation linked to by Duke40 earlier is an interesting watch if you haven't done so already.

 

 

So, to deal with seismic isolation, you would rather use the air-cushion (or alternative) and cup-and-ball, but these do not mean that there is no benefit in reducing the cabinet vibrations.

 

Managing both of these issues can bring handsome rewards.

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For those interested in the cup and ball isolators this is a nice animation of what they do.

 

Inner Pendulum Motion Service Level Earthquake

 

Here is a very nice video of a table top illustration of how effective these devices can be.

 

 

[video=youtube;7Q-5EZHrtiQ]

 

 

 

 

Glad to see they are using cups of liquid. Basically what I did a few years ago evaluating such products.

 

YashN in another thread mentioned cup and ball devices were treated like a pendulum when used for seismic control. I didn't know that before he mentioned it, but that was the conclusion I came to working with them. Being a pendulum it was worthwhile to size the radius of the cup based upon what frequencies you wished to filter out.

 

Here is a paper explaining how they work.

 

https://www.asee.org/documents/sections/pacific-southwest/2008/Porbaha_Ali_et_al%20Base%20isolation.pdf

 

Just a comment, on the glass lens that John Swenson is showing. That sounds like a good idea for precise surfaces available in various curvatures. However, when I was messing with such items glass never worked as well as metal or ceramic devices. Using glass marbles for the bearing was not good at all, and glass dished out for the cup while better than using glass marbles still seemed less good than metal even aluminium. Not saying they aren't worthwhile. At one point I was bouncing a laser pointer off a mirror, shooting the beam all the way across the room and this amplified movement of the mirror to evaluate effectiveness. Tiny movements could be seen by the dancing laser dot 20 feet away. Glass never would settle down like metals would. They seemed to ring too easily. Glass marbles could be worse than nothing at all.

 

Now I never found anything that worked as well as a platform floating on a sand bed. But sand is messy. I ended up using layered constrained mode damping shelves. They worked pretty well and were not picky at all like cup and ball or damped spring systems. I mentioned elsewhere that I think it possible that memory foam might effectively work like sand in a less heavy and less messy system. I have not experimented with that yet however.

 

Sorry, if some of this is a repeat, as I didn't read much of the thread before posting. Hope some of it is worthwhile to some people. Some people will find it useless to them I am sure.

And always keep in mind: Cognitive biases, like seeing optical illusions are a sign of a normally functioning brain. We all have them, it’s nothing to be ashamed about, but it is something that affects our objective evaluation of reality. 

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For those interested in the cup and ball isolators this is a nice animation of what they do.

 

Inner Pendulum Motion Service Level Earthquake

 

Here is a very nice video of a table top illustration of how effective these devices can be.

 

 

[video=youtube;7Q-5EZHrtiQ]

 

 

lots of snippage

 

 

 

Interesting video. Can you explain the relevance to the type of vibrational motions of much smaller amplitude and most likely much higher frequency that appear to have an effect on sound quality?

 

I am not so worried about the earthquakes (though my US home is on the Hayward Fault) in the context of audio reproduction.

You must have chaos within you to give birth to a dancing star

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Interesting video. Can you explain the relevance to the type of vibrational motions of much smaller amplitude and most likely much higher frequency that appear to have an effect on sound quality?

 

I am not so worried about the earthquakes (though my US home is on the Hayward Fault) in the context of audio reproduction.

 

Take a look at the video in post #284 and basically all of the discussion from Barry...

Positive emotions enhance our musical experiences.

 

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Interesting video. Can you explain the relevance to the type of vibrational motions of much smaller amplitude and most likely much higher frequency that appear to have an effect on sound quality?

 

I am not so worried about the earthquakes (though my US home is on the Hayward Fault) in the context of audio reproduction.

 

The reduction even for smaller movements should be the same even though not visible. Above a certain frequency it should be relatively impervious. The motion in that video is low frequency of roughly 1 hz. Notice how the splash in the upper glass is a small fraction of the lower glass. At higher frequencies that should hold as well even if the splash is so small as to be invisible.

 

So in this type of isolator, any vibration from the ground or from the lower shelf should be decoupled at frequencies of some few hertz and higher. Now direct sound impinging on the upper shelf won't be diminished though effects of it impinging on the lower shelf would not be transmitted into the upper shelf. One thing I don't know is what level of stiction there is. Does it take some minimum level of energy to actually move the component freely? I do know when I experimented with similar devices floor vibration from music was reduced in some directions on the turntable and tube preamp I had at the time. So these do function to some point with our audio equipment.

 

The way I came to think of these, and as it turns out how they are engineered is modelling them as pendulums. Think of your shelf suspended by 4 wires at the corner going to a point several feet overhead. The longer the pendulum the lower frequency at which it will swing back and forth. Above that natural frequency of the effective pendulum it will be decoupled from movement of the point which supports the shelf.

And always keep in mind: Cognitive biases, like seeing optical illusions are a sign of a normally functioning brain. We all have them, it’s nothing to be ashamed about, but it is something that affects our objective evaluation of reality. 

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The reduction even for smaller movements should be the same even though not visible. Above a certain frequency it should be relatively impervious. The motion in that video is low frequency of roughly 1 hz. Notice how the splash in the upper glass is a small fraction of the lower glass. At higher frequencies that should hold as well even if the splash is so small as to be invisible.

 

So in this type of isolator, any vibration from the ground or from the lower shelf should be decoupled at frequencies of some few hertz and higher. Now direct sound impinging on the upper shelf won't be diminished though effects of it impinging on the lower shelf would not be transmitted into the upper shelf. One thing I don't know is what level of stiction there is. Does it take some minimum level of energy to actually move the component freely? I do know when I experimented with similar devices floor vibration from music was reduced in some directions on the turntable and tube preamp I had at the time. So these do function to some point with our audio equipment.

 

The way I came to think of these, and as it turns out how they are engineered is modelling them as pendulums. Think of your shelf suspended by 4 wires at the corner going to a point several feet overhead. The longer the pendulum the lower frequency at which it will swing back and forth. Above that natural frequency of the effective pendulum it will be decoupled from movement of the point which supports the shelf.

 

Thanks for your thoughtful reply. I had read#284, but as a Californian (though not native and only part-time) I perhaps associate seismic with events that occur that will make me forget about the music I am listening to and focus on survival.

 

I have not done much to mitigate vibration in my system. A few of the inexpensive vibration control pads that were recommended by someone (Guido perhaps?), two sets of cones (cheap ones) plus some of the Ikea wood cutting boards. Also no A/B testing. I just added them and left them. That is why I am interested in learning from those of you have have more experience in this.

You must have chaos within you to give birth to a dancing star

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Thanks for your thoughtful reply. I had read#284, but as a Californian (though not native and only part-time) I perhaps associate seismic with events that occur that will make me forget about the music I am listening to and focus on survival.

 

I have not done much to mitigate vibration in my system. A few of the inexpensive vibration control pads that were recommended by someone (Guido perhaps?), two sets of cones (cheap ones) plus some of the Ikea wood cutting boards. Also no A/B testing. I just added them and left them. That is why I am interested in learning from those of you have have more experience in this.

 

For someone just starting to deal with vibration, these sorbothane pads are hard to beat. Not extremely critical in tuning and work on lots of equipment.

 

http://www.amazon.com/Isolate-Sorbothane-Vibration-Isolation-Circular/dp/B0042U8P9C/ref=sr_1_3?ie=UTF8&qid=1435722579&sr=8-3&keywords=sorbothane

 

Unlike other methods that decouple vibration, the sorbothane simply soaks up vibration and turns it into heat. It is some of the finest material available for that purpose. Now lots of footers are molded to different shapes and combined with different things to do more, but even these simple inexpensive pucks under you equipment give you a good result and good taste for what is possible.

 

You also can get thin sheets of sorbothane. This is excellent for damping out vibration in metal covers on your equipment. You really don't need to cover an entire surface to benefit. Strips placed at thirds will soak up much of the vibration from a metal cover. There may be better material, but contact cement is one of the better ways to attach such strips. Contact cement is an adhesive that dries into a rubber compound that stays flexible. This lets the strip move and soak up energy better than if it were held with other adhesives.

And always keep in mind: Cognitive biases, like seeing optical illusions are a sign of a normally functioning brain. We all have them, it’s nothing to be ashamed about, but it is something that affects our objective evaluation of reality. 

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...So, fine with mass loading to reduce speaker cabinet vibration, but what Townshend and Barry want to do is cope with seismic vibration coming from the ground up into the components.

 

These are two different things.

 

For seismic isolation, you do not want the arrangement spiked to the floor (assuming it is a concrete surface), although spikes can be beneficial against cabinet vibrations.

 

So, to deal with seismic isolation, you would rather use the air-cushion (or alternative) and cup-and-ball, but these do not mean that there is no benefit in reducing the cabinet vibrations.

 

Yes thanks YashN, agree to all. I spoke with Max years ago about his then-current Seismic Sinks. They have easily measurable effects for vinyl and tubes, and good effects for other electronics; big electrolytic and small ceramic caps can ring. I mainly wanted to compare cost and benefit for different approaches to vertical isolation.

 

You can post-edit, but I think it's within a time-frame of 30 mins or less.

 

Yes, but for a long technical post it's a silly PITA, nobody likes it.

 

...Glass never would settle down like metals would. They seemed to ring too easily. Glass marbles could be worse than nothing at all.

 

Now I never found anything that worked as well as a platform floating on a sand bed. But sand is messy. I ended up using layered constrained mode damping shelves. They worked pretty well and were not picky at all like cup and ball or damped spring systems. I mentioned elsewhere that I think it possible that memory foam might effectively work like sand in a less heavy and less messy system. I have not experimented with that yet however.

 

Word, sand is a PITA. I used Sound Anchors for my last setup and have good results even with a sub sitting on the base. They are super heavy and are filled with a dense foam...very damp. Constrained damping layers are really the best for vertical isolation for speakers, and fair for components. But geez you need so much mass coupled (later with bearing systems) right to the speakers to avoid LF distortion...we used 200lb slabs, and that was below 240lb main cabinets and 420lb (separate) sub cabinets. There was a (IIRC) 0.5" Ensolite layer between the upper and lower slabs. It's camping mattress material of old, like current memory foam but much stiffer.

 

Unlike other methods that decouple vibration, the sorbothane simply soaks up vibration and turns it into heat.

 

Well it's good, but only a good portion of the kinetic energy becomes heat, while the momentum passes through. The higher frequencies are generally attenuated, with lower frequencies increased as momentum is conserved.

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In my experience, Sorbothane is *not* a good idea. Its resonance is too high, effectively, up in the bass, and as a result, it will bring on bass bloat, while remaining useless for isolating from the very low, seismic frequencies.

 

By all means however, I always suggest folks try everything and hear it for themselves. If you hear it as I do, you'll find this material is good for "coloring" the sound but not for making an isolator for an audio (or video) component. (By the way, I *do* suggest trying the isolators we're discussing for video gear too. I've found improvements in contrast, depth of black, focus, etc. etc. -- all the video analogs to what we discuss with audio gear.)

 

Best regards,

Barry

Soundkeeper Recordings

http://www.soundkeeperrecordings.wordpress.com

Barry Diament Audio

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That is a great video.

 

For vertical damping has anyone tried the neodymium magnetic devices?

 

Hi jabbr,

 

As yet, I have not been able to find anyone who has disproven Earnshaw's theorem which dates back well over a century. (Earnshaw spoke of the instability in certain systems, and this is exhibited in the "mag lev" devices I've seen so far.)

 

Close inspection of all the magnetic "levitation" devices sold for audio (at least all of the ones I've seen to date) will reveal a physical contact point against which the device (supposedly being levitated) will come into contact at least some if not all of the time.

 

For example, one scheme uses disk-shaped magnets with holes in their centers. The magnets have a solid post running vertically through their center holes, and they are added to the post with opposing poles facing each other. The magnets repel each other but due to the inherent instability of such, there is lateral motion so they invariably end up resting against the post. The post transmits vibrations up to the load as if the magnets were not there. With magnets, without magnets, it doesn't matter because the post is providing the transmission, with a result of zero isolation.

 

If someone ever does get this and disproves Earnshaw (an enormous "if"), the resonance in that magnetic repulsion will become the topic of discussion. (I would imagine the magnet strength would need to be matched to the load. Change components and unless it weighs exactly the same as the old component -- with exactly the same weight distribution -- you also will need new magnets. But all that is *if* someone finds a way around Earnshaw.

 

Do you have a link to the type of device to which you are referring? I'm always curious to check out all approaches and open to the idea that I might be surprised. (It has happened before. ;-})

 

Best regards,

Barry

Soundkeeper Recordings

http://www.soundkeeperrecordings.wordpress.com

Barry Diament Audio

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Interesting video. Can you explain the relevance to the type of vibrational motions of much smaller amplitude and most likely much higher frequency that appear to have an effect on sound quality?

 

I am not so worried about the earthquakes (though my US home is on the Hayward Fault) in the context of audio reproduction.

 

What we are discussing is seismic events, not seismic shock, i.e. vibrations transmitted through the ground: it could be natural ground motion, but also vehicles nearby or further away, the flexing of large structures like bridges, heavy road-work, etc...

 

It is very worthwhile to watch that Townshend video as well as read the paper I linked to from their website as well.

 

In fact, it is beneficial to read the thread from the start.

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Sorry, if some of this is a repeat, as I didn't read much of the thread before posting.

 

You would certainly find a lot of interesting things if you read from the beginning. Lots of good posts.

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Hi jabbr,

 

As yet, I have not been able to find anyone who has disproven Earnshaw's theorem which dates back well over a century. (Earnshaw spoke of the instability in certain systems, and this is exhibited in the "mag lev" devices I've seen so far.)

 

Close inspection of all the magnetic "levitation" devices sold for audio (at least all of the ones I've seen to date) will reveal a physical contact point against which the device (supposedly being levitated) will come into contact at least some if not all of the time.

 

For example, one scheme uses disk-shaped magnets with holes in their centers. The magnets have a solid post running vertically through their center holes, and they are added to the post with opposing poles facing each other. The magnets repel each other but due to the inherent instability of such, there is lateral motion so they invariably end up resting against the post. The post transmits vibrations up to the load as if the magnets were not there. With magnets, without magnets, it doesn't matter because the post is providing the transmission, with a result of zero isolation.

 

If someone ever does get this and disproves Earnshaw (an enormous "if"), the resonance in that magnetic repulsion will become the topic of discussion. (I would imagine the magnet strength would need to be matched to the load. Change components and unless it weighs exactly the same as the old component -- with exactly the same weight distribution -- you also will need new magnets. But all that is *if* someone finds a way around Earnshaw.

 

Do you have a link to the type of device to which you are referring? I'm always curious to check out all approaches and open to the idea that I might be surprised. (It has happened before. ;-})

 

Best regards,

Barry

Soundkeeper Recordings

www.soundkeeperrecordings.wordpress.com

Barry Diament Audio

 

The lateral contact points are certainly an issue. On the other hand horizontal vibrations are handled by the roller blocks. I was considering that for applications where more lateral stability than afforded by inner tubes is desirable, magnets might have a roll to play. I am certain there is a much better design than what is currently available and which could essentially eliminate the lateral contact points.

Custom room treatments for headphone users.

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What we are discussing is seismic events, not seismic shock, i.e. vibrations transmitted through the ground: it could be natural ground motion, but also vehicles nearby or further away, the flexing of large structures like bridges, heavy road-work, etc...

 

It is very worthwhile to watch that Townshend video as well as read the paper I linked to from their website as well.

 

In fact, it is beneficial to read the thread from the start.

 

I basically helicoptered into the thread due to my interest, but also too little time to give the topic what it deserved. Thanks to you, esldude, Barry, Sam, and so many others for sharing your knowledge and experience.

You must have chaos within you to give birth to a dancing star

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Thanks to you, esldude, Barry, Sam, and so many others for sharing your knowledge and experience.

 

You're welcome, add to those, Duke40, John Swenson and many others :)

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