Vibration Management

Stacore

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Feb 23, 2017
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LL21

Well-Known Member
Dec 26, 2010
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great stuff! nice video!
 
Oct 12, 2013
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Essex UK
I've just finished watching a programme on TV about the constructuon of the £15bn Crossrail to link the areas to the west and east of London and run underground central London.
The line will run under the Barbican Concert Centre whose concert hall is two storeys down and obviously a major area of concern has been to avoid the noise and vibration from the trains travelling up into the concert hall.
To avoid that that section of the line is being suspended on springs within a Magnacrete base, a very expensive and dense form of concrete. I wasn't aware of Magnacrete until then and wonder whether anybody has or is considering using it for audio purposes.
 

Stacore

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Feb 23, 2017
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High mass + amorphic structure may indicate good internal daming. A simple relative test is to drop a bearing ball on tested materials and observe
how high an how many times it springs back. The lower and the fewer times it bounces back the better is the damping. One can make this test with a slate and granite
to see why snooker tables are made of slate.
 

Mike Lavigne

Member Sponsor & WBF Founding Member
Apr 25, 2010
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High mass + amorphic structure may indicate good internal daming. A simple relative test is to drop a bearing ball on tested materials and observe
how high an how many times it springs back. The lower and the fewer times it bounces back the better is the damping. One can make this test with a slate and granite
to see why snooker tables are made of slate.
one of these can be useful.

http://www.herzan.com/products/site-survey-tools/va-2-triaxial-vibration-sensor.html
 

bonzo75

Member Sponsor
Feb 26, 2014
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London
I've just finished watching a programme on TV about the constructuon of the £15bn Crossrail to link the areas to the west and east of London and run underground central London.
The line will run under the Barbican Concert Centre whose concert hall is two storeys down and obviously a major area of concern has been to avoid the noise and vibration from the trains travelling up into the concert hall.
To avoid that that section of the line is being suspended on springs within a Magnacrete base, a very expensive and dense form of concrete. I wasn't aware of Magnacrete until then and wonder whether anybody has or is considering using it for audio purposes.
Interesting info, thanks.
 

Stacore

Industry Expert
Feb 23, 2017
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Not sure if that's the right thread but could not find a better one.

One more empirical data point for something I've been strongly advocating [after my mentor Barry Diament] - suspending speakers. This one is by our distributor (KlangLoft) and I haven't heard the system myself
yet so pls treat it accordingly.

As Michael reports, suspending his speakers had quite a profound effect in his system and in his circumstances of a suspended wooden floor. The most important effect was reportedly cleaning of a bass bloat, which in turn resulted in revealing new layers of musical information. Buried previously under an over exposed LF. As far as I understand, this LF bloat was a result of the suspended wooden floor happily storing and releasing back the LF energy. Most probably releasing back both to the speaker cabinets as well as to the rest of the system (building structures can transmit vibrations to a surprisingly large distances). Breaking the speaker/floor vibration path resulted here in breaking various feedback loops (feedback to the cabinets, feedback to the amplifiers, feedback to the source), with reportedly good sonic consequences.

An interesting question is how universal are such findings. An immediate counterexample would be those speakers, which are intentionally designed to couple to the floor and their LF output relies on that. OTOH designing such speakers, it is hard to predict and take into account the behavior with all types of floors (suspended, concrete, wood panels, parquet, tiles, etc). I guess as usually the ultimate proof is in the pudding.


Zdjęcie 20.02.2019, 14 03 00.jpg

Cheers,
 

PeterA

Well-Known Member
Dec 7, 2011
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North Shore of Boston
That's a very interesting application for your platforms, Jarek. I suspect one challenge would be realigning the tweeter height and tilt relative to the listener. My own speakers are quite sensitive in this area. There may also be challenges with the LF driver in a multi driver design and how it is located relative to the floor to maintain whatever sonic traits the designer had in mind.
 

Blue58

Active Member
Jan 20, 2013
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London, UK
Hi Jared,
My AG Duos are on carpet over suspended flooring (1st floor bedroom) and I too had bass bloat from energy released from the flooring. My solution was using the Herbies Audio Lab Giant Gliders that decouple the speakers and allow some movement in the speaker. Result! bass bloat gone and I’ve never looked back.
I believe Boenicke also use some form of decoupling too.
Cheers
Blue58
 
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Stacore

Industry Expert
Feb 23, 2017
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Thank you guys for the feedback! Yes Peter, you are absolutely right with our current designs there is a rise of 11-14cm of the tweeter, which might be an issue in some systems. But what I meant was rather a general observation - a proper suspension of speakers may sometimes be highly rewarding. This goes much against some of the common and well seasoned belief circulating around for decades that speakers should be hard coupled to the floor. The argument sometimes used is a Doppler modulation of the tweeter output by the bass drivers. I've never been really convinced by this as Doppler effect depends on the ratio of the source velocity to the speed of sound, which I think here is very low. This is in brief my personal motivation to testing suspensions under speakers.

Cheers,
 

LL21

Well-Known Member
Dec 26, 2010
10,896
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Not sure if that's the right thread but could not find a better one.

One more empirical data point for something I've been strongly advocating [after my mentor Barry Diament] - suspending speakers. This one is by our distributor (KlangLoft) and I haven't heard the system myself
yet so pls treat it accordingly.

As Michael reports, suspending his speakers had quite a profound effect in his system and in his circumstances of a suspended wooden floor. The most important effect was reportedly cleaning of a bass bloat, which in turn resulted in revealing new layers of musical information. Buried previously under an over exposed LF. As far as I understand, this LF bloat was a result of the suspended wooden floor happily storing and releasing back the LF energy. Most probably releasing back both to the speaker cabinets as well as to the rest of the system (building structures can transmit vibrations to a surprisingly large distances). Breaking the speaker/floor vibration path resulted here in breaking various feedback loops (feedback to the cabinets, feedback to the amplifiers, feedback to the source), with reportedly good sonic consequences.

An interesting question is how universal are such findings. An immediate counterexample would be those speakers, which are intentionally designed to couple to the floor and their LF output relies on that. OTOH designing such speakers, it is hard to predict and take into account the behavior with all types of floors (suspended, concrete, wood panels, parquet, tiles, etc). I guess as usually the ultimate proof is in the pudding.


View attachment 48785

Cheers,
Can you make them for a Wilson X1/Grand SLAMM? I have heard great benefit with the Stillpoints Ultra 5s under the Wilsons, as have a number of other big Wilson owners including Jacob Heilbrunn.
 

Stacore

Industry Expert
Feb 23, 2017
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Gdańsk, Poland
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Hi LL21, thank you for the question. Yes, this it is definitely doable *if* the 11cm speaker elevation is ok (e.g. the further away you listening place is from the speakers the lesser the chance it will matter). The big weight (250kg) is actually a blessing for pneumatic suspensions :) PM me if interested.

Cheers,
 

PeterA

Well-Known Member
Dec 7, 2011
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447
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North Shore of Boston
That just looks wild. Jarek, do you think that if one pushes back on the front baffle the speaker will move slightly because of the compliance of the air bladders, or is it rock solid stable as if it were spiked to the floor? If it does tilt back slightly, would this not indicate that the speaker might move during very dynamic passages? That would surely not be good, but it might corrupt the sound less than the interaction of the vibrations with the floor.

I'm still hoping someone tries your lower profile constrained layer entry level platforms under speakers. Those might in effect be quite similar to some speaker footers like Magico's M Pods, just a platform rather than three or four separate footers.

Fascinating stuff!
 

Stacore

Industry Expert
Feb 23, 2017
516
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28
Gdańsk, Poland
stacore.pl
Thank you Peter! I was not there so cannot answer detailed questions. Hope Michael spots this thread and chimes in.

As for the Intro platform, let me make two remarks: 1st of all it's not much lower at approx. 7.5cm vs 11.5cm of the pumped Basic+. Second, and more importantly, it is a rigid design and hence its LF performance is much compromised compared to the Basic/Basic+ and LF decoupling is what plays the leading role here.

Cheers,
 
Jan 19, 2019
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11
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50
That just looks wild. Jarek, do you think that if one pushes back on the front baffle the speaker will move slightly because of the compliance of the air bladders, or is it rock solid stable as if it were spiked to the floor? If it does tilt back slightly, would this not indicate that the speaker might move during very dynamic passages? That would surely not be good, but it might corrupt the sound less than the interaction of the vibrations with the floor.

I'm still hoping someone tries your lower profile constrained layer entry level platforms under speakers. Those might in effect be quite similar to some speaker footers like Magico's M Pods, just a platform rather than three or four separate footers.

Fascinating stuff!
Yes the speaker moves if you push it. The advantage of the decoupling is so huge, that I would not think about any disadvantage of them moving.
And after considering, that I am not able to keep my head stable and solid in one place (I do move my head while listening to music ;-) I don't think it makes a big difference if the speaker moves a few millimeter back and forward.
 
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PeterA

Well-Known Member
Dec 7, 2011
5,552
447
83
North Shore of Boston
Yes the speaker moves if you push it. The advantage of the decoupling is so huge, that I would not think about any disadvantage of them moving.
And after considering, that I am not able to keep my head stable and solid in one place (I do move my head while listening to music ;-) I don't think it makes a big difference if the speaker moves a few millimeter back and forward.
Thank you for confirming what I suspected. I don't doubt your observations about improved sound quality. However, many speaker manufacturers go to great lengths to secure their drivers in a baffle in what I assume is an effort to reduce micro movements of the drivers. They also tend not to place speakers on springy supports. I have noticed an improvement in the sound of my system when I reinforced and better secured the floorboards beneath my speakers, so that the speakers rock back and forth a bit less.

People use the fact that they move their heads during listening to argue for the relative unimportance of time alignment of drivers or precise laser measurements for speaker positioning and set up. I have found that with precise set up, the sound is more coherent and better coupled to the room. This in turn results in better sound throughout the room allowing one to take his head "out of the vice".

I am intrigued by these reports of air isolation under speakers. I would like to directly compare the results between such isolation and a non-compliant support keeping the speaker height and all other speaker positioning consistent. I strongly suspect that results are dependent upon what frequencies are being affected and how those interact with the room dimensions and overall frequency response of the system. If the room starts to resonate because of speaker movement, the resulting distortion can not be good for sound quality. I suspect driver movement, ie minute shifts in the baffle location, during play can also not be good for sound quality.
 
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