Bass level and moving objects - AVS Forum
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post #1 of 29 Old 05-31-2013, 01:39 PM - Thread Starter
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So here's a question that will pertain to me..........

In AVS Forum participants' experience, at what bass SPL or db level do objects tend to move significantly ( pictures on wall, curio objects in cabinets, glassware on tables, etc)? I am thinking about purchasing a subwoofer for my ~2100 cu ft family room open to kitchen, and I have 2 large entertainment cabinets which both have curios and pictures on shelves, along with pictures on fireplace mantle.......if any of these items were to be damaged by excessive bass levels ( esp. the Hummel figurines!!), my goose would be cooked.......

I normally do NOT listen to music/ Bluray discs at above reference levels ( or ~95db)......and probably do NOT need bass to exceed these levels .........
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post #2 of 29 Old 06-01-2013, 07:58 AM
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It has to be pretty damn loud. But, things can move. You can use an isolating sub riser as well. They can be home made pretty easy. It will especially help ( sonically and vibration)if your sub is on hard flooring rather than carpet.
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post #3 of 29 Old 06-01-2013, 08:32 AM
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Originally Posted by nodnerb View Post

You can use an isolating sub riser as well... It will especially help ( sonically and vibration)if your sub is on hard flooring rather than carpet.
No, it won't. The floor and everything else will vibrate just as they did without one, as those vibrations are caused by the acoustic output of the sub, not by the sub being in contact with the floor. If the floor is vibrating that can cause the sub to vibrate atop it, and that a riser can help with. But so will rubber feet, or a piece of this cut to size:
http://www.homedepot.com/webapp/wcs/stores/servlet/ProductDisplay?storeId=10051&langId=-1&catalogId=10053&productId=202015909&R=202015909#.UP66YGeYUYc
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I have 2 large entertainment cabinets which both have curios and pictures on shelves, along with pictures on fireplace mantle......
So do I, along with pictures hung on the walls. I never have had anything vibrate, but my floor, ceiling and walls are structurally sound, and I don't run at silly loud levels.

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post #4 of 29 Old 06-01-2013, 02:52 PM - Thread Starter
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^^^^ Thanks for the input, Bill...........and I think the last point about not running at "silly loud levels" is the key point.....
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post #5 of 29 Old 06-01-2013, 04:11 PM
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Originally Posted by padgman1 View Post

^^^^ Thanks for the input, Bill...........and I think the last point about not running at "silly loud levels" is the key point.....
Not that I can't, my system is quite capable of well beyond silly. I'm content these days with just slightly excessive. rolleyes.gif

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post #6 of 29 Old 06-01-2013, 05:26 PM
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I might add that even though you might "think" that the level is low enough so that things don't move, don't be mislead into a false sense of security. Over time things just like the curios you mentioned will travel slowly until one day, months, mabe even years down the road something will fall and then I'm afraid that goose, albeit a tad older will be well done.

Just keep a watchful eye on the stuff and you should be fine.

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post #7 of 29 Old 06-01-2013, 10:00 PM - Thread Starter
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^^^^^ Either keep watch or just glue them suckers down so I don't have to worry, right??
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post #8 of 29 Old 06-01-2013, 10:20 PM
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Bill what do you think of what this guy says about isolators and spiked feet?

"It’s no secret that the deep bass is extremely difficult to contain, which is why Grimani recommends putting subwoofers and floorstanding speakers on rubber blocks instead of placing them directly on the floor. Doing so reduces the transfer of acoustic energy into the floor, which, by the way, is exacerbated by the spikes found on some speakers. “All spikes do is ensure that low-frequency vibration from the woofers is really pushed down into the floor—not a good idea if you’re trying to keep things quiet,” Grimani says. Mason Industries sells Super W Pads for placement under compressors, HVAC units, and other machinery in industrial spaces. Intended to reduce noise and vibration, the pads come in a sheet made up of 2-by-2-inch rubber waffle pads, which are perfect for decoupling subwoofers and speakers. All you have to do is break off a few squares and put them under the corners of your subwoofers and speakers. Every little bit helps."

Source: http://www.hometheater.com/content/reduce-home-theater-silence-page-2
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post #9 of 29 Old 06-02-2013, 06:55 AM
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Originally Posted by DotJun View Post

Bill what do you think of what this guy says about isolators and spiked feet?
Stick to his day job? rolleyes.gif
To be fair, with respect to his methods used in the room construction, they're valid. But as to what feet and spikes actually do, not so much. Subwoofers do not transfer low frequency vibrations to the floor by being in contact with the floor, period. A vibrating floor may transfer low frequency vibrations to the sub, but all it takes to absorb those is rubber feet, or carpet, or a simple vinyl pad.

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post #10 of 29 Old 06-02-2013, 07:03 AM
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Originally Posted by Bill Fitzmaurice View Post

Stick to his day job? rolleyes.gif
To be fair, with respect to his methods used in the room construction, they're valid. But as to what feet and spikes actually do, not so much. Subwoofers do not transfer low frequency vibrations to the floor by being in contact with the floor, period. A vibrating floor may transfer low frequency vibrations to the sub, but all it takes to absorb those is rubber feet, or carpet, or a simple vinyl pad.

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post #11 of 29 Old 06-02-2013, 07:21 AM
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Quote:
Originally Posted by Bill Fitzmaurice View Post

Stick to his day job? rolleyes.gif
To be fair, with respect to his methods used in the room construction, they're valid. But as to what feet and spikes actually do, not so much. Subwoofers do not transfer low frequency vibrations to the floor by being in contact with the floor, period. A vibrating floor may transfer low frequency vibrations to the sub, but all it takes to absorb those is rubber feet, or carpet, or a simple vinyl pad.
+1
I can easily get objects moving in the Cave which has a concrete slab floor. It's all about sound pressure.

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post #12 of 29 Old 06-02-2013, 04:39 PM
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Quote:
Originally Posted by Bill Fitzmaurice View Post

Stick to his day job? rolleyes.gif
To be fair, with respect to his methods used in the room construction, they're valid. But as to what feet and spikes actually do, not so much. Subwoofers do not transfer low frequency vibrations to the floor by being in contact with the floor, period. A vibrating floor may transfer low frequency vibrations to the sub, but all it takes to absorb those is rubber feet, or carpet, or a simple vinyl pad.
You're gonna tell Anthony Grimani to "stick to his day job?" Really??? His current "day job" is designing and constructing some of the very highest-end HT's on the planet.
http://www.pmiltd.com/about.html Check out his portfolio.

Do you really think this guy has no idea how to isolate a subwoofer?:

Prior to founding PMI, Ltd., Mr. Grimani had long-term stints at Dolby and THX. At Dolby, he helped develop the standards for surround sound. At THX, he developed the THX certification process. So, yeah, he should stick to his day job. rolleyes.gif

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post #13 of 29 Old 06-02-2013, 05:08 PM
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His credentials are nice and all, but lets see some evidence that speakers and subs do transfer energy to the floor before we solve a problem that doesn't exist.
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post #14 of 29 Old 06-02-2013, 05:47 PM
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At THX, he developed the THX certification process.

OK.. What was his standard on THX LFE then... mmm.

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post #15 of 29 Old 06-02-2013, 06:03 PM
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Originally Posted by shadyJ View Post

His credentials are nice and all, but lets see some evidence that speakers and subs do transfer energy to the floor before we solve a problem that doesn't exist.
+1. Just like high price cable companies isolation device companies are long on spiel and short on proof. And more than one industry professional who should have known better has fallen for unsubstantiated claims made by purveyors of every sort of snake oil imaginable.

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post #16 of 29 Old 06-02-2013, 06:47 PM
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Originally Posted by Bill Fitzmaurice View Post

Stick to his day job? rolleyes.gif
To be fair, with respect to his methods used in the room construction, they're valid. But as to what feet and spikes actually do, not so much. Subwoofers do not transfer low frequency vibrations to the floor by being in contact with the floor, period. A vibrating floor may transfer low frequency vibrations to the sub, but all it takes to absorb those is rubber feet, or carpet, or a simple vinyl pad.
Well he's in trouble then because that is his day job. smile.gif
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post #17 of 29 Old 06-02-2013, 06:51 PM
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Originally Posted by Bill Fitzmaurice View Post

+1. Just like high price cable companies isolation device companies are long on spiel and short on proof. And more than one industry professional who should have known better has fallen for unsubstantiated claims made by purveyors of every sort of snake oil imaginable.
It's funny you mention this because at work there doesn't seem to be any rhyme or reason as to what gets isolation equipment and what doesn't. For instance we have smallish motors the size of a pb ultra 13 that are on rubber/spring isolation racks but then our 2 mega watt motor/generators are not.
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post #18 of 29 Old 06-02-2013, 07:05 PM
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Wont make any difference.. Take a car with open headers and ruv it up in the garage and see how it shakes things up. Now take that same car and pull the shocks and tires and drop it to the floor. Once again ruv it up. I guarantee you it will shake things up just the same.. just sayin. The analogy you make is totally different.

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post #19 of 29 Old 06-02-2013, 08:31 PM
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Originally Posted by DotJun View Post

It's funny you mention this because at work there doesn't seem to be any rhyme or reason as to what gets isolation equipment and what doesn't. For instance we have smallish motors the size of a pb ultra 13 that are on rubber/spring isolation racks but then our 2 mega watt motor/generators are not.
I see plenty of reasoning there. The smaller motors will vibrate and that vibration can be transferred to the floor. Being small it's relatively easy to iso-mount them. The big mothers are so heavy that they either don't vibrate or if they do you couldn't find a isolation mount big enough to handle them. Subs don't need isolation mounting because they simply do not vibrate in the lows; if they did they would be unlistenably defective.

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post #20 of 29 Old 06-02-2013, 09:49 PM
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Originally Posted by shadyJ View Post

His credentials are nice and all, but lets see some evidence that speakers and subs do transfer energy to the floor before we solve a problem that doesn't exist.
Lots of subwoofers that don't use some sort of "balanced -force" driver layout have appreciable cabinet resonance. Certainly those forces can be transmitted to the floor. I've seen subwoofers move across the floor on hard wood or tile floors. I've even seen some subwoofers rock at low frequencies. I'm not saying all subwoofers do this, but certainly some do. Of course, some will call those subs "defective," and I won't disagree that the cabinet resonances in those subs should be tamed. Nonetheless, they still exist and isolation pads can improve the result with those subs.

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post #21 of 29 Old 06-02-2013, 10:04 PM
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Originally Posted by Bill Fitzmaurice View Post

+1. Just like high price cable companies isolation device companies are long on spiel and short on proof. And more than one industry professional who should have known better has fallen for unsubstantiated claims made by purveyors of every sort of snake oil imaginable.
Yeah, Tony is big-time into snake oil... like bass traps and acoustic panels and diffusers... all the really esoteric, expensive stuff that doesn't really make your system sound any better: rolleyes.gif

http://www.youtube.com/user/msracoustics?feature=watch

He's also big time into sound isolation and building rooms that don't transmit sound to adjacent spaces.

And he doesn't use "SubDude's" to isolate the subwoofers or the rooms. He uses rubber isolation blocks. It's not like he's using expensive or esoteric products to do this stuff, so please get over the snake oil thing.

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post #22 of 29 Old 06-02-2013, 11:04 PM
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Originally Posted by Bill Fitzmaurice View Post

I see plenty of reasoning there. The smaller motors will vibrate and that vibration can be transferred to the floor. Being small it's relatively easy to iso-mount them. The big mothers are so heavy that they either don't vibrate or if they do you couldn't find a isolation mount big enough to handle them. Subs don't need isolation mounting because they simply do not vibrate in the lows; if they did they would be unlistenably defective.
I see the logic and this might not be the same thing but as far as not having isolators big enough, aren't there isolators that are used on large structures for earthquakes? Big as in multi-story buildings.
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post #23 of 29 Old 06-03-2013, 06:34 AM
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Originally Posted by DotJun View Post

I see the logic and this might not be the same thing but as far as not having isolators big enough, aren't there isolators that are used on large structures for earthquakes? Big as in multi-story buildings.
Yes, but they aren't there to keep vibrations in the building from causing the earth below to shake. smile.gif
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Yeah, Tony is big-time into snake oil... like bass traps and acoustic panels and diffusers... all the really esoteric, expensive stuff that doesn't really make your system sound any better:
I gave him credit where it was due, and called him on where it was not. Specifically: Grimani recommends putting subwoofers and floorstanding speakers on rubber blocks instead of placing them directly on the floor. Doing so reduces the transfer of acoustic energy into the floor That simply isn't true. Neither is: “All spikes do is ensure that low-frequency vibration from the woofers is really pushed down into the floor Spikes do not serve as a conduit for low frequency vibrations.

I also recommend using rubber feet when subs are on bare floors, not because it prevents the transfer of acoustic energy into the floor, but because it prevents the vibrations of the floor from causing the sub to vibrate atop it.
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post #24 of 29 Old 06-03-2013, 09:02 AM
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Originally Posted by Bill Fitzmaurice View Post

I gave him credit where it was due, and called him on where it was not. Specifically: Grimani recommends putting subwoofers and floorstanding speakers on rubber blocks instead of placing them directly on the floor. Doing so reduces the transfer of acoustic energy into the floor That simply isn't true.
I agree that they don't stop "acoustic " transfer of energy to the floor. However, they can stop mechanical transfer of energy to the floor. If the subwoofer has some cabinet resonance, that mechanical energy can certainly be mechanically transferred to the floor. Isolation blocks can stop that transfer. It's a semantic difference, but I'm sure that's what he meant.[/quote]
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Neither is: “All spikes do is ensure that low-frequency vibration from the woofers is really pushed down into the floor Spikes do not serve as a conduit for low frequency vibrations.
Oh c'mon. If you have speakers or a sub with some cabinet resonance, the BEST way to couple that energy to the floor is to put the box on spikes. rolleyes.gif
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Originally Posted by Bill Fitzmaurice View Post

I also recommend using rubber feet when subs are on bare floors, not because it prevents the transfer of acoustic energy into the floor, but because it prevents the vibrations of the floor from causing the sub to vibrate atop it.[/quote[
Maybe *your* subs don't generate any mechanical resonances. Mine don't either. But many subs do. Isolation blocks can stop the transfer of energy in both directions.

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post #25 of 29 Old 06-03-2013, 09:39 AM
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Maybe *your* subs don't generate any mechanical resonances. Mine don't either. But many subs do. Isolation blocks can stop the transfer of energy in both directions.
Subs that aren't defective don't have mechanical resonances within the sub woofer pass band. If they did they would function so poorly that they wouldn't be able to generate enough low end to vibrate anything. Panel resonances do occur, but they occur well up in the midrange, 500Hz or higher. No floor is going to be vibrated by a panel vibrating perhaps a tenth of a millimeter at 500Hz. As for spikes, if they were going to transfer any of that 500Hz or so vibration they'd have to be mounted to the sub where the panel vibrates the most, in the middle. But spikes are mounted at the corners of the sub, where it is structurally the strongest and most stiff, and there is no vibration to transfer.
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It's a semantic difference, but I'm sure that's what he meant.
Whether he meant to say it or not doesn't matter, he did, and it was incorrect. As a result the OP and who knows how many others are encouraged to believe an audio myth and spend money fixing something that isn't broken. IMO that's the sort of thing this forum is here to prevent.

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post #26 of 29 Old 06-03-2013, 09:50 AM
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Originally Posted by padgman1 View Post

So here's a question that will pertain to me..........

In AVS Forum participants' experience, at what bass SPL or db level do objects tend to move significantly ( pictures on wall, curio objects in cabinets, glassware on tables, etc)? I am thinking about purchasing a subwoofer for my ~2100 cu ft family room open to kitchen, and I have 2 large entertainment cabinets which both have curios and pictures on shelves, along with pictures on fireplace mantle.......if any of these items were to be damaged by excessive bass levels ( esp. the Hummel figurines!!), my goose would be cooked.......

I normally do NOT listen to music/ Bluray discs at above reference levels ( or ~95db)......and probably do NOT need bass to exceed these levels .........

I have my subs on DIY sub iso platforms, the room is 1st floor with basement under it and floor is carpeted. If I play the Crossover sweep on THX Optomiser (200hz - 20hz) even at -30db when the tone hits 20hz, stuff all over my house vibrates, rattles, moves (pictures on wall or curio type things). Never caused anything to fall but after watching a movie at -30db all pictures on 1st floor are crooked. My wife hates it.

Shawn
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post #27 of 29 Old 06-03-2013, 10:47 AM - Thread Starter
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I thank everyone (so far) for their input..............

A future sub will go on carpet ( thick berber) so I probably will not need any isolation/rubber pads.....

Any actual research on said isolation pads on subwoofer output/ SQ/ vibration reduction on different surfaces ( hardwood/concrete, carpeted room, etc)?
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post #28 of 29 Old 06-03-2013, 11:10 AM
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Originally Posted by padgman1 View Post

I thank everyone (so far) for their input..............

A future sub will go on carpet ( thick berber) so I probably will not need any isolation/rubber pads.....

Any actual research on said isolation pads on subwoofer output/ SQ/ vibration reduction on different surfaces ( hardwood/concrete, carpeted room, etc)?
I measured the response of my THT sub and my David tower with the test mic in the room, in the next room, and in the room below, with the cabinet sitting on a carpeted floor, on four inches of high density acoustic foam, on rubber feet and on spikes. In each case the measured responses of the four options were identical. I didn't go to the effort of removing the carpet to see how that would measure, but the effect of a carpet on in-room response and transmission through the floor lies above the subwoofer frequencies, as carpet is acoustically 'invisible' below roughly 200Hz.

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post #29 of 29 Old 06-03-2013, 11:53 AM - Thread Starter
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Originally Posted by Bill Fitzmaurice View Post

I measured the response of my THT sub and my David tower with the test mic in the room, in the next room, and in the room below, with the cabinet sitting on a carpeted floor, on four inches of high density acoustic foam, on rubber feet and on spikes. In each case the measured responses of the four options were identical. I didn't go to the effort of removing the carpet to see how that would measure, but the effect of a carpet on in-room response and transmission through the floor lies above the subwoofer frequencies, as carpet is acoustically 'invisible' below roughly 200Hz.

Thanks, Bill...........good to know...........
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