"Isolation pad" for subs? - AVS Forum
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post #1 of 60 Old 04-08-2012, 10:06 PM - Thread Starter
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What is an isolation pad and where can I get one? Do they work? Can I make one?

In terms of LFE, size does matter!
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post #2 of 60 Old 04-08-2012, 11:56 PM
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an isolation pad prevents the sub from transmitting its vibrations to your home structure.

wal-mart sells a foam "seat" cushion for hunters that is about 1.25" thick, 18" wide and 14" deep. it is made to insulate hunters butts from cold rocks or snow, but it will also minimize vibrations from your sub to the floor. costs about $10.

if you want to spend more money, i think there is a product called subdude or something like that. about $50+ for that one...http://www.auralex.com/sound_isolati...de/subdude.asp
available on amazon...

you could probably visit the dumster of a carpet store and get all the padding that you need to decouple your sub from the floor for free if that is your thing.

the theory is that you do not want your sub to vibrate your structure because it wastes a whole lot of energy and creates annoying resonances. dual opposed wont vibrate the structure, neither will subs built with heavy cabs and light drives. if using a light enclosure and heavy drives, you may get some benefit from decoupling the enclosure from the enclosure, but its a cludge, not an optimal design.

as a side note, the whole "spiked" mains design was to couple the enclosures to the floor in order to minimize the vibrations of the cabs, which in theory gave better midrange performance.

when monster subs came on the scene, this idea got thrown out, as the vibration coming from the enclosure could not be held be the floor and it created all kinds of resonances and vibrations in the structure.

the response solution was to simply decouple it from the structure.
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post #3 of 60 Old 04-09-2012, 05:14 AM
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Quote:
Originally Posted by LTD02 View Post

an isolation pad prevents the sub from transmitting its vibrations to your home structure.

That's what sellers of them say, but it's not the case. A sub with panels that vibrate so badly that they could cause the floor to vibrate is defective.
What can happen with a 'soft' floor is that it can vibrate as a result of the acoustic output of the sub, and the vibrating floor can cause the sub atop it to vibrate. You can spend $50 or more for an isolation pad, but a piece of this cut to size works just as well:
http://www.walmart.com/ip/Ozark-Tria...-Blue/16783660

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post #4 of 60 Old 04-09-2012, 05:51 AM
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I did some "testing" with different foams I had. That harder foam doesn't do much for isolating. The thicker open cell foam seemed to work much better.


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post #5 of 60 Old 04-09-2012, 10:32 AM
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Quote:
Originally Posted by Bill Fitzmaurice View Post

That's what sellers of them say, but it's not the case. A sub with panels that vibrate so badly that they could cause the floor to vibrate is defective.
What can happen with a 'soft' floor is that it can vibrate as a result of the acoustic output of the sub, and the vibrating floor can cause the sub atop it to vibrate. You can spend $50 or more for an isolation pad, but a piece of this cut to size works just as well:
http://www.walmart.com/ip/Ozark-Tria...-Blue/16783660

Thanks for the link to the Wal-Mart material. I have a bunch of leftover carpet pad laying around, would that effectively be the same as this camping pad?
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post #6 of 60 Old 04-09-2012, 10:37 AM
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Auralex also makes Acoustic Pads as well under MOpad line as well, and they always worked great at all the studios I worked at over the years. Regular 2" thick Pads will get the job done as well, but They aren't balanced frequency wise.. But may not be a big deal for your situation though....
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post #7 of 60 Old 04-09-2012, 12:30 PM
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Quote:
Originally Posted by jholzbauer View Post

Thanks for the link to the Wal-Mart material. I have a bunch of leftover carpet pad laying around, would that effectively be the same as this camping pad?

+1, you just have to experiment to see how many layers it takes to do the job.

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post #8 of 60 Old 04-09-2012, 04:53 PM
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Quote:
Originally Posted by Bill Fitzmaurice View Post

That's what sellers of them say, but it's not the case. A sub with panels that vibrate so badly that they could cause the floor to vibrate is defective.
What can happen with a 'soft' floor is that it can vibrate as a result of the acoustic output of the sub, and the vibrating floor can cause the sub atop it to vibrate.

If that's the case then why would an isolation pad be desirable at all?

Do they actually cause an appreciable reduction in resonances (i.e. crap in your house vibrating)?


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post #9 of 60 Old 04-09-2012, 07:49 PM
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Quote:
Originally Posted by halo0 View Post

Do they actually cause an appreciable reduction in resonances (i.e. crap in your house vibrating)?

No. Stuff vibrates because of the acoustic output of the subs.

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post #10 of 60 Old 04-09-2012, 07:52 PM
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^Then what "job" is being done when you reach the correct number of layers?

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Originally Posted by Bill Fitzmaurice View Post

+1, you just have to experiment to see how many layers it takes to do the job.



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post #11 of 60 Old 04-09-2012, 07:55 PM
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"A sub with panels that vibrate so badly that they could cause the floor to vibrate is defective."

that's not what i'm talking about. i'm talking about having a heavy driver in an unbalanced/underweight cabinet where the entire cabinet is vibrating from the movement of the driver.

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post #12 of 60 Old 04-10-2012, 06:06 AM
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Quote:
Originally Posted by LTD02 View Post

i'm talking about having a heavy driver in an unbalanced/underweight cabinet where the entire cabinet is vibrating from the movement of the driver.

If it's moving about energy is being wasted. Stop it from moving. The cab is still technically defective, it shouldn't be unbalanced/underweight.
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Then what "job" is being done when you reach the correct number of layers?

The job that I noted in my first post.

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post #13 of 60 Old 04-10-2012, 12:01 PM
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How about a hunk of marble about inch thick sitting on top of your floor carpet and padding?

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post #14 of 60 Old 04-10-2012, 01:32 PM
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Originally Posted by Ratified View Post

How about a hunk of marble about inch think sitting on top of your floor carpet and padding?

If the sub is moving about because it's too light you'd do better to put the marble on top of the sub.

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post #15 of 60 Old 04-10-2012, 03:12 PM
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Not to keep the sub from moving, but to isolate it from the floor.

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post #16 of 60 Old 04-10-2012, 03:25 PM
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elemental designs was selling some isolation pads at one point. Not sure if they were anything more than MDF platforms with closed cell foam feet. But you should get in touch with Alex , as i am sure he could give you the scoop.

Tim
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post #17 of 60 Old 04-10-2012, 03:47 PM
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These have to be some of the stupidest posts I have ever read...The sub is not heavy enough if it causes vibrations??? Lets be serious, I guess my Seaton Subermersives are defective.

Favele, pm when you get a chance and I will give you my low down on subdudes. Best things I ever bought, made a HUGE difference. you will not regret it. Dont want to start a war here (probably already have)
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post #18 of 60 Old 04-10-2012, 03:50 PM
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Quote:
Originally Posted by drpete12 View Post

Favele, pm when you get a chance and I will give you my low down on subdudes. Best things I ever bought, made a HUGE difference.

What kind of difference exactly?


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post #19 of 60 Old 04-10-2012, 04:44 PM
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Quote:
Originally Posted by drpete12 View Post

These have to be some of the stupidest posts I have ever read...The sub is not heavy enough if it causes vibrations???

They wouldn't seem so if you read them to the point of comprehending what was said.

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post #20 of 60 Old 04-10-2012, 05:06 PM
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I put 4 hockey pucks on my subs @ $0.99 each.

Cheap and effective.


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post #21 of 60 Old 04-12-2012, 05:02 PM
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Halo0:

When I got my 2 seaton submersives (which I ran extremely hot the first day or two to see what they could do). Everything downstairs in the kitchen would rattle. Pictures fell off the wall. The transferance of vibration from the sub to the floor and floor to other structures was OUTRAGEOUS. When the subdudes came in, I kept the subs equally "hot". I placed both subs on a subdude and tried the same movie scenes (Thor was a big one for me).

Yes you could hear bass downstairs, I dont expect the subdudes to stop 4800 watts of bass from being heard downstairs. But I had NO rattling of dishes, the pictures werent shaking and the amount of vibration heard downstairs was almost zero (note bass was still heard).

All the trouble I was having was from the physical vibrations of the sub being carried thru the house wood structure, not from the bass waves given off from the sub. Best way to describe it is if you could suspend your sub from the ceiling with 3 or for springs. The sub would transfer no vibration (in theory) to the house structure, but you would still get vibrations from the bass waves. The subdudes isolate it in this manner. For the money they did wonders.

You could probably do better with a free floating floor that is isolated with varying isolation products but that is not a 50-100 dollar fix.

If you place a 500 pound piece of marble on top of sub all you are going to do is make sure its vibrations are better transferred to the house structure. I suppose that in theory you could put enough weight on it so that the vibration does not have enough energy to carry on thru the house but let me tell you this: I beleive (dont quote me) the weight of the seaton sub is around 140 pounds. I have a JTR t-12 sitting on top of it, that is about 125 pounds. You are talking 265 pounds and without subdude it went thru the house. How much more should I really put before you think it wont vibrate?

Hope this helps
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post #22 of 60 Old 04-12-2012, 05:43 PM
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Thanks for that. I'm building a sub right now that will probably be a similar weight to a submersive so it's good to know the sub dude can handle that. Your endorsement is enough evidence for me to give it a try, if it does what you say it will be worth its weight in gold.


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post #23 of 60 Old 04-12-2012, 09:11 PM
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Quote:
Originally Posted by Bill Fitzmaurice View Post

A sub with panels that vibrate so badly that they could cause the floor to vibrate is defective.

Just finished an evening stressing out the Plutos with some bass-heavy without any subs running. Sitting about 2-3m away on the couch with my feet up I got a real nice massage from the couch and footrest. After the music stopped I felt a little numb tingle ... and this is from two 5" drivers! (yes, the cones were bouncing good and plenty)

The vibration is not coming from the sound, it's from the sprung-mass of the driver accelerating. Mind you, these are up-firing drivers so their inertia is driven right into the floor.
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post #24 of 60 Old 04-13-2012, 04:48 AM
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Halo0

no problem. There havent been very many things in my home theater I have done that have made a profound change for very little dollars. The subdudes were definitely one of them. Just a note, I ordered the gramma's, they are slightly larger dimension than the subdudes but are the same materials.
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post #25 of 60 Old 04-13-2012, 05:34 AM
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24 posts and not a single mention of Sorbothane...
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post #26 of 60 Old 04-13-2012, 05:50 AM
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Down in the theater building threads we have been building stages filled with sand. Pretty good as a dampener for vibrational transfer. Keep it 1/2 inch from all the walls.


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post #27 of 60 Old 04-13-2012, 06:18 AM
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Quote:
Originally Posted by martinq View Post


The vibration is not coming from the sound, it's from the sprung-mass of the driver accelerating. Mind you, these are up-firing drivers so their inertia is driven right into the floor.

I guess that's possible, but that would indicate a poor design, and I very much doubt that's the case. Any energy expended in bouncing the cab about is energy not being utilized as sound output, and good speaker designs well implemented and constructed simply don't do that. Good speakers do produce high acoustic output, and it's high acoustic output that causes objects and structures to sympathetically vibrate.

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All the trouble I was having was from the physical vibrations of the sub being carried thru the house wood structure,

I think Mark would disagree that his subs vibrate. Knowing the quality of his work I'm sure they're as inert as the Rock of Gibraltar.

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post #28 of 60 Old 04-13-2012, 06:27 AM
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THX recommends using isolation material-see below.


http://drhart.ucoz.com/index/architr...tions_thx/0-49

3. Isolation Pads One Mason "Super W" pad (Durometer 40) is used under each corner of the screen woofers and the subwoofers to isolate the vibrations of the speakers from the baffle structure. A list of Mason Industries' representatives is available from the THX design office.
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post #29 of 60 Old 04-13-2012, 06:59 AM
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Quote:
Originally Posted by Bill Fitzmaurice View Post

I guess that's possible, but that would indicate a poor design, and I very much doubt that's the case. Any energy expended in bouncing the cab about is energy not being utilized as sound output, and good speaker designs well implemented and constructed simply don't do that.

I wouldn't call the Pluto a poor design, I don't think Linkwitz would agree. It is very light though as the 'box' is a 3' piece of 4" sewer pipe. No doubt an isolation pad/springs would keep the wooden floor from drumming ... but that would take out all the fun! Dual-opposed or a concrete floor would also 'fix' this issue, but I'm definitely not complaining.
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post #30 of 60 Old 04-13-2012, 08:03 AM
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Quote:
Originally Posted by localhost127 View Post

24 posts and not a single mention of Sorbothane...

Do you have experience with it? I see they sell quite a few different types at Amazon. Perhaps I'll make some feet for my sub with it and compare it to a subdude.


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