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post #1 of 53 Old 07-20-2011, 07:56 PM - Thread Starter
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http://www.acousticalsolutions.com/v...isolation-pads

http://www.auralex.com/sound_isolati...ion_gramma.asp

Does anyone know what the difference is functionally between these two? I've read about people using either of these as sub risers. I'm hoping to diminish noise/vibration in rooms around/below me without sacrificing sound quality or levels in my own room. Does anyone know which of these would be better for this?

Thanks a lot for any help,
Dave
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post #2 of 53 Old 07-21-2011, 05:41 PM
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What kinds of floors do you have? Wood, carpet, etc

Personally, I would use the Gramma over the anti vibration pad due to the fact that it gets it a bit more off the floor.

Read more here -

http://forum.blu-ray.com/subwoofers/...er-risers.html
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post #3 of 53 Old 07-22-2011, 06:58 AM - Thread Starter
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Hey, thanks for the reply. It is a wooden floor. Originally, I was going to opt for the Gramma too, but it just seemed like the vibration pad might be better for cutting off sound/vibration to the downstairs. But, it also seems like the vibration pad might cut off some of what I hear in my own room.

Thanks again!
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post #4 of 53 Old 07-22-2011, 07:53 AM
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I have a neighbor who lives underneath my living room and two 15's. She can only hear my sub now when played loud really late at night. I had 1 14" sub and before I got the gramma she could hear it all the time. Go for the gramma.
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post #5 of 53 Old 07-22-2011, 11:49 AM - Thread Starter
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I think we have a winner. Thanks a lot!
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post #6 of 53 Old 07-22-2011, 08:18 PM
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The GRAMMA is 23" x 15". Do you need an isolation platform that long for the footprint of your sub? If not, Auralex also offers the SubDude and SubDude(HD), 15" x 15" isolation platforms specifically with subs in mind. Both SubDudes are functionally identical; the only advantage of the SubDude(HD) is that it is wrapped in a more aesthetically pleasing, home friendly black fabric.

http://www.auralex.com/sound_isolati...de/subdude.asp
http://www.auralex.com/sound_isolati...subdude_hd.asp

AJ
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post #7 of 53 Old 07-22-2011, 08:47 PM
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Subdued is better for smaller subs. The only reason I have the gramma is because my subs are 20wx25d. Subdueds look better anyways. Grammas are $49 at guitar center.
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post #8 of 53 Old 08-05-2011, 10:08 AM
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I'm going to snag a couple of these from work. They're about 2" thick and dense.

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post #9 of 53 Old 08-05-2011, 11:46 AM
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No WAF to worry about there
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post #10 of 53 Old 08-05-2011, 01:29 PM
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Build your own. that's what I did, and they were cheap ($15 ea?), easy (2 hours ea?), and matches the subs and my room (Exactly the same dimensions as the sub, and the carpet is leftover from the installation).





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post #11 of 53 Old 08-05-2011, 02:21 PM
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That's a solid looking riser. Nice work!
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post #12 of 53 Old 08-05-2011, 02:30 PM
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Quote:
Originally Posted by leninGHOLA View Post

That's a solid looking riser. Nice work!

Thanks! The base is an old 1" solid wood butchers block, cut to size and wrapped in the carpet. This was then screwed onto the 6" tall foam corners that originally packed my sub. The foam was wrapped in black felt, and the centre 'void' was filled with 2" pyramid foam. The whole thing stands 7"-8" tall.

The sub's spikes sit on the included metal discs, which in turn sit on the carpeted riser.

It does wonders for the vibrations.

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post #13 of 53 Old 08-05-2011, 02:41 PM
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I though I recognized that eD cork-looking foam. Yours is halfway between a riser and a full on bass trap.

My DIY was fairly similar, but a couple inches shorter, and not as well finished. They were throwing out some MDF and acoustic foam at work, so my total cost was just the regular speaker carpet.
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post #14 of 53 Old 08-05-2011, 03:38 PM
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Quote:
Originally Posted by leninGHOLA View Post

What kinds of floors do you have? Wood, carpet, etc

Personally, I would use the Gramma over the anti vibration pad due to the fact that it gets it a bit more off the floor.

Read more here -

http://forum.blu-ray.com/subwoofers/...er-risers.html

Isolation will have an effect, undoubtedly. Simply raising the sub off the ground a bit as Blu-Ray suggests, probably not.

Hearing is believing....WOW!

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post #15 of 53 Old 08-05-2011, 04:16 PM
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Originally Posted by tesseract67 View Post

Isolation will have an effect, undoubtedly. Simply raising the sub off the ground a bit as Blu-Ray suggests, probably not.

Hearing is believing....WOW!

Yea, my thought was the rubber isolation mat simply wouldn't decouple as well as a Gramma. The mat is intended more for industrial use, likely not resonating at the same frequencies as a sub. Though, two layers would probably do the trick. Having not tested anything beyond traditional riser or "the rug trick" myself, I can't say for sure.

I don't put much stock in the vertical axis theory. As long as the sub is isolated, there shouldn't be much in the way of sound difference after that, barring room treatments.
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post #16 of 53 Old 08-05-2011, 04:21 PM
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The commercially available products are nice .. however, a little DIY like 5seonds said can save you some cash .. which is kinda nice these days ..

There is a difference .. my dual configuration was much more pleasing and less wall rattling after de-coupling ..

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post #17 of 53 Old 08-05-2011, 04:26 PM
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I use 3/4x16x16" rubber decking tiles made for patios and such. I seen some last week at the hardware store for $2.50 each. They are made out of recycled tires, their purpose is to dampen footfalls. They don't let the sub wiggle around like some devices do. Definitely made an improvement on my suspended hardwood flooring, although probably not as good at isolation as the Gramma.

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post #18 of 53 Old 08-05-2011, 07:47 PM
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Quote:
Originally Posted by machavez00 View Post

I'm going to snag a couple of these from work. They're about 2" thick and dense.

Quote:
Originally Posted by leninGHOLA View Post

No WAF to worry about there

She wouldn't be able to see it. I may need one only (cut it into four pieces small enough to fit under each foot)

This is bigger than our ottoman and the WAF would be 0

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post #19 of 53 Old 08-06-2011, 10:07 AM
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Quote:
Originally Posted by machavez00 View Post

This is bigger than our ottoman and the WAF would be 0

It has the same footprint as the sub itself, so it takes up no room at all. (It does make the sub taller/more noticeable, so there is that I guess.) I would not have been able to get away with this in the livingroom, but in the TV room downstairs, no problem from the wife. Saying that, I would not have been able to get away with the size of the A2-300 in the livingroom either, so it's a moot point!
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post #20 of 53 Old 03-04-2013, 07:14 AM
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I want to build my own subwoofer isolation rise with the left over material from my studio build for two 15 inch subs I have MDF , quietrock , 4 inch thick rockwool and some 2 inch 12×12 wedged acoustic tile will this combo work well together as a sub iso riser ? Please help no money left to buy a Gramma !
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post #21 of 53 Old 03-04-2013, 07:23 AM
 
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Quote:
Originally Posted by BIGBOC View Post

I want to build my own subwoofer isolation rise with the left over material from my studio build for two 15 inch subs I have MDF , quietrock , 4 inch thick rockwool and some 2 inch 12×12 wedged acoustic tile will this combo work well together as a sub iso riser ? Please help no money left to buy a Gramma !

As to a choice in building materials and what one has around the home? If it hinders heat transmission, it will hinder sound and vibration transmission.

Steel vs foam.

When it comes to energy disbursement, thicker is better as there's more material in which to diffuse the energy.

Wood vs thick foam pillow like a sofa pad.

Example; a wood frame (plywood flooring) for support with wood stub legs to raise off the floor with an old spare pillow in the frame and the subwoofer on top of the pillow. If a fifth stubby leg is added to the center of the bottom, one could use sheetrock for the bottom of the wood frame.

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post #22 of 53 Old 03-04-2013, 07:43 AM
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So do I need to put legs on it or will the rockwool support it
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post #23 of 53 Old 03-04-2013, 08:04 AM
 
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So do I need to put legs on it or will the rockwool support it

No sure how you plan to place the rockwool but yes, a thick pad of unsupported rockwool would do the trick as well.

For purpose of stability, it wouldn't hurt to put a small, similar sized piece of stiff material under any legs on the subwoofer (two or three inches square) but if no legs and properly centered for stability, depending on the thickness of the rockwool, subwoofer being placed flat on the pad of rockwool, you should be good.

The problem I see with your above, if the unsupported rockwool is not thick enough, the rockwool will compress under the weight of the sub and now the rockwool becomes hard (compacted) and will transfer energy to the floor which has the affect of diminishing the energy diffusion you're looking for.

The ideal is to have the weight of the subwoofer absorbed by the supporting material and there to be no additional compaction at the bottom (pad to floor contact) where the isolation material meets the floor.
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post #24 of 53 Old 03-04-2013, 08:49 AM
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Quote:
Originally Posted by tmgaus51 View Post

Hey, thanks for the reply. It is a wooden floor. Originally, I was going to opt for the Gramma too, but it just seemed like the vibration pad might be better for cutting off sound/vibration to the downstairs. But, it also seems like the vibration pad might cut off some of what I hear in my own room.


Thanks again!

I use multiples of these under my fairly potent subs on a suspended wood floor and they work great. I also own Great Grammas and prefer these unobtrusive yet effective isolators.

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post #25 of 53 Old 03-04-2013, 09:21 AM
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Does anyone know what the difference is functionally between these two? I've read about people using either of these as sub risers. I'm hoping to diminish noise/vibration in rooms around/below me without sacrificing sound quality or levels in my own room. Does anyone know which of these would be better for this?
Next to high priced cables and power conditioners isolation pads and spikes are the biggest scams in audio. The following quoted claims are taken straight from the websites of manufacturers of these devices.

The Isolation Claim: ‘Its purpose is to prevent sound from transmitting through your subwoofer to surrounding surfaces. Subwoofers create big vibrations (low frequencies) that you can feel in the floor and in objects placed nearby. When the source of the vibrations is coupled directly to the floor it causes these objects to vibrate or resonate…’

The Truth: The source of these vibrations is the movement of the driver cone. The claim would only be true if you coupled the driver cone to the floor. If the cabinet panels vibrate enough to cause the floor to vibrate the speaker is defective.

The Decoupling Claim: ‘Isolators for your speakers…will decouple your speakers from the surface they rest upon, resulting in a more pure, accurate tone. Low frequencies will be projected and will no longer lack the definition you desire. Mid and high frequencies will be crisp and intelligible. Rattles and resonances will be a thing of the past.’

The Spike Claim: ‘By rigidly coupling a loudspeaker enclosure to a floor by means of a spiking system, it is possible to dramatically improve clarity, stereo imaging and bass response. This is very apparent with subwoofer systems.’

The Quandary: These sources claim the same benefits from coupling and from decoupling. Who’s telling the truth?

The Truth: Both are lying. Isolation and coupling makes no difference. To test this I measured the response of my THT and my David with the test mic in the room, in the next room, and in the room below, with the cabinet sitting on the carpeted floor, on four inches of high density acoustic foam, on rubber feet and on spikes. I’d post the measured results for each set of comparisons, but there would be no point. In each case the measured responses of the four options were identical.

Note that this was on a carpeted floor. There may be some slight benefits to isolation devices or rubber feet on a bare floor, or on a bare shelf or stand. But you never want a bare floor, it’s an acoustical nightmare. If you only have area rugs in your listening room stick a piece of felt carpet padding, a carpet scrap or rubber feet under your speaker. If you're using bookshelves on a bare shelf or stand small rubber feet or felt pads are all you need to prevent spurious vibrations.

The Endorser Claim: ‘I tried them and they work, I know what I’m hearing!’

The Truth: The first thing you learn in an acoustical engineering course is that you don’t know what you’re hearing. If you did you’d be able to listen to a speaker, take pencil and graph paper in hand, and draw a frequency response chart, THD chart and waterfall plot, all with 1/24 octave resolution and 1/10dB accuracy. Our ears just aren’t that good, not by a very wide margin. But our imagination works very well, and that clouds our audio judgment, leading to placebo effect. In short, if you think something will make a difference in the sound, it will.

One item that's always missing from both manufacturers and owners claims are measured results, before and after. We often say 'If you don't have a picture it didn't happen'. In this case that picture is measured in-room response. When virtually anyone who's really serious about their sound has REW or the like that's not a lot to ask.

For an in depth examination of why we really don’t know what we’re hearing check out this video:
http://www.youtube.com/watch?v=BYTlN6wjcvQ
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post #26 of 53 Old 03-04-2013, 09:34 AM
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Quote:
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The Truth: The source of these vibrations is the movement of the driver cone. The claim would only be true if you coupled the driver cone to the floor. If the cabinet panels vibrate enough to cause the floor to vibrate the speaker is defective.

therefore, all subs whose cabinets vibrate have defective drivers.

Ah the truth ... how refreshing ... rolleyes.gif

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post #27 of 53 Old 03-04-2013, 10:36 AM
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therefore, all subs whose cabinets vibrate have defective drivers.

Ah the truth ... how refreshing ... rolleyes.gif

He's not necessarily pinning this on defective drivers, as far as I can tell. He's saying that the speaker as a whole is defective, which I take to mean that a whole host of things could be wrong, but that the design and construction of the cabinet and bracing would be most suspect.

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post #28 of 53 Old 03-04-2013, 11:03 AM
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He's not necessarily pinning this on defective drivers, as far as I can tell. He's saying that the speaker as a whole is defective, which I take to mean that a whole host of things could be wrong, but that the design and construction of the cabinet and bracing would be most suspect.
A subwoofer cabinet that vibrates within the subwoofer pass band is defective. Well designed and built subs shift any panel resonances well up into the midrange, where they're incapable of transmitting any low frequency vibrations to the floor. If there was a shred of truth to the claims of the isolation shysters we'd listen to our subs by putting an ear against them.

Anyone who has the before and after measured charts, by all means post them.

A high percentage of the guys in the DIY section have REW or other measuring gear, and most of them have sub setups that are gargantuan compared to those used by the average sub owner in this section. Not to be insulting, but guys who really know what they're doing don't buy subs, they build them. Most of those who build them design them. In three years I haven't seen a single post in the DIY section about isolation.

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post #29 of 53 Old 03-04-2013, 11:25 AM
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Quote:
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A subwoofer cabinet that vibrates within the subwoofer pass band is defective. Well designed and built subs shift any panel resonances well up into the midrange, where they're incapable of transmitting any low frequency vibrations to the floor. If there was a shred of truth to the claims of the isolation shysters we'd listen to our subs by putting an ear against them.

Anyone who has the before and after measured charts, by all means post them.

A high percentage of the guys in the DIY section have REW or other measuring gear, and most of them have sub setups that are gargantuan compared to those used by the average sub owner in this section. Not to be insulting, but guys who really know what they're doing don't buy subs, they build them. Most of those who build them design them. In three years I haven't seen a single post in the DIY section about isolation.

Kinda hard to isolate an IB sub, lol

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post #30 of 53 Old 03-04-2013, 11:32 AM
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Kinda hard to isolate an IB sub, lol
I don't know what that has to do with DIY, but in any event IB stands for 'infinite baffle'. All sealed subs are infinite baffle.

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