# Auralex great gramma



## asere (Dec 7, 2011)

Would a platform under the sub help with reflections? I think its called a subdude. Currently I have a flat response on my sub so not sure if it would help.


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## Prof. (Oct 20, 2006)

A Subdude is designed to reduce the transmission of vibrations through the floor..helping to reduce any losses in the frequency response..
If your FR is flat now, you may not need it..


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## theJman (Mar 3, 2012)

A platform like the SubDude isolates the cabinet from the floor, thereby "decoupling" the vibrations it transmits. Often time you'll hear the room resonate from the direct contact, causing things to vibrate in a sympathetic manner. You can often minimize the extraneous unpleasant sounds by insulating the sub from the room itself.


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## tesseract (Aug 9, 2010)

I use SubDudes under each of my subs to help mitigate room (and other rooms, too) vibrations. Flat frequency or not, rattles are distortion and addressing them cleans up the sound.

I have suspended flooring (crawlspace) which ripples with the very low bass waves, the SubDudes took much of it away. I do miss that. :hsd:


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## asere (Dec 7, 2011)

Will it keep the pressure in the room from traveling or be heard in another room? Say if someone is asleep?


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## tesseract (Aug 9, 2010)

No, the very long wavelengths will still travel though the structure as before.


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## asere (Dec 7, 2011)

When there are low frequencies like in a movie is the sub suppose to sound like an echoe apart from tight bass?


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## tesseract (Aug 9, 2010)

It sounds like you might be describing "boominess". This could be caused by placing the sub too close to boundaries. Perhaps you could try moving the sub out away from a wall, little by little, see if this helps.


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## asere (Dec 7, 2011)

Its smooth at times, boomy at other times. Were its at now has highest spl.


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## tesseract (Aug 9, 2010)

asere - Trying the Gramma or SubDude might help push it toward smooth all the time.


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## asere (Dec 7, 2011)

85 is a lot not knowing if it will work.


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## asere (Dec 7, 2011)

Just bought the auralex great gramma. We'll see how good it is.


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## theJman (Mar 3, 2012)

Just curious; what sub(s) do you have?


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## asere (Dec 7, 2011)

theJman said:


> Just curious; what sub(s) do you have?


I own the Hsu vtf3 mk4


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## asere (Dec 7, 2011)

theJman said:


> Just curious; what sub(s) do you have?


I don't have a problem with rattles just trying to see if bass will be tighter. Like I said it before my sub sits on carpet. We'll see if great gramma works.


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## Todd Anderson (Jul 24, 2009)

I don't think there is much evidence that it makes bass tighter. I talked to Dr. Hsu and he he didn't think it would have a noticeable effect. I'd assume what does happen is that, through decoupling from the floor, and vibrations or sub movement on the floor are removed and that may make the bass sound cleaner...


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## asere (Dec 7, 2011)

27dnast said:


> I don't think there is much evidence that it makes bass tighter. I talked to Dr. Hsu and he he didn't think it would have a noticeable effect. I'd assume what does happen is that, through decoupling from the floor, and vibrations or sub movement on the floor are removed and that may make the bass sound cleaner...


I hear you and hope I didn't waste money. I don't have the room rattling and sub does not shake. All I get is clean bass with pressure at high at high spl's. Oh well could improve something I suppose.


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## Todd Anderson (Jul 24, 2009)

Certainly no harm in trying it. I use them... Not sure how much they help with improving bass (all room variables removed), but the fact the subs are decoupled from the floor has helped reduce some rattle...


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## asere (Dec 7, 2011)

27dnast said:


> Certainly no harm in trying it. I use them... Not sure how much they help with improving bass (all room variables removed), but the fact the subs are decoupled from the floor has helped reduce some rattle...


Stupid question..when people say rattle do they literally mean the house rattles?


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## theJman (Mar 3, 2012)

asere said:


> Stupid question..when people say rattle do they literally mean the house rattles?


In my case it was things in the house that rattled, like windows, closet doors, etc.


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## Todd Anderson (Jul 24, 2009)

asere said:


> Stupid question..when people say rattle do they literally mean the house rattles?


Like Jim said... add vibration sound through the walls.


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## asere (Dec 7, 2011)

27dnast said:


> Like Jim said... add vibration sound through the walls.


I don't know about wall vibrations in my case since nothing rattles but I feel the high spl pressures.


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## Todd Anderson (Jul 24, 2009)

Realistically, I don't think a small MDF board with some foam on the bottom of it is going to do much to change your sub's performance. Maybe you should start considering some bass traps in your room?


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## theJman (Mar 3, 2012)

27dnast said:


> Realistically, I don't think a small MDF board with some foam on the bottom of it is going to do much to change your sub's performance. Maybe you should start considering some bass traps in your room?


Agreed. The sensation of pressure is not due to resonance. In that case a Gramma won't help.


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## asere (Dec 7, 2011)

theJman said:


> Agreed. The sensation of pressure is not due to resonance. In that case a Gramma won't help.


I just got a refund from ebay on the auralex with the buyers protection. Turns out seller was not going to ship the item. I guess it's meant to be that way although I'm tempted to go out and buy an mdf board and foam and build my own.


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## Todd Anderson (Jul 24, 2009)

You know, I think your HSU sub would fit on a regular Gramma Pad sold on Amazon right now for $50.

Check the dimensions... but It's a fairly cheap alternative to going through making it yourself. Might be worth checking out... if you don't like it, return it!:T


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## asere (Dec 7, 2011)

27dnast said:


> You know, I think your HSU sub would fit on a regular Gramma Pad sold on Amazon right now for $50.
> 
> Check the dimensions... but It's a fairly cheap alternative to going through making it yourself. Might be worth checking out... if you don't like it, return it!:T


I've looked into it. It's too small my hsu is 25x17. Thanks for info!


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## Todd Anderson (Jul 24, 2009)

Size of the cab doesn't matter... It's the placement of the spiked feet in the bottom...


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## asere (Dec 7, 2011)

27dnast said:


> Size of the cab doesn't matter... It's the placement of the spiked feet in the bottom...


so it does not matter if all feet hang or just two?


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## theJman (Mar 3, 2012)

asere said:


> I've looked into it. It's too small my hsu is 25x17. Thanks for info!


The Great Gramma is 30x19. Why would that be too small?


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## asere (Dec 7, 2011)

theJman said:


> The Great Gramma is 30x19. Why would that be too small?


The great gramma is not too small. I was referring to the regular one someone here suggested. I'm looking into getting the great.


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## Todd Anderson (Jul 24, 2009)

asere said:


> so it does not matter if all feet hang or just two?


Of course that would matter... my point is simply that you should see if the feet are a few inches off of the sides (dimension-wise). If they are the feet would still be able to fit on the smaller pad.


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## asere (Dec 7, 2011)

27dnast said:


> Of course that would matter... my point is simply that you should see if the feet are a few inches off of the sides (dimension-wise). If they are the feet would still be able to fit on the smaller pad.


Good point. I'll measure the feet tonight thanks!


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## asere (Dec 7, 2011)

27dnast said:


> Of course that would matter... my point is simply that you should see if the feet are a few inches off of the sides (dimension-wise). If they are the feet would still be able to fit on the smaller pad.


I measured the feet last night and it's 23x15 the exact same dimensions as the regular gramma. What might be a problem is that the gramma would not be outside of the feets it would be parallel or or 1mm or 2 mm under the feets. I'm afraid that would be pushing it because sub can easily slide off.

By the way the Hsu has the round rubber feet not the spikes.


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## Todd Anderson (Jul 24, 2009)

I agree... it's pushing your luck. I would go big. Does the Subdude come in a smaller size than the great gramma (but larger than the Gramma)?


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## asere (Dec 7, 2011)

27dnast said:


> I agree... it's pushing your luck. I would go big. Does the Subdude come in a smaller size than the great gramma (but larger than the Gramma)?


The subdude is even smaller


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## 7channelfreak (Jan 9, 2012)

I use the great gramma under my svs pb13U.


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## asere (Dec 7, 2011)

7channelfreak said:


> I use the great gramma under my svs pb13U.


Is yours on carpet?


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## 7channelfreak (Jan 9, 2012)

asere said:


> Is yours on carpet?



Mine is on tile presently but will be moving to a carpeted media room in a few months.


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## asere (Dec 7, 2011)

7channelfreak said:


> Mine is on tile presently but will be moving to a carpeted media room in a few months.


Will you be using the gramma once you move to carpeted media room?


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