Auralex Gramma

[ahblaza]

Hello,
I would like your opinion on purchasing the Auralex Gramma for my Epik Lengend sub. Right now the sub is placed on thick carpet with concrete floor. I know that people have reported a marked improvement with carpet over wood and sub floors, but some have said there was not a substantial improvement with carpet and concrete floors. I would appreciate anyone that has my carpet and concrete situation to comment on their experience. Thank you for the time, I look forward to your reply.
Jeff

I realize the Gramma is a decoupling device, what results is the Gramma designed to achieve? Thank you.

 

[sholling]

In my opinion they're a great idea for apartments and condos and homes with wood floor. I'm not convinced that they're any kind of panacea for subs on carpet over concrete - especially not with front and side firing subs. I'm sure they will help in some situations with some subs and hurt in other situations and with other subs. In other words in your situation it's a crap shoot and I'd save money and put time into placement and EQ.

 

[Alex2507]

I'm sure they will help in some situations with some subs and hurt in other situations and with other subs.

How could it hurt?

 

[just-some-guy]

How could it hurt?

lighten your wallet. if your not happy with them.

 

[ahblaza]

In my opinion they're a great idea for apartments and condos and homes with wood floor. I'm not convinced that they're any kind of panacea for subs on carpet over concrete - especially not with front and side firing subs. I'm sure they will help in some situations with some subs and hurt in other situations and with other subs. In other words in your situation it's a crap shoot and I'd save money and put time into placement and EQ.

Sholling, thanks for the reply, I kind of expected that answer. I've experimented with placement and believe I have found the optimal space. Could you elaborate on EQ? Thanks my friend.
Jeff

 

[Alex2507]

Usually I'm down with Sholling's recommendations, always respect his opinions and am aware of other members who share his view of the Gramma on concrete slab floors. However I'm also aware of other well respected members whose opinion is more in line with that of this guy:

An Auralex Gramma is what you want They do wonders for your sub, regardless of floor type.

... so ... hurry up and order yours today.

 

[sholling]

Sholling, thanks for the reply, I kind of expected that answer. I've experimented with placement and believe I have found the optimal space. Could you elaborate on EQ? Thanks my friend.
Jeff

Keeping it simple (because I'm not an expert on EQing subs) just because your sub is in the best spot in your room doesn't mean that the frequency response doesn't have huge room created peaks and holes. The only way to tell for sure is to use a computer and calibrated mic or subwoofer EQ device like an SMS-1. I'm still learning this black art so I'll leave it to the experts to give you details.

As for what can an isolation pad hurt it depends on the sub. I used to swear by them but not so much any more. For example I found that they were counter productive for my big front firing Hsu ULS-15. I still think they have a place... Apartments, bare floors, wood floors over a room or crawl space etc. Carpet over concrete with a side firing sub is a crap shoot.

I'll probably be having an old speaker, subwoofer, and isolation pad garage sale this summer.

 

[ahblaza]

Keeping it simple (because I'm not an expert on EQing subs) just because your sub is in the best spot in your room doesn't mean that the frequency response doesn't have huge room created peaks and holes. The only way to tell for sure is to use a computer and calibrated mic or subwoofer EQ device like an SMS-1. I'm still learning this black art so I'll leave it to the experts to give you details.

As for what can an isolation pad hurt it depends on the sub. I used to swear by them but not so much any more. For example I found that they were counter productive for my big front firing Hsu ULS-15. I still think they have a place... Apartments, bare floors, wood floors over a room or crawl space etc. Carpet over concrete with a side firing sub is a crap shoot.

I'll probably be having an old speaker, subwoofer, and isolation pad garage sale this summer.

Thanks my friend, I don't have access to the devices you mentioned for EQing, I will look into what you have suggested though. Thanks again.
Jeff

 

[just-some-guy]

ya know what i have been wondering about these.

i used to have my subs sitting on blocks of closed cell foam. i made the front blocks larger for the driver weight. but the front always sagged down.

the gamma foam is long blocks, seemingly the same at the back as the front.
do these sag down in the front ? if not, what keeps em from doing so ?

 

[sholling]

ya know what i have been wondering about these.

i used to have my subs sitting on blocks of closed cell foam. i made the front blocks larger for the driver weight. but the front always sagged down.

the gamma foam is long blocks, seemingly the same at the back as the front.
do these sag down in the front ? if not, what keeps em from doing so ?

They don't sag because of the density of the foam but they can shimmy.

 

[just-some-guy]

They don't sag because of the density of the foam but they can shimmy.

that is what i figured. must be some pretty solid stuff. which, in turn, makes me wonder how it works.

 

[ahblaza]

Usually I'm down with Sholling's recommendations, always respect his opinions and am aware of other members who share his view of the Gramma on concrete slab floors. However I'm also aware of other well respected members whose opinion is more in line with that of this guy:



... so ... hurry up and order yours today.

Thanks Alex, I also respect Sholling opinions and often pursued his recommendations. I also have much respect with John's recomm's. and bought my subwoofer because he owned it and spoke highly of it, so for $50 I might as well give it a shot, thanks my friend.
Jeff

 

[j_garcia]

You don't need a gamma for this sub, the opposed driver config means little is transmitted to the floor. I have a gramma and it didn't make any difference sound wise with the empire.

 

[FirstReflection]

The job of the GRAMMA (or SubDude, or any other decouling device) is to act as a "shock absorber" between your subwoofer and the floor. The construction of your floor (wood frame, concrete, marble, etc.) is not what determines whether or not the GRAMMA will give you any sort of audible result/improvement. ALL types of floor construction move in sympathy with the vibrations of your subwoofer. Concrete flooring is typically more dense and has more mass, which means that it takes more energy in order to get it to move than a typical wood floor. But concrete WILL STILL MOVE and decoupling is still something that will almost always improve the bass within your theater as well as greatly decrease the bass that is heard in other rooms outside of your theater.

So whether or not the GRAMMA will be useful to you is more about how effective your CARPET is acting as a decoupling device - it's not about the concrete floor beneath it. If you have a very thick carpet pad and thick carpet, then that might act as an effective decoupling device and the GRAMMA won't really add anything. However, a lot of carpet and carpet pads get "crushed" enough by the weight of many subwoofers that they fail to actually decouple the subwoofer. Furthermore, many subwoofers have "feet" of some sort (rubber feet, spikes, cones, etc.) Having all of the downward force of the subwoofer's weight "focused" into those four little feet means that those feet often "penetrate" many carpets and carpet pads, which in turn, means that the subwoofer is once again "coupled" to the floor.

It is rather easy to tell whether your subwoofer is already effectively decoupled or not. If it is not effectively decoupled, you will notice things like windows rattling, other objects in the room vibrating - and perhaps the easiest test of all - if you go into other rooms of the house, you will be able to hear the bass thumping away, even when you cannot hear the higher frequencies.

If your subwoofer is already effectively decoupled by your carpet and carpet pad, then you will only notice the rattling, vibrations and "bleeding" of bass into other rooms at a handful of very specific frequencies (those being the inherent resonant frequencies of the materials that make and populate your room, which will react to bass that is simply travelling through the air, rather than the structure-borne transmission, which is what decoupling devices eliminate).

The final piece of the puzzle is just how much your subwoofer physically shakes to begin with. If your subwoofer has a balanced driver arrangement (subwoofer drivers firing in opposing direction, in phase), then it might not shake very much to begin with! This is the idea behind something like the Paradigm Sub1 and Sub2. If your sub already doesn't shake on it's own, then it isn't going to transmit energy into the surface beneath it.

Personally, I decouple every speaker. It never hurts the sound quality and almost always helps - even if only a little bit. But if $50 is money that you would rather keep (and I can certainly understand wanting to do so!), then I understand wondering whether the GRAMMA will be of any value to you. I would say, do my recommended listening tests first - especially going into other rooms of your house while you have some solid bass playing. If you can clearly detect that bass thumping away, then I would recommend that you try a GRAMMA isolation riser. Buy it from a retailer that offers a good return policy. Nothing tells you whether or not a GRAMMA was worth it better than hearing the results for yourself! We can speculate, but the results can sometimes be surprising. Sometimes, we expect the GRAMMA to make a big difference, but it doesn't. Sometimes, we don't expect any change, but then there's a VERY noticeable difference with the GRAMMA in place.

The GRAMMA is not magic and it is not a panacea for all bass problems. It is simply an effective decoupling device that I think is reasonably priced and therefore, I heartily recommend it! But the point is to decouple your subwoofer. Whether you accomplish that with the GRAMMA or whether it is already accomplished with a thick carpet pad doesn't matter! You just want to avoid having the structure of your house shake in sympathy with your subwoofer, and the GRAMMA will do that if it isn't being done already

 

[Alex2507]

The GRAMMA is not magic ...

... is too.

EDIT:
Nothing is simple any more ... maybe it never was.

 

[walter duque]

One thing is for sure that since I got my subdude the pictures in the apartment next to me have not come off the wall.

 

[ahblaza]

You don't need a gamma for this sub, the opposed driver config means little is transmitted to the floor. I have a gramma and it didn't make any difference sound wise with the empire.

Thanks John, I was waiting for you to chime in before I bought the Gramma, the folks at Epik said the same thing about the opposed driver config. I don't have any pictures falling rattling off the walls or the sub moving or shifting, I believe it is decoupled well from the concrete floor. Thanks to first reflection for your input. Thanks again John.
Jeff

 

[billy p]

We're looking to replace the carpet throughout our main floor with hardwood and I already noticed pictures and other thing rattling in other rooms, so I'll definitly look into buying one of these....now.

 

[just-some-guy]

The job of the GRAMMA (or SubDude, or any other decouling device) is to act as a "shock absorber" between your subwoofer and the floor. The construction of your floor (wood frame, concrete, marble, etc.) is not what determines whether or not the GRAMMA will give you any sort of audible result/improvement. ALL types of floor construction move in sympathy with the vibrations of your subwoofer. Concrete flooring is typically more dense and has more mass, which means that it takes more energy in order to get it to move than a typical wood floor. But concrete WILL STILL MOVE and decoupling is still something that will almost always improve the bass within your theater as well as greatly decrease the bass that is heard in other rooms outside of your theater.

So whether or not the GRAMMA will be useful to you is more about how effective your CARPET is acting as a decoupling device - it's not about the concrete floor beneath it. If you have a very thick carpet pad and thick carpet, then that might act as an effective decoupling device and the GRAMMA won't really add anything. However, a lot of carpet and carpet pads get "crushed" enough by the weight of many subwoofers that they fail to actually decouple the subwoofer. Furthermore, many subwoofers have "feet" of some sort (rubber feet, spikes, cones, etc.) Having all of the downward force of the subwoofer's weight "focused" into those four little feet means that those feet often "penetrate" many carpets and carpet pads, which in turn, means that the subwoofer is once again "coupled" to the floor.

It is rather easy to tell whether your subwoofer is already effectively decoupled or not. If it is not effectively decoupled, you will notice things like windows rattling, other objects in the room vibrating - and perhaps the easiest test of all - if you go into other rooms of the house, you will be able to hear the bass thumping away, even when you cannot hear the higher frequencies.

If your subwoofer is already effectively decoupled by your carpet and carpet pad, then you will only notice the rattling, vibrations and "bleeding" of bass into other rooms at a handful of very specific frequencies (those being the inherent resonant frequencies of the materials that make and populate your room, which will react to bass that is simply travelling through the air, rather than the structure-borne transmission, which is what decoupling devices eliminate).

The final piece of the puzzle is just how much your subwoofer physically shakes to begin with. If your subwoofer has a balanced driver arrangement (subwoofer drivers firing in opposing direction, in phase), then it might not shake very much to begin with! This is the idea behind something like the Paradigm Sub1 and Sub2. If your sub already doesn't shake on it's own, then it isn't going to transmit energy into the surface beneath it.

Personally, I decouple every speaker. It never hurts the sound quality and almost always helps - even if only a little bit. But if $50 is money that you would rather keep (and I can certainly understand wanting to do so!), then I understand wondering whether the GRAMMA will be of any value to you. I would say, do my recommended listening tests first - especially going into other rooms of your house while you have some solid bass playing. If you can clearly detect that bass thumping away, then I would recommend that you try a GRAMMA isolation riser. Buy it from a retailer that offers a good return policy. Nothing tells you whether or not a GRAMMA was worth it better than hearing the results for yourself! We can speculate, but the results can sometimes be surprising. Sometimes, we expect the GRAMMA to make a big difference, but it doesn't. Sometimes, we don't expect any change, but then there's a VERY noticeable difference with the GRAMMA in place.

The GRAMMA is not magic and it is not a panacea for all bass problems. It is simply an effective decoupling device that I think is reasonably priced and therefore, I heartily recommend it! But the point is to decouple your subwoofer. Whether you accomplish that with the GRAMMA or whether it is already accomplished with a thick carpet pad doesn't matter! You just want to avoid having the structure of your house shake in sympathy with your subwoofer, and the GRAMMA will do that if it isn't being done already

i have a few things to say about this :
1. did you, just now, type all that out ?
2. while i agree that decoupling does reduce structural agitation, there is still going to be some transmission. as that is exactly what a sub is supposed to do = cause the human body to vibrate. and in doing that, it will cause other things to vibrate.
3. what you say above, would be cause enough for me too buy 2 of them.
but, i am trying/hoping, to move. and after a lil while, i will be doing new subs. of yet to be determined configurations.

 

[j_garcia]

With all other subs I have tried it with, a Gramma is a definite improvement and totally worth it. With these particular subs and how they behave, they aren't necessary as far as I can tell. I have placed items on top of this sub (to keep the cats from napping on it) and there are no rattles, vibrations or movement of those items. That's something I would not, and probably could not, have done with previous subs.