DIY Subwoofer Risers

[PurpleJesus74]

Hey Forsberg,i like your risers,there different than the others having no legs.So are they basically precise cut pieces of wood with carpet on top?They look nice,also where did you get the rubber feet you put on the bottom of the sub?Thanks.

[Driver_King]

The riser should have legs. Otherwise, the advantages may be non-existent. The idea of a riser is to correct vertical placement, its effect on standing waves, and the axial room mode. Not having legs does not do much for any of this.

[Fors*]

Originally Posted by Driver_King

The riser should have legs. Otherwise, the advantages may be non-existent. The idea of a riser is to correct vertical placement, its effect on standing waves, and the axial room mode. Not having legs does not do much for any of this.

I was thinking the same thing, until I saw how Auralex did theirs. As you can see in the link below, I simply followed their lead.....and they seems to be one of the best in the biz about acoustics.

http://www.amazon.com/Auralex-SubDud...9557829&sr=8-8

[Driver_King]

They do have small legs on them though. Big Daddy originally made his with small legs and then he added longer legs to the riser and legs to his sub and noticed a bigger difference.

[Fors*]

Originally Posted by Driver_King

They do have small legs on them though. Big Daddy originally made his with small legs and then he added longer legs to the riser and legs to his sub and noticed a bigger difference.

If so, that could be an easy "add-on" for me, as I have many things I could use as legs since the bottom is only the hard foam. Thanks for the heads up!

[liquidice]

BD, not sure if you mentioned this yet or not, but did you mess around with your VELODYNE after building all your risers and stuffing the boxes? Just wondering if your graph changed at all from when you first had the EQ and calibration set up.

[aramis109]

Originally Posted by Driver_King

They do have small legs on them though. Big Daddy originally made his with small legs and then he added longer legs to the riser and legs to his sub and noticed a bigger difference.

To my understanding, those legs are actually foam however. It's a matter of decoupling more than anything else. I'll be able to confirm that tomorrow when mine arrives.

[jomari]

The Grammas from auralex were intended as decouplers and not as risers, with its primary goal is to isolate the amp/subwoofer from the ground further reducing the coupling with the floor and the room.

With risers you are addressing the room mode. two different things.

[JJ]

Wait, Jomari - explain this further, the difference between a riser and a decoupler for a subwoofer.

[jomari]

Originally Posted by JJxiv1215

Wait, Jomari - explain this further, the difference between a riser and a decoupler for a subwoofer.

isolation comes in two forms : decoupling or coupling, you either want the device (which can be a speaker, an amp, a turntable) to either couple (interact) with the room or not.

Decoupling prevents it, or minimizes it at least.

Coupling increases its participation in the room, which is done mostly with speakers, and allows you to have more interaction with it. There are a number of reasons why most people prefer to decouple the speakers, including 'false' gain increases, as well as coloration.

You want to listen to the music, and not the room. - the reasoning behind acoustic treatments.

in regards to risers,

you are addressing, well, i saw liquidice post something before, and would like her/him/it to post it again here. personally, i was impressed by it, and hope she/he/it/they can repost it here.

or you can also ask BD again.

[Fors*]

Originally Posted by aramis109

To my understanding, those legs are actually foam however. It's a matter of decoupling more than anything else. I'll be able to confirm that tomorrow when mine arrives.

So, should I also attach foam legs to the foam padding under the "decouplers" I built (I believe this is the correct term now, right?) I have a lot more of the hard foam used initially, and cutting some pieces to use as legs would be no problem at all.

Also, I saw the below post that Driver King "slid the Polly-fill foam" underneath his subwoofer.....

Originally Posted by Driver_King

I added some padding to the inside of my DIY subwoofer and then slid the Poly-fill foam underneath it. The difference the stuffing made was also just about as big as adding a riser. No kidding. I'm not sure the pad did much but I know filling a huge empty enclosure with a pound of Poly-fill did.

So, does this mean I would have some additional benefits if I simpy used some Polly-fill to fill the void under my decoupler (riser?) thus acting like a bass trap or I should simply use the Polly-fill only under the subwoofer itself?

[Big Daddy]

Originally Posted by liquidice

BD, not sure if you mentioned this yet or not, but did you mess around with your VELODYNE after building all your risers and stuffing the boxes? Just wondering if your graph changed at all from when you first had the EQ and calibration set up.

Yes, everytime I change anything that affects the subs, I have to go back and redo the equalization with the Velodyne.

[JJ]

Still waiting for someone to explain decouplers from risers. lol. I'm trying to find liquid's post!! Because I thought buying a Auralex Gramma/SubDude would be the same as making a riser.

[Big Daddy]

Originally Posted by JJxiv1215

Still waiting for someone to explain decouplers from risers. lol. I'm trying to find liquid's post!! Because I thought buying a Auralex Gramma/SubDude would be the same as making a riser.

Decoupling (isolating) the sub from the floor and raising a subwoofer are two different concepts. Each one helps in a different way. If I were to pick one option, I would raise the sub.

[JJ]

Originally Posted by Big Daddy

Decoupling (isolating) the sub and raising a subwoofer are two different concepts. Each one helps in a different way. If I were to pick one option, I would raise the sub.

Yes, but - why?

[jomari]

Originally Posted by JJxiv1215

Still waiting for someone to explain decouplers from risers. lol. I'm trying to find liquid's post!! Because I thought buying a Auralex Gramma/SubDude would be the same as making a riser.

posted my reply here

about the risers, i was hoping that liquid can get credit for this one. she explained it somehow very well, and wanted her to try to find it again. i cant.

anyways, the risers as mentioned by BD is a different concept.

[JJ]

Originally Posted by jomari

posted my reply here

about the risers, i was hoping that liquid can get credit for this one. she explained it somehow very well, and wanted her to try to find it again. i cant.

anyways, the risers as mentioned by BD is a different concept.

I saw that post, Jom, but still trying to get some more info.

[jomari]

Originally Posted by JJxiv1215

Yes, but - why?

because risers address the subs interaction with the room modes.



decoupling speakers removes the interaction of the speakers, while risers ADDRESS room interaction.

passive acoustics versus active acoustic treatments.

[JJ]

I need to go back and re-read the Subwoofer Guides. I have a basic understanding of this, but still do not fully understand the differences between what a riser would do and what a decoupler would do.

[jomari]

hmm. to oversimplify it, we normally look at placement in a 2 dimensional scenario, moving it left and right, closer or farther from the wall... in this case we are address the third part, which is location in respect to its height position, being more active in addressing acoustic challenges.

the decouplers are passive.

lets put it this way...

Risers address the problem, while
Decouplers prevent the problem.

Found LiquidIces posting!

here and i quote,

Subwoofer placement doesn't only deal with horizontal (moving it around the floor of your area), but also vertical, meaning, get that that thing up off the floor! You can call me crazy all you want, the impacts of getting a sub off the floor is remarkable.