DIY Subwoofer Risers

[Big Daddy]

Originally Posted by JJxiv1215

Yes, but - why?

See my post on the ED thread.

https://forum.blu-ray.com/showpost.p...postcount=2200


Also read the information about SubTrap.

SubTrap.jpg


SubTrap2.jpg SubTrap3.jpg

18” SubTrap (50 Hz) Standard, most Subwoofers: $469
22” SubTrap (30 Hz) Large Subwoofer: $586
http://www.asc-home-theater.com/subtrap.htm


"Once you hear the difference, you’ll never go back. The SubTrap is more than a simple isolation stand. In addition to isolation, it absorbs excess bass and decouples your sub-woofer from room mode. The end result is a unique product available only from ASC. Raise your subwoofer up to its full performance potential. Just slip the ASC-SubTrap underneath your subwoofer and you’ll create the powerful “SubStack.” Instantly improve bass detail, changing “muddy” low frequency playback into a richly detailed picture. Not only does the SubTrap increase bass extension and punch, it also gets rid of "one note bass"."

"By raising the sub off the floor and putting a SubTrap under it, the subwoofer is effectively decoupled from the vertical room mode. Excess bass buildup is reduced and the playback volume of the subwoofer can be cranked up much higher than before."

Reviews:
http://hometheaterhifi.com/volume_12...ap-6-2005.html
http://www.stereophile.com/musicinth...ic/index1.html

[JJ]

And yet at the same time, risers and decouplers look basically the same to me, outside of materials - is there a difference in materials or height that separates the two?

A carpet/wood riser a la BD Grampa or a foam Auralex Gramma - they appear to be of similar heights.

[jomari]

Originally Posted by JJxiv1215

And yet at the same time, risers and decouplers look basically the same to me, outside of materials - is there a difference in materials or height that separates the two?

A carpet/wood riser a la BD Grampa or a foam Auralex Gramma - they appear to be of similar heights.

Well, simply put, acoustic materials vary as to what you'd want it to do. in this case it wouldnt matter as long as its not reflective, wood for example. the reason why most of the DIY risers are built and covered with carpeting or what not, is to decouple it. in a way, the risers can be decouplers too bud.

[Big Daddy]

Originally Posted by JJxiv1215

And yet at the same time, risers and decouplers look basically the same to me, outside of materials - is there a difference in materials or height that separates the two?

A carpet/wood riser a la BD Grampa or a foam Auralex Gramma - they appear to be of similar heights.

The legs on the Gramma are about 2.5 inches. When I raised my cylindrical Hsu subs by a combined total of 10", the bass sound increased by approximately 10dB. You do not need to raise a subwoofer. You can hang it a few feet away from the ceiling without any padding and still get the same effect. This is a direct result of vertical room modes (standing waves created by the interaction of waves with the ceiling & floor).

[JJ]

No, no, I know about materials and reflectivity - but if a riser can also be a decoupler, can the reverse also not be true?

[jomari]

Originally Posted by JJxiv1215

No, no, I know about materials and reflectivity - but if a riser can also be a decoupler, can the reverse also not be true?

true, but in this case it also cant imo...
see for example fosbergs version. its not a riser, but more of a decoupler. raise it up further and then technically it would be both. some decouplers dont have that much height in general. decouplers are also used for bookshelf speakers, and for studio monitors as well. at that point they'd be on stands.

we're getting into potatoes tomatoes here. my head hurts...

[Big Daddy]

I posted Big Daddy's rule of thumb on the ED thread. I will post it here again.

Rule of thumb:

• An average home in the U.S. has a ceiling about 8ft high.
• Rule of 25: It is normally a good idea to put the sub approximately up to 25% away from the boundaries. For a riser, it means ceiling & floor.
• 8ft x 0.25 = 2ft.
• Raise your subwoofer approximately 2ft or less. You can also try to hang it 2ft away from the ceiling, but do it at your own risk. The WAF is waiting.

[JJ]

Aha - so the difference is height. Gotcha. Now it all makes sense.

[jomari]

Originally Posted by JJxiv1215

Aha - so the difference is height. Gotcha. Now it all makes sense.

Yay!

[JJ]

Originally Posted by jomari

Yay!

Coulda said this from the getgo,

[Big Daddy]

Originally Posted by JJxiv1215

Coulda said this from the getgo,

Many people have done years of research at the National Research Council of Canada and at Harmon International under the guidance of Dr. Floyd Toole (currently, a Vice President at Harmon).

The 25% Subwoofer Positioning: This solution is suggested by Todd Welti at Harmon International:

You shrink the whole room by 25% and put the subwoofers at the corners of that virtual room. Of course you get incredible performance, but that is not practical for most people. But if you use two or four subwoofers in the corners or the wall midpoints, you can get pretty good performance.”

[erict]

BD, I see you used acoustic foam (black stuff) from parts express when you built you're riser. When you added longer legs you added some more dampening material but it's white. What did you use? Can I use this instead of the black acoustic foam?

[Big Daddy]

Originally Posted by erict

BD, I see you used acoustic foam (black stuff) from parts express when you built you're riser. When you added longer legs you added some more dampening material but it's white. What did you use? Can I use this instead of the black acoustic foam?

I had some of that black foam (1/2" thickness) left over from when I built my 15" subwoofer. They are from Parts Express and it takes 5-6 days to get them. They also have 1" thickness, but relatively expensive. The white foam was from Wal-Mart fabric & craft department. They are approximately $7.50 each. I believe they are 12" x 17" (2" thickness). They are not as dense as the black foam.

http://www.parts-express.com/wizards...TOKEN=83436569

[erict]

Originally Posted by Big Daddy

I had some of that black foam (1/2" thickness) left over from when I built my 15" subwoofer. They are from Parts Express and it takes 5-6 days to get them. They also have 1" thickness, but relatively expensive. The white foam was from Wal-Mart fabric & craft department. They are approximately $7.50 each. I believe they are 12" x 17" (2" thickness). They are not as dense as the black foam.

http://www.parts-express.com/wizards...TOKEN=83436569

Thanks. What was the foam designed for? Is it mattress pad material? I going to try Joann's or Michaels for something.

[Big Daddy]

Originally Posted by erict

Thanks. What was the foam designed for? Is it mattress pad material? I going to try Joann's or Michaels for something.

I believe they are for baby pillows.

[erict]

Thanks BD

[Fors*]

I'm bumping this as it seems to have gotten lost in this thread and I see no posts in reply to my questions.....

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?

[crazyBLUE]

Originally Posted by Big Daddy

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.

I agree here ! Raising the sub witch is now 14" higher has made the biggest difference in the way it sounds !!

[erict]

Though using a subdude would achieve both by rising and isolating, right?

[Big Daddy]

Originally Posted by forsberg21

I'm bumping this as it seems to have gotten lost in this thread and I see no posts in reply to my questions.....



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.....



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?

You can do both. You don't want to leave a big gap between the riser and the floor. Fill that area with as much foam as you can to dampen the riser. Use a little spray glue. Cover them with carpet.