DIY Subwoofer Risers

[jomari]

Originally Posted by abc5

i have a question about this... if some foam or acoustic foam will help the riser due better dampening, would the foam be better off instead of being underneath the mdf/plywood platform as i've seen, be placed on top of the platform, then carpeted or whatever....

it would make the top more spongy, but they sell high density foam that's really firm... and you can put those coins at the bottom of each of your sub spikes so the spikes dont punch through over time.

foam doesnt work as efficient as fiberglass or polyfill, when it comes to the lower frequencies. it can deflect or diffuse but doesnt absorb anything.

[abc5]

Originally Posted by 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.

hey quest BD.... 2ft off the floor... how about a wall... does it also need to be away from a wall?

[jomari]

Originally Posted by abc5

hey quest BD.... 2ft off the floor... how about a wall... does it also need to be away from a wall?

yes, applying the quarter wall to avoid room interaction with the subwoofer.

[crazyBLUE]

Originally Posted by abc5

so back to the questions

does a riser platform need to be built, or just find 4 posts that can serve as 4 legs as long as they can be screwed into the bottom of the sub, acting like 4 long spikes? i'm seeing pics of a custom riser, plus long pegs on the sub replacing standard spikes...are both necessary?

No ~ Both are not necessary , That is something I just did & it really gave me insight as to how a subwoofer higher up would sound !

Do you mean this as for the legs you see , Remember I am crazy ~ But its a good crazy .




I have 3 subs on tall risers now ~ 14 , 19 & 28 inches off the floor . I say the higher the better , But thats just my opinion

[Big Daddy]

Originally Posted by abc5

hey quest BD.... 2ft off the floor... how about a wall... does it also need to be away from a wall?

A wall is a boundary and the 25% rule applies to all boundaries. Basically, the 25 percent rule is a rule of thumb to avoid energizing the first harmonic of the axial mode. In some situations, depending on the dimensions of the room, the 25% point may fall in the minimum point of the second harmonic. It may be better to move the subwoofer a bit more away from the boundary. For more detailed explanation and diagrams, read https://forum.blu-ray.com/subwoofers...oom-modes.html.

[abc5]

Originally Posted by crazyBLUE

No ~ Both are not necessary , That is something I just did & it really gave me insight as to how a subwoofer higher up would sound !

Do you mean this as for the legs you see , Remember I am crazy ~ But its a good crazy .




I have 3 subs on tall risers now ~ 14 , 19 & 28 inches off the floor . I say the higher the better , But thats just my opinion

so you have 3 subs w/ standard cone spikes, just tall risers?

my sub placement is gonna be alot like your picture, where it's on the left side of the whole entertainment platform, lcd being center, with a wall like yours on the left of the sub. my left wall is about say, 5 feet wide, before connecting to the large backwall.... you think i'll need some of that acoustic foam as well? I'm gonna be able to give my sub 1 feet away from the back wall, but I probably can only give 2 inches gap away from the left wall. to the right of my sub would be my left front tower, the most i can give between the sub and my left tower is 1 inch... is this really a bad situation, should I put foam between the sub and the left tower?

[crazyBLUE]

Originally Posted by abc5

so you have 3 subs w/ standard cone spikes, just tall risers?

my sub placement is gonna be alot like your picture, where it's on the left side of the whole entertainment platform, lcd being center, with a wall like yours on the left of the sub. my left wall is about say, 5 feet wide, before connecting to the large backwall.... you think i'll need some of that acoustic foam as well? I'm gonna be able to give my sub 1 feet away from the back wall, but I probably can only give 2 inches gap away from the left wall. to the right of my sub would be my left front tower, the most i can give between the sub and my left tower is 1 inch... is this really a bad situation, should I put foam between the sub and the left tower?

You will not need foam between the sub & left tower abc . Big Daddy taught me that the subwoofer is made to blend with the speakers .Do what BD & jomari have suggested to you , They are the experts at this !! Good luck & hope you can find the sweet spot for the sub .

[vsidhu]

I'm back! I've been busy with mcat stuff, but I managed to finish my riser. I've still got to attach the polyfill at the bottom and get a nice thick piece of high density foam for the top. There is polyfill in between each layer (not visible) and the feet will have furniture pads. I've still got to work the finish with very fine steel wool. If it doesn't work out well as a riser at least I'll have a fancy side table for my drink

[vsidhu]

pic size

sorry

[Big Daddy]

Originally Posted by vsidhu

pic size

sorry

You can use a picture editing program and decrease the width of the pictures to 700 or less pixels. If you do that, the pictures will become easier to see and we won't need to scroll to the right or left. Don't adjust the height as the editing program automatically sets it.

[mcdev]

Hey guys. Lots of great information here, it is almost overwhelming.

I am thinking about building a riser/decoupler. I understand most of details but I have a question about the top of the stand. If I were to use solid plywood, would I benefit from covering it with some foam, insulation or rock wool or will some carpet be sufficient? By my way of thinking, it makes sense to add a dampening layer to the surface directly below the sub (a down firing ED A2-300).

How about this thought. Instead of a solid top surface, I cut out the center to allow the sound from the sub travel through the dampening material below. This material could be insulation, foam or rock wool as well.

Which materials are ideal for filling the void underneath the stand? With or without the hole in the top, is acoustic foam the best solution or is rock wool a good option. If acoustic foam is the preferred option, should it be egg crate or the more rigid type?

Thanks for the help and I look forward to getting this project underway!

[mcdev]

Just of the sake of providing the most information that might be helpful to answer my question....

As of right now, my design is a box with the side stopping about an inch or so from the floor, on rubber isolation feet. I plan on using plywood for the sides and top with 2x2 stock as backing/legs in the corners. I intend to fill the void with a dampening material and potentially cover the top with an additional layer of dampening material and carpet while keeping the bottom of the sub about 1 1/2" from the top of the riser. The carpet will stop at the top and I will paint the rest of it black. The plan is to screw and glue all joints to reduce vibration and provide a fairly robust construction.

[crazyBLUE]

Originally Posted by mcdev

Just of the sake of providing the most information that might be helpful to answer my question....

As of right now, my design is a box with the side stopping about an inch or so from the floor, on rubber isolation feet. I plan on using plywood for the sides and top with 2x2 stock as backing/legs in the corners. I intend to fill the void with a dampening material and potentially cover the top with an additional layer of dampening material and carpet while keeping the bottom of the sub about 1 1/2" from the top of the riser. The carpet will stop at the top and I will paint the rest of it black. The plan is to screw and glue all joints to reduce vibration and provide a fairly robust construction.

Do you mean something like this . I built this one for my 10 inch sub ?

& do put a layer of carpet on top .

[mcdev]

Yeah, something like that, only with solid sides. Have you found that to work better than a solid top, or a solid top with dampening material?

[crazyBLUE]

Originally Posted by mcdev

Yeah, something like that, only with solid sides. Have you found that to work better than a solid top, or a solid top with dampening material?

I put the hole in the top because the sub that is on it is a front firing & the bass port is on the bottom . I don't think it made a difference for me . For you with the eD being a down firing sub I wouldn't put the hole in the top . I would just put a layer of carpet on the top of the stand .

[rickdeth]

I decided after reading on here and being cheap and not wanting to spend money on an auralex subdude, that i should just make a sub-riser.

Anyways made one, painted it up and bought some foam from wal-mart. I have 2, 2" thick pieces of foam underneath the riser. Ill have to demo some more stuff tonight to see if i can hear any results.

Thanks for the info fellas!

[bobbydrugar]

Random question I have seen many different variations on custom sub risers and was just wondering is there any metric to determine how tall the riser should be or does it even matter and it just needs to be isolated from the floor?

Thanks,
T

[kareface]

Originally Posted by bobbydrugar

Random question I have seen many different variations on custom sub risers and was just wondering is there any metric to determine how tall the riser should be or does it even matter and it just needs to be isolated from the floor?

Thanks,
T

You can't know with out a mic. The best thing you can do is try propping it up at that height and listen yourself to see if it's any better. I would like to add, I love bigdaddy, and I agree with 99.99% of what he says. However (of course following that there has to be a "however"), I don't completely agree with the 25% rule. I know where it's coming from, the white paper with the quad sub positioning. The problem is this rarely seems to translate over to 1 or 2 subs in my experience and room dimensions and listening position play a critical role in any acoustic situation. I've found for avoiding standing waves odd ratios tend to be better, but nulls or peaks at the listening position is never going to be the same. You have to just test it out before you build, otherwise you might end up making the situation worse.

[jomari]

i like using the quarter rule, but as a guideline towards placement on a horizontal plane. in general it works, but not as efficient with vertical (or rising the sub) concerns.

as always, any calibration is 'incomplete' without using an SPL meter.

[bobbydrugar]

Appriciate all the help I Will just experiment then to see what works out best

Thanks,
T