The Ultimate Riser? KaboomY?

[Rolyasm]

Hey all,
I am coming down to the wire with all these decisions. Am planning 4 sub drivers (15" or 18" avalanche), built into my riser that is appx. 8x15 and high enough for the drivers. I just read on page 5 or so of the old forums about getting boominess out of a poorly constructed riser. I was planning on building the riser directly onto the floor, creating a box for my subs at the same time. the floor would be concrete, and the walls of the riser butted up against framed walls. Any way to make this better? should I isolate the riser from the concrete floor? Perhaps lay some roofing material down first? Add some sand on top of the cement? Thanks.
roly

[Chris D]

I have a riser, and am very hesitant about what you propose. I would run it by a theater/audio technician/designer. Normally, a riser doesn't have any speakers place on or in it, so you don't need to isolate it from the floors/walls. But you DO have to stuff it full with insulation so that there is no airspace to resonate inside. Even better is to fill it completely with sand.

But you're wanting to use this as BOTH a riser and a subwoofer enclosure. It's probably possible somehow to do this properly, but I personally wouldn't want to try it. I think it would just turn out poorly.

On the other hand, is your intention to use the sub drivers for TACTILE sensations? (vibrations through the riser, not to create sound?) If so, I would just buy tactile-specific transducers for this purpose, which would solve the problem. Not sub drivers. Check out Clark Synthesis Tactile Transducers-- www.clarksynthesis.com

[aud19]

Might be able to to do something with using sonotube for instance within the riser as the actual speaker enclosures.... I would think you'd still want to find a way to de-couple it from the riser itself.... Is there a reason why you want to build it in to the riser specifically? Other than saving a little space in the room, I'm not sure what the point would be over a "normal" subwoofer?

If you have the space you could possibly build a transmission line sub based in (maybe?) the riser....?

[Rolyasm]

Well, I got the idea from the DIY forum. Thomas and a bunch of the guys in there thought it would be a good idea. You can read the whole thread under DIY "Underfloor sub. Will it sound good?" maybe take a read and see what you think. I was told it would sound awesome. I hope it is so. I don't want to spend $1000.00 dollars on the drivers for tactile sensations. I was hoping this would give me some butt-kicking bass.
Roly

[cdwitmer]

Wait a minute . . . aren't "tactile sensations" and "butt-kicking bass" the same thing?

Seriously, it should work well. You do not want to decouple it from the concrete floor, or add anything to the concrete except possibly some fiberglass or holofil speaker batting -- the rationale behind that, as you know, is that it can "fool" the drivers into working as if that they are working in a larger space. Direct coupling to the concrete is one of your keys to success, because in order for for the bass to cause the floor above to vibrate seriously, it is going to have to either separate the vertical joists from the wood ceiling and/or concrete floor, or else it is going to have to cause the joists to behave elastically along their length, stretching and springing back like a spring. That, of course, is not going to happen. What will happen is that you will get some flexing of the ceiling panels between the joists, but it will not turn the whole riser into a giant bass shaker (especially if you have carpeting and padded seats), and it will not noticeably color the bass. It does need to be solidly constructed, however, and sealed. No doubt about that.

[Rolyasm]

Thanks for the optimism CD. The riser is complete. Wow, it looks big in my little room. I am going for it, so good or bad, it will be done. Any suggestions on wiring before I seal the thing up? Also, I was going to put insulation on the edges, floor, ceiling, but wasn't sure what to use for the inside. Is the entire riser going to be filled with insulation, or holofil? thomas mentioned an amount of lb. per square foot. Also, If I get the wiring done, then put the front of the riser on, can I blow in insulation using the driver holes? Does it matter what kind of insulation I use? thanks
Roly

[cdwitmer]

Thomas responded under your main thread on the DIY board, but I would ask there about the wiring. I think you can do all wiring after everything is complete, but it might be better to do the wiring at this stage. By doing it now, you might save time and effort, and the final results might be more attractive.

[Rolyasm]

Thanks for the help.
roly

[Chris D]

Well, no, actually, you still have a difference in the design and implementation of tactile products and audible woofers. Tactile products can be made to transmit all audio frequencies, not just bass, like Clark Synthesis' line, which is more full-range. Audible woofers need to be placed and built to properly transmit sound waves, not vibrations.

Again, we're blurring the line between something purposed to transmit TACTILE energy vibrations vs. something designed to transmit AUDIBLE airwaves energy.

Roly, since you've built it, the bottom line now is that I hope it works for you, and please tell us all what you find!

[Rolyasm]

I will let you know how it works. If you see me in here crying, you will know I failed.

[cdwitmer]

And if you are never heard from again, we will know it succeeded.