I am going to build a huge box and am planning on layer some half in ply I have with three quarter MDF. I would assume I would want an adhesive that will stay pliable to help dampen the vibrations I would expect from panels this big and also prevent some transfer of energy to my house since this will be built into the attic. Has anyone used a tar based adhesive? Any ideas on product? Oh yeah and cost matters. Maybe something I can buy large containers.
Thanks in advance,
Zach
I wouldn't recommend tar-based products to glue anything, you can save that to stick on the inside panels to dampen vibrations.
Glue should keep it's form. At higher temperatures, tar can shift in the long run. (pun intended)
Waterproof wood glue is all you need or even regular wood glue for inside use.
Get the pressure evenly spread on the whole surface for drying.
Don't forget to add a lot of dowels, 1" by 1" or other form of bracing!
I guess it would, it's 'a glue'.
But don't expect it to dampen all that much, it can help against ringing but you really should concentrate on keeping the panels from flexing.
Just as Bart West said it would be best to add ample amounts of bracing. I have a cabinet that is green glues with adequate bracing and the cabinet is very dead. That being said I might have been fine with just the bracing or adding more instead of the green glue.
Just remember that you glue and screw if you use the GG.
Budget is one of the most important aspects of this build. I bought a gallon of Titebond for the cost and simplicity of cleanup. The sheer size/budget is going to prevent the kind of bracing we have seen in the builds on here but I am going to use existing joists and studs to place the walls against for bracing.
This build is going to take me forever. I hope I can get started soon so I am not in the hot FL attic.
Zach
I think I just read another member doing 16cuft each with , I believe, 15hz tune. I thought those would be big but these cabs are going to be gigantic.
55ft³ would be ideal for an EBS (Extended Bass Shelf) to -6dB at 10.5hz with two SI18 D2
Not ideal for these drivers but possible.
So 60ft³ is not too much, as you'll have to account for space taken from the port(s).
Hi Bart. Would you think it is ideal or not. Your post reads as both. I always talk about actual volume after all is taken into account. this build will give the opportunity to test different sizes so I am going to. For the fun of it I will even try them as an IB even though they do not seem to be designed for it.
Zach
I meant your enclosure volume would be ideal for the simulation but it's up to you to decide if you really want to tune that low.
I think it has no benefit and you would lose some frequency gain where it counts, from 15hz and up.
My opinion is, that anything below 15hz is used maybe 1% of the time in 1% of the movies or even less, so for this once every 10.000 or less, i would prefer to bring out the frequency's that are produced regulary with a bit more efficiency, from 15hz↑ anything lower is cone movement, no sound. If you want the movement, place shakers under the couch from 15hz↓
But that's up to you.
I'll sure follow your thread and build! Have fun! :hsd:
As compliant as the suspension is you should definitely be careful with them in IB in a box that big. Don't throw too much power at them or you will bottom them pretty easily i'd think. I mean, these are an 18 that is fine in very small boxes by most 18 inch driver standards.
Not looking at my modeling right now but 1600 watts total puts then just above xmax way down low. Well within xmech. The IB test is only to hear the "sound" that many rave about.
Zach
With 45cuft and 13hz port 1600 watts puts you over Xmax at 28hz. With 1200 watts, 13hz port with 13hz Hpass you hit Xmax at 9hz and almost 20hz. Anything larger than this and you need to use less wattage.
14 Hz tune, 1300 watts and a 4th order 11.5 Hz high pass. That gets me 25-28 mm excursion at full power from an EP2500/4000. I can work with that.
Zach
Bart,
Have you read Steve Callas' LLT explained which is in his signature line? I am basing my design on those points and want to keep the port output low in the audible frequency range. I really hope to carve some time out on Saturday to start.
Zach
Yes I read Steve's explanations and don't see where the difference is in what you state:"port output low in the audible frequency range"
How low do you think a human can hear?
lower than audible would be a sensation, a feeling. So that's why I would use shakers if really needed but I wouldn't use them anyway, have no need for moving the couch up and down through a soundtrack.
Pure sound from 20hz and down is hard to hear. Distortion and rattling stuff is not the 20hz or 15hz I mean.
But that's just my opinion, please go ahead and build a 10.5hz sub, don't let anyone keep you from doing want you want!
I hope you compare with a HPF at 15hz and then no filter. I would like to know your experience.
I re read my last post and I sounded like a smart "rear end". Bad sentence structure and word choice. I apologize for that. I respect the opinion of everyone on this board. I was just curious of what was behind your opinion.
My budget and the size of hole I can cut in our wall is limiting me to two drivers. For such a large space I need output and want extension. An LLT makes sense to me. The port output will be limited to below 35Hz and below where are hearing sensitivity is decreased and below most music. It just seems like the right move for me.
I love experimenting so yes, I will tweak the high pass filter before settling.
Zach
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