can i turn my house into a horn?

gavman said:
ok, ive gone a bit quiet, here's why:

i'm paying for my main speakers till the spring

i've reached the (obvious) conclusion that i need to move in and site my main speakers before i can then work out where to site the sub(s)

i'm also going to need another pair of ears cos it's a two man job working out the best place to mount. one person needs to sit in the listening position, and another to hold a sub box in the location proposed. that way any problems can be heard before install.
tenson, could be a job for you if you're interested?
you'll have a good chance of selling me some of your room conditioning gear too....:)

ps on the drivers, aurasound are working on some 15's, that may be ready by the time i am!

gav
Click to expand...

Hi,

Sounds like you are getting there :)

I would usually be happy to have the chance to show you the SoundSpace treatments, but you are a LONG way from me so I'm not sure it would be at all practical. Let me know when you are going to do it and we shall see about it then.

Good luck with it!
 
You have solid concrete floors yet are obsessed with mounting vast subs from a weak resonating ceiling. I can't see this being as good as two sealed subs in either corner.
 
i think you've missed the point somewhat 4wd?

1 not sealed boxes but infinite baffles; the speakers are effectively in another room (the loft), using that whole room area for the backwave

2 mounting in the corners of the room will cause massive time alignment issues, especially as the main speakers will be six feet out into the room.
this way the array(s) will be the same distance from the listening position as the main speakers

have a look at the Cult of the Infinitely Baffled:
http://ibsubwoofers.proboards51.com/index.cgi?

gav
 
I understand the loft is not sealed. I can't see how a resonating ceiling is going to sound any good at all. I guess it's a very cheap diy option. Perhaps if you were building a dedicated room from scratch it maight be ok. But only if you had solid concrete ceiling etc.

If it were me, I'd just get some sealed subs in the room. Either in the corners, or next to the main speakers. Or if you want to hide them how about using a room next door?
 
The main advantage is being able to get some stupidly low frequencies. Which I think is what attracted Gav to this method in the first place.

I don't see it being an issue if you mount the drivers on to a joist and re-enforce the ceiling around that area. Maybe pt some big stone slabs on top of the joists directly over where the drivers mount (leaving room for air to move obviously).
 
I think you'll find a van load of 18's are going to vibrate the hell out of your entire ceiling. Adding a slab or partial local reinforcement isn't going to change that. The vibrations up there will cause total havoc imho.
 
You need to remember there is not a lot of pressure on the other side so its not like a box sub where there is a lot of pressure trying to vibrate the thing. The woofers can also be physically connected back to back (via stiff connecting rods or somesuch) so that they cancel out the vibrations from one another. This is a very effective means of minimising vibrations in a design like this.
 
It will be interesting to see if the theory pans out in practice. Having played with large overpowered car subs, I know the amount of vibrations which are possible! Get it installed and take some photo's of the structural damage which ensue's! :D
 
Nice orb like enclosure. I was recently loking at some carbon fibre cabs of similar design. Where did the guy obtain the metal ikea alike salad bowls from?
 
4WD said:
. I guess it's a very cheap diy option.

If it were me, I'd just get some sealed subs in the room. Either in the corners, or next to the main speakers. Or if you want to hide them how about using a room next door?
Click to expand...

i strongly recomend you use the link i've made you

i don't think you've grasped the issue yet...and the options you mention have been covered already. this is not about hiding speakers or hanging them from a ceiling.
the manifold(s) will not be visible from the listening position as they sit in the loft atop the joists, to which they will be permanantly secured in a way that will allow no movement or vibration, using the same ties/brackets that are used to hold the house together.
the fact that they are not in a sealed box completely transforms the character of the sound, this is the "infinite baffle" part, and the raison d'etre of the whole project.

follow the link, 4wd, then tell us what you think?

gav
 
4WD said:
It will be interesting to see if the theory pans out in practice. Having played with large overpowered car subs, I know the amount of vibrations which are possible! Get it installed and take some photo's of the structural damage which ensue's! :D
Click to expand...

try playing with overpowered pa's :)

by placing two drivers in a manifold facing inward towards each other the majority of the vibrations cancel each other out, reducing the likelihood of sructural damage.
however with a line array this can be an issue.
and , like tenson says, any vibration is much reduced by the lack of an enclosure to push against
re: car subs, really not relevant here. you might have 2 x 15 inch drivers in an enclosed volume (car) of about 125 cu ft. i (currently) plan to use 4 x 15 inch drivers in a combined room volume of maybe 5000 cu ft. plus, my drivers will be operating at half of the efficiency of drivers in a sealed enclosure.

there will of course be vibrations, and one of the first jobs is to ensure that plasterboard, skirting etc is securely fixed and unable to resonate, but the sort of ceiling flex you assume is impossible due to the equivalence of sound pressure on each side.
like i said, follow the link and you will see many pictures and hear tetimonials from dozens of highly enthusiastic users who have no structural issues.

gav
 
Gav, with regards to 'facing the drivers in' I would suggest you do it so that the backs of each driver are connected to each other. It gives much better physical connection than relying on the manifold to connect them together. Not sure if this is what you were describing anyway. Have a look at the 'orb' DIY link I posted above to see exactly what I mean. This guy used some PVC pipe.
 
yep, my left-handedness coming to the fore

i meant the opposite way round, with the drivers firing at each other

but what the chap's done there is applicable for an "outey" manifold

i'm still undecided on that detail- "inney or outey"- as there are pros and cons to each.

by having an outey you can get the drivers closer to the main speakers physically, and there is no compression. the con is that in my view this works best with a single manifold placed equidistant from the two walls the speakers are firing at.
otherwise there will be differences in the time taken for the various driver's outputs to reach the listener, with obvious degradation to sq.

with an inney all drivers are in the same enviroment and the manifold functions more like a point source, making it possible to employ more than one.
however if the manifold outlet into the listening room is less than the combined surface area of the drivers, there will be compression.

i'm leaning towards a pair of "inney"s because i think i'll get tighter, punchier bass, and having 30 square inch holes in my ceiling not a problem.
this gives me the flexibility to upgrade later and add more drivers, up to four in each manifold
 
A picture says a thousand words!

roomjk8.jpg


That is what I would do. I would not rely on the manifold enclosure to connect the drivers vibration wise, the connecting rods are very important IMO.
 
oh dear. i can't draw

you've shown it the opposite way to how i plan to do it
if you were to have the config you've shown the manifold would need to be an "outey"

in your illustration i would describe the drivers as back to back, firing out

mine will be facing in toward each other, with the magnets protruding from the boxes. the box(es) will be in the loft, open side venting down into the listening room

gav
 
Why would it have to be an outie to have the drivers that way around? Its doesn't matter what side of the cone you are listening to.

I would really suggest you do it that way so you can link the drivers back to back for vibration cancellation.
 

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