can i turn my house into a horn?

gavman said:
ib placement require twice as many drivers as a sealed box for a given room size
gav
Click to expand...

Really how come?

You should certainly get some pretty deep bass. My estimate is that if you put a 1st order filter on at 10Hz-20Hz and taking account for cabin-gain you would easily get below 10Hz.

12Hz apparently gives women a 'good time' BTW. I know why you really want it ;)
 
i know nothing, i just quote what i see

the cult's rule of thumb is to take the number of drivers required in a box enclosure in a given room
and double it

so if your box has 2x12, then for IB you need 4X12 for the same effect, with (apparently) 250watts for each 15 or 18 inch driver

the power rating for drivers goes down by more than 50% when used in an IB

manufacturers quoting 300 watts handling in an enclosure,
same unit 140 watts IB

remember too that you create the same spl in the venting area (loft) as you do in the listening area; the sound is not focused in any way

it seems 2xalesis ra500 would be required in my system, or one behringer europower2500, to provide the necessary headroom

gav
 
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I doubt it is the power rating that goes down when in IB, but rather the power requirement for the same SPL as efficiency will be higher.

With the double the drivers thing, are you sure they don't say that in comparison to a ported enclosure rather than a sealed one?

I'll have to read the site in more detail. Did you start any threads?

Edit: ahh okay the reason they suggest double the drivers is simply because you will be more enclined to push them to low frequencies since you can reach them more easily, and the Xmax will be reached more easily too. In a sealed box it is harder to make it go so low, so Xmax is not as easily pushed. Basically it is more tempting to push the IB subs too hard.

Having refreshed my memory of the site I would suggest a far better driver than the Definimax 18 would be the Kilomax 18. The only thing is that it has an 'accordion' surround rather than a foam / rubber one that the IB site suggested. But it did say some accordion types are okay.
 
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gav, you may want to discuss the relative benefits of IB versus sealed boxes vs horn loaded sub cabs here -

http://billfitzmaurice.com/phpBB2/viewforum.php?f=5

Of course, its a forum for horn loaded subs, so you won't get completely unbiased advice - but the people on there will more likely have tried IB and sealed boxes - something the average audiophile hasn't of course (I haven't tried IB for example)
 
many thanks guys

i have indeed joined and began a thread on the IB forum

i'm already learning good stuff

they have some strong opinions on kit. the amps are available over here (Behringer europower 2500 is the hands down favourite), the drive units i'm enquiring about.

there's a strong chance this thread might follow a process that began with a question here and ends with an IB installation
i've spoken to my builder in detail about knocking two holes in my ceiling, and it's not a problem as it coincides nicely with other work.
we're going to create two loft acces sized hatches, roughly above the main speakers (i haven't sussed that bit yet. there's formulas and computer programs to tell me exactly where)
meantime joiner is building two boxes, cube shaped and open on one side.
(apologies to diyers.
me got ten thumbs and cack hands)
these will sit above the openings with the open side downward.
from the lounge you see two holes, stand underneath you see the box interior.
from the loft you see the whole box, probaly sitting atop the joists (tba), and
you will also see the magnets and the back of the speakers, the fronts facing inward (or down). in each cube it is possible to mount 4 drivers, 1 or 2 being the opitmum. two can be used facing each other- this will cancel some mechanical vibration for those concerned about neighbours or structural damage (!). a single driver works best aimed at the floor, apparently.
so i'm deciding how many drivers to use; today i'm thinking start with one 18 in each box, with a view to having two in each box eventually. nine or twelve is possible (see pics at the cult of the infinitely baffled)
i'm taking the phased approach so i can get the best drivers possible...it may be that 2 will be plenty with the better drivers, but i think i will end up blowing them, so better to run twice as many half as hard

they say 5 hz at high spls availiable

what does THAT feel like??:JOEL:
worlds colliding?

if this works i'm looking a "sticky";)
 
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yes rob, they are very popular. Adire seem to be one of the "go to" brands.
they make a driver called the Tumult 15d4 (i think) that is probaly top of my list now.

if anyone can find that locally i'd like to know

they retail for about $700 each stateside

gav
 
Chat to the guy from Mad About Sound, if he can get the Tempest, he may be able to get the Tumult.
 
i've written a new tune:D

it goes

tenson, tenson, sherlock of the year
helping me get bass
deeper than i can hear

those Aura sound drivers are pretty much state of the art, according to our sceptic chums. apparently they are used by wilson in their speakers, and if they're good enough for wilson...

so i've found my drivers.
they're priced at just over $900 each, which means i'm looking at £2000 for the four that i require.
i should stress that this is viewed as overkill by those from the colonies.
not the size and number of drivers, but the price.
they are somewhat spoilt for choice with high spl drivers cheap and plentiful as a result of the cult of car stereo db drag racing, and don't seem to have quite the same painstaking audiophile approach, favouring those designs offering the best bang for your buck.
i should also point out that they consider $150-$300/driver to be perfectly sufficient, and their amp of choice (behringer europower 2500)
(that's 2500 watts!)
sells for less than £300. i plan to use my ksa100 mk2 to do the same job @ five times the price
so i'm really hoping that someone will take a more reasonable approach than me, and show you how it can all be done for under a grand.?
this for bass of a character impossible to acheive by in room solutions..
we could then see if my megabucks approach is just a waste of money. i'm sure someone could enjoy that...
if you're reading this, go and have a look at the cult of the infinitely baffled. everything's explained properly, despite this you can still get the idea by looking at the pictures first (that's what i did), so even if you're as dull as i am you can't help but understand it in the end....

good luck!

gav
 
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Just came across your IB venture after seeing your Krells for sale. Fwiw I use a pair of Adire Audio Tumult 15" drivers in a 16 cubic foot 'riser' under my sofa driven by a Crown K2 amp via a Marchand Electronics Bassis www.marchandelec.com/wm8.html with a Paradigm x30 crossover and a BFD for equalisation.

The reason for my post is that I tried the loft installation and had to abandon it due to resonance problems, the ceiling plaster boards vibrated against the joists, if you want to use a loft installation you will probably need to put something between the joists and the boards to control the vibration.

Another issue was that of locating the driver, the sound just didn't sound right coming from the ceiling, although with the driver centrally located between the main speakers the sound was acceptable. For me I much preferred the sound when the driver was below ear level, ideally at the front between the main speakers.

Good luck with the project, if you're able to get the Tumult you'll be very impressed, quite a step up from the Tempest and Shiva.

Regards
Gary
 
I was under the impression that 6hz was the frequency your stomach exploded (hence death) and the only way to truely achieve it was to have a concrete driver?
 

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