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Roof space IB for dedicated cinema room.

Johnny.G

Active Member
After deciding to make use of above roof space iv'e decided to build a 2 x Fi IB318 drivers in manifold above cinema room.
A few pics to set the scene of what spaces above and below to play with.

This is the room to be modded.
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Update:
It's now April 13th, 2014 and the room as evolved a bit since the opening pic of this thread showing proposed cinema room project......
 

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Johnny.G

Active Member
And the roof space above .... Looking into the loft space above the cinema from the side entry, the screen is to the lower left. These pics are taken on a 10mm lens so proportions look stretched etc. The roof space dimensions are 3m wide x 4.9m long and aprox 1.6m to apex . Room below is virtually the same with a ceiling height of just under 2.3m. The outlet on the manifold will be within the middle black acoustic tile and will morph in nicely with a suitable grill of some description.
More to follow when time permits ...
 

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Johnny.G

Active Member
Bit more info.... re:loft above, the crawl boards will be moved to the right as you look from the side view, peel back the roof insulation exposing the ceiling joists below, which run from left to right of the pic when looking at the side view, the new manifold will sit on top of the joists, where the motorised screens Austrian Drape power supply is fixed but will be relocated, and nestle up to the lower purlin on the left with the two ends of the manifold carrying on down to emerge into the room below and into the modded black acoustic tile. The manifold will look very similar to this borrowed pic from another forum.
 

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Baggy

Well-known Member
I'll be watching to see how you get on.
When I get around to rebuilding mine I'll be using a similar manifold design but two of them to make use of the 4 IB315's I have stashed away from my previous IB.
Mine will be floor mounted because I have a half height cellar under the floor.
My outlets will be about 14" x 8", constrained by the joist gap and the width of the floorboards.
 

Johnny.G

Active Member
I,m waiting for some 5mm studs for the Q18 driver on my other build to be delivered and do some cabinet finishing etc and then get that upstairs to give it a run. Looking forward to getting stuck in to this IB build though. Contacted Am at BladeICE the other day re: 2 x IB318,s etc so the balls rolling on that one.
Dictated by ceiling joist gap, my manifold mouth inside measurements will be 23.5" long x 16" wide..... looking at some of moonflys past posts, which have been very helpful, when he was doing some puts me in the right ball park (hopefully) ;)
 

Baggy

Well-known Member
I,m waiting for some 5mm studs for the Q18 driver on my other build to be delivered and do some cabinet finishing etc and then get that upstairs to give it a run. Looking forward to getting stuck in to this IB build though. Contacted Am at BladeICE the other day re: 2 x IB318,s etc so the balls rolling on that one.
Dictated by ceiling joist gap, my manifold mouth inside measurements will be 23.5" long x 16" wide..... looking at some of moonflys past posts, which have been very helpful, when he was doing some puts me in the right ball park (hopefully) ;)
Sounds plenty. How big's your room?
I've attached some photo's so you can see where mine will go.
You can see from the underfloor shot where the two cut outs will be.
 

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Johnny.G

Active Member
Most interesting, see what you mean re: floorboard constraints. Floor looks fabulous though. Under floor space looks ideal, and the positioning of the two manifold outlets in relation to the screen / speaker set-up also looks spot on. As Moonfly once said in one of his past posts ..." it's as if it was meant to be" . Might have mis-quoted slightly Dan, but near enough :)
 

Baggy

Well-known Member
Yes the joists are spaced at 14" and the floorboards are just over 8" width.
Last time I removed two adjacent boards giving about 17" x 14" but decided this time to have two manifolds.

Got to use that space for something otherwise it just fills with junk:D

Getting back to your project, how big is that room?
 

Johnny.G

Active Member
Forgot to mention the room size, its as near as damn it 2.9m wide x 4.9m long and about 2.3m ceiling to floor, bog standard rectangle shape
 

Baggy

Well-known Member
Two IB318's should be really good in that room.

Mine is about the same height & length but slightly wider at 3.75m.
 

Baggy

Well-known Member
But 4 split into 2 manifolds would be better :devil:
Maybe but at least starting with 2x 18" there's an upgrade path if required.
 

Member 639844

Former Advertiser
2 drivers will be fine, and 4 are only really necessary if you find they are being bottomed out a lot. I would go for the 4 in a pair of manifolds though to give a complete system with in effect a pair of subs. I would still do split manifolds no matter what as its a form of natural eq that helps flatten a response and give a smoother more seamless integration. 2 drivers will sound more or less the same as 4, with only a sense of greater effortlessness being the real difference, but its a fairly subtle one.
 

Johnny.G

Active Member
And do you know ..... apart from the extra cost, it would be an absolute doddle to do :D . I'm fed up with you seed planters! :laugh: and in a way it's logical because the EP4000 will have a redundant channel with me running the one manifold with drivers in series, leaving the possibility of a second manifold on the the amps second channel . Quote "It's meant to be"
 
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Member 639844

Former Advertiser
Thing is, two subs are always better than one from the EQ POV. Even if you only run with 2 drivers, I would put them in two manifolds.
 

Johnny.G

Active Member
With you on the two separate sub idea, one 318 in each manifold, but upgrading to two per manifold at a later date when wallet has recovered :eek: I do like the idea of two in a manifold though for the mechanical forces cancellation...Thinking about wiring them from the EP4000..... initially do i just use 2ohm vc and wire the two separate 318's in series for 4ohm total load from ch1 on the amp, and then at upgrade time with two 318's per manifold, wire extra circuit from amp ch2 to feed No2 manifold, using the two 2ohm vc in series for a 4ohm load for ch1 & ch2 on the amp. Eventually would like to use the new Antimode 2 which has two channel output with the ability to eq the two subs fully.
Thoughts appreciated on this please.:smashin:
 

Member 639844

Former Advertiser
The ep4000 is a 2ohm stable amp, and an IB has moderate power requirements meaning its not a heavy 2 ohm load on the amp either. Your having 2 separate manifolds so treat them as 2 individual subs. Wire one driver to each channel, and run a test tone to each one, one at a time. Use the gain on the ep4000 to set each channel to 75db in the main listening position, and combined they will be about 3db hotter. Once you run the antimode etc, you will have a very nice sounding system.

Just make sure you build your manifolds in a way adding more drivers is simple should you ever want to do that (you might feel there is no need), and make sure you build them really solid as a single driver will move a bit if your manifold isnt upto the job.
 

Johnny.G

Active Member
With you :thumbsup: will build with extra strength then and can pre-cut them for the extra driver if required and use the 25mm mdf circles that were scrap pieces from the other build to help make up the manifold blanking pieces.
I plan to reinforce the ceiling joists arrangements etc around each manifold as well to help cut down any structual problems with plaster boards and such further down the line.

Just paid Am for the two 318's, eta 3 - 4 weeks.
 
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Johnny.G

Active Member
Guru's, there's a reason why i'm asking this, which will be revealed later ... Looking at the mock up pic for the manifold outlets which are shown at full size, they are shown in position 1 with the joists slots marked with the white stickers. Position 2 would be to move both manifolds inward to the next joist slot. In this No2 position the gap between the two manifold inner edges would be about 26 inches. Manifold inner dimensions are 16" wide x 23.5" long.
 

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Member 639844

Former Advertiser
Was there even a question in there :laugh:

With dual manifolds/subs, you want to spread them a bit and avoid having them close to each other.
 

Johnny.G

Active Member
Yes .... it was disguised :laugh:
It was all to do with structual obstacles above and the positioning of the acoustic tiles below Dan ...... Position 1, the spaced out version means ive got to re-frig the left hand tile a tad more towards the wall to make the manifold fit. The right hand manifold drops in place spot on. Position 2, closer together, meant no work involved with tile moving for both manifolds. It's not a major problem to shift the tile and i have already got the plan in my head how to get a finished look across all three tiles without seeing any joins etc. Pic shows how the manifold is landing just too much over the edge of the tile.
Up above, the two manifolds will butt right up and be fixed to the lower purlin, so that bit of the job has worked out :smashin:. The left hand crawl board will be gone as well. Any thoughts about isulation between the rafters ?
Thanks for the input Dan, appreciated.
 

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Member 639844

Former Advertiser
Looks to me like the simplest solution is to just re-jig the panels. Its gotta be easier to make them again than anything else.
 

Johnny.G

Active Member
I didn't make those panels Dan they were commercial things from a company nearby to me, they were spray glued into position so with a bit of careful leverage they might part company with the ceiling with out too much hassle
 

Baggy

Well-known Member
How's the planning coming?

I've started mine
 

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Johnny.G

Active Member
Ohhhhh looking nice Baggy :smashin:. Been working a bit on my other sealed Q18 build today with giving the cab a first coat of paint finish. Also set up the Q18, EP4000 & laptop this afternoon playing a gentle 20hz tone to help supple it up a bit. I'm not that far off lugging the cab upstairs now and fitting the driver propper and having a few weeks using it. I'm chomping at the bit really to give my full attention to the IB build, the 318's will be another 3 - 4 weeks yet before they land. Iv'e aquired more speaker cable to run two circuits up to the manifold positions so can install that when i get a minute. Hoping to get down to the wood merchants in the next day or so to get the 20mm ply for the manifold inners and then do the sandwich job as in your pic as well.
If your not starting a thread up on your build Baggy, please keep your pics and progress coming . :smashin:
 

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