Infinite Baffle subs build in the Bat Barn

Shockabuku

Member
Hi all. I thought I'd start a new thread in the subs forum to detail my infinite baffle build that I've been covering in my DIY build thread (link in my sig). There don't seem to be very many IB builds here in the UK, so I hope this might be of interest to some of the bass heads on here :hiya:.

No prizes for guessing that forum member Nimby put me onto the idea of infinite baffle sub designs. From there, I spent a lot of time scouring the Infinitely Baffled forums for builds ideas, and finally I'm now building my very own own monsters of sub-bass
icon_buttrock.gif
.

1. The room
I'm nearing the end of converting the upper floor of a ~200 year-old detached barn into a dedicated home cinema. The room measures 31ft x 15ft x 14ft max (vaulted ceiling). Here's how the room started out...

batbarn_interior1.jpg


..and here's how it's looking at approx 80% completed...
img_0980.jpg


2. The subs
A room this size was always going to stuggle with "conventional" subs, and I really don't have the budget for 4 x PC-13s, so for about the price of a single PC-13, I'm building two IB enclosures, each of which will house two 18" Fi Audio IB specific drivers. Fi are pretty much the only company on the planet currently making IB specific drivers, and as such they're not the easiest things in the world to obtain! After a few months of trying, mine are finally on a boat from America, and are expected to arrive in the UK next week :clap:. You can see details of the drivers HERE.
 

Shockabuku

Member
3. The manifolds
The ground floor of the barn is of course a similar size to the upper, with an approx 8ft ceiling. My plan is to mount the two manifolds to the ceiling of the ground floor, firing up into the cinema room. Obviously, this will involve cutting holes in the floor of the cinema room, which in fact is the next job on my list :eek:.

As of today, I've built the manifolds & other than some priming and painting, they're pretty much ready for the drivers. I'm following the recommended build from the Infinitely Baffled sub nerds, which involves a double-skin box, 18mm ply laminated to 18mm MDF.

Here are some images detailing the build process. First, putting the MDF panels together...
img_1140.jpg


img_1145.jpg


Ply panels going in...
_mg_1175.jpg


_mg_1177.jpg


_mg_1180.jpg


MDF base in place...
_mg_1182.jpg


Interior joints filled...
_mg_1184.jpg


And here are the manifolds, awaiting some attention from a router...
_mg_1189.jpg


Next comes the hole cutting. First, I marked out the widest point with a low budget compass...
_mg_1220.jpg


A woodworker friend of the family came around with his router to help out. Here he's making a circle cutting jig...
_mg_1223.jpg


Luckily we've had some respite from the rain today, so we could make the dust outside...
_mg_1227.jpg


First a recess in the MDF, half an inch deep...
_mg_1230.jpg


Next, change router bit & cut out a 16 3/4" hole through the MDF & Ply...
_mg_1229.jpg


And here they are, all cut & sanded down...
_mg_1245.jpg


They certainly weigh a lot less now, although that'll change when 64lbs worth of drivers are inserted into each manifold :devil:.
Here's a shot of the bottom of the barn, where the manifolds will be mounted...
_mg_1254.jpg


The manifolds will be fixed to these beams. As you can see, they'll need a bit of sorting to get them nice & level, and I suspect some expanding foam will come in handy to ensure a good seal between back & front of the subs...
_mg_1255.jpg


_mg_1256.jpg


Fingers crossed, the subs should arrive next week sometime, and then the real fun starts. In between now & then, I need to think about cutting some holes in the floor :eek:.
 

suniil

Well-known Member
Now that's something serious :smashin:

Glad you picked the right choice of driver! Shame, I'm in discussion wtih Scott (FI Car audio) and thinking of getting the stuff in sea pallet to reduce the freight. We could have imported together :(

Anyways looking forward to see the progress pictures, and you would be the proud owner an IB with dual 18" drivers
 

AngelEyes

Distinguished Member
That barn is gorgeous, what a fantastic cinema room. Thanks so much for sharing and do keep it coming :smashin:

Out of interest have you chosen your positions for the IBs? I assume at this stage you have some flexibility so it would be worth doing some calculations to get the best positions to avoid room modes... having said that the vaulted ceiling will probably inject a whole new dynamic, hopefully positive :)

What amps and EQ are you planning to use?

When can wee come round for a listen :D

Adam
 
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AngelEyes

Distinguished Member
Anyways looking forward to see the progress pictures, and you would be the proud owner an IB with dual 18" drivers

I think he will have 4 drivers in total, 2 in each enclosure, right?
 

Member 96948

Distinguished Member
Just when you thought it was safe to go out again.....:D

To echo Adams thoughts, what a fantastic room. Puts me in mind if the house we bid on and lost last year.:(

That barn is gorgeous, what a fantastic cinema room. Thanks so much for sharing and do keep it coming :smashin:

Out of interest have you chosen your positions for the IBs? I assume at this stage you have some flexibility so it would be worth doing some calculations to get the best positions to avoid room modes... having said that the vaulted ceiling will probably inject a whole new dynamic, hopefully positive :)
Just what I was thinking. I'd have thought the quarter points were the place to start, but with so little actual wall, I'll bet it measures pretty damn well anyway. It would be easy enought to find out as a DF sub placed on the floor would be very close to mimicking the upward facing manifold. I'd certainly be interested to see how it measures currently.

I'm also interest to know why you settled on a 2x2, rather than 1x4 manifold.

Lucky sod.:D

Russell
 
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cribeiro

Well-known Member
Gorgeous!

I'd be worried about possible structural damages, though, if those beams are really 200 years old :rolleyes:
 

AngelEyes

Distinguished Member
Gorgeous!

I'd be worried about possible structural damages, though, if those beams are really 200 years old :rolleyes:

They don't build em like they used to, I wouldn't give it a second thought :D

Also interested in the rest of the kit, it looks such a large space for those standmounts to fill, however I must confess I don't know what they are :)

I really am impressed with the project, this really epitomises Home Cinema for me, glorious building with bags of character and seriously mental kit :thumbsup:

Very jealous :mad: ;)

Adam
 

Shockabuku

Member
Thanks guys, I'm certainly having fun with this part of the project :thumbsup:. Regarding placement, I've done the "sub at the seating position, crawling on the floor" trick, and actually I found the room to be fairly flexible in this regard. I also have to consider the aesthetics of holes in the floor - and safety - I have a young daughter. So, they'll be located in between the main LR speakers and the centre speaker, which will keep things tidy.

I went for two manifolds of two drivers each, rather than 1x4 following some discussion on the Infinitely Baffled forum. There are potential issues with delay due to the drivers lower down the stack, but I don't think there's a lot to decide between the two really, but two just made more sense to be, and I think should provide more chance of an even sound signature for all listening positions. I also prefer the aesthetics of two smaller boxes, and my back was weeping at the thought of a single huge manifold with 4 drivers!

To be honest, I think the barn will definitely be the weak point in the whole setup...based on what I have read about similar IBs, I suspect I could do some damage if I turn the gain up a litle too much :eek:. I'm just hoping I can turn it up high enough to enjoy before things start breaking :rotfl:.

Ah yes, amplification. I have a T.Amp TA2400 MK-X, which will feed 1200w max into each manifold...

img_1006.jpg


I also have a Behringer BFD which I'll be using with REW to calibrate the setup once installed.

The vaulted ceiling is indeed a bit of a head-scratcher, acoustically. Following a recommendation from a knowledgable forum member, I've done a load of acoustic panels to absorb some of the stray reflections up there. Obviously it won't have much if any effect on sub-bass, but in theory should improve the higher frequencies...

img_1027.jpg
 

AngelEyes

Distinguished Member
Thanks guys, I'm certainly having fun with this part of the project :thumbsup:. Regarding placement, I've done the "sub at the seating position, crawling on the floor" trick, and actually I found the room to be fairly flexible in this regard. I also have to consider the aesthetics of holes in the floor - and safety - I have a young daughter. So, they'll be located in between the main LR speakers and the centre speaker, which will keep things tidy.

I went for two manifolds of two drivers each, rather than 1x4 following some discussion on the Infinitely Baffled forum. There are potential issues with delay due to the drivers lower down the stack, but I don't think there's a lot to decide between the two really, but two just made more sense to be, and I think should provide more chance of an even sound signature for all listening positions. I also prefer the aesthetics of two smaller boxes, and my back was weeping at the thought of a single huge manifold with 4 drivers!

To be honest, I think the barn will definitely be the weak point in the whole setup...based on what I have read about similar IBs, I suspect I could do some damage if I turn the gain up a litle too much :eek:. I'm just hoping I can turn it up high enough to enjoy before things start breaking :rotfl:.

Ah yes, amplification. I have a T.Amp TA2400 MK-X, which will feed 1200w max into each manifold...

img_1006.jpg


I also have a Behringer BFD which I'll be using with REW to calibrate the setup once installed.

The vaulted ceiling is indeed a bit of a head-scratcher, acoustically. Following a recommendation from a knowledgable forum member, I've done a load of acoustic panels to absorb some of the stray reflections up there. Obviously it won't have much if any effect on sub-bass, but in theory should improve the higher frequencies...

img_1027.jpg

The crawling around 'myth' won't really tell you a great deal, so I would ignore any advice based on that little gem. :D

Room EQ wizard should be the order of the day along with Russells suggestion of using DF subs in the proposed locations to give some idea of room response.

It may sound like a 'faf' but all that effort in construction resulting in a hideous room response at the seating position will be a lot worse :lesson: :) There is after all only so much a BFD can do to help.

From what I have gathered the vaulted ceiiling should actually help quite a bit but you won't actually know until you run some sweeps.

Not sure on your aesthetic tastes but there is nothing stopping using some sturdy grates/grills to cover the IB vents so they are safe to walk over. The only real issue you have to worry about then is how it impacts on the floor below :rolleyes:

Adam
 

Member 96948

Distinguished Member
Also interested in the rest of the kit, it looks such a large space for those standmounts to fill, however I must confess I don't know what they are :)
Sonus Fabers mate. Beautifully crafted Italian speakers designed for the highest quality accurate reproduction. Nothing that would interest you then.:D

Russell
 
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AngelEyes

Distinguished Member
:offtopic:

I am guessing you have a Sony Projector there, and forgive my ignorance but 2.35:1 is the more common 'cinema' ratio right? Do you need an Anamorphic lens for that?

If I were to have a dedicated room I think I would opt for a true 'widescreen' option rather than 16:9. Any negative issues with this kind of setup?

Sorry for the questions, you ahve just rekindled my interest again :D

Adam
 

AngelEyes

Distinguished Member
Sonu Fabers mate. Beautifully crafted Italian speakers designed for the highest quality accurate reproduction. Nothing that would interest you then.:D

Russell

Silence wuffian :nono:

Don't tell anyone but I have been considering demoing some 'non' M&K speakers :eek:

Adam
 

Shockabuku

Member
Cheers fellas, I'll see what I can do about getting my mitts on the calibration kit from a mate of mine, just to make sure before I make those holes ;).

The speakers are indeed Sonus Fabers, but unfortunately not the lovely Cremona Auditor. Mine are the humble (well, if you can call £1200 for a set of speakers humble!!) Concerto Home, along with the matching Solo centre speaker. I did have the matching Walls (monopole side surround speakers) in my previous setup, but I fancied something more enveloping in this room, so bought some M&K 55MkII tripoles. The Walls are now hooked up to a tube amp and a Squeezebox in the living room, and sound rather nice :D. The Concertos aren't the most transparent speakers in the world, but I don't care because I think they sound just gorgeous, and are a pretty fine piece of furniture in their own right.

Regarding the projector, it's a Sony VW60, and yes I'm using a Prismasonic anamorphic lens. Most films these days are coming out in the wider aspect ratios...2.35:1 to 2.40:1, and having created this setup, I would never go back to 16:9 now. It's not cheap, and it's a bit fiddly to set up, but it is worth it imho if you don't exclusively watch older films, and you have the space.
 

Shockabuku

Member
Now that's something serious :smashin:

Glad you picked the right choice of driver! Shame, I'm in discussion wtih Scott (FI Car audio) and thinking of getting the stuff in sea pallet to reduce the freight. We could have imported together :(

Anyways looking forward to see the progress pictures, and you would be the proud owner an IB with dual 18" drivers

Ah yeah, that's a shame, although you know there is a UK importer for Fi stuff? The price over here is of course MUCH higher than you'll pay in the 'States, but I guess shipping four 32lb drivers isn't going to be cheap!
 

Member 96948

Distinguished Member
They do look rather lovely, not the model you linked to though, these look front ported?

Adam
Have a look here. When I read in magazines about top quality fit and finish on speakers, I often wonder if they've ever met a pair of SFs - They make most stuff look DIY.

Russell
 

AngelEyes

Distinguished Member
Have a look here. When I read in magazines about top quality fit and finish on speakers, I often wonder if they've ever met a pair of SFs - They make most stuff look DIY.

Russell

I did have a Google earlier and have been drooling ever since, gorgeous furniture. Hiding in my M&K 'hole' has been a good way of stopping me spending any more money but when I poke my head out and see gorgeous things like that... :rolleyes:
 

AngelEyes

Distinguished Member
Regarding the projector, it's a Sony VW60, and yes I'm using a Prismasonic anamorphic lens. Most films these days are coming out in the wider aspect ratios...2.35:1 to 2.40:1, and having created this setup, I would never go back to 16:9 now. It's not cheap, and it's a bit fiddly to set up, but it is worth it imho if you don't exclusively watch older films, and you have the space.

This is my thinking exactly, I do have some classic Japanese stuff in my collection and of course good old Star Trek :D but most is wider than 16:9 and I think I could live with the black bars on the sides of the odd 16:9 title.

Any rough guide to how much Anamorphic lenses and a wider screen adds to the average budget? I have been guessing around 50%, hopefully it isn't much more than that :)

Adam
 

suniil

Well-known Member
Yeah, just saw it in your link! UK prices are not very high when you compare shipping & VAT.

BTW, TA2400 looks very good, please share your thoughts when everything put together.

Ah yeah, that's a shame, although you know there is a UK importer for Fi stuff? The price over here is of course MUCH higher than you'll pay in the 'States, but I guess shipping four 32lb drivers isn't going to be cheap!
 

micb3rd

Active Member
Very cool, I read most of your room build thread, I look forward to seeing the results come to fruit.
 

jason shep

Well-known Member
Thats going to be a stunning cinema :thumbsup:

Shockabuku,i built an IB 6 months ago & it is the cleanest bass i have ever experienced,have fun :)
 

Gregory

Active Member
Not sure on your aesthetic tastes but there is nothing stopping using some sturdy grates/grills to cover the IB vents so they are safe to walk over. The only real issue you have to worry about then is how it impacts on the floor below :rolleyes:
Adam

I had a similar issue with an IB I built into the floor. After much (failed) faffing about looking for grilles that were solid enough, but with mostly open area, I've hit on getting a grill made from 10mm stainless steel by bespoke waterjet cutting - allows me to get the size exactly right, make it strong but mostly open air and fit with the rest of the decor. Your area is bigger, but you can get waterjet cut panels up to about 25mm thick, so I'd have thought you could make it tough enough to park a car on (never miond a small child). If you can create a CAD drawing of what you want then getting it made is a doddle

Does remind me that I never got round to recalibrating the BFD after finishing!

Love the project BTW

Cheers

Greg
 

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