Infinite baffle subs.

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Hi everyone
I need some feedback on a subwoofer system I have in mind. My room is 27' long, 9' high and 11' wide. At one end I want to install two Peerless XLS 830452 drivers in the corners of a cabinet open to the 18" void under my house. They will be driven by 350 watts of class D, fed through a Tannoy active crossover. The system they will complement is a pair of Vulcans with Fostex Fe203en-s driven by AN Conquests. I thought I'd let the Vulcans go down to 120hz and cross over there. This is for music not HT. As an idiot, I humbly ask if this is a sensible plan or if there are any issues I need to be aware of?
I'm going for this approach because it seems simple and I've no idea how to design a box, the carpentry will not be a problem because it's something I can do.
Many thanks.
 
Excursion!

I'm using a single Peerless 12" in my loft, I can't remember the model number, its an XXLS with Aluminum cone. My loft is obviously huge and my listening room a measly 3 x 4 m2. My DEQ 2496 has hold of a few peeks and troughs and I've been gentle with my house curve. Diana Krall Girl in the other room sounds a treat, Double bass and piano going down a treat and yet when I listen to Somafm's Drone Zone, I can feel my sofa move, but I don't hear much bass! So I'm thinking maybe thats below my hearing. However, if I watch a movie, I gotta be careful, theres a whole lot of movement going on!! Always be careful if you play movies through an IB, especially Blu Ray and Action movies. You need some good excursion, I think Ive got 15mm in one direction, you should aim for 30mm!! My previous system had 2 15" drivers with 30mm one way, driven by 450w rms amp, but thats tied up in my Divorce :(
Maybe just try and see, have a look to see if you can reverse any openings if it doesn't work. My 12" was in a box, but I had to have an IB, I'm bitten by it :)

Mike

Cheers
 
Construction

Hi doubtingthomas, just in case you haven't looked at the construction side of things, your Manifolds are best solid. On the Cult website, they recommend I think it was 18mm mdf with an 18mm ply skin. Solid bracing, and a solid attachment to the floor. So with that in mind, mines chip board and some scraps of wood to stitch to my rafters :) :ashamed:

But like I said, my other one is at the ex wife's house, and I'm a single parent, I have my eldest daughter who lives with me and 12 year old girls are expensive :)
 
some pics

My IB on a budget:D My source is a PC running Linux Ubuntu 12.04, I have an Asus Xonar DS soundcard, I'm using optical out, a Yamaha RX-V565 Surround Reciever, ( I'm 2 channel only- I have centre and surrounds but rarely watch movies), you can see my Beringer ECM8000 mic and a pre on the floor in one pic. The car amp is an MBQuart, I don't belive its quoted power, but its happy driving the Peerless. And yes, thats all chipboard. I also have a Radio Shack digital SPL meter and a spare hard drive with, yuck, Window$ 7 on it, wich I run REW. REW is a good bit of software for measuring things :) and its free. Can never get it running under Linux, hence my Windoze 7 hdd.
REW - Room EQ Wizard Home Page

Mike
 

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I believe so

Yeah, I'd say. No box is good :) My first impression was, wheres the bass gone? But more like wheres the boom gone? My 2 15"s made a concrete slab outside the patio door, vibrate. The Prodigy live HD made my back brick wall vibrate against my back. The neighbours could never hear it! I think the large Sonotubes are supposed to be near IB, though I've never heard one, also there's a Tapped horn, Tapped Horn Experiments, never played fully with one :) but I had a Linkwitz Transform on a 12" sealed box, that was beastly :D, but no, give me an IB any day :)
Mike
 
Not optimal IB driver (small, low excursion and low Qts), but if you already have those go ahead.

Without HP filter xmax is achieved with 15W/driver at 5 Hz. => 104 db/1m

With 2nd order HP filter at 10 Hz xmax is achieved with 60W/driver at 5 Hz. => 110 db/1m
 
 
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But......

18" void under my house


Me thinks the driver will see a small volume, although large lounge. Also, not wanting movies to be played through the system extreme xmax shouldn't be that critical! I never had the luxury of buying to suit the numbers. I bought what I could afford and stuck a driver in the loft. Sounds good to me, but if you can afford the gear and shipping, yes FLI drivers are more like it. I even experimented with a really budget £30 driver just to experience how it sounded. I cut a piece of ceiling out knowing full well I could put it back and filler the cut, re-patched floorboards are hidden under a carpet.

Mike:)
 
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