Dual opposed 12" Infinity Reference sealed subwoofer

Hi, hope you can help to suggest improvements / changes to my plan. Looking to start my first DIY build on a fairly tight budget, and have (after reading and reading everything I can find) come up with this plan. Primary focus is music, but it’s going to be used for HT too. Big room with high (9ft) ceilings, open plan family room / kitchen / great room, probably around 1000 sq ft total.

Amp: Crown XLS 1000
Drivers: Dual opposed Infinity Reference 1262W 12”
Cab: Sealed, 3 ft^3

Any thoughts / problems or improvements with this set-up? I plan on mounting the Crown behind my TV and running the cables semi-hidden. It'll be used primarily for music, and the sub input will be from a Denon 1712 AVR.

Thanks!

Andrew

Thanks both. I'm definitely open to design changes, although I like the external amp to give the flexibility to hook up a 2nd somewhere down the road. Right now, this is compromise-driven, so I stuck at a set maximum dimension (~24" cube max), hence the idea of sealed with lots of power. Also, and with the old quote about a true compromise being where neither party is completely happy, I've got very little flexibility on positioning. It has, at least, a wall and a corner, and the listening position has a wall behind it, so hoping not to find myself in a null. My old 8" Sony sub did a fairly good job in here, so I hope the position isn't too bad.

With all that said, I'm starting to model in WinISD so I'll push a few different ideas through there and report back. I've been going back and forth to a single driver (e.g. 12" Titanic) or a single 15" Dayton HF.

Thanks – yes, I modeled it last night briefly, will spend more time with it tonight when I’m home from work.. still a huge rolloff below ~30hz. Possibly I’m modeling something incorrectly, because the Crown should push a fair amount of power... I’ll check again tonight and post a few charts.

Ok, I’ve modeled different drivers and I’m spinning circles. I’m hoping someone could give a little advice to help narrow down my ‘hardware’ choices. My max outer dimensions are 24” high, 18” deep and 24” wide (I could go up to 32” wide it I really needed to, but that will reduce the WAF significantly….). I’d like to use an external amp so I can add another sub down the road and use the same amplifier. I’d like to use the Crown XLS1000 as it seems to offer the best bang for the buck.

I’d like to spend < $200 on the driver if possible, with a focus on good musicality. Would appreciate any more input from anyone on box dimensions, driver etc. Is the dual infinity a bad idea in this box?

Thanks for the info and reply!

I'm still thinking of the dual 1262W, largely a cost based decision, but also I like the flexibility of tearing down the cabs and building two if I decided that was a good route. Right now, WAF is my primary factor....

It's been a while since my last EE class, so a question. I have a Crown XLS 1000 amp, which I'll drive with my Denon into something (miniDSP or ART) to send a 1.4V pro-level signal. The 1262W is DVC, 4ohm per voice coil. If I wire the two voice coils per sub in series, then both speakers in parallel, it'll be a 4 ohm load, correct? I plan on wiring that way, then bridging the Crown to present a 4 ohm load to the amp, which on paper nets 1100W, or 550 per driver.

Does it make sense to wire this way? I'll add a hipass to prevent over-excursion (and I plan on building sealed), but I think this is the easiest way to present a 4ohm load to the amp without two sets of wires.

The amp looks great - I plugged in my iPod via an RCA and hooked them up to a pair of Polk Monitor 70s that I have - I know the iPod doesn't give 1.4V, but even with the gain at ~40% the Polks were pretty loud. I plan on mounting the amp behind a 60" wall-mounted plasma.

Apnea

Such a great forum. Thanks for the quick reply; I'll order up a pair of the Infinities and model a decent sealed enclosure - I'll post some results / pics. Cheers!

Space - I don't have room for two boxes, so this is a compromise. As for dual, well it also gives me an opportunity to build a 2nd if I move and get more room for the A/V part of a busy household

That's great news - I'm going to get cutting once the drivers arrive, and I'll let you know how my wife reacts... So, no high-pass filter, interesting - I've heard conflicting thoughts on them for small sealed. I figure that the drivers are $60 each, if I blow one, it's not going to hurt too badly.

So in a complete change of heart, I think I'll build a pair of boxes. I made some mock-ups and it is aesthetically more pleasing, plus likely will sound better to boot. Question: my Crown amp is rated 550W@2ohms; I can wire the DVC 1262W to present 2 ohms to each channel, or I can get the 1260W which is SVC and 4 ohms. I'd rather 2 ohms stereo - any problems with that, given I'll be running two channels at 2 ohms, not bridged 4 ohms? I suspect the amp internally still sees 2 ohm per channel even in 4 ohm bridged mode, so I think it nets out the same.

Thanks for the encouragement to build a pair - form ever follows function.

Thanks - my plan was a little unclear. I'm going to keep 2 drivers, but split the cabs into two separate boxes. So they'll be single driver cabs, but two separate enclosures. Primarily aesthetics, but I'm keen to smooth out the in-room response, especially as my positioning options are exceeding limited.

19.5" L/W/D would net out about 4 ft^3 - would you recommend then somewhere around 2 cubes for a single driver? That would be ideal. In the longer term, I'll probably shift these to the basement and build something meatier, but this seems like a great inexpensive way to dip my toes in DIY. Each box should end up costing ~$90 to $100, which is just amazing. I've got access to a great wood shop, so tool costs are out of the equation at least.

No problem, thanks for the reply.

I took a look and I _think_ I can load them 2 ohms per channel - have a look:

http://www.crutchfield.com/S-qvxDk7TNTTL/p_1081262W/Infinity-1262w.html?tab=features_and_specs#details-tab

So I think that means I can get 2 ohms per woofer, so with 2 cabs I'll present 2x2ohms, one per channel of my Crown amp. I sure hope that's right because the order has already shipped!

Great - I can breathe again

Some output from winISD, plotting a single driver in 1.25 cubes (internal) with 500W (over the maximum specs given by Infinity, but we'll see about that.....)

I had to guess at some of the T/S specs, and I couldn't find a file for winISD - I hope I guessed right


Max SPL - not stellar, but I'm in this for the experience, so for < $100 a cab, I'm happy


Over-excursion of around 3mm - I'm not too concerned, should I be? I could wire the 2 voice coils in series to present 350W per driver, but I don't like leaving headroom on the table