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Discussion Starter #1
Wife and I recently purchased a new house and she is not letting me bring in my DIY sub - I know, a divorce should be in order but looks like I'm going to give in. Frankly there really isn't a good place for it anymore so I'm considering going with an Infinite Baffle design using the attic as my enclosure and mounting the Titanic to a manifold and feeding the output through the ceiling into my living room.

So what I have is a Parts Express/Dayton 15" Titanic Mark IV (but could be a Mark III) driven by a Dayton SPA500 (540w) plate amplifier.
Driver parameters: http://www.parts-express.com/pedocs/specs/295-405s.pdf
Amp: http://www.parts-express.com/dayton...er-plate-amplifier--300-807#lblProductDetails

In it's current configuration it's running in a sealed 4.5 cubic foot box (a box I originally built for an Adire Tempest - old school). It's a pretty good set up for rock music but less so for home theater - I think it starts gradually rolling off below 30-35Hz. Deep enough for most music but not so much with the lower frequencies often found in movies these days. Overall I enjoy my sub a lot but I'm now being forced (a divorce may be unavoidable) to rethink my strategy. My wife wants to do away with my sub altogether (DIVORCE!) but I don't think that is an option for me. Additionally to complicate things, I just don't have the excess funds right now to throw at audio equipment so there are no new or additional drivers or amplifiers in my plans at this point. No duals, no quads, no...

Other pertinent details:
The amp from what I understand has a 3rd order subsonic filter that kicks in at 18Hz - so low bass extension will be severely limited - may be a good thing since I only have 1 driver and don't want to kill it with LFE. Amp also has a narrow band (single) parametric EQ filter so a very minor adjustment can be made should I run into a severe peak or valley in response.
Living room is around 3500 cubic feet but also opens up to kitchen and nook.
Today my sub can easily overwhelm the rest of my system so the gains are turned down on my sub.
Remainder of my system is: Denon AVR-X2100W receiver (likely a bit over 100w/ch at 4 ohms), L-R - M&K S125, Center - M&K S150, 2 surrounds - M&K S85.

So...I have a few questions and am looking for guidance.
With all of the above, how would you expect that my sub and amp would perform in IB config compared what I am used to today? For music, for HT? I'm guessing improved low frequency response until the subsonic filter is reached. Less midbass? Less midbass may not be bad as I hear a little bit much currently.
Sound quality improve? Likely I think.
Overall output - same, less? Drastic change?
Any design considerations I should be looking at? Well besides the obvious of making the manifold large enough to accommodate 1 or 3 more drivers for future growth :)

Basically I'm just trying to figure out IF it's worth the time and effort of doing the work or will it be a huge fail.
 

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Discussion Starter #3
I fully understand that a single 15" "modest excursion" driver won't work miracles and blow my socks off but will it at least give me decent low end re-enforcement? I'm also a bit confused about the modest excursion comment. 19mm throw of a 15" sub is nothing to sneeze at...still more throw than a RSS390 (14mm) and equal to that of an Ultimax 15. Yes I get it that many now are using the Fi drivers with 30mm of excursion but that wasn't always the case. Many in the past have seemed very satisfied with the PE DVC drivers and some even more modest than those.

I guess it all comes back down to there is no replacement for displacement and the need for more than 1 drivers (or even 2) is an almost essential requirement.

BTW, I took a shot at WINISD and came up with the following for my existing equipment in an IB configuration:

Max excursion never exceeded (but very close) since there is a built in 3rd order highpass in the amplifier.
SPL at 20Hz - 90db
30Hz - 96db
40Hz - 98db
50Hz - 99db

As my sealed sub sits today (according to WINISD):
20Hz - 101
30 - 108
40 - 112
50 - 114

Sigh...yes underwhelming in IB. Still better than going without a sub at all? Since my wife is 100% against a sub on the floor, does anyone see any alternatives? Maybe building a large ported box in the attic and still using a manifold to direct sound into the room below? Thoughts, suggestions, links?
 

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Don't give in. It's your house too, and it's important to you. Explain that to her.
Frankly, I agree. Don't you have to pay bills there also? :eek:


Anyways, Instead of an IB, what about keeping it in a sealed enclosure and firing it into a manifold in the attic? Visually the same but still the seal cabinet performance.
 

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Tell her no sub on floor cost 1k. 2 Fi drivers,1 amp, some wood and labor. Build the manifold big enough and ready to accept 2 more drivers so you can sneak them in down the road if you need to. Tell her you put the Mk and amp in the classifieds to help finance it. Whether it sells or not is irrelevant, you look like youre trying to save a buck. Of course all this hinges on the "Sale" to the wife, and the availability of the funds to make it happen.
 

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Can you rebuild the sub into something a little more discreet like a side table or sofa table?
 

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Discussion Starter #8
All great ideas gents and I actually pay all of the bills. She's a stay at home mom so she suffers in her own way :)

Frankly we have a built-in the wall cabinet that holds the TV, receiver, and all electronics. There truly isn't a good location for a large sub, end tables, or anything as such. It's an odd shaped living room and we are still working on furniture adds, layout, etc. A big sub on the floor just isn't very practical (have I been listening to my wife too much???). Something more discrete is in order for sure. We have a row of big picture windows...maybe a custom sub/window seat with a bit of (practical) storage would work. Otherwise I think I'll remove the plate amp, seal the opening in the box, and move it to the attic with a custom manifold (aka another mdf beast).
 

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The potential performance of a sealed box and IB is essentially the same. In fact, frequency response for a Titanic MKIV 15 in 4.5CF sealed is almost identical to IB. You're likely power limited, not excursion limited, in both the sealed and IB alignments, assuming that plate amp has a typical 20Hz rumble filter. So there's certainly no reason to put a sealed box in your attic.

Note that the room and placement has huge impact on the response you get from a sub. So there's no guarantee the response you'll get in the new house with an IB will be anything like what you get now. So you'll want to go through normal planning for the IB, i.e., sub crawl, preferably by getting a mic and taking measurements. In fact, measuring it in the old house might show you what you're getting now. Your comments about how it overwhelms you now and that you keep the gain turned down makes me thing your current placement and room have some modes that make it boomy up top. My sealed subs in my living room get a huge peak in the 50-60Hz area which I EQ out to keep them from sounding boomy. So you might be surprised by how the sub sounds in the new place if it's not exciting the same boomy response.
 
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