Which Type of Enclosure would be recommended for a 14' x 20' living room?

[Max_Powers]

Hello, I am planning on building a subwoofer for my home theater as I am currently using a MTX thunder car audio sub that was left over and it does not go low enough (for the sake of home theater)

My living room is 14 feet X 20 feet and has a strange geometry with a lot of wide open spaces.(i have attached an artistic rendering of the space below)

I am having trouble on deciding on whether I should go with a ported (most likely slot port) enclosure or a sealed enclosure.


With both routes, I plan on utilizing two subwoofers.

\\\If I go with ported box, I plan on using two of these: http://www.parts-express.com/pe/show...number=295-464

\\\If I go with a sealed box, then I plan on using two of these instead: http://www.parts-express.com/pe/show...number=295-512


Because of the strange room geometry; Which setup do you think will best suit this space? Any help will be gladly appreciated

[Pete Schumacher]

Re: Which Type of Enclosure would be recommended for a 14' x 20' living room?

If you have the inclination, build multiple subs and place them at different locations. It will be much easier to arrive at a satisfactory level of smooth bass response throughout the room.

If you have the option to only build one, place it as close to you as possible so that you reduce the load on the amp and woofer. If you can't place it near you and only can build one, build with as large a driver as you can and power it adequately.

[Max_Powers]

Re: Which Type of Enclosure would be recommended for a 14' x 20' living room?

Ok, that sounds reasonable. It brings me to another question, so using one of these Y-splitters to split my receiver's LFE would be ok?

(1male to 2female)

http://www.parts-express.com/pe/showdetl.cfm?partnumber=184-224

Would there be any degradation or loss, or would I not have to worry about it since it is an analog signal?

I heard that you cannot split a Toslink optical cable since it is digital and if a splitter (1female to 2male) is used, signal only goes through one path and cannot be split.

[Jay1]

Re: Which Type of Enclosure would be recommended for a 14' x 20' living room?

What size of enclosure are you willing to deal with?

Ported will give you more bang for your buck down low, but a larger more complicated build is required.

[bkeane1259]

Re: Which Type of Enclosure would be recommended for a 14' x 20' living room?

You've got the right thinking with the dual subs. Either route you choose, I’d say to locate one in front by your equipment and one in back by your couch. This will help to reduce room modes. No matter what, I envision your kitchen becoming a huge bass mode, but the great thing about having dual subs is that you can experiment with placement and choose what sounds best to your ears.

[bkeane1259]

Re: Which Type of Enclosure would be recommended for a 14' x 20' living room?

In so far as going ported or sealed, I’m sure you’ve read that sealed sounds more “musical” and ported can have higher output at the risk of sounding “boomy.” This is very true IMO. My HT subs are sealed, but I don’t have a need for ridiculously high output, so all is good.

If you go sealed you will need more amplifier power to reproduce the same sort of levels as a ported alignment given the same input signal. This might be a factor if you have a strict budget. The Ultimax driver is a beast. Don’t pair it up with a Dayton SA100. Think more along the lines of a Crown XLS series amp.

Yes, you can split a LFE output from your HT and you DO NOT need a $15 y-adapter to accomplish that. You won’t be able to tell the difference between that and a $2 y-adapter.

If I was you, I’d go sealed with lots of power. One sub up front – one in the back and a nice powerful Crown XLS to drive BOTH boxes. By running the Crown amp in stereo mode, you will have independent gain control over each sub. Just an idea. You could always do individual plate amps for each sub, but I don’t like running long lengths of RCA cable. A very long run of RCA cable could present some noise and/or signal loss problems.

Good luck.

[Max_Powers]

Re: Which Type of Enclosure would be recommended for a 14' x 20' living room?

Thank you for all this useful information, I am now aiming towards using a single enclosure with two 15" subwoofers, I like the idea of sealed (I am running two JLs in a sealed box in my car and love it) I am just worried about whether it will sound exceptional. However, the idea of two larger woofers in a sealed enclosure sounds like a good idea. Plus, i believe it will be easier to build a box for it and not really have to tune it. That brings me to another question, If i purchase the 15" Ultimax,
Cabinet recommendations:
• Sealed 3.1 cubic ft. (net internal) with 3 lbs. of Acousta-Stuf polyfill, f3 of 35 Hz with a 0.707 Qtc alignment

Regarding the f3, how does one tune a sealed box, or does it not matter? besides the acousta stuff and volume.

Also, If I plan on using two of these, do I basically double the recommendations for the volume, ie. sealed 6.2 cu. feet?

In addition, regarding the crown xls amplifier, I was looking at the input, Do I basically use a (1male to 2male) splitter from the receiver LFE to the input for CH 1 and CH 2?

Thank you all once again for your input

[fbov]

Re: Which Type of Enclosure would be recommended for a 14' x 20' living room?

+1 to a lot of what's been said, but there's more...

Regarding this post, you want 2 subs in different locations. You don't get that from a single enclosure. Splitter is fine given you're working with high impedence signals. You "tune" a sealed box by box size; the amount of fill is more of a fine tuning. It affects the frequency response via Qtc, Q higher than 0.7 gets a bit boomy, lower gets better LF extension but poorer excursion control. Both are subtle compared with box size or port tuning affects. Where sealed really shines is in the infrasonics when combined with room gain (or cabin gain in a car). The inherent LF roll-off is shallower than vented and there's no issues of driver overexcursion... before you fry the voice coil.

The only hardware I'll disagree with is the Crown amp... there are many excellent alternatives that are a lot easier to implement because they are designed for this application. I've got two sealed 15's that are comparable to Umax 15, each with a 500W plate amp that does all the boosting and filtering I need.

The Crown is just a pro amp, so you need a miniDSP or something similar to provide the boost/filter. You'll need XLR cables for your connections, likely with an interface box, and fan mods may be desirable if the amp's in the room. A fair comparison includes all necessary elements, plus required learning. With a SW plate amp, you'll need a long RCA cable... and a short learning curve. Your call...

I'll also address what no one else has - what to expect in your room. It's actually fairly good. You may have walls at 20' and 14' but the openings in them substantially modify their standing wave behavior; the entire space you sketched is involved at minimum. And that's good, because the more variation in lengths, the more you chop up the standing wave pattern, the more modes populate the room, reducing the spacing between modes, which is what sounds good.

This is where I'm going to disagree with Pete on placement. You can set up a uniform sound field in the entire room if you just avoid corners and mid-wall placement. Corners excite all modes, mid-wall excites the 2nd harmonic. At 1/4 to 1/3 points, you minimize energy into 1st and 2nd harmonic in that direction. I have a similar room in size and complexity, and I have no peaks at these frequencies. I do have tails in the acoustic decay curve, but lower than the room fundamental indicating house resonance from one big doorway. Unfortunately, the sub ends up in the middle of the room (in mid-air) if you try to do this in more than one direction

In your room, the 20' dimension is broken up by a perforated wall (you show a dotted line) between living room and atrium/foyer, which broadens and flattens that direction's modes as some energy reflects at 20' and some at ~25'. In the 14' direction, the distance far longer than 14' as the entire path to the kitchen is involved, and that involvement is complex due to the intervening walls. The other doorway you show off the foyer can be thought of as the mouth of a port, and the rooms beyond a big box.

The final bit is that your room appears to be stick construction, single-layer drywall, above grade, and so leaky compared with soundproofed rooms or basement locations. You also have a large window area, another good place to leak energy. I expect that you'll have a very uniform bass sound field up to about 70Hz, where the floor-ceiling modes start, and most rooms' frequency response starts to get bumpy because the room's no longer as leaky and modal density isn't high enough.

HAve fun,
Frank

[the kid]

Re: Which Type of Enclosure would be recommended for a 14' x 20' living room?

I see you are wanting to use 2 subs in 1 box. The recommended replies are to use 1 sub in 2 (each) box and locate these around the room. If you can, a suggestion would be (though extra money) to get some wood and build 3 boxes. 1 box for 2 subs, and 2 separate boxes for each sub. You don't need to pretty them up or finish them in order to try both, 1 sub box, then 2 sub boxes. See which one fits you the best. Then you can finish up whichever one wins. Use the other box(es) for another project or for testing.

My room is 14x20 with 10' ceiling. No open walls. I am using 2 12" subs (1 in each box) and it has made a difference from just 1 15" that I started with. I am using 1 amp to play both.

[bkeane1259]

Re: Which Type of Enclosure would be recommended for a 14' x 20' living room?

The only hardware I'll disagree with is the Crown amp... there are many excellent alternatives that are a lot easier to implement because they are designed for this application. I've got two sealed 15's that are comparable to Umax 15, each with a 500W plate amp that does all the boosting and filtering I need.

The Crown is just a pro amp, so you need a miniDSP or something similar to provide the boost/filter. You'll need XLR cables for your connections, likely with an interface box, and fan mods may be desirable if the amp's in the room. A fair comparison includes all necessary elements, plus required learning. With a SW plate amp, you'll need a long RCA cable... and a short learning curve. Your call...

Sorry Frank, but that is simply not true. The Crown XLS series have RCA inputs (as well as XLR and 1/4" inputs) and 4th order LR adjustable crossovers and the learning curve is no steeper than using plate amps. Plus, they can handle 2-ohm loads AND you get a FREE CROWN BASEBALL CAP with an amp purchase. That's crazy sweeeeeeeet!! :D

[bkeane1259]

Re: Which Type of Enclosure would be recommended for a 14' x 20' living room?

Thank you for all this useful information, I am now aiming towards using a single enclosure with two 15" subwoofers, I like the idea of sealed (I am running two JLs in a sealed box in my car and love it).......

Please do not do that. Understand that you're not dealing with a car environment. Even in small room, multiple subs placed in different areas of the room are always better than a single sub (or a single box with two sub drivers). It's great that your budget allows for something like two Ultimax drivers. DON'T stick them in one box. Build two boxes and experiment with the room placement. It will be 100% obvious to you why this is being recommended.

If you have friends that live close enough to you, borrow an additional sub and try an experiment before you buy anything for yourself. Just get two subs in your room and put one in front and one in back and notice how much more balanced the bass is as you walk around the room. With a single sub, you should be able to walk around and find an area that is lacking in bass and an area that is booming out of control. Using two subs helps to tame that behavior so that the bass is more uniform across the whole listening space. THIS is what everyone is trying to explain. Hope it makes sense, but you'll only know for yourself if you try it.

Best of luck and keep us posted.

[Chris Roemer]

Re: Which Type of Enclosure would be recommended for a 14' x 20' living room?

Your room isn't THAT huge. I'm pretty sure that a single 12" (personally, I'd go HF vented) given enough power should be adequate for your wants, unless you want to damage something.

[bkeane1259]

Re: Which Type of Enclosure would be recommended for a 14' x 20' living room?

Chris,

Even in my horrible listening space, two subs are better than one. Having a single sub up by the TV creates the worst bass modes on our L-shaped couch. My designated couch position happened to be the worst too, when we had a single sub. I felt like I was sitting in a bass cannon. :eek:

[fbov]

Re: Which Type of Enclosure would be recommended for a 14' x 20' living room?

Sorry Frank, but that is simply not true.... 4th order LR adjustable crossovers...

...which add nothing in a SW application assuming an AVR to do LFE. I did not speak off-hand.

Maybe Crown's datasheets are wrong, but 50Hz a bit high for anything but crossing to main speakers, best done by the AVR, so no value added. This amp requires additional processing capability to affect boost and cut filters in the 10-30Hz range where sub amps already work. Granted, $400 for 500+W x2 channels is pretty good, but my plate amps were $460, and have boost/SSF options as well as PEQ, both of which must be added. The 2x4 miniDSP is $125, so I stand by my advice.

Per Crown (emphasis added, ed.)
PureBandTM Crossover System
Crossover Filter: Linkwitz-Riley 24dB per Octave
Crossover Frequency Range: 50 Hz - 3 kHz (on 1/2 octave centers! ed. )...

I will admit I missed the RCA jacks... but that was the least of it.

HAve fun,
Frank

PS Bill without knowing a lot about your room, I can't comment on why you get what you do. In a room like this, a single sub may well be all that's needed. Remember it's "loudspeakers and rooms," never one without the other here. I have two subs, well, because...

[bkeane1259]

Re: Which Type of Enclosure would be recommended for a 14' x 20' living room?

To each his/her own. Nobody has a more funky setup than I do. One sealed sub on a bridged Adcom - one commercial vented sub with its own plate amp.