Question about stacking subwoofers

[Kain]

I have a small room, about 1,552 cubic feet. I have my subwoofer located on the right wall (in correlation to when you are sitting down to watch a movie) and in the mid-way point between the corner of the wall and center of the wall (towards the front of the room). In this current state, it is quite difficult to localize the bass. My question is, if I were to add another subwoofer (the same one) and stack it on top of the current one, will the sound be localizable? In general, when you stack subwoofers, does the bass become localizable (especially in smaller rooms)?

[derrickdj1]

In theory you will gain 6 db with stacked indentical subwoofer and 3 db is they are not co-located. Localization should not increase if the subs are recalibrated to a lower spl. The most even coverage would be one in the R front corner and L back corner. The closer the subwoofer are to the main, they will be harder to localize. That is why 80 Hz and lower is often quoted as be the frequency that the subwoofer sound is omnidirectional.

How do you like the Seation SubMersive?

[Kain]

Thanks for the reply.

I love the SubMersive. There is a very recently introduced version where you get a 4000W amp (or 6000W amp in case you not in the US) with a master/slave combo. Was just thinking how stacking the master/slave subwoofers would sound.

[PrestonTom]

If the sub is crossed low enough, it will not be readily localized.

It is hard to give a precise cutoff frequency since the sub may distort and produce energy at higher frequencies. So go ahead and add a second sub since it will increase the SPL, as noted above. Additionally, you might get some better low end response due to mutual coupling of the two boxes. Try it and see.

Another view is not to put it in the same location. A different location will perhaps excite an additional set of room nodes. This could produce a smoother response across the low end. Certainly you would want at least one sub near a corner since that will excite the largest number of room nodes.

[mustang guy]

Out of curiosity, why do you want to localize sub-bass? I had always considered the omni-directional properties of very low frequencies to be a good thing. I am just wondering in what situation would this be a bad thing.

[Kain]

Out of curiosity, why do you want to localize sub-bass? I had always considered the omni-directional properties of very low frequencies to be a good thing. I am just wondering in what situation would this be a bad thing.

Does my post make it sound like I actually want to be able to localize the bass? []

I just wanted to know if stacking subwoofers would make it easier to localize the bass, not that I actually wanted it that way.

[mustang guy]

Out of curiosity, why do you want to localize sub-bass? I had always considered the omni-directional properties of very low frequencies to be a good thing. I am just wondering in what situation would this be a bad thing.

Does my post make it sound like I actually want to be able to localize the bass?

I just wanted to know if stacking subwoofers would make it easier to localize the bass, not that I actually wanted it that way.

Okay, I am dumb...

[Kain]

Based on what your home theater consists of...you are certainly not dumb. []

[SuBXeRo]

localization really comes down to your crossover. Personally, i like to have my subs crossed at 60hz but then again, the RF-7's dig deep enough that this is a happy mix. I'd also like to add that placement is also a big deal.. I know everyone says bass is omnidirectional and it is but the placement is crucial because it add add or detract room gain and how much of the bass actually gets to you after traversing couches, walls, tables, carpets etc. Having 2 subs helps to even out room response and this is a true statement. This is why i purchased 2 svs cylinder subs. One hasn't been working right and im on a third replacement amp for it. Well, where i am going here is i have had good time to test 1 vs 2 subs. Although one can carry the deep end, i do find the response lacking depending on where I sit. I am also having a tough time finding just the right location for them. In my defense, i just moved into a house and things are very dynamic at the moment. Aside from what i have said, you have an awesome expensive sub and it may take a while to accommodate it and get things tuned up right.

[Islander]

I don't find that bass is omnidirectional, just less localizable the lower you go. If you have a sub directly to your side, it will likely be pretty obvious that the sound is coming from one side of the room, so in that case you'd want a second sub directly to your other side.

In most cases, you'll want the sub to be between the main speakers, or at least near them, since its purpose is to augment the bottom end of the mains, not to be a separate sound source.

Also, since subs roll off on their top ends, just like full-range speakers roll off on their bottom ends, it's usually necessary to set the sub's high frequency cut-off well above the nominal low-frequency cut-off of the main speakers. That way, you don't get a dip in the overlap area between the primary ranges of the sub and the main speakers.

If your speakers can reach pretty low, like RF-7s, Khorns, or the like, you can set the sub cut-off low, but with La Scalas that start to roll off at around 100 Hz, the smoothest response is obtained with a much higher sub cut-off, as high as 120-150 Hz, depending on the room and various other factors.

[derrickdj1]

Bass is omnidirection below 80-100 Hz due to the length of the waves length compared to the distance between our ear and the ability to process directional clues. A nearfield sub can be heard if the bass volume is higher than the mains at the LP. This will require turning down the subwoofer. Locating the sub closer to the mains allows the use of a higher xo. The puzzling thing is deciding on ported or sealed subwoofer for a home system since there are pro's and con's to each type.

[mustang guy]

The smaller the listening area, the higher the frequency. If a hip hopper comes down our street, we can tell which direction he is coming from. Sound travels at 1125fps, so if you take that divided b y 80HZ, you get a 14' wave length. 100HZ is a 11.25' wavelength. Perhaps those numbers related to either the seating position, and/or the room size could give you the ability to mathematically predict at what frequency the cutoff would be optimal. I'm sure there are studies and papers on this subject. It would be interesting to get to the bottom of it.

[CECAA850]

Localization is an issue if care isn't taken in set up. Experimentation in your room with placement and crossover points is needed to truly prevent it. My sub drivers are about 8 feet above my mains but the bass sounds like it's coming directly out of my mains. It doesn't just happen that way though. It takes a lot of time to fine tune each room to get it right.

[derrickdj1]

CECAA850 you have a great system: it would be a real treat to hear it.[]

[CECAA850]

CECAA850 you have a great system: it would be a real treat to hear it.

Thanks. Your sig doesn't show your location but if you're ever in S.E. TX, you're welcome to stop in.

EDIT, our systems probably have more similarities than differences[Y]