How many sealed 18" subs in a 2400 cu ft HT?

1992 Views 7 Replies 7 Participants Last post by BP1Fanatic, Jan 20, 2022

djbachelor

Discussion Starter · Jan 7, 2022

Several years ago, I built a large sonosub for my small basement theater--a UXL18 in a 26" tube tuned to about 13.5 hz. It definitely shakes the room/house at some frequencies!

However, it's boomy, not smooth throughout the room, and I've become interested in more finesse over sheer output. I should say, I think you could get finesse with these in a larger space; but I failed to account for any in-room realities-- low frequency treatments, ability to adjust locations, add multiple subs to handle room nodes etc.

I'm increasingly sure that several sealed subs (along with bass traps) would serve me better in this space. My question is, how many? I'm eyeing the Dayton ultimax, which definitely looks like the sweet spot in performance and cost; I don't want to spend extra on luxury drivers and diminishing returns in output, since I plan to add multiples.

I see some people saying, "sure you could get enough output from sealed--IF YOU BUILD 12!" But I just can't see needing that much output after room gain in a 2400^3 closed space. Am I wrong thinking that 2-4 sealed 18s, or 6 MAX (4 front, 2 rear) wouldn't be plenty into the single digits?

I could add that I'm not really a bass FANATIC--and don't feel the need to go extreme overkill like some impressive setups I've seen in here. I just want balanced, clean output at moderately-loud, thrilling volumes--not necessarily reference of heart-stopping levels.

Thanks for the advice!

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T-Dub

· #2 · Jan 13, 2022

I recommend you go over to AVS Forums with this question. I’ve noticed a trend here at HTS, there is little to no respond to questions & the advice is not as good here. It seems like HTS is dwindling down with not much support. At least that’s what I’ve seen. You’ll get quick responses at AVS Forums & more of them as well.

FYI You are asking a loaded question & you are going to get answers across the gamut. But you’ll get responses at least that’s for sure.

Go have fun!!

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Mr645

· #3 · Jan 14, 2022

I think 2 would be plenty.

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BP1Fanatic

· #4 · Jan 15, 2022

4, 1 for each wall or corner.

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theJman

· #5 · Jan 17, 2022

djbachelor said:
Several years ago, I built a large sonosub for my small basement theater--a UXL18 in a 26" tube tuned to about 13.5 hz. It definitely shakes the room/house at some frequencies!

The word "basement" suggests concrete. Is that a good assumption on my part? A solid structure like that creates some pretty big challenges for subwoofers.

djbachelor said:
I see some people saying, "sure you could get enough output from sealed--IF YOU BUILD 12!" But I just can't see needing that much output after room gain in a 2400^3 closed space. Am I wrong thinking that 2-4 sealed 18s, or 6 MAX (4 front, 2 rear) wouldn't be plenty into the single digits?

I could add that I'm not really a bass FANATIC--and don't feel the need to go extreme overkill like some impressive setups I've seen in here. I just want balanced, clean output at moderately-loud, thrilling volumes--not necessarily reference of heart-stopping levels.

If they're properly designed and use quality parts you won't need anywhere near a dozen. However, no matter what you do they probably won't provide the desired result if they aren't placed and tuned correctly. That part is frequently overlooked when doing a project like this, but it's imperative to a successful outcome.

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rgoebel

· #6 · Jan 20, 2022

djbachelor said:
Several years ago, I built a large sonosub for my small basement theater--a UXL18 in a 26" tube tuned to about 13.5 hz. It definitely shakes the room/house at some frequencies!

However, it's boomy, not smooth throughout the room, and I've become interested in more finesse over sheer output. I should say, I think you could get finesse with these in a larger space; but I failed to account for any in-room realities-- low frequency treatments, ability to adjust locations, add multiple subs to handle room nodes etc.

I'm increasingly sure that several sealed subs (along with bass traps) would serve me better in this space. My question is, how many? I'm eyeing the Dayton ultimax, which definitely looks like the sweet spot in performance and cost; I don't want to spend extra on luxury drivers and diminishing returns in output, since I plan to add multiples.

I see some people saying, "sure you could get enough output from sealed--IF YOU BUILD 12!" But I just can't see needing that much output after room gain in a 2400^3 closed space. Am I wrong thinking that 2-4 sealed 18s, or 6 MAX (4 front, 2 rear) wouldn't be plenty into the single digits?

I could add that I'm not really a bass FANATIC--and don't feel the need to go extreme overkill like some impressive setups I've seen in here. I just want balanced, clean output at moderately-loud, thrilling volumes--not necessarily reference of heart-stopping levels.

Thanks for the advice!

I too have explored many options to answer the home theater bass question. I started with the Shiva 12" in a massive ported box. LF extension was fantastic, but I was able to bottom it out with only 650W on some movie tracks (large basement space at the time). My next attempt was to add the big brother to the Shiva, the Tempest 15", this time both in sealed boxes in different corners. It was satisfactory, but like U2 says, still not what I was looking for. At this time I was in a house with the theater in the main floor. I went big next, with an infinite baffle setup using 8 12" NHT surplus subs (IIRC). I had approximately 1500W available and in a 13'x14' living room, the bass was tactile and surreal. Then I got married and had kids and the home theater went on hiatus. When I finally moved to a house suitable for a theater again, I finished a section of the basement as a theater room. The big question was, what to do about the bass. I loved the infinite baffle setup, but realistically, with young kids sleeping when the adults finally get to watch a movie, how much bass did I really need? Plus, the subs would need a high SAF (spouse approval factor). I decided to start with the old Tempest in a sealed box, located in the center, under the screen. I reasoned that if it proved inadequate, I could build the infinite baffle to fit the same opening (there is storage space behind the screen). I am pushing 1500W (don't need all of it, but its available) and have been very happy with it for several years now. It is tight and musical and provides plenty of impressive punch for sound effects. The theater room may be a bit smaller than yours (12'x24'x7' ceiling), but I think sometimes a bad (or mediocre) experience can make us think we need way more than we do. In reality, a well designed and tuned setup can be simple and cheap. Obviously the Tempest isn't made anymore, or I would suggest 2 for good measure and call it a day. Good luck and happy sub-hunting!

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nathan_h

· #7 · Jan 20, 2022

djbachelor said:
Several years ago, I built a large sonosub for my small basement theater--a UXL18 in a 26" tube tuned to about 13.5 hz. It definitely shakes the room/house at some frequencies!

However, it's boomy, not smooth throughout the room, and I've become interested in more finesse over sheer output. I should say, I think you could get finesse with these in a larger space; but I failed to account for any in-room realities-- low frequency treatments, ability to adjust locations, add multiple subs to handle room nodes etc.

I'm increasingly sure that several sealed subs (along with bass traps) would serve me better in this space. My question is, how many? I'm eyeing the Dayton ultimax, which definitely looks like the sweet spot in performance and cost; I don't want to spend extra on luxury drivers and diminishing returns in output, since I plan to add multiples.

I see some people saying, "sure you could get enough output from sealed--IF YOU BUILD 12!" But I just can't see needing that much output after room gain in a 2400^3 closed space. Am I wrong thinking that 2-4 sealed 18s, or 6 MAX (4 front, 2 rear) wouldn't be plenty into the single digits?

I could add that I'm not really a bass FANATIC--and don't feel the need to go extreme overkill like some impressive setups I've seen in here. I just want balanced, clean output at moderately-loud, thrilling volumes--not necessarily reference of heart-stopping levels.

Thanks for the advice!

It’s a math and physics problem. The short answer is that one would get you reference volume.

Bassaholic Subwoofer Room Size Rating Protocol

This article outlines our test procedure in determining a subwoofers room size recommendation based on its max CEA SPL output while making room size and subwoofer distance assumptions.

www.audioholics.com

But you’ll need two to manage standing waves. And it is easier to manage standing waves over a larger listening area with four.

https://www.harman.com/documents/multsubs_0.pdf

And if you want to do it right, you’ll get something like a miniDSP 2x4 HD to time align them, correct them, and integrate them with the rest of your system.

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BP1Fanatic

· #8 · Jan 20, 2022

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