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Subs for open ended Theater

post #1 of 45
1/18/13 at 11:11am
Thread Starter 
Hi Guys,

I posted this in the Subwoofer section, but thought the DIY croud my have a recommendation. I know nothing about building speakers though.....

From my understanding (definitely no expert) a subwoofer works by pressurizing the room for the chest pounding effect. What if you have an open ended theater?

I'm looking for recommendations on a subwoofer (or two) for my freshly built theater. The back end of the the theater opens to another room (bar area of sorts) separated by a half wall bar behind the 2nd row of seats. The theater itself is about 2,600 cubic feet. The area directly behind the theater is around 1,800 cubic feet and also opens up to a pool table area. It would nearly be impossible for me to "pressurized" the whole area behind the theater but what kind of power should i be looking at here? What kind of results should I expect with the open theater arrangement.

My current speakers are M&K S-150's accross the front and the SS-150 surrounds if it matters. I would also like to position the subwoofers on the front wall behind the screen (built a false wall)

Just need to add the subwoofers. Was considering a pair of PC-13 Ultra's or very tentatively considering DIY. Would like to keep pricing under under 2k

Any thoughts or a direction I should persue based on this scenario?
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post #2 of 45
1/18/13 at 12:48pm
Quote:
Originally Posted by Gomdaf View Post


From my understanding (definitely no expert) a subwoofer works by pressurizing the room for the chest pounding effect.
'Chest pounding' is mainly sourced from 50 to 80Hz, and you don't need to pressurize the room to get it, you just need a good 110dB or so at the LP.
What 'pressurizing' accomplishes is to realize 12dB/octave of cabin gain below the frequency where the longest room dimension is 1/2 wavelength. But this assumes a very tight and well built room; chances are you won't get that much. And as 20 feet is 1/2 wavelength at 28Hz, and 30 feet is 1/2 wavelength at 19Hz, for the most part you'll only get appreciable cabin gain in the 'chest pounding' bandwidth in a tiny room, or a car.
Quote:
I would also like to position the subwoofers on the front wall behind the screen (built a false wall)
Subs need to go where they need to go, which seldom coincides with where you want them to go. And even more seldom does having both subs at the front of the room work well. There are plenty of sources on sub placement that you should check out before making any irreversible plans.
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post #3 of 45
1/18/13 at 1:06pm
For $2k you should be able to get your chest pounded. You really ought to try DIY. You'll get way more for your dollar with $2k to spend.
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post #4 of 45
1/18/13 at 1:26pm
Thread Starter 
Thanks for the replies guys. I'm seriously considering DIY. I've done some reading and i'm just a little hesitant because I really don't know the first thing about it. I suppose i'm handy enough with the woodworking part of it.

I just get a little confused with the various builds, can't decide ported vs sealed, crossover, 2 ohm vs 4 ohm, size of cabinet for particular woofer, etc etc. I've looked around for a build that i could shamelessly copy but can't seem to find a true "step by step" for dummies.

Would a couple of 15" sealed work well? I have about 23" of depth behind the screen wall so I supose I could build up as opposed to out to get the cabinet volume. I'm not looking for obnoxious at this point. I'm looking for something that might slam as hard as a dual PC13U's for reference.

Is it really as easy as builiding a cabinet, cutting a hole, screwing in a woofer and plate amp and attaching a couple of wires? (just pissed off the whole DIY speaker community, i know...)

I take it I don't need a crossover, that would be handled in the Onkyo I have? And then MultEQ XT32 will handle the EQ?

can anybody recommend a build that i could copy to get what i'm after? I've paged through numerous builds, but can't find one that fits the bill and is a step by step type thing for the noob. I mean, i'm not really even sure how to cut a perfect 15" hole for the baffle, lol

BTW, This would be 90% home theater use.
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post #5 of 45
1/18/13 at 2:29pm
It really is that easy. If going sealed, very easy. If ported, just ask for a little more help. I suggest posting the exact:

Budget;
Dimensions;
and other requirements.

And just say, "what should I do".

Chances are people will say get 4 Dayton 18" subs. Put them in sealed boxes where you can. And power them with a pro amp. I'm not current on the best drivers and amps, so I'll let others guide you from here biggrin.gif
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post #6 of 45
1/18/13 at 2:31pm
I was tempted to go the DIY route, except I don't have any DIY skills or tools. I went with Chase Home Theater subs and couldn't be happier.
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post #7 of 45
1/18/13 at 2:41pm

4 of these

http://www.diysoundgroup.com/flat-packs-1/subwoofer-flatpacks-2/4-sub-flat-pack.html

 

4 of these

http://www.parts-express.com/pe/showdetl.cfm?partnumber=295-472

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post #8 of 45
1/18/13 at 3:41pm
Quote:
Originally Posted by tuxedocivic View Post

For $2k you should be able to get your chest pounded. You really ought to try DIY. You'll get way more for your dollar with $2k to spend.

I just purchased 6 SI 18's, 2 EP4000's, and all the materials for 500.00 less than I paid for my PB12/2 Ultra a few years ago.
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post #9 of 45
1/18/13 at 3:50pm
Powered by 1 or 2 nu3000dsp's (or equivalent). I'm noticing the DIY thread pattern here. biggrin.gif

"'Chest pounding' is mainly sourced from 50 to 80Hz"

I would take that further and say even up to 300hz, but then it isn't a sub-woofer, it's a woofer or mid-woofer. Hint Hint wink.gif


"Technically" it is possible to pressurize rooms above 1/2 wavelength, but it will become unevenly distributed and thus seating & woofer location dependent.
This is independent of the sound level (for the most part).
That said, placement becomes far less important once you have 4 subs sprinkled about the room.
However... sound above 100hz, becomes more and more directional, so the requirement of frontal placement for such woofer configurations increases.
I just thought I'd mention it.


Additionally it should be noted that for the first 18miliseconds or so, it is physically impossible to pressurize a room (at any frequency) because the speed of sound (although fast) is not instant, it typically takes 36 to 50ms to start taking affect, up to a max of about 1/4 of a second. A trivial fact, but I just thought I'd state it.
There is a special-case to that where that is not true, and that is in hyper-sonic waves, but that's a totally unrelated topic to speakers wink.gif
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post #10 of 45
1/18/13 at 4:30pm
Thread Starter 
Quote:
Originally Posted by bass addict View Post

I just purchased 6 SI 18's, 2 EP4000's, and all the materials for 500.00 less than I paid for my PB12/2 Ultra a few years ago.

Thats insane... smile.gif

Quote:
Originally Posted by Mrkazador View Post



4 of these
http://www.diysoundgroup.com/flat-packs-1/subwoofer-flatpacks-2/4-sub-flat-pack.html


4 of these
http://www.parts-express.com/pe/showdetl.cfm?partnumber=295-472

This is good stuff! This is the "easy button" i'm looking for. Are these cabinets pretty decent? At that price, considering tools and trial and error I could'nt build it cheaper.

What if I went with 2 instead of 4? Is four a little overkill or do you think it would make a big difference?

Would this give me the same kind of slam as a PC13U you think?

What would be a fair priced amp suitable to run with these? Plate amps or rack mount suggested?

Also...I should have elaborated on the "chest pounding" comment. I just kind of threw that phrase out there. I'd like the lower slam as well. Like I said this will be used almost always for Home Theater
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post #11 of 45
1/18/13 at 4:54pm
Quote:
Originally Posted by Gomdaf View Post


What if I went with 2 instead of 4? Is four a little overkill or do you think it would make a big difference?

Overkill? Heck no. biggrin.gif Each doubling of drivers gives a 3db increase, same as a doubling of power.
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Would this give me the same kind of slam as a PC13U you think?

Ummm, yes, and then a whole lot more. smile.gif
Quote:
What would be a fair priced amp suitable to run with these? Plate amps or rack mount suggested?

The EP4000 is a popular choice. 2 per bridged channel getting 900 watts per driver in a 4cf enclosure. Done bun. smile.gif
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post #12 of 45
1/18/13 at 4:54pm
"Additionally it should be noted that for the first 18miliseconds or so, it is physically impossible to pressurize a room (at any frequency) because the speed of sound (although fast) is not instant, it typically takes 36 to 50ms to start taking affect, up to a max of about 1/4 of a second. A trivial fact, but I just thought I'd state it.
There is a special-case to that where that is not true, and that is in hyper-sonic waves, but that's a totally unrelated topic to speakers"

if the room is small relative to the size of the wavelength (i.e. in the pressure vessel zone where the long dim. <1/2 lambda) the speed of sound increases dramatically. this came up when a guy tried to create a double bass array, but it didn't work as expected. then i read about this effect from some physics professors in europe. i don't think i have the reference handy. a trivial fact, but interesting none the less.
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post #13 of 45
1/18/13 at 5:07pm
since it is a large room, i'd probably suggest ported enclosures. four big ten cubic footers tuned to around 18-20hz with the driver that mr. k mentioned and a good amp or two should produce some prodigious bass in that room. as mentioned, a lot of the smack you in the face bass is in the 50-300hz region which typically means mains that can produce high spl's--one reason why many folks are jumping on the new high sensitivity kits these days. :-)
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post #14 of 45
1/19/13 at 11:24am
Thread Starter 
Couple more questions

Since this would be my first attempt at DIY sub was thinking of the EP4000 and two of the Dayton 18's with flat packs mentioned above. The size and level of difficulty seems right for a first attempt. I can always double up later if I crave more.

I'm a little confused on ohms and hook up. Do I get 4 ohm 18's (each in separate cabinets mentioned above) for the EP4000?

How would they be hooked up?

I have an Onkyo 5009 and would like it to do the EQ via audyssey XT32 for simplicity. How will these play together and how does the hook up map out?

Also, with two of these, can I expect to go down to 20hz?

What would be the advantage of a dual opposed cabinet?

Excuse the noob questions, I've only owned active subs in the past but this just seems like a way better bang for the buck and just wanted to clarify a few things before I make the plunge.
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post #15 of 45
1/19/13 at 12:27pm
Quote:
How would they be hooked up?

If running 2, you would run each one off a channel of the 4000.
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I have an Onkyo 5009 and would like it to do the EQ via audyssey XT32 for simplicity. How will these play together and how does the hook up map out?

Sub out from Onkyo to input on 4000 via xlr adaptor. With sealed you might need to invest in an eq for the lower end however. REW is a really helpful feature for determining what you are working with.
Quote:
Also, with two of these, can I expect to go down to 20hz?

Of course. How much output at that frequency will depend on a few different factors.
Quote:
What would be the advantage of a dual opposed cabinet?

Less material and a little more inert setup.
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post #16 of 45
1/19/13 at 1:01pm
Thread Starter 
Thanks!

So 2 of these http://www.parts-express.com/pe/showdetl.cfm?partnumber=295-472 in the 4.5 flat packs, an Ep4000 ans some binding posts and I should be good to go?

Also would the audyssey capabilities of EQing 2 subs still work in this scenario? I was under the impression you used both preouts on the onkyo running to each sub in an active scenario.
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post #17 of 45
1/19/13 at 1:20pm
You will also need RCA to male xlr adapters or cables like these

http://www.monoprice.com/products/product.asp?c_id=102&cp_id=10244&cs_id=1024404&p_id=4779&seq=1&format=2
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post #18 of 45
1/19/13 at 1:22pm
Quote:
Originally Posted by brian6751 View Post

You will also need RCA to male xlr adapters or cables like these

http://www.monoprice.com/products/product.asp?c_id=102&cp_id=10244&cs_id=1024404&p_id=4779&seq=1&format=2

Quote:
Originally Posted by bass addict View Post


Sub out from Onkyo to input on 4000 via xlr adaptor.

I think I covered that already. smile.gif
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post #19 of 45
1/19/13 at 1:31pm
Well excuuuuuuuuuse ME!

Post padding again I see. tongue.gif
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post #20 of 45
1/19/13 at 1:45pm
Quote:
Originally Posted by brian6751 View Post

Well excuuuuuuuuuse ME!

Post padding again I see. tongue.gif

lol. Ya gots ta do what ya gots ta do. biggrin.gif
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post #21 of 45
1/23/13 at 7:51pm
Thread Starter 
Follow up question here. Does anybody know The shallowest you can make a cabinet for the 18" Dayton HO. From what I'm reading these play better in a smaller cab compared to some of the other 18's. (correct me if I'm wrong).

I did some re-measuring behind the screen wall where I will be placing two of these and it seems I'm left with around 19" from false wall frame to back wall. Is this feasible to stuff a sealed 18?

I'm reading that the HO's are happy in a 3.75 to 4 cu ft box. I can build taller, but definitely not deeper. On the same note, how much space do these require in front?

If 18's won't fit I guess I could go to 15's.......
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post #22 of 45
1/24/13 at 4:45pm
Thread Starter 
Anybody?
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post #23 of 45
1/24/13 at 5:12pm
Quote:
Originally Posted by Gomdaf View Post

Anybody?

I don't think shallow will be a problem as long as you build it to the right volume. So you have an AT screen? Which material? Typically you need an inch or so but you might want to check with the screen manufacturer. I am using Seymour Centerstage XD and an inch is sufficient.

One option would be to just to a single baffle and brace the cabinet well. I know Bill Fitzmaurice has discussed using 1/2 ply vs 3/4 and doing proper bracing. Something to consider in your situation.
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post #24 of 45
1/24/13 at 5:13pm
Quote:
Originally Posted by Gomdaf View Post

Anybody?

I don't think shallow will be a problem as long as you build it to the right volume. So you have an AT screen? Which material? Typically you need an inch or so but you might want to check with the screen manufacturer. I am using Seymour Centerstage XD and an inch is sufficient from woofer to screen.

One option would be to just to a single baffle and brace the cabinet well. I know Bill Fitzmaurice has discussed using 1/2 ply vs 3/4 and doing proper bracing. Something to consider in your situation.
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post #25 of 45
1/24/13 at 5:37pm
Thread Starter 
Thanks ack. Its a Seymour center stage DIY screen. The way i built the frame it will be at least a couple of inches off speaker. I don't mind building it taller to make up the volume. I was just concerned there might be some limit on how shallow for one reason or another. This will be my first sub project. For a smaller cab 18 is the Dayton HO the way to go? I've downloaded winisd and am starting to try and learn a little more. Is there a unit converter for the parameters?

I would have gone with Eric's flat packs in a heart beat but I don't think they'll fit....

I guess this boils down to this

A KISS (keep it simple stupid) system that:

1) fits behind screen wall 19" deep, width and especially height can go bigger. So smallest cabs as possible to not sacrifice driver capabilities
2) 2 18's, or 15's
3) sealed to keep it simple
4) for home theater almost always.

My conclusion: 2 Dayton HO's powered by an EP4000 or inuke3000 in a 3.75 cu inch box. As long as shallow isn't a problem, build them 17" deep and go taller to make up the volume. Does this sound feasible? Any obvious problems?

I just need to learn how to work winisd to get some proper box sizes based on 17" deep.

Any other suggestions?
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post #26 of 45
1/24/13 at 5:51pm
Quote:
Originally Posted by Gomdaf View Post

Thanks ack. Its a Seymour center stage DIY screen. The way i built the frame it will be at least a couple of inches off speaker. I don't mind building it taller to make up the volume. I was just concerned there might be some limit on how shallow for one reason or another. This will be my first sub project. For a smaller cab 18 is the Dayton HO the way to go? I've downloaded winisd and am starting to try and learn a little more. Is there a unit converter for the parameters?

I would have gone with Eric's flat packs in a heart beat but I don't think they'll fit....

I guess this boils down to this

A KISS (keep it simple stupid) system that:

1) fits behind screen wall 19" deep, width and especially height can go bigger. So smallest cabs as possible to not sacrifice driver capabilities
2) 2 18's, or 15's
3) sealed to keep it simple
4) for home theater almost always.

My conclusion: 2 Dayton HO's powered by an EP4000 or inuke3000 in a 3.75 cu inch box. As long as shallow isn't a problem, build them 17" deep and go taller to make up the volume. Does this sound feasible? Any obvious problems?

I just need to learn how to work winisd to get some proper box sizes based on 17" deep.

Any other suggestions?

I don't see any issues with what you have planned. Do you have space in your room for two more smaller sealed 15"'s in the rear of the room? You could go with 3.5 cu ft or so. If you go with something like the DVC 385-88 drivers at $120 apiece you could have four of these off a single iNuke3KDSP for about the same price as 2 18's. 2 subs behind the screen and 2 subs in the back of the room.

Otherwise the dual 18's in 3.75-4 cu ft boxes should be fine with an EP4K and about 2" between the screen.
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post #27 of 45
1/24/13 at 5:57pm
Here is what 4 DVC-385-88 15" Dayton drivers look like (yellow) in 3.5 cu ft each vs 2 Dayton 18" HO drivers in 4 cu ft each (red). Both getting 2K watts total:



The other benefit would be smoother bass response with 4 spread across the room and being able to tame room modes more.
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post #28 of 45
1/28/13 at 6:42am
Quote:
Originally Posted by Gomdaf View Post


My conclusion: 2 Dayton HO's powered by an EP4000 or inuke3000 in a 3.75 cu inch box. As long as shallow isn't a problem, build them 17" deep and go taller to make up the volume. Does this sound feasible? Any obvious problems?

I just need to learn how to work winisd to get some proper box sizes based on 17" deep.

Any other suggestions?

17" deep is pleanty. Mounting depth on the HO18 is only 8.94". Build the box to whatever shape works.
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post #29 of 45
1/28/13 at 10:59am
Gomdaf, I'm putting in an AT screen and am at the stage of laying out my Screen frame wall. 17" will be about my max on depth, 30" width and 8ft of vertical height, as you can see box dimens. are very interesting to me also. I want to use the Dayton 18 but would go to 15 as well. I will only be putting 1 sub in corner behind screen. I have a 12" PSB sub I can add in elsewhere if desired. Getting to clean 20HZ with reasonable SPL is the goal. Placement is restricted to this location. Anyways I will be following your thread closely, one first time builder to another.
Thanks, keep up the good questions,
thx

PS: I am considering a sealed enclosure 28" x 28" 16 = 5.47 cu ft, this is inside volume with1" thickness and bracing. Size can changed depending on the driver requirements but would like to maintain 16" depth (not sure where on the face the driver should be mounted, eg: center, top, bottom? does it matter?)
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post #30 of 45
1/28/13 at 11:16am
Quote:
Originally Posted by RLthx View Post

Gomdaf, I'm putting in an AT screen and am at the stage of laying out my Screen frame wall. 17" will be about my max on depth, 30" width and 8ft of vertical height, as you can see box dimens. are very interesting to me also. I want to use the Dayton 18 but would go to 15 as well. I will only be putting 1 sub in corner behind screen. I have a 12" PSB sub I can add in elsewhere if desired. Getting to clean 20HZ with reasonable SPL is the goal. Placement is restricted to this location. Anyways I will be following your thread closely, one first time builder to another.
Thanks, keep up the good questions,
thx

PS: I am considering a sealed enclosure 28" x 28" 16 = 5.47 cu ft, this is inside volume with1" thickness and bracing. Size can changed depending on the driver requirements but would like to maintain 16" depth (not sure where on the face the driver should be mounted, eg: center, top, bottom? does it matter?)

If you have a big space and don't need < 20hz I would recommend building a ported enclosure (or horn if you can fit it). Sealed is the wrong choice here.

You could build a THT LP with the 15HO and have a great setup in an 18x18 footprint.
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