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post #1 of 32 Old 07-23-2019, 08:28 PM - Thread Starter
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Pondering a subwoofer build

Hello all. So I'm in the research phase of changing my basement family room to a semi dedicated HT room. The room is currently 25' x 11.5' I've been doing research of projectors, seating, carpeting, etc and finally have come to subwoofers!

So, I am going to be building a false wall in the front which will have a 150" Spandex screen on it, and behind it my LCRs. But I was also wondering if I can put my sub behind this screen. I was first thinking of using my PowerSound Audio 1500 but then I'm thinking for a true theater experience, one 15" sub probably won't cut it.

I will probably have the false wall come about 18" to 2' in front of the front wall, so that cavity will be approx. 18" to 2' x 11.5' wide by 7.5' tall.

So, a few questions:

Can I put a sub behind the screen or will port air and driver movement cause the screen to vibrate (I'm assuming it will) if front facing?

Can I just put a ported sub so the ports/driver all face sideways to resolve the issue above, if there is an issue?

If memory serves me right, a DIY sub will get you WAY more bang for buck. Is that true? I hear so much about subs like the SVS PB16 kicking a$$ but would love to build something that powerful or better for much(?) less money. And yes, I know that compared to some of the subs people have built here including sealed/ported/IB, the PB16 is a joke.

The way I see it, I have a nice cavity where I can put my LCR speakers (3 floorstanders) and still have room to build a sub with an enclosure of approx. 18" (or 24") x 36" x whatever height I want up to 7 ft (or 2 of them, 1 on either side of the center channel speaker)


In full disclosure, I have never built a sub or speaker. But I have master carpentry skills so building is not an issue. Its design, materials, etc what I would need help with. And overall, if I'm missing something obvious or if I've captured it all, any guidance would be greatly appreciated!

Thanks!
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post #2 of 32 Old 07-23-2019, 08:47 PM
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Pondering a subwoofer build

Generally, a single Full Marty Loaded with a UM18 will out perform a PB16.

Cost for PB16? $2500

Cost for Full Marty? $1000 (and that’s being generous)

I built mine for $600. Complete with an iNuke NU6000DSP, so I have another channel for a second Marty. So I could do two for $1000 really.

So to recap, you can get 4 PB16-Killers for cheaper than what the PB16 costs!

But I realize that your space behind your false wall cannot allow this large of a subwoofer.

This was just an example to show how much bang for your buck DIY gets you.

Leave it at 8 ohms and call it a day :)

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post #3 of 32 Old 07-23-2019, 09:30 PM
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Do you have a frequency range, SPL, and cost target? You've got a lot of space to work with so you have a lot of flexibility. You could do a bunch of sealed subs. Or few big ported subs. Or a couple big horns. Depends on what you're trying to do.

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post #4 of 32 Old 07-23-2019, 10:22 PM - Thread Starter
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Thanks for the quick responses. I was about to ask what's a Marty sub but a quick google has shown me the way lol!

In terms of what i'm looking for? Hit you in the gut bass is what i'm looking for. I used to own an SVS PB2 Plus that was awesome (the old large one that had the dual 12" drivers in it). I replace it with a PSA V1500 which is good, but not as good as I thought it would be.

However, now that I'm going to have this unique (to me) space between the false wall and the actual basement wall, I figure, let's get a proper sub built and something that will make it feel like there really is a dinosaur in the room, or an actual freight train right next to me, etc. I don't think I've ever experienced that kind of bass.

It doesn't need to be this ridiculously large sub that is gigantic with 16 18" drivers powered by 100,000 watts of power just for the sake of having the most bass in my city. However, I want to build something powerful enough that I never say, its really lacking.

What I was imagining was using the space to the left of the center channel, so say a footprint of 3' x 1.5' and maybe 4' tall, so that would get me a pretty large box, maybe minus the bracing like 16 ft^3 or so. That seems pretty big compared to my approx. 5 ft^3 PSA sub!

If I can get a nice sub built in that size range or so that had some great output, that would be fantastic. I figure that if its not so expensive, and I'm still wanting more, I can always build and add a second one to the right side of the center speaker in the future.

The good thing about this setup is that its all going behind a white over black spandex screen, so none of it will be seen and I could care less about the finish of it. I don't need to recess the driver (unless there are other advantages), and assuming I use the correct material, I don't need to finish the cabinet either. So i'm assuming once I have a solid design, the building of it will be super simple.

If I can get a PB16 killer for $600 like Russdawg, that would be mind blowing!
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post #5 of 32 Old 07-23-2019, 10:38 PM
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Quote:
Originally Posted by midfidude View Post
Thanks for the quick responses. I was about to ask what's a Marty sub but a quick google has shown me the way lol!



In terms of what i'm looking for? Hit you in the gut bass is what i'm looking for. I used to own an SVS PB2 Plus that was awesome (the old large one that had the dual 12" drivers in it). I replace it with a PSA V1500 which is good, but not as good as I thought it would be.



However, now that I'm going to have this unique (to me) space between the false wall and the actual basement wall, I figure, let's get a proper sub built and something that will make it feel like there really is a dinosaur in the room, or an actual freight train right next to me, etc. I don't think I've ever experienced that kind of bass.



It doesn't need to be this ridiculously large sub that is gigantic with 16 18" drivers powered by 100,000 watts of power just for the sake of having the most bass in my city. However, I want to build something powerful enough that I never say, its really lacking.



What I was imagining was using the space to the left of the center channel, so say a footprint of 3' x 1.5' and maybe 4' tall, so that would get me a pretty large box, maybe minus the bracing like 16 ft^3 or so. That seems pretty big compared to my approx. 5 ft^3 PSA sub!



If I can get a nice sub built in that size range or so that had some great output, that would be fantastic. I figure that if its not so expensive, and I'm still wanting more, I can always build and add a second one to the right side of the center speaker in the future.



The good thing about this setup is that its all going behind a white over black spandex screen, so none of it will be seen and I could care less about the finish of it. I don't need to recess the driver (unless there are other advantages), and assuming I use the correct material, I don't need to finish the cabinet either. So i'm assuming once I have a solid design, the building of it will be super simple.



If I can get a PB16 killer for $600 like Russdawg, that would be mind blowing!

Well the key to all of it is sales!

I got my UM18 driver for $200, iNuke for $300, and wood for $100.

I’d recommend two UM18’s in a box that fits your size area behind the screen, tuned to around 15hz since you have that much box space vs a normal Full Marty which is only 10ish cubic feet?

Powered by an iNuke NU6000DSP (One per channel), you’d get some ginormous bang for your buck. Could definitely be done for $1000 and some elbow grease!

I’d ask some of the more experienced builders here to help design you a box based on your space requirements. But two UM18’s on an iNuke, you can’t go wrong!

Leave it at 8 ohms and call it a day :)
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With them dimensions you could about fit the submaximus v3 there 25.5 x36 by 80 tall. The price to performance is unmatched. There a horn sub design but unlike most horns they dig deep because of there shear size. I have 4 in my room and when the bass hit it feels like the San Andreas fault is being activated lol. This is one of my buddies next to it hes only 5ft 4 but still gives you an idea of how big they are. These also are doable for your first build with some patience and time. These where actually my first sub builds.

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post #7 of 32 Old 07-24-2019, 03:52 AM
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This should fit behind your false wall.

https://www.diysoundgroup.com/flat-p...8-cabinet.html

DIY Soundgroup used to sell them unassembled for less. If you ask, they may still have some unassembled flatpacks laying around.


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post #8 of 32 Old 07-24-2019, 06:39 AM - Thread Starter
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Originally Posted by hd0823 View Post
With them dimensions you could about fit the submaximus v3 there 25.5 x36 by 80 tall. The price to performance is unmatched. There a horn sub design but unlike most horns they dig deep because of there shear size. I have 4 in my room and when the bass hit it feels like the San Andreas fault is being activated lol. This is one of my buddies next to it hes only 5ft 4 but still gives you an idea of how big they are. These also are doable for your first build with some patience and time. These where actually my first sub builds.

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Geez man! What are you trying to do? Crack your house in half?!
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post #9 of 32 Old 07-24-2019, 06:56 AM - Thread Starter
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Originally Posted by dftkell View Post
This should fit behind your false wall.

https://www.diysoundgroup.com/flat-p...8-cabinet.html

DIY Soundgroup used to sell them unassembled for less. If you ask, they may still have some unassembled flatpacks laying around.


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Thanks dftkell.

These looks really awesome. Question though, it looks like those have a footprint of 16" x 30" and about 30" tall. However, I have the ability to go twice that height to really create a huge box with an awesome amount of net volume.

I should make the biggest box I can no? Assuming its properly braced of course.

Or is there a limitation on how much volume should be used for a single driver ported sub?

That brings me to another question... ...what is the advantage of using multiple drivers in the same ported sub? There's obviously a substantial increase in price when adding a nothing high quality driver, so people must be doing it for some reason...

I'm trying to understand the best way to go, but I don't understand the pros/cons to a larger box vs a box with multiple drivers in it. For example, let's say a net 10 ft^3 box with a single 18" driver vs a 7 ft^3 box with 2 drivers, or maybe the same 10 ft^3 box with 2 drivers instead of one.

Lastly, are there rules to internal bracing, in terms of do/don'ts, how much of the total % volume of the box should go in bracing, etc?

Sorry, it's all pretty new to me so trying to figure out what to do!

Thanks again!
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post #10 of 32 Old 07-24-2019, 07:19 AM
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Quote:
Originally Posted by midfidude View Post
Thanks dftkell.



These looks really awesome. Question though, it looks like those have a footprint of 16" x 30" and about 30" tall. However, I have the ability to go twice that height to really create a huge box with an awesome amount of net volume.



I should make the biggest box I can no? Assuming its properly braced of course.



Or is there a limitation on how much volume should be used for a single driver ported sub?



That brings me to another question... ...what is the advantage of using multiple drivers in the same ported sub? There's obviously a substantial increase in price when adding a nothing high quality driver, so people must be doing it for some reason...



I'm trying to understand the best way to go, but I don't understand the pros/cons to a larger box vs a box with multiple drivers in it. For example, let's say a net 10 ft^3 box with a single 18" driver vs a 7 ft^3 box with 2 drivers, or maybe the same 10 ft^3 box with 2 drivers instead of one.



Lastly, are there rules to internal bracing, in terms of do/don'ts, how much of the total % volume of the box should go in bracing, etc?



Sorry, it's all pretty new to me so trying to figure out what to do!



Thanks again!
I would go as large as you can and maybe look at the bc21ds115 or lavoce San 214.5 both are 21 inch subs and work very well in a larger ported box just ask @eng-399

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post #11 of 32 Old 07-24-2019, 07:26 AM
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Originally Posted by midfidude View Post
Thanks dftkell.

These looks really awesome. Question though, it looks like those have a footprint of 16" x 30" and about 30" tall. However, I have the ability to go twice that height to really create a huge box with an awesome amount of net volume.

I should make the biggest box I can no? Assuming its properly braced of course.

Or is there a limitation on how much volume should be used for a single driver ported sub?

That brings me to another question... ...what is the advantage of using multiple drivers in the same ported sub? There's obviously a substantial increase in price when adding a nothing high quality driver, so people must be doing it for some reason...

I'm trying to understand the best way to go, but I don't understand the pros/cons to a larger box vs a box with multiple drivers in it. For example, let's say a net 10 ft^3 box with a single 18" driver vs a 7 ft^3 box with 2 drivers, or maybe the same 10 ft^3 box with 2 drivers instead of one.

Lastly, are there rules to internal bracing, in terms of do/don'ts, how much of the total % volume of the box should go in bracing, etc?

Sorry, it's all pretty new to me so trying to figure out what to do!

Thanks again!
Usually the biggest box you can fit is the way to go.

Rather than do multiple drivers in a single box, it is usually more beneficial to have multiple boxes with a single driver so that they can go in different locations in the room. This will help smooth out the response in room.

So, what I am doing is doing 2 boxes that are 24"W X 54"H X 18"D and tuned to around 20 or so using the LaVoce SAF184.03 which is still on sale at PE actually. These will be powered by an NX6000D. This works out to about similar volume to a mini-marty I think.

So were I you, I would look at the Ultimax or other similar driver in the +/- 300 price range (2 of them) and put them in 2 boxes of around 10 cu. to fit behind your false wall and powered by the 6000D.

Good luck!

Edit - bracing:
There's no hard and fast rule to bracing, just needs to be adequate. In a box like what I described, 3-4 window pane braces should make it pretty sturdy. Many people just use dowel rods from side to side, some use 2X4's.

Last edited by scottvalentin; 07-24-2019 at 07:31 AM.
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post #12 of 32 Old 07-24-2019, 08:49 AM
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First, the answer to all your questions is, for the most part, yes. You have three basic options for sub builds.

First, DIYSG and GSG offer pre-cut, pre designed sub cabinet panels. You'll pay a small premium for them to design and cut your boards but they go together perfectly. You may, however, pay a lot in shipping costs. Also in this camp are finding a cabinet shop or car audio place to build a cabinet for you. I don't see these as a necessary nor cost effective option for someone with your carpentry skills.

Second, if you have some skills and tools you can grab existing plans and build your own boxes. The Marty variants are very popular, as are the VBSS's. As a master carpenter these would be an absolute breeze for you. My carpentry skills suck and I managed (with a bit of post-build material removal and wood filler).

Third, you can design or have designed very specific custom subs designed just for you to accommodate your exact space considerations. Folks use computer software to compute box and port size to match specific drivers. Then, you build the boxes.

In general, bigger boxes and bigger drivers give you more output and lower tuning options. Also consider that you can't really have "too much." You can always reduce the gain on a sub that gives you more than you need, but you can only turn an inadequate sub up so high.

That's the box part. The other considerations are drivers and amps. For super-budget builds many folks use the PA460 driver in a VBSS cabinet. You can find the driver for $80 (I'm building a few now and they come to like $105 per assembled box!). UM18's are very popular too. When on sale you can grab them for $250. Both of these drivers marry nicely to the inexpensive Behringer dsp amps. Many on here have moved to 21" drivers from LaVoce and B&C. I have no experience with those, but the drivers are a step up in price and some use significantly more powerful amps to power them, which may have cost and electrical circuitry considerations, but I'll let the 21" driver guys chime in on that.

How many do you need? To answer that question you need to know what you have with regard to room acoustics. I would recommend this as an absolute requirement:

https://www.minidsp.com/products/aco...urement/umik-1

Grab this $75 mic and download free REW software. You'll use this to figure out how many subs you need, where they should go, and to calibrate them once you put them in place.

SPEAKERS: 3 x DIYSG 1099's LCR; DIYSG HTM 6's and 8's surround; 4 x RSL C34E's atmos.
SUBS: 4 x UM18-22 Mini Marty's (and always building, currently working on VBSS's).
SIGNAL CHAIN: Denon X4400; Minidsp 2x4 HD; 2 x Jensen Iso Sub 2RX; 2 x NX6000d.
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post #13 of 32 Old 07-24-2019, 09:29 AM
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First, the answer to all your questions is, for the most part, yes. You have three basic options for sub builds.



First, DIYSG and GSG offer pre-cut, pre designed sub cabinet panels. You'll pay a small premium for them to design and cut your boards but they go together perfectly. You may, however, pay a lot in shipping costs. Also in this camp are finding a cabinet shop or car audio place to build a cabinet for you. I don't see these as a necessary nor cost effective option for someone with your carpentry skills.



Second, if you have some skills and tools you can grab existing plans and build your own boxes. The Marty variants are very popular, as are the VBSS's. As a master carpenter these would be an absolute breeze for you. My carpentry skills suck and I managed (with a bit of post-build material removal and wood filler).



Third, you can design or have designed very specific custom subs designed just for you to accommodate your exact space considerations. Folks use computer software to compute box and port size to match specific drivers. Then, you build the boxes.



In general, bigger boxes and bigger drivers give you more output and lower tuning options. Also consider that you can't really have "too much." You can always reduce the gain on a sub that gives you more than you need, but you can only turn an inadequate sub up so high.



That's the box part. The other considerations are drivers and amps. For super-budget builds many folks use the PA460 driver in a VBSS cabinet. You can find the driver for $80 (I'm building a few now and they come to like $105 per assembled box!). UM18's are very popular too. When on sale you can grab them for $250. Both of these drivers marry nicely to the inexpensive Behringer dsp amps. Many on here have moved to 21" drivers from LaVoce and B&C. I have no experience with those, but the drivers are a step up in price and some use significantly more powerful amps to power them, which may have cost and electrical circuitry considerations, but I'll let the 21" driver guys chime in on that.



How many do you need? To answer that question you need to know what you have with regard to room acoustics. I would recommend this as an absolute requirement:



https://www.minidsp.com/products/aco...urement/umik-1



Grab this $75 mic and download free REW software. You'll use this to figure out how many subs you need, where they should go, and to calibrate them once you put them in place.
Your pretty much right on the 21s more so on the lavoce being only available in 8 ohm but this is to get max output the thing about the 21 pro drivers are they are so sensitive most 97db or higher so they get super loud without as much power going to them. So a inuke will work on the 21s just fine eng-399 runs 2 inuke 6000dsps on his and its nuts in there. I went for over kill and got 2 240v xbs 20000q clone amps but this is definitely not needed

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Thank you everyone for your replies. Based on your responses, I think I will most likely go for 2 boxes, built upon the tried and tested UM18s Ultimax that people seem to be raving about on many of these threads. The price point seems right, especially if I can get them for that sale price of $200 to $250 each.

18x32x48 (or 60, we'll see), those give me boxes with 16-20 ft^3 of volume minus the internal bracing and subwoofer volume, so maybe 12-16 ft^3 boxes (no idea how much bracing and driver take up)...

Those driven by by the inuke 6000dsp.

All in all, this should run me about $1k+/- it looks like, and from what I understand, if I have 2 of these designed and built correctly, it should beat the pants off anything made by SVS, Velodyne or JL Audio... ...or maybe not? Is that REALLY possible for $1k?! That doesn't seem right that something like this could outperform a $16k Gotham? Of maybe that's a little much...

In terms of placement, I don't really have a lot of flexibility there so they need to go behind the screen due to the narrowness of the room and quite a few openings. So the placement will have to do. Might be dating myself, but wasn't there a device called a Behringer Feedback Destroyer that use to help if placement was less than optimal in normalizing the peaks and dips in frequency response to smooth it all out?

Thanks again.
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post #15 of 32 Old 07-24-2019, 01:04 PM
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Whats a Gotham?


JTR makes a great dual sub, it'll beat the pants off these DIY subs but it aint cheap either.
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I'd recommend using the full width and depth you can and then going a couple inches under 4'. That way, if you decide you want more output, you can stack another pair on top of the ones you have. That should put you roughly equal to a full marty in terms of volume per sub which would be great for a UM18. I'm at work right now but I can design something for that configuration if you're interested (assuming no-one else does by later tonight).

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Whats a Gotham?
https://www.jlaudio.com/g213v2-gloss...bwoofers-96240

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post #18 of 32 Old 07-24-2019, 01:33 PM
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Pondering a subwoofer build

Quote:
Originally Posted by midfidude View Post
All in all, this should run me about $1k+/- it looks like, and from what I understand, if I have 2 of these designed and built correctly, it should beat the pants off anything made by SVS, Velodyne or JL Audio... ...or maybe not? Is that REALLY possible for $1k?! That doesn't seem right that something like this could outperform a $16k Gotham? Of maybe that's a little much...

JL Audio Gotham:

Dual 13.5” sealed woofers (that’s around 250 square inches of cone area) on 4500 watts. In an enclosure is 21.5”x34”x24” (10 cubic feet)

Dual UM18’s:

Dual 18” ported woofers (that’s around 450 square inches of cone area) on 4000 watts. Two enclosures of 36”x18”x48” (your specifications) (34 cubic feet).

You tell me if it’s gonna beat the pants off a JL Audio Gotham.

I mean the JL Audio is much prettier and comes with EQ and stuff but in terms of raw performance, it’s not even a fair fight.

Leave it at 8 ohms and call it a day :)
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post #19 of 32 Old 07-24-2019, 02:03 PM
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Ummm yea, these will be better than that.


Keep in mind the EQ it comes with is to be flat, much like the SVS and I find that limiting since that goes out the window when it plays in your room. With an inuke w/DSP you have absolute control.


edit: JTR I was talking about


http://jtrspeakers.com/captivator-4000ulf.html

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post #20 of 32 Old 07-24-2019, 03:53 PM - Thread Starter
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Originally Posted by Trimlock View Post
Whats a Gotham?


JTR makes a great dual sub, it'll beat the pants off these DIY subs but it aint cheap either.
I'm assuming you're being sarcastic in regards to the Gotham and that these DIY subs will destroy it...!
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post #21 of 32 Old 07-24-2019, 03:58 PM - Thread Starter
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Originally Posted by Trimlock View Post
Whats a Gotham?


JTR makes a great dual sub, it'll beat the pants off these DIY subs but it aint cheap either.
Quote:
Originally Posted by CrusherW9 View Post
I'd recommend using the full width and depth you can and then going a couple inches under 4'. That way, if you decide you want more output, you can stack another pair on top of the ones you have. That should put you roughly equal to a full marty in terms of volume per sub which would be great for a UM18. I'm at work right now but I can design something for that configuration if you're interested (assuming no-one else does by later tonight).
Crusher, thanks so much. That's indeed very kind of you. Honestly, I'm not there yet, but will be in due time (maybe about 2-3 months away by my estimation). I'm tearing the room apart so that will take some time, need to build a platform for the second row of seating, paint the room, new carpeting, etc so it will be some time before I get there.

But I wanted to see if what i'm expecting is possible, putting it behind the screen, using that cavity, etc. And the possibilities you guys are saying are making me downright giddy!

I will CERTAINLY take you up on your offer when the time comes as i'm a complete newbie when it comes to the design aspect and honest would just prefer an expert walk me through it than learn it all from scratch if that's not too much to ask (I know, maybe not the best way).

Thanks again!
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post #22 of 32 Old 07-24-2019, 04:04 PM - Thread Starter
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Originally Posted by Russdawg1 View Post
JL Audio Gotham:

Dual 13.5” sealed woofers (that’s around 250 square inches of cone area) on 4500 watts. In an enclosure is 21.5”x34”x24” (10 cubic feet)

Dual UM18’s:

Dual 18” ported woofers (that’s around 450 square inches of cone area) on 4000 watts. Two enclosures of 36”x18”x48” (your specifications) (34 cubic feet).

You tell me if it’s gonna beat the pants off a JL Audio Gotham.

I mean the JL Audio is much prettier and comes with EQ and stuff but in terms of raw performance, it’s not even a fair fight.
Awesome!

It just blow me away that they can charge $16k for that thing. I'm sure its astonishingly good, and damn pretty, same level as pretty as the Nautilus speaker line in my opinion, but $16k for something that can bested for a fraction of the price? Crazy!


Quote:
Originally Posted by Trimlock View Post
Ummm yea, these will be better than that.


Keep in mind the EQ it comes with is to be flat, much like the SVS and I find that limiting since that goes out the window when it plays in your room. With an inuke w/DSP you have absolute control.


edit: JTR I was talking about


http://jtrspeakers.com/captivator-4000ulf.html
That's another part i'll be coming back here for help on. Have no idea how to tune/EQ the thing so I'll need guidance there too!
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post #23 of 32 Old 07-24-2019, 05:07 PM
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Originally Posted by midfidude View Post
Crusher, thanks so much. That's indeed very kind of you. Honestly, I'm not there yet, but will be in due time (maybe about 2-3 months away by my estimation). I'm tearing the room apart so that will take some time, need to build a platform for the second row of seating, paint the room, new carpeting, etc so it will be some time before I get there.

But I wanted to see if what i'm expecting is possible, putting it behind the screen, using that cavity, etc. And the possibilities you guys are saying are making me downright giddy!

I will CERTAINLY take you up on your offer when the time comes as i'm a complete newbie when it comes to the design aspect and honest would just prefer an expert walk me through it than learn it all from scratch if that's not too much to ask (I know, maybe not the best way).

Thanks again!
Feel free to PM me or start a thread or whatever then. Or if you want, I could give you an overview of how to design one yourself (though I'm sure not sure I'd do any better than any other resources). I think things would make a lot more sense to you in terms of performance expectations once you start modeling different setups and can see what effects what. Knowing a little bit makes you dangerous

"Becoming educated is more than just acquiring knowledge. It involves the ability to see the world in ways never before conceived."
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post #24 of 32 Old 07-24-2019, 05:25 PM - Thread Starter
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So using Crusher's advice and maximizing space that I have in this cavity between the "real" wall and the false wall, would this make more sense?

I am going to have my left and right front speakers approximately 7.5 feet apart in this cavity. So I was thinking maybe I should use that space in between those two to put a massive sub in between the false wall and the real wall, a footprint of 7ft x 18" and 3ft tall (almost like a massive TV stand rectangle). I could then either put the center channel right on top of this beast (can you do that or will the cabinet vibrate so much it will mess up the sound from the center), or I could mount it or put it on a shelf a few inches higher on the "real" wall behind.

From my take, the JTR Captivator 4000ULF has a volume of appox 19.5 ft^3 (minus internal bracing, driver, insulation etc).

This sub that i'm proposing would have a volume of approx. 31.5 ft^3 (minus internal bracing, driver, insulation etc).

Is this crazy or doable? Do the same properties apply where I can use just one driver for this beast if I wanted to go this route? Seems insane to only have 1 18" driver in a fridge sized (yes I'm exaggerating) sub, but that's based on absolutely zero knowledge!

The only downside I can see so far is that this thing would weight a million pounds so moving it will be a joy.

Or is this crazy and I'm missing something obvious?

Thanks for all your insight.
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post #25 of 32 Old 07-24-2019, 05:40 PM
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Quote:
Originally Posted by midfidude View Post
Hit you in the gut bass is what i'm looking for.
V.B.S.S.

@Russdawg1 "But two UM18’s on an iNuke, you can’t go wrong!" If it is an inuke6k on a dedicated 20 amp circuit with bass torture tracks, you can.

Another thing not mentioned is simulation software. WinISD is mentioned often. It is free. It will give you the dimensions to optimize a box to get flat frequency response. It also gives port dimensions if you want to go ported. When you start a project, and select a speaker from the database, it will recommend ported or sealed based on the T/S parameters.

If bad sound were Faital, good sound would be almost impossible
Killed two Mach5 21s and three UM-18s (and counting?)

Last edited by bebb; 07-24-2019 at 05:50 PM. Reason: additional information
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post #26 of 32 Old 07-25-2019, 07:20 AM - Thread Starter
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So all of this excitement may be all for naught.

My room is 11.5' x 25' with the second row of seats having to go all the way back at 25' away (with the false wall coming 2 feet out, it will be 23' away). I know its not ideal, but I don't really have much choice due to room openings, stairs, etc.

Due to room height constraints, I think I have to go with a much smaller 16:9 screen or an anamorphic 2.39 screen. Why? Because my basement ceiling height is quite low at about 7'3", so for me to be able to put two rows in this semi dedicated theater, I need to raise the second row about 16" off the ground. However, even with that, with an (almost) full wall 16:9 screen, I'm not so sure the second row will be able to see the bottom parts of the screen. Therefore, a 2.39 screen works much better. With dimensions of 56x135 (146" diag), this will ensure that both rows will be able to see the entire screen. Mind you, it does reduce the size of any 16:9 content to 115" daig, but so be it.

But back to why this is relevant to the sub build. With the 150" daig 16:9, most of the false wall was going to be open (73" height of that screen), only covered by the giant screen. Now imagine a front false wall that is 11.5' wide and 7'3" tall, but of which the bottom half is regular drywall and stud, and the top half is mostly a hole covered by the screen frame and screen. Now, I can't just put the sub behind this false wall the same way as if the studs/drywall weren't there in on the bottom half, can I? This seems like the sub is kind of "out of the room" at this point, blocked by a wall in front of it, and won't perform the same.

Am I thinking about this all wrong??!!
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post #27 of 32 Old 07-25-2019, 07:25 AM
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Originally Posted by midfidude View Post
I'm assuming you're being sarcastic in regards to the Gotham and that these DIY subs will destroy it...!
Haha sorry, no I was being serious and I could have googled it. I do remember that sub now but the DIY's will be better than that thing.
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post #28 of 32 Old 07-25-2019, 07:43 AM
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Originally Posted by midfidude View Post
So all of this excitement may be all for naught.

My room is 11.5' x 25' with the second row of seats having to go all the way back at 25' away (with the false wall coming 2 feet out, it will be 23' away). I know its not ideal, but I don't really have much choice due to room openings, stairs, etc.

Due to room height constraints, I think I have to go with a much smaller 16:9 screen or an anamorphic 2.39 screen. Why? Because my basement ceiling height is quite low at about 7'3", so for me to be able to put two rows in this semi dedicated theater, I need to raise the second row about 16" off the ground. However, even with that, with an (almost) full wall 16:9 screen, I'm not so sure the second row will be able to see the bottom parts of the screen. Therefore, a 2.39 screen works much better. With dimensions of 56x135 (146" diag), this will ensure that both rows will be able to see the entire screen. Mind you, it does reduce the size of any 16:9 content to 115" daig, but so be it.

But back to why this is relevant to the sub build. With the 150" daig 16:9, most of the false wall was going to be open (73" height of that screen), only covered by the giant screen. Now imagine a front false wall that is 11.5' wide and 7'3" tall, but of which the bottom half is regular drywall and stud, and the top half is mostly a hole covered by the screen frame and screen. Now, I can't just put the sub behind this false wall the same way as if the studs/drywall weren't there in on the bottom half, can I? This seems like the sub is kind of "out of the room" at this point, blocked by a wall in front of it, and won't perform the same.

Am I thinking about this all wrong??!!
Make the whole false wall acoustically transparent. Only the screen part need be white.

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post #29 of 32 Old 07-25-2019, 07:52 AM - Thread Starter
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Originally Posted by Augerhandle View Post
Make the whole false wall acoustically transparent. Only the screen part need be white.
Thanks. That might have to be the way to go. So I could just use speaker cloth material for that, with a few studs for support here and there? So that confirms that I couldn't put the sub behind the half drywall wall like that correct?
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post #30 of 32 Old 07-26-2019, 12:29 PM
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I've been researching the exact same stuff for a while and even though I'm a ways away from pulling the trigger here are a few threads that would help a lot:

Minimalist Screen Wall: Not only is BIG one of the best resources on this forum, this method makes the whole wall AT, not just the screen, and with not much bracing.
https://www.avsforum.com/forum/19-de...reen-wall.html

Cyclops Sub: This DIY sub has a shallow footprint and the people on this thread are all about suggesting new ideas. It could use the UM-18 and dig deep.
https://www.avsforum.com/forum/155-d...02-design.html

Shallow Sub: Here is another thread with a great shallow, custom DIY sub discussion.
https://www.avsforum.com/forum/155-d...tm-12-lcr.html

I'd love to hear about your decision and build since once I get going on a full house remodel my next home theater with DIY speakers and AT screen will be in the works.
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