Someone crunch up these numbers! (big sub) - AVS Forum | Home Theater Discussions And Reviews
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post #1 of 93 Old 11-29-2006, 06:48 PM - Thread Starter
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Ok, so I'm making a temporary sealed enclosure for all 4 18" woofers I have sitting in my room (Mach 5 MJ18). The enclosure is gonna be 7'x2'x2' roughly 800L.

I need someone to model this with whatever program so I can see what to expect.


Edit: This IS NOT the subwoofer going into the theater, the box will not be used, just the drivers.
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post #2 of 93 Old 11-29-2006, 06:59 PM
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Looks pretty darn good if ya ask me! Thats 200w/driver. The final Qtc is ~ .5 on the dot.


112db at 10hz. That seems ok...:P

BTW this is assuming an Le of 1.0...I dont know what the actual Le spec measures on these drivers...overall the above is a good indication of max output from 4 of these drivers in a box that size.

Only time will tell what the future holds...so until then JAM LIKE THERES NO TOMORROW!
-Rob

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post #3 of 93 Old 11-29-2006, 07:03 PM
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Quote:
Originally Posted by crackyflipside View Post

The enclosure is gonna be 7'x2'x2' roughly 800L.

So has anyone built a box yet to look just like a coffin? It'd double as a great conversation piece... "oh, that's my sub".
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post #4 of 93 Old 11-29-2006, 07:08 PM
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....where demands are met with enthusiasm!
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post #5 of 93 Old 11-29-2006, 07:09 PM
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The box is a bit too big giving a low Q which puts the F3 at a very undesirable 66hz and it is
-16db at 20hz so some EQ might be needed and or a smaller box.
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post #6 of 93 Old 11-29-2006, 07:26 PM
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Actually no matter what size the box is you'll have a relatively high f3 with these drivers, with their Fs of 30hz. The larger box ensures good efficiency down in the lower frequencies.

I'd keep the low Q allignment/large box, and incorporate some EQ.

Only time will tell what the future holds...so until then JAM LIKE THERES NO TOMORROW!
-Rob

My Natalie P project
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post #7 of 93 Old 11-29-2006, 07:41 PM - Thread Starter
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You guys are thinking this too hard.... This is not a permanent project, this is just something I can make to mess with (and test) the drivers until IB is ready to be made. It may even double as a christmas and new year parties subwoofer.

Oh Exocer, how do you get 112db from that graph, I see only 102db at 10hz ???
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post #8 of 93 Old 11-29-2006, 07:43 PM - Thread Starter
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Quote:
Originally Posted by stevdart View Post

....where demands are met with enthusiasm!

My Winisd was acting stupid so I figure someone on here has to have the specs for these cheap-o drivers already saved on their modeling programs.
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post #9 of 93 Old 11-29-2006, 07:47 PM
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Quote:
Originally Posted by crackyflipside View Post

This is not a permanent project, this is just something I can make to mess with (and test) the drivers until IB is ready to be made.

Ahhh! your doing an IB with these eventually. That should be real nice with 4 18"s.
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post #10 of 93 Old 11-29-2006, 07:51 PM - Thread Starter
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Quote:
Originally Posted by Habs4life View Post

Ahhh! your doing an IB with these eventually. That should be real nice with 4 18"s.

Yup yup yup!

I just want to experience the subwoofage so I can get an idea on what to expect from the IB.
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post #11 of 93 Old 11-30-2006, 05:52 AM
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man, you guys are anal!!!! heheheh....I love you guys!

yo chris, you still going to chuck's this weekend?
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post #12 of 93 Old 11-30-2006, 06:44 AM
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Originally Posted by ssabripo View Post

man, you guys are anal!!!! heheheh....

Pot, meet kettel!

Mister I only want a driver with a silver cone, and mister I hate seams, I can't handle two visable seams.


Sheeeeachhhhhhhhhh!
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post #13 of 93 Old 11-30-2006, 07:03 AM
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Quote:
Originally Posted by ---k--- View Post

Pot, meet kettel!

Mister I only want a driver with a silver cone, and mister I hate seams, I can't handle two visable seams.


Sheeeeachhhhhhhhhh!

tis true!

but the man just wants a weekend project to play with until he is ready to isntall the IB!
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post #14 of 93 Old 11-30-2006, 09:47 AM - Thread Starter
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Quote:
Originally Posted by ssabripo View Post


yo chris, you still going to chuck's this weekend?

Yeah, but I gotta build the coffin on friday for the drivers (as Darin calls it).

Can anyone answer me why Exocer says 112db at 10hz when all I see on his graph is about 102db?
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post #15 of 93 Old 11-30-2006, 09:51 AM
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Quote:
Originally Posted by crackyflipside View Post

Yeah, but I gotta build the coffin on friday for the drivers (as Darin calls it).

Can anyone answer me why Exocer says 112db at 10hz when all I see on his graph is about 102db?

LOL....the coffin!! that's classic! hehehe.

Exo just made a typo.....it's 114dB @ 20hz, and 102dB @ 10hz......pretty freakin awesome if you ask me!
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post #16 of 93 Old 11-30-2006, 09:51 AM
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Quote:


Can anyone answer me why Exocer says 112db at 10hz when all I see on his graph is about 102db?

I'm gonna guess either a typo or he just read it wrong if the model is right. Quickly glancing at it, the 100db level can look a little like 110. These drivers aren't very efficient down low and don't have lots of excursion to spare, so I wouldn't expect too much low end.
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post #17 of 93 Old 11-30-2006, 09:58 AM - Thread Starter
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Yeah, I figured it was a typo, I was just making sure he didn't have another graph or something that he didn't post.

I'm still not sure what exactly to use to build the box. I have plenty of 5/8" scrap plywood nextdoor. I figure using double 5/8" to make the bracing, and double up on the baffle, the rest of the sides with a single layer should be fine.

Bracing on all walls except for baffle (ThomasW-style), and some shelf bracing in between the drivers.



I figure I can drill some small holes in the back and run some 12awg wire to get them ready for the amp, then seal the holes with epoxy or liquid nail.
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post #18 of 93 Old 11-30-2006, 10:12 AM
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800 liter, double wall, braced, and sealed enclosure as something to use just to mess around with? That's some dedication. Even with plywood, it's gonna be HEAVY. Have you considered maybe going smaller and just using lots of fill?
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post #19 of 93 Old 11-30-2006, 10:33 AM - Thread Starter
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Quote:
Originally Posted by SteveCallas View Post

800 liter, double wall, braced, and sealed enclosure as something to use just to mess around with? That's some dedication. Even with plywood, it's gonna be HEAVY. Have you considered maybe going smaller and just using lots of fill?

Oh c'mon Steve, you should know the best about going big with the enclosure, you're not wimping out on me are ya?

Well, I forgot to mention that the face of the box is basically the IB's future manifold, for the IB we are just gonna take off the back end of the sealed box and stick it in the roof.

We have upgraded our idea of fastening the box, we will probably arc-weld some braces from steel truss to steel truss then mount the IB to that. We were worried that the vibration from the IB could affect the integrity of those little metal anchors in the concrete deck.


Edit: Coffin will be built on Saturday, testing will commence on Sunday.
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post #20 of 93 Old 11-30-2006, 11:21 AM
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I'm not wimping out on you, but wanting to build a disposable double wall, adequately braced, 800 liter, sealed enclosure that will get used for a few weeks is probably where I draw the line There, you've exposed my limits. Wouldn't two drivers in 400 liters suffice for messing around?
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post #21 of 93 Old 11-30-2006, 12:31 PM
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Oh sorry for the typo.

Chris, looks like we've got similar numbers.

Only time will tell what the future holds...so until then JAM LIKE THERES NO TOMORROW!
-Rob

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post #22 of 93 Old 11-30-2006, 08:01 PM - Thread Starter
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Quote:
Originally Posted by SteveCallas View Post

I'm not wimping out on you, but wanting to build a disposable double wall, adequately braced, 800 liter, sealed enclosure that will get used for a few weeks is probably where I draw the line There, you've exposed my limits. Wouldn't two drivers in 400 liters suffice for messing around?

I think you didn't read part of my post, the front baffle and all sidewalls of the sealed enclosure are going to end up being the manifold for the IB. All I am doing for the temporary sealed sub is adding a back panel.

And used for a few weeks... this will only be a sealed enclosure for about a day and a half unless I buy a 2500.
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post #23 of 93 Old 12-01-2006, 11:02 AM
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Interesting to say the least...

Sent from my 80-286 DOS 3.2/Windows 3.0 machine using Terminal
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post #24 of 93 Old 12-01-2006, 09:14 PM - Thread Starter
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Interesting to say the least...

Hahaha, you know your woofers are tempting me to do this.
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post #25 of 93 Old 12-01-2006, 09:34 PM
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I can't imagine 4 of these 18" drivers not being enough for most dedicated home theaters.

But we all know how it is...once you get lots of bass you only want more I suspect Chris might be ordering another quadruplet set of drivers in the future for even MORE headroom

Only time will tell what the future holds...so until then JAM LIKE THERES NO TOMORROW!
-Rob

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post #26 of 93 Old 12-02-2006, 01:42 PM - Thread Starter
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Quote:
Originally Posted by Exocer View Post

I can't imagine 4 of these 18" drivers not being enough for most dedicated home theaters.

But we all know how it is...once you get lots of bass you only want more I suspect Chris might be ordering another quadruplet set of drivers in the future for even MORE headroom

In a year or two I will upgrade to some 30mm xmax 18's.

Until then, I guess I'll have to deal with having only 4 12mm xmax 18" drivers.
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post #27 of 93 Old 12-02-2006, 02:00 PM
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Woah, 30mm xmax 18" drivers? INSANE hahaha.

I thought Sherv was sick

Are these the upcoming mach 5 high excursion 18" drivers by any chance?

Only time will tell what the future holds...so until then JAM LIKE THERES NO TOMORROW!
-Rob

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post #28 of 93 Old 12-02-2006, 02:32 PM - Thread Starter
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Quote:
Originally Posted by Exocer View Post

Woah, 30mm xmax 18" drivers? INSANE hahaha.

I thought Sherv was sick

Are these the upcoming mach 5 high excursion 18" drivers by any chance?

I don't plan on upgrading any time soon so time will tell what I'll upgrade to.
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post #29 of 93 Old 12-02-2006, 02:54 PM
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Yeah fair enough...you haven't even completed this project yet

Only time will tell what the future holds...so until then JAM LIKE THERES NO TOMORROW!
-Rob

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post #30 of 93 Old 12-03-2006, 04:00 PM - Thread Starter
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How to make an audiophile subwoofer in 2 hours and 30 minutes.



Step 1. Make the baffle out of a single layer of 5/8" plywood and cut holes using a Sawzall.






Step 2. Find the most dirty termite infested 2x4 members to stiffen the front baffle because everybody knows, the more rotten the wood, the faster the bass.






Step 3. Make the back of the sub like the front, the wood bracing doesn't have to match or be the correct length, because if it does, the sub won't be musical.






Step 4. Put it together with sides, who needs bracing on the side walls, it will make the subwoofer heavy and in turn, it will sound heavier (not good) Besides, who uses braces? That's right, only losers and nerds; your audiophile subwoofer is no punk.








Step 5. Put in audiophile grade cable that is a multitude of colors with no red cables because they are inherently slow (which is why stoplights and signs are always red)Put in drivers. Sealants are not needed because it will muddy the sound.





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