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LTD-M18 Sub Build - Page 4

post #91 of 370
"I will be interested to see how impactful these monsters are going to be."
Me too, chaluga!
The 316 project is ri-dunk-u-lous!!biggrin.gif
post #92 of 370
Thread Starter 
Quote:
Originally Posted by chalugadp View Post

Here is the drawing with measurements



Man this is going to be a beast cool.gif

So I've done a few re-measurements Donny and I have enough room to push these to 78" tall, otherwise 32" wide and 22" deep are still the other dimensions.
post #93 of 370
Quote:
Originally Posted by chalugadp View Post

DO you have the link to his ?

started a proper thread:

http://www.avsforum.com/t/1516234/8x-18-lms-5400-ultras-sealed-to-27-cube-15hz-ported-build/0_100
Edited by notnyt - 2/5/14 at 6:52pm
post #94 of 370
Quote:
Originally Posted by jbrown15 View Post

So I've done a few re-measurements Donny and I have enough room to push these to 78" tall, otherwise 32" wide and 22" deep are still the other dimensions.

They're going to rock being on that narrow of a base and having a driver that high in the air.

Also looking at the 3d model, you have 4 of the braces listed, but one will be a different size since it will not be up against the port. Keep an eye on that.

EDIT: 3 will be a different size, the size you listed doesn't account for the port.
post #95 of 370
Thread Starter 
Quote:
Originally Posted by notnyt View Post

They're going to rock being on that narrow of a base and having a driver that high in the air.

You think so? I talked to LTD02 about this when we were coming up with the design, he didn't seem too concerned about the cabinets rocking. We could also mount the drivers a little lower in the cabinets too, the bottom one could be mounted near the bottom and the top driver could be installed closer to the middle of the cabinets.
post #96 of 370
Quote:
Originally Posted by jbrown15 View Post

You think so? I talked to LTD02 about this when we were coming up with the design, he didn't seem too concerned about the cabinets rocking. We could also mount the drivers a little lower in the cabinets too, the bottom one could be mounted near the bottom and the top driver could be installed closer to the middle of the cabinets.

My sealed boxes rocked with heavier drivers mounted lower in about the same depth of a cab. Did it impact sound? Who knows. I can almost guarantee you that those will in fact rock at higher excursion levels and low frequency.
post #97 of 370
Quote:
Originally Posted by notnyt View Post

My sealed boxes rocked with heavier drivers mounted lower in about the same depth of a cab. Did it impact sound?
It did. The driver creates sound by literally pushing and pulling against the air in front of the cone. If some of that energy is used to push the cabinet back and forth instead of pushing the air back and forth less sound is produced. If I was building a sub with two large drivers I'd make it dual opposed, which will eliminate any rocking and lost SPL.
post #98 of 370
Quote:
Originally Posted by Bill Fitzmaurice View Post

It did. The driver creates sound by literally pushing and pulling against the air in front of the cone. If some of that energy is used to push the cabinet back and forth instead of pushing the air back and forth less sound is produced. If I was building a sub with two large drivers I'd make it dual opposed, which will eliminate any rocking and lost SPL.

True, but it's a sealed box and still creating the same amount of displacement/pressure change in the room.

EDIT: and yes, I know it affected the sound, but I meant to a noticeable degree.
post #99 of 370
Quote:
Originally Posted by notnyt View Post

True, but it's a sealed box and still creating the same amount of displacement/pressure change in the room.

EDIT: and yes, I know it affected the sound, but I meant to a noticeable degree.
If the cone was moving back and forth by 15mm and the box was rocking back and forth by 3mm there'd be a fair amount of SPL loss.
post #100 of 370
Quote:
Originally Posted by notnyt View Post

Quote:
Originally Posted by jbrown15 View Post

So I've done a few re-measurements Donny and I have enough room to push these to 78" tall, otherwise 32" wide and 22" deep are still the other dimensions.

They're going to rock being on that narrow of a base and having a driver that high in the air.

Also looking at the 3d model, you have 4 of the braces listed, but one will be a different size since it will not be up against the port. Keep an eye on that.

EDIT: 3 will be a different size, the size you listed doesn't account for the port.

All four braces are the size listed. Me knows my way around sketchup cool.gif
post #101 of 370
Quote:
Originally Posted by chalugadp View Post

All four braces are the size listed. Me knows my way around sketchup cool.gif

How does that work if 3 braces go front to port, and one goes front to back?
post #102 of 370
There won't be any rocking except maybe in jbs theater by things other then subwoofers tongue.gif
Box will be attached to wall.
post #103 of 370
Quote:
Originally Posted by chalugadp View Post

There won't be any rocking except maybe in jbs theater by things other then subwoofers tongue.gif
Box will be attached to wall.

Well, that will sure solve the problem. Hopefully those are some concrete walls smile.gif
post #104 of 370
Cool it's back! Do you guys have any plans to brace the top and bottom?. a couple dowels top to bottom?
Edited by steve nn - 2/5/14 at 7:56pm
post #105 of 370
Quote:
Originally Posted by notnyt View Post

Quote:
Originally Posted by chalugadp View Post

All four braces are the size listed. Me knows my way around sketchup cool.gif

How does that work if 3 braces go front to port, and one goes front to back?
Cuz all go front to port. I haven't included the 1 by 1 support braces . Only the plywood needed to be cut. The nice birch plywood jbs getting .
post #106 of 370
Quote:
Originally Posted by steve nn View Post

Cool it's back! Do you guys have any plans to brace the top and bottom?. a couple dowels top to bottom?
Will be lots of vertical 1 by 1 support pieces. Jb is going to be cutting those by his bare hands cool.gif
post #107 of 370
Quote:
Originally Posted by chalugadp View Post

Will be lots of vertical 1 by 1 support pieces. Jb is going to be cutting those by his bare hands cool.gif

cool.gif I want a vid of that lol. seriously!!
post #108 of 370
as for rocking, the reason that I wasn't concerned in this particular case is what I mentioned in post #2: the low ceiling joists could offer a method for bracing the cab. but then it was pointed out that the cabs could be bolted to the wall. so long as the wall is quite sturdy, that should solve that.

anyway, a question was asked about reconfiguring for two cabs again, with some additional limitations.

these would be about 38" tall, 32" wide, 22" deep. 3" slot port that is 40" long (one brace down the middle). net cab volume roughly 11 and change. tuning roughly 15-16hz.



post #109 of 370
Thread Starter 
So with the cabinet now being smaller the port only needs to be 3" high?
post #110 of 370
Jbrown, you went off the deep end!! I likey smile.gif
post #111 of 370
Thread Starter 
Quote:
Originally Posted by basshead81 View Post

Jbrown, you went off the deep end!! I likey smile.gif

Bass you're back!!! Excellent.

Yes I have gone a little crazy!...lol
post #112 of 370
Quote:
Originally Posted by LTD02 View Post



Quite impressive! eek.gif
Quote:
Originally Posted by jbrown15 View Post



Yes I have gone a little crazy!...lol

Understatement of the new year!biggrin.gif
post #113 of 370
Quote:
JB> Yes I have gone a little crazy!...lol




smilie_happy_053.gif
post #114 of 370
Thread Starter 
Quote:
Originally Posted by steve nn View Post


smilie_happy_053.gif

LOL..... Steve you're always good for a laugh! haha

So I had to change the plans up a little after realizing how much of a pain in the a$$ it was going to be to get two monster subs into my basement with the only access by going threw the house. So I've decided on four large single ported cabinets. Each one will be 32" wide, 22" deep and 40" high.
post #115 of 370
Lol.. hey jb.. Yeah I saw that! 4 is going to be a job but with chals help and the tool situation it should work out just fine. It’ll help you out in other ways also like you just suggested. Heck you never know, maybe you’ll part them differently at some point.
post #116 of 370
Quote:
Originally Posted by steve nn View Post

Lol.. hey jb.. Yeah I saw that! 4 is going to be a job but with chals help and the tool situation it should work out just fine. It’ll help you out in other ways also like you just suggested. Heck you never know, maybe you’ll part them differently at some point.

Maybe he'll be fine with two and give me two of them cool.gif
post #117 of 370
Thread Starter 
Quote:
Originally Posted by chalugadp View Post

Maybe he'll be fine with two and give me two of them cool.gif


LOL.... I think best case scenario is I realize three is enough and give you the forth!..lol
So I'd have three and you'd have three.....lol smile.gif
post #118 of 370
Sounds good
post #119 of 370
"So with the cabinet now being smaller the port only needs to be 3" high?"

I was trying to figure out what you meant...yes. the cross sectional area of the port is on a 'per driver' basis.

3" x ~19" or whatever it works out to will be fine for each of these cabs which are loaded with one driver each.

if the cab size was doubled and the drivers were doubled, the port size cross sectional area would be double (it would be as if the two ports were simply combined into one big one).
post #120 of 370
in the monster cab, the port was going to be about 4" x 29" or so = 116 sq inches cross sectional area for two drivers.

in each of the smaller cabs, the port is going to be about 3" x 19" or so = 57 sq inches cross sectional area for one driver.

that is roughly the same amount of cross sectional area 'per driver' in both instances, thus they will perform pretty much the same from an air flow perspective.
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