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-   -   LMS 5400 18" 6.1 cu ft sealed (https://www.hometheatershack.com/forums/sealed-subwoofer-build-projects/16189-lms-5400-18-6-1-cu-ft-sealed.html)

ISLAND1000 01-24-09 12:55 AM

LMS 5400 18" 6.1 cu ft sealed

This project began on a Friday afternoon and was ready to use Sunday evening. You might call it a weekend project.


The Driver is an LMS 5400 18" and the Amp is a Crown XTi 4000.


The LMS is rated @2500 watts and the XTi is rated 1200 watts per channel @ 4 ohms, 3200 watts bridged mono @ 4 ohms.
The LMS has a reputation for being ultra linear with a huge XMAX and powerful. The XTi is a modern PRO amp with included 6 band PEQ and extremely versatile when connected to a laptop.
The sealed box is 6.1 cu. ft. including driver and braces made with 3/4" MDF. Outside dimensions are 22.5x22.5x24.5. Box inside is sound deadened to prevent internal reflection with 1.5 inches of egg crate foam.
Construction is glue and screws with battens at every panel intersection and braces from side to side, top to bottom and back meeting at midpoint fastened with glue and screws.


Gluing and screwing batten to a side


Band clamp holding side and top at perfect 90 degree angle.


Sides, top and bottom glued and screwed.


Back glued and screwed to sides top and bottom.


Speaker terminals installed.


Battens and braces installed inside box.


Speaker baffle installed. Size comparison of LMS and Cadence Heavy Weight 18" sit on top.


LMS installed, box complete.


Cadence installed. Cadence was blown up . . . . only a 400 watt driver!


XTi and laptop showing one screen shot with two control panels

Glue is Titebond Wood Glue, screws were 1 1/4 drywall screws pre-drilled and counter sunk.
I had a 4x8 foot sheet of MDF cut to my dimensions at "Home Depot" at 4PM on Friday. I had the driver mounted and electrical connections completed by 8PM on Sunday. I fired it up gently at 9 pm not wanting to blow out any glue.
To say the immediate effect upon startup was startling would be an understatement. The bottom end was huge! I didn't throttle up for three days to give the glue a chance to cure correctly. When I did throttle up I blew up my older Cadence 18" Heavy Weight series driver. It was rated at 400 watts RMS.
I mounted the LMS driver, it eventually broke in and I became competent at using the PEQ of the XTi after 3 months. The sub and amp are excellent together. The driver is more potent than the amp. By that I mean the amp will go into protection before the driver reaches XMAX. My guess (not measured) is that the amp will deliver about 700 to 900 watts at around 20hz. That's enough to set up a noticeable vibration in my concrete floor.
The XTi allows you to make a response curve be anything you want including the best "boom box" I ever heard. Or for the purists, you can have the flatest response and have your New York Philharmonic sound like it's right there in your HT area.
Where the excitement really gets to me is watching DVDs. Explosions, Dinosaur footsteps, animations, Transformers, chopper blades, gunshots, aliens etc. are all amazing. And if you want, you can outdrive practically any set of mains there is.
My listening area is large and opens up to the rest of the house. The ceiling is cathedral and is 33 feet high at the peak. No matter, the LMS and XTi can fill it with so much bass you can't hear to talk.


View of 33 foot cathedral ceiling.


HT area.


HT area


HT area from above.

I actually completed this build last year and have lived and played with it and for sure have gotten my money's worth out of it.
What would I do differently? I'd redo the box, change the shape from almost square to more of a rectangle and add a different more substantial brace system. I might make another box out of oak or birch plywood and finish it in a nice stain and varnish. I might try the driver in a ported box just for fun. I'm curious too about an amp that's more known for driving subs like the I Tech 8000 amp from Crown. Other than that I don't think there's much reason to change anything. I go to sleep at night well pleased with my choice of sub and amp. I'm guessing I sleep with a big grin on my face. :bigsmile:
I've got to give this forum a lot of credit for gettin me going. The experts on here were a huge help identifying the LMS as THE driver to have and all sorts of DIY secrets along the way. Some of the members and some of the admins were inspirations with the projects THEY built. There are many JAW dropping, eye popping, breath stealing projects to see on here. I can spend all evening rereading the planning and building of these monster projects. It's all good.
Let me suggest to any reader thinking about whether a "super sub" is worth your time and resources . . . . YES IT IS! GIT ER DUN!

kryptonitewhite 01-24-09 01:28 AM

Re: LMS 5400 18" 6.1 cu ft sealed

Incredible. Solid looking enclosure, no need to comment on the sub or amp...speaks for itself. I am still mind blown having received my IB3 18 today.... I can not fathom your super sub... I am still taking mine in. I enjoyed your reveiws...thats a large room to fill!

38mm! 44mm! 4 10.1" slugs! 2500rms/8000 peak! Titanium former.... where does it end??? 4" coil...

ISLAND1000 01-24-09 01:51 AM

Re: LMS 5400 18" 6.1 cu ft sealed

LOL, it ain't over till it's over. Stay tuned there's gotta be more on the way!

kryptonitewhite 01-24-09 01:53 AM

Re: LMS 5400 18" 6.1 cu ft sealed


ISLAND1000 wrote: (Post 143838)
LOL, it ain't over till it's over. Stay tuned there's gotta be more on the way!

Only thing more I would want is turn that into an LLT... and back the knob down a notch, cuz that's just TOO much!

Can you make a vid?

Pinhead-227 01-24-09 01:57 AM

Re: LMS 5400 18" 6.1 cu ft sealed

Holy cow!

ISLAND1000 01-24-09 02:08 AM

Re: LMS 5400 18" 6.1 cu ft sealed

The LMS doesn't model well as an LLT but who's to say I shouldn't.
I did make a vid of the sub bouncing a tennis ball. I tried to synchronize hitting the spl just as the ball hit the cone. I got the ball to bounce half way to the ceiling once. I don't know if I saved vid or not. I'll look.
The cone does move! I did solid tones from 10hz through 125hz. That is when I could get the cooling fan in the XTi to turn on. Those low hz s really suck up a lot of juice from the amp. The cone really moves. I thought I had bottomed the driver voice coil twice but it turned out that the amp limiter was making an oscillating sound almost the same as a voice coil bottoming. Now THAT was scary.

Blaser 01-24-09 02:58 AM

Re: LMS 5400 18" 6.1 cu ft sealed

Great Job Phil :T Any chance we could see a REW FR?

joorge 01-24-09 03:40 AM

Re: LMS 5400 18" 6.1 cu ft sealed

I knew someone would get around to weaponizing a woofer.

Mike P. 01-24-09 07:52 AM

Re: LMS 5400 18" 6.1 cu ft sealed

Looking good Phil! It must be nice to be the proud owner of one of the best subwoofers ever built that is no longer available. You are one of the lucky few! :T

tcarcio 01-24-09 08:28 AM

Re: LMS 5400 18" 6.1 cu ft sealed

Great job, I use Crown amps also and love them. Congrats....:T

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