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Discussion Starter · #1 ·
I want to build a custom cabinet and make the most of my LMS-Ultra 5400 18"sub-woofer. Should I use passive radiators? and how big should I make the cabinet? Thanks
 

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Depends what your after. Make the most of your woofer and have lots of room, I would say build a Ghorn. If you only have one and dont plan on getting more than ported with PR or port would be next. I like sealed because I am always after reaching single digits in movies. SO how big do you want to go?

18hz tune is not to big and would have plenty of power for most movies. Here are some links to others builds to give you some ideas:
Sealed dual opposed
Ported 15hz PR
 

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I second the g-horn if you have the space. It has the most output for a single driver enclosure for that amount of space. I am designing ported enclosures for my 2 Ultras, and it is tough to do for my space and placement requirements, and budget.
 

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Discussion Starter · #4 ·
Yes, I'm looking for low single digits for movies also, and might build another one in a year or so. I was thinking about taking one full 4x8' 3/4" sheet of birch plywood and cutting it into 2x2x2' squares well actually 26"L x22"h 22"D. So, I think what your saying is keep it sealed with no Radiators? and will this be of sufficient size?
 

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Single digits are possible but you will need many more woofers to have any real affect. Have you ever experienced single digits before?

Small sealed with a big amp will be the best thing to start. Then just grow your system as you can. You could go for ported but I would prefer 18hz tune myself. Anything lower and the cabinet will get huge to fit the port. And if you can have a large cabinet like 15cuft or larger, why not try a horn. Just my thoughts. To each their own. You may prefer ported IDK.

Either way you have a TC Ultra and thats awesome. Great start. Now lets get a build thread. :D Did you have a look at the links I posted earlier?

If I could afford it I would copy WarpDrv's build. But that is a few dollars that I dont have.
 

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Discussion Starter · #7 ·
I'm a newbie when it comes to diy speakers, In the past I've always bought the speakers already made, But I'm really more of a do it your self-er kind of guy. So I decided to take on this project, and am looking to learn as much as I can before I get started. I would like to go with a small to medium size cabinet for the 5400. but I wasn't sure if I should use radiators because my definitive's have'em... I'm not sure if Ive ever experienced single digits myself. I just thought lower is better when it come to movies and listening to music. I'm worried that with out the radiators the woofer will be overworking in a small enclosure because of air pressure??? and it seem like at least one radiator would help with that??? but I don't want to give up the lows... Thank for your input chrapladm
 

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Chrapladm - Do you prefer the 18hz tuning because of enclosure size?
I prefer the tuning because its adds quite a bit of spl over the sealed from 12hz-50hz and still in a small enclosure type. The 15hz tuning adds a lot from 11-40hz over the sealed but from 22hz and up the sealed wins. And thats where most of the bass is in movies.
I'm a newbie when it comes to diy speakers, In the past I've always bought the speakers already made, But I'm really more of a do it your self-er kind of guy. So I decided to take on this project, and am looking to learn as much as I can before I get started. I would like to go with a small to medium size cabinet for the 5400. but I wasn't sure if I should use radiators because my definitive's have'em... I'm not sure if Ive ever experienced single digits myself. I just thought lower is better when it come to movies and listening to music. I'm worried that with out the radiators the woofer will be overworking in a small enclosure because of air pressure??? and it seem like at least one radiator would help with that??? but I don't want to give up the lows... Thank for your input chrapladm
If you have room and more money to spend then build a ported cabinet using PR's. You will need two PR's though. If you want to stay small then shoot for a simple 18-20hz tune and around 6cuft or 24" cube cabinet. PR's wont make chuffing sounds so finding a port that works with this woofer wont be a problem.:T

If you listen to a lot of music then you dont need to go much lower then 25-30hz. So if this is the case sealed would be best. Would be a very good all around subwoofer and can be put in a small 3cuft cabinet.. Trying to build for single digits requires at least eight 15's or possibly eight 18's, Or if you have the space four monster horns.

SO maybe just start off with a sealed and see how you like it. Then if you just want more low end build a ported sub if you have the room. Or if you come into some more money just add more Ultras sealed.
 

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Discussion Starter · #9 ·
Thanks Chrapladm,
So, far lower bass you recommend the radiators? I'm thinking about making the sub as small as I can with the 2 radiators. I'm watching a video right now
. Is it better to use pressed board or hard plywood. or does it matter. or pressed if I'm going the paint it and hard plywood if I'm going to stain it?
 

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PR's are a great option to rid chuffing if designed properly. You still need a large cabinet for tuning really low. How big of a cabinet do you want to go?
 

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Discussion Starter · #11 · (Edited)
I just bought the components yesterday. And I decided against pr's. ill probably build another sub after I finish building the main speakers. Two foot square seem to be pretty popular. I was told the lms driver is made for smaller sealed enclosures.
 

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2.5-4cuft would be for sealed. 20"cube works or other variation in size for your taste.
 

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I don't think anyone has mentioned using a Linkwitz Transform or some kind of active filtering to boost the low end (as long as you have an amp that can handle it). You'll have to be more careful designing around the limits of the driver, but it might be able to dig a little deeper for you.
 

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4 cuft is right about the best default sealed size for the LMS U.

As chrapladm has already mentioned you need a lot more drivers to achieve true single digit performance from a sub system. To really get into the single digits with the LMS U in a medium sized room will probably take at least 4 sealed.

The LMS U is the ultimate sub, it just has it's limitations just like every other driver.
 

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Sorry to kind of high jack the thread but when I plug in the numbers for a 6 cube box it's not a very flat response at all. It all rolls down after 150Hz or so. Would the wiring in parallel be the issue because the all the specs are in parallel? would it make a difference in the model. I will be using series for 4Ω. Trying to get close to flat response without a lot of eq. I have a feedback destroyer pro that i will be using for Eq. the closest I got to flat response was with a vented box but i'm trying to stay away from that style as I will be quite close to the sub.
 

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The LMS Ultra is made to go low, not high. It is actually really good that it can play up to 150hz before it begins to roll off, if you want something to go higher then look into pro sound subs but you will sacrifice low end performance.

You will want to use the LMS Ultra with main speakers that extend to at least 80 hz cleanly but a little lower is even better. My mains extend to 23 hz but when I had the LMS Ultra pair I crossed over at 60hz for music and 80 hz for movies. It still sounded very good crossing over at 80 hz for music but I got a little better integration at 60hz in my room.

Your not going to get a very flat response with hardly any subs in sealed enclosures modeling in WinISD. That is what EQ and DSP is for, to manipulate the signal and shape it to what you want it to look like.

6 cuft sealed is OK with the LMS ultra but watch how much power you put into it. Only use that size enclosure if you are limited to about 1700 watts. 4 cuft gives you more power handling at about 2500 watts. There is not a big difference in performance between 6 and 4 cuft but the smaller box gives you more driver protection so it is the preferred size to go with.
 

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That's why I like 4 cuft, only a 1.2 db difference at 20 hz which is not too noticeable but you gain some more power handling which is important when you boost down low.
 
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