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Discussion Starter · #1 ·
Hello,

Looking to build a box to be use with the TC sounds ultra 5400 18 driver. I am thinking of going with the matching PR too, but I am not 100% sure. This sub will be mainly use for music so accuracy will be very important. I have a rack amp that will put out 1300 watt @ 8ohm to drive this.

So far I used WinISD, but I really don't know what the graph mean. I have this setup with the PR. Therefore if someone would can help give me some pointer that will be awesome. I would like to keep the box as small as possible.

Thanks!
 

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The graph represents the slope of the drivers response. If you look at it from right to left you can actually see it's meaning IMO. Starting from the right side you can see where the line peaks at what decible level (far left of graph), and the farther you go down in frequency (left to right), you can see how the sound level drops/slopes. You can mess around with box sizes, and types with WinISD, or Unibox, or others. Your main objective is to get the smoothest line across the graph, and the least steep slope as the frequency drops. I'm just now starting to learn about it myself, and theres quite a bit to it. I've never modeled a LMS Ultra 18 myself, but if you're looking for small you're most likely going to want to go with sealed, or a PR set-up. If you wanted a ported LFE sub, you would be looking at a pretty massive box with that driver!
 

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Remember that with if you're going to use passive radiators you need around 2x the surface area, so you'd need at least 2 18" PR which would get pretty expensive. You'd be smart to just port it.
 

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Remember that with if you're going to use passive radiators you need around 2x the surface area, so you'd need at least 2 18" PR which would get pretty expensive. You'd be smart to just port it.
Smart if you want to save the money, but if the money isnt the concern, and you want a smaller cabinet, then smart would be to use the pr's. Basically, its a personal choice.
 

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The LMS is difficult to port well due to needing a massive port area to avoid compression and the fact that the motor is so strong it gives a peaky response in larger enclosures. This is why PR's are easier with this driver, plus it keeps the total cabinet size down. I'd do that or go with a sealed enclosure between 100 and 200L. It will eat everything that 1300w amp has and ask for seconds, so don't worry about that.
 

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Discussion Starter · #7 ·
I tried to run the project again so i can upload it, but it kept giving me an error. So how big of a box will I need volume wise?
 

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I spoke with Thilo over at TC Sounds and he recommended a 5.4 cu ft box with dual 18" PR's. I did ask him about using a single 18" PR in which you lose a little but he said that the dual PR's keep the box from walking during high excursion.

I am planning on building sealed enclosures myself as I am mostly concerned with musical accuracy and with the pair I have the SPL will be there for movies. Ricci knows his stuff when it comes to the LMS along with just about any sub. His suggestions of 100L to 200L = 3.5 to 7 cubic feet are right were I am at.

Do you know what the 4 ohm rating is of your amp? If you pass on the dual pr's that is an extra $360 in your pocket, maybe you could sell your current amp and get something more powerful.

Just looking at a quick WinISD Pro plot it looks like the performance is a match if you do a 7 cuft. sealed compared to a 5.5 cuft. dual 18" PR with 1500 watts. Maybe someone else can confirm this, a sub guru perhaps?
 

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The maximum that can be added to the TC VMP PR's is an additional 2000g. This post from Kyle on TC's own forum covers a lot of information on the PR's.

http://www.tcsounds.com/forums/index.php?/topic/2-new-tc-product-information/

255L with 2 18" VMP's with the full 2000g on each looks good. That's about a 16.5hz tune. A 13 or 14hz, 4th order hpf looks about right for use with an amp of between 2000 to 4000w.
 
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