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Discussion Starter #1
Hi,
I built a sealed box (~100 l] for my LMS Ultra about a year ago. I recently bought 2 TC Sounds VMP 18 passive radiators and now I'm thinking my next build.

Should I use both PRs for the LMS Ultra or is one sufficient? I'm planning on buying one more LMS Ultra when one is available (they seem pretty rare these days). If I only need one PR / Sub then I would use the other one for my second sub sometime in the future.

Also I would be grateful if any of you had scetches or photos of similar builds and could share them. I tried to look but didn't find much. Any tips and advices would be much appreciated as well.

Thank you!

Ps. Here is some build photos of my current sub:
http://1drv.ms/20BItN4
 

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A PR really needs to have a larger surface area than the driver itself, so in the case of an LMS-5400 you should be using a minimum of a 21" PR (for a single). Dual 15's should work, and definitely dual 18's would. With the xmax of the LMS I don't see a single 18" working.
 

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A PR really needs to have a larger surface area than the driver itself, so in the case of an LMS-5400 you should be using a minimum of a 21" PR (for a single). Dual 15's should work, and definitely dual 18's would. With the xmax of the LMS I don't see a single 18" working.
^ Exactly what he said. You need to use both 18" PR's for the system to work properly. If you only use one 18" PR you'll have limited output at the PR's resonant frequency (tuning) and you will more than likely stress the PR's parts past their limits from over-excursion.
 

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Discussion Starter #4
Thanks! I will use both of them.
Can you tell me how much clearance will be needed for the PR's outside the box?
I have my first design sketch ready, but it seems the drivers wont fit so I still have to make the box a little bigger. What do you think?
 

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HTS Moderator , Reviewer
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Clearance outside the box??? Do you mean between the cone and the next physical object like a wall, chair, cabinet, etc?
 

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Depending upon what the adjacent surface is - reflective, like a wall, or absorbent, like drapes - I'd leave no less than 1 foot. Realistically, it should probably be more; those are large PR's and they're going to be moving an awful lot of air.
 
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