For years I have procrastinated and procrastinated building the mother of all subwoofers. I have gotten to the point where my own slackness is really ticking me off. For 4 or 5 years I have had 1 x TC Sounds LMS 5400 Ultra sitting in a box, along with another 2 x 18" TC Sounds VMP passive radiators.
I have even had the design done for several years, and my CNC machine is up to building it. I also have a Crown I-Tech 9000HD to power it. If I don't build it now I am going to be too old to enjoy it, so as soon as the weather gets better I have committed to getting this beast underway.
Comments and suggestions most welcome.
I have even had the design done for several years, and my CNC machine is up to building it. I also have a Crown I-Tech 9000HD to power it. If I don't build it now I am going to be too old to enjoy it, so as soon as the weather gets better I have committed to getting this beast underway.
Comments and suggestions most welcome.
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Are you suggesting moving the PRs more in line with the active driver?
One PR will be on the left and the other on the right, with the active driver facing forward.
I think Rademakers was pointing out that the notches need to be half depth on each side to successfully create a Cross Lap joint.
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Yes the plan is to slot as much as possible to interweave the pieces.
Material I am looking at something like 19mm-25mm ply internal. Up to 40mm for external walls depending on the weight.
Looking to rejig the design to get the volume down. TC Sounds suggests two box sizes
6.4 ft3 (181 litres) 1550g moving mass, 18Hz
8.4 ft3 (238 litres) 1650g moving mass, 15Hz
Being that the driver is 470mm wide, the smallest I could possibly make each side is 500mm, and probably a meter tall making it 250 litres minus cones etc.
I mocked up the driver and PRs to get a better idea of real world dimensions.
Material I am looking at something like 19mm-25mm ply internal. Up to 40mm for external walls depending on the weight.
Looking to rejig the design to get the volume down. TC Sounds suggests two box sizes
6.4 ft3 (181 litres) 1550g moving mass, 18Hz
8.4 ft3 (238 litres) 1650g moving mass, 15Hz
Being that the driver is 470mm wide, the smallest I could possibly make each side is 500mm, and probably a meter tall making it 250 litres minus cones etc.
I mocked up the driver and PRs to get a better idea of real world dimensions.
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The box will to a large degree. TC Sounds PR's have an unusual mass system that allows you to add additional weight to the PR to tune as well.
Although the way I see it, air is compressible (otherwise there would be no turbos and it would be a very sad world). And if air can be compressed (which it can) then we need to consider the path of the air movement inside the box and its effect on timing relative to the active driver.
Theoretically the PR should move before the box sides due to a little thing called path of least resistance, but I propose that depending on where you place the PRs in the box, you might be able to increase of decrease the amount of resistance before the PRs move.
Although the way I see it, air is compressible (otherwise there would be no turbos and it would be a very sad world). And if air can be compressed (which it can) then we need to consider the path of the air movement inside the box and its effect on timing relative to the active driver.
Theoretically the PR should move before the box sides due to a little thing called path of least resistance, but I propose that depending on where you place the PRs in the box, you might be able to increase of decrease the amount of resistance before the PRs move.
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So long as the bracing is open and the box has a reasonable aspect ratio, the air within the box will act as a simple spring. One you get towards high-aspect-ratio cabinets, transmission line effects start to come into play.
Your cabinet will be fine.
I'd go for PRs arranged opposite to each other, so there's force cancellation and the cabinet itself doesn't walk around. You're looking at over a kilo of mass vibrating around.
So, the conclusion is that your cabinet is fine. Just make sure the PRs are mounted on opposite panels when you build the thing. You could have main driver and one PR firing forwards, and one PR firing backwards, or PRs firing out of each side with the driver firing forwards, or...
You get the idea.
Chris
From what I've read you are over thinking and under building here. I won't cry if there is some vibration in the cabinet I'm building. Build big cabinets and there won't be as much vibration but that defeats what I'm trying to do by adding PR's.
The weight system to tune on the back is a standard set up with larger PR's that I've seen.
Grant.
I'm torn between two trains of thought at the moment...
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My main reason for going PR over ported is to eliminate port noise. Both designs require a similar sized box.
I'm in a similar place to what you're describing but I just got the PR's a couple weeks ago. That is my interest in this thread.
Mine won't be a mother of all and it will still be more than I use.
Good luck on the build.
Grant.
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If mine is the mother of all subwoofer builds, I found the grand daddy earlier...
4 x TC Sounds LMS 5400's, 8 x 18" TC sounds VMPs.
2 x Crown I-Tech 8000s (I am using 1 x I-Tech 9000HD)
Cost him $20k to build mine will be about $10k.
Sometimes things get a little out of hand... Wish you success with yours, looks like you have some good gear there to start with.
Thanks. I hear Bruce Edgar built a sub for the army to simulate mortar rounds, etc. If I remember right they proposed 500 15 inch drivers. Bruce built a horn with 4 18 inchers. The test was done with Pink Floyd outside
. There are levels of grand daddies. My plans are to build the box and listen to it, then finish it if I like what I hear. That way if something's not what I want I don't have so much into the build.
Grant.
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