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Discussion Starter #1 (Edited)
2 UM18-22 slot ported build ''A New Level" tall boy build

'' A New Level'' Everyone know I like theme named boxes so these will be called tall boys A New Level.... This from a Pantera song I like and thought about when designing these. Cliff currently has one Monoprice Monolith 15 THX in his room and running that nearfield along with one Dayton 12'' driver up front. I tested his room and figured out where the best spot to place these new slot ported boxes that I'm building. When measured the monoprice sub and also got a response from that so these will bring his room to A New Level!



The box size is



66'' tall

24'' wide

18'' depth

The tune is 17hz
The port height is 3 inches tall and 42.25 long.

External cubic ft. external 14.28 cubic ft.



internal cubic ft before subtracting the driver, bracing and slot port. 13.85 cubic ft



after bracing and slot port it should be around 11.75 to 12 cubic ft.



both of these boxes need 5 sheets of 3/4 MDF total so they might have some weight to them. Having tall boxes there not cut sheet friendly when trying to fit all the cuts on a sheet so a lot of wood was wasted but the end result will be worth it.



Standing waves inside the box....... There very tall!!

Since the boxes are tall I might have some standing waves inside the box which I'll fix with a pillow. With a tall box the internal standing waves and create some problems. So you take the height 5.5 ft. times that by 2 and the equals 11ft.

1130FPS/11 equals roughly 102hz. and Cliff so far wants to cross these at 120 hz. so I do some more reading and figure out where to place them.
 

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The box size is

66'' tall
24'' wide
18'' depth
Mine is bigger than your's...hehe

Mine are 75" tall and 24x24.

I'm chiming in to say that at over 400lbs each with 2 LMS-ultra drivers, the boxes do not 'walk' around on the floor. I've monitored that for the last year. The biggest advantage is that since the 18's are at different heights off the floor, it evens out the room response quite a bit. I was creative with internal damping to address standing waves inside the boxes.

I look forward to your results.
 

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Discussion Starter #5
Mine is bigger than your's...hehe



Mine are 72" tall and 24x24.



I'm chiming in to say that at over 400lbs each with 2 LMS-ultra drivers, the boxes do not 'walk' around on the floor. I've monitored that for the last year. The biggest advantage is that since the 18's are at different heights off the floor, it evens out the room response quite a bit. I was creative with internal damping to address standing waves inside the boxes.



I look forward to your results.


400 lbs. wow that’s some weight! What height did you cut out your drivers? So far the plan is having the bottom of the hole for the driver being 10 inches above the port so let’s say 18” would be the center of the sub above the slot port.
 

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400 lbs. wow that’s some weight! What height did you cut out your drivers? So far the plan is having the bottom of the hole for the driver being 10 inches above the port so let’s say 18” would be the center of the sub above the slot port.
It's evenly distributed between the top of the port and the top of the box. I think 7" down from the top for the top driver and 7" above the port. I'd say the top of the top 18 is about 5' 7" above the floor.

the TC's are 165lbs of the total weight
 

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Having a driver above the other seems to fill in the floor dip in the response.
I'm far from an authority on the topic. Perhaps more informed minds can chime in on the issue.
 

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Discussion Starter #11
Man you really are a building beast! I can’t even think about another build right now, and you just keep rolling on lol


Thanks man ya I keep going and going three more boxes to go after these two are are finished to go. Your 1899’s are unreal with the way they look! I looked at the pictures you posted and my mouth dropped.
 

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Looking forward to watching the progression of this project!

The flare you are putting on the internal entrance of the port.... do you think that would yield any advantages doing the same with a mini-marty port?
 

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Discussion Starter #14
Looking forward to watching the progression of this project!

The flare you are putting on the internal entrance of the port.... do you think that would yield any advantages doing the same with a mini-marty port?


My personal opinion on having flared ports is yes it would help but every 90 degrees bend would have to have a smooth angle on it. Mtg90 suggested this to me during the My B&C build when he sent me the 3D image of the box I built. I see car audio guys doing this all the time so anything that can help the air port velocity have a nice transition through the port from the beginning to out of the box helps. I wonder how I can test this?
 

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I am planning on a sub box build in the future and was leaning towards a mini Marty. Do you prefer an angle transition over KERF? Seen KERF a lot in car audio but not as much on here so far.
 

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Discussion Starter #16
I am planning on a sub box build in the future and was leaning towards a mini Marty. Do you prefer an angle transition over KERF? Seen KERF a lot in car audio but not as much on here so far.


I haven’t tried a kerf bend yet in any boxes but I’ve seen Seaton Audio have a really nice bend on the bottom slot port of one of his cabinets he sold. I think an angled bend on the wood is pretty easy to do with out scraping to much wood if you mess it up like I did on my buddy box I’m building in this thread. Try both out though and see how it works out it’s just wood.
 

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looks awesome. keep the pics coming.
 
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Nice work! I would love to hear them when they are finished. I could also be available for help if needed. I'm just a few minutes from you. :)
 

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Discussion Starter #19
2 UM18-22 slot ported build ''A New Level" tall boy build

Nice work! I would love to hear them when they are finished. I could also be available for help if needed. I'm just a few minutes from you. :)


Thanks these are going together pretty smooth so far last night I glued the baffle together so next up is the window bracing. The plan is to cut all the window bracing today or tomorrow which ever day I have time then glue this all together and start all the finish work on them. As for hearing the sub in the box as long as I have one of Cliffs um18 drivers when there done it shouldn’t be a problem but if he picks it up beforehand it’s up to him because there not mine I’m just building the box for him.

No glue on these yet when I took this picture but here’s the hole cut out for it.
 

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As for hearing the sub in the box as long as I have one of Cliffs um18 drivers when there done it shouldn’t be a problem but if he picks it up beforehand it’s up to him because there not mine I’m just building the box for him.
I have a couple UM18's here if you need borrow one for fitment/testing.
 
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