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Discussion Starter · #1 · (Edited)
This is more of a place holder since I will not get started for a while but here are the first few pics. I already have the two Ultimax 18" drivers and the two 10" diameter sonotube ports. I'm still deep into drywalling the basement to give this the attention it needs. Special thanks to a handful of smart and patient forum members for their contributions to this design. Chime in and let people know who you are if you can.

The Design:



The 12 foot Tube:



Cut to 6 foot each, meet the Odin Brothers:

 

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Will post updates as they occur and leave this post on the forum as long as forum moderators don't start griefing me again.

What does this mean? There are countless build threads that are abandoned or shelved for extended periods of time.
 

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Discussion Starter · #3 ·
After nearly 2 years I have started assembling the subwoofers! I bought 3 sheets of 3/4" MDF (4'x8') and had them delivered. They actually measured as 49"x97" so I was able to get more cuts out of them since my rounds were actually 24" diameter. The sonotube was delivered back in 2018 as a 12' long x 24" D tube that I cut in half giving two 6' tall subs housing an 18" Ultimax in each. I made a minor alteration to the plans shown above. I am eliminating the bottom floor caps and using only 3.5" dowel feet instead of the 6" depth shown. The rest of the design is what we will see here moving forward. I hope those involved in helping me finalize this design remember your contributions and I thank you again for them.

First step was to make a test disc to check for fitting in the sonotube. Once I confirmed the round fit snug enough with room for adhesive all around I went ahead and routed 8 disks.

















Once the rounds were completed I measured and test cut for the internal ports. These were also sonotubes measuring 48" long. Each tube had a different diameter so I had to make two sets of top cap ports. The top caps will have two layers of internal mdf for an interior thickness of 1.5" and a third outside layer that measures 24.75" diameter to sit nearly flush with the top of the tube. I went with the same method for the bottoms caps but instead I replaces the inner most layer of MDF with 3/4" plywood so I can more easily mount into the surface.











That's as far as I got. I don't have enough clamps to assemble all the ends at once so it will take the rest of the week to laminate all these. Once I have more to share I'll post it here.
 
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Awesome, Sonosubs rule! I miss mine but I have an IB now so nothing in the room. If I had to build an enclosure it would be a sonosub again, even sealed.
 

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Discussion Starter · #6 ·
Looking good. If you are foregoing a baseplate, you are going to want to make sure the feet sit very flat/level on the floor and the tube isn’t able to tilt or rock at all.
Yeah, I realized the subs would just be too high and super heavy the more MDF is added. I will be carefully setting up my miter saw to get as straight of cuts as I can. I also thought of attaching some dampeners or pads to the bottoms of the feet. These subs will be on a basement floor with memory foam padding and carpeting which i assume will help make up for any imperfections in my cuts.
 

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Discussion Starter · #8 ·

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"I am eliminating the bottom floor caps and using only 3.5" dowel feet."
wookiegr
Have you considered cutting the centers out of the bottom floor caps to make them lighter, while keeping the tubes more stable than just using the legs..?
 

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Discussion Starter · #11 ·
"I am eliminating the bottom floor caps and using only 3.5" dowel feet."
wookiegr
Have you considered cutting the centers out of the bottom floor caps to make them lighter, while keeping the tubes more stable than just using the legs..?
I have not. However, I used up my MDF. I'll have to see how things go with the plan I have in place.
 

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Discussion Starter · #12 · (Edited)
Ports are glued and finished. Just need sealing and painting. Started on the baffle legs. Setup a clamp on my miter saw to cut them all at exactly 3.5" long. The dowel rod is 2" in diameter. When originally cutting out the rounds I made sure to have a full mark line running through all 4 quadrants so when it came time to center and mark the legs those line would be there. I measured 1" in from the outer edge on the mark lines to create my pilot holes for the legs. I wanted the dowels to be flush with the outer edge of the baffle surface. No particular reason. Once all the pilot holes were made I applied a small amount of wood glue to the dowel to ensure it stays put. I used a 3" construction screw from the underneath surface of the baffle up through to the finished surface into the dowel. I don't recommend screwing from the leg into the baffle. I have 2" adhesive pads coming in the next few days that will go on the bottoms on the legs so bare wood in not in contact with the carpet.

I also mounted the driver in the baffle to mark the drill holes for mounting it. I have t-nuts to install. I started drilling the holes for the speaker terminals. I forgot to take a picture of them but they'll be in the next round of pics. Tonight and tomorrow I hope to seal and paint all four endcaps and very very soon install into the sonotube. My goal is to have these powered up and running before the end of the weekend so I can focus on getting the screen installed before next weekend.
























 
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Discussion Starter · #15 ·
Placing the sub into the baffle I marked the holes with a red marker. I drilled the holes through with a bit roughly the size of the bolt then on the inside areas where the t-nut goes I opened the hole using a bit one size larger to fit it in easily. I did not want to drill a hole any larger than needed. Once the t-nuts are placed I dabbed a small amount of the PX careful not get any in the holes but to simply help secure the t-nut in the plywood. I used a c-clamp to compress them in. Some people use a hammer or get them in just enough then use the bolts screwed in with the driver in place to fully secure them. I glues and c-clamped. As you can see they are fine, fully secured and ready for the driver installation for when the time comes. After these pics were taken I went ahead and painted all the endcaps and am now ready to glue these into the sonotubes this evening.









Glamor shot



There were a lot of holes that had to be cut out. With the massive size of the cylinder when it stands fully erect I expect these holes to take a serious pounding once it's given the proper motivation.
 
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Discussion Starter · #17 ·
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Discussion Starter · #18 ·
Subs are done and in full service. Here are the remaining pics of the process.

Encaps are spray painted and left to sit overnight.






Here are the 2" pads that are stuck to the legs.








Speaker terminals ordered from parts express. I soldered the speaker wire to the ends then heated shrink tubing over the ends to protect them.





Placed them into the pre-drilled holes of the baffle end cap.





Filled the internal holes with silicone to seal it in.





Once the end caps (baffle) are completed it's time to apply adhesive to the inner top of the sonotube. Sometime the tubes get damaged and the edges get dinged or crushed. It's a tricky task to shimmy the endcap in while the tube is all bent up so a second person with a flat head screwdriver or some other tool to help pry the ends open is needed. On the clean ends with no damage the end caps should fit snugly in with minor use of a rubber mallet if you cut the discs accurately.



I installed the top caps with the ports just outside the theater room since the overall ceiling height was larger. Attempting to insert the end caps with a huge 4 foot long 10" diameter erection into the top of a 6 foot tall sonotube requires a lot of space. Once the tops were installed I moved them into the theater room for the remainder of the assembly due to the weight of final sub. It's a lot easier to not have to navigate it around when it's so heavy.



With the top end caps out of the way it's time to flip the subs over to install the baffle end. Again, you apply a generous amount of glue and they go right in with little trouble. Depending on your methods you could run some staples or nails around the perimeter and into the mdf to secure it more but I used Loctite PL 3X adhesive, nothing is going anywhere. I taped the speaker wire to a leg to prevent any wires from getting into the glue as it's installed.





Grab whatever black paint you have laying around and finish the tubes. I opted not to prime and sand the end caps or wrap the tube in a nice fabric because these will be buried behind the acoustic screen and never seen. Saves some time and money.





Drop the subs in! I wired them into a 4ohm load which is common. I forgot to take pictures.

 

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Looking good. I wish it was easier to source Sonotubes here in the UK.
 

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Discussion Starter · #20 ·
These subs are done and installed. No further posting will be made here. All future posts will be in the main Home Theater Build thread on my signature.

 
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