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Discussion Starter #1 (Edited)
Who said big bass does not come in “smaller” packages? :D


THE MINI DEVASTATOR 40"x25.5"x24" FOUND HERE



NOTE: THERE IS A LARGER LFE VERSION FOUND HERE


SAF 184.03/18" PRO MORE FRIENDLY VERSION HERE


The design is a 6th order bandpass non flared horn contributed by @LTD02, a big thanks for his work on this project!

The design found its roots in an outdoor sub project that just so happened to play very nicely with the B&C 21DS115. The tune has been dropped slightly to aid with HT, still very capable at delivering music at high levels. More bracing has been added to endure the added pounding of a 21DS115 or similar sub. This design makes very efficient use of material, similar to a Marty sub in that respect. If you are wondering why so much mid bass, John Wick and for science :)

This is the near-field measurement layered over the top of the model. Driver is a 21DS115-8. A thanks goes out to Dan and John for getting this put together!








Current suitable driver list (Note: an Fs of close to 30Hz and a Qts of .3 or lower appear to be the predominating factors if a driver will work or not)

Alpine:
-SWS-15

B&C:
-21DS115
-21SW115
-21SW152
-18DS115
-18SW115
-18TBW100

Beyma:
-18PWB1000Fe
-18PW1400Fe

Dayton:
-PA460

Lavoce:
-SAN 214.50
-SAN 184.03
-SAF 184.03


Stereo Integrity:
-HST-15


Added bonus for me at least, the sub is nestled safely out of the reach of adventurous toddlers.

Dark gray - Devastator, light gray - ported enclosure
As you can see there are efficiency gains across a wide range 20 - 110Hz, (though I would probably cross at 80Hz to 100Hz) more efficiency in the upper mid bass range than the lower end. As John Madden would say in Madden 96, “That outta clean out the sinuses!”


Simulation based on the 21DS115






Can it be tuned lower?

Chrapladm
"And now that I think of it. Just leave the cabinet the way it is. If you want a lower tune plug a port. 2 ports is about 15.75hz roughly. When just plugging the end of the port that gives an extra 10 Liters roughly also. And because I know someone will ask, a single port is about 11hz tune. Doesnt look very good with the 15SWS.

So I would keep the cabinet the dimensions and just build yourself some small port plugs if you want. This is what I will be doing. No need to change cutlist or any dimensions
."


The enclosure is not all that large relative to a tapered horn design or a lot of other things around here :)





Just give me the darn cut list! Here it is! Do not forget to take a notch out of the front port braces leaving space for excursion. Two full sheets of MDF (97"x49") and five 2”x4”s are all that is required. If using plywood double check the dimensions of your material. MDF can also vary in size, if it is NOT 97x49 it is not fitting on two sheets of material.





















Assembly, we suggest building from the side, then from the front towards the back. Attach the front panel and top. Use lots of glue/loctite, this needs to be airtight.


















Brad suggestion, not scale.
































Attach the bracing assembly all as one unit. A lot of weight or some long screws might come in handy. If you want the hatch to sit flush, take the height of the gasket off of the 2x4s on the upper half of the bracing assembly.





Attach the back panel, add the sub, add the speaker terminal, attach wire and close the hatch. Next, test your neighbor's pain tolerance\structural integrity :)




Amp suggestion: An iNuke6000D/NX6000D will not have a problem driving two, one on each channel. The high pass filter should be set at 18Hz using the high shelf work around solution on the amp's DSP. There is not a preset filter for reducing the two peaks at the moment. The peaks should be around 20Hz and 70Hz. REW and the built in DSP will be able to clean up the peaks.



More detailed information is attached in the at the bottom of the post. This is a horn loaded design, making it airtight is crucial, use lots of glue/loctite.


http://starwars.wikia.com/wiki/Devastator

-John
 

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:D


Make sure you build the hatch hole large enough to fit the driver through.

The cutlist will only work with MDF for anyone looking. You won't get two 24" panels out of plywood.


I'm curious to see a measurement once one of these is up and running. I wonder what if any benefit there would be to angle the panel in front of the driver to make this more similar to the skhorn.
 

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What's going on in the picture with the red circle and the one immediately after it? (Sorry if that's a stupid question.)

Also, what material do you recommend for a gasket to seal up the hatch?
 

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Discussion Starter #9
The red circle is showing brads coming in at an angle to hold the panel in place. You can't come at it flush due to the brace on the other side.



I forgot what the gasket tape suggestion is for the 21DS115, I have a lot left over from the first sub project. I picked it up on Parts Express.
 

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Discussion Starter #11
To speed up assembly I picked up a brad nailer cheap. Brads and Premium Loctite 3X is what I am planning on using for assembly after conversing with John. Drilling and counter sinking takes a lot of time. I did that on my first sub :)
 

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Make sure you build the hatch hole large enough to fit the driver through.

The cutlist will only work with MDF for anyone looking. You won't get two 24" panels out of plywood.


I'm curious to see a measurement once one of these is up and running. I wonder what if any benefit there would be to angle the panel in front of the driver to make this more similar to the skhorn.
with no other changes, reducing throat to about 1/2 the size of the exit has the effect of pushing the efficiency peak up in frequency. i kind of thought that it was good where it was, so i didn't change it. different shapes and lengths have various advantages and disadvantages.
 

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Please add some build pictures when you do :)
And any observations/measurements or impressions after testing when complete, even if only purely subjective.

Excellent design. @LTD02 is mad helpful to those on this forum.:)


"I forgot what the gasket tape suggestion is for the 21DS115, ..."

FWIW, gasket tape can be bought at hardware stores. Ace, Home Depot, etc.
 

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What happens to the tune and efficiency if you extend the port? For example, you could take the port along the bottom to the back wall and then go up the back wall rather than the baffle wall.

Mike
extending the port will lower the tune. this one is around 19hz.
 

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any chance for the hornresp inputs to determine suitability for other drivers?
i think this is a cool use of a 1/4 wave resonator.
 
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