21" Folded Horn Subwoofer

So, just for the fun of it, I decided to take the most massive semi-budget driver I could find, and make a fun project out of it. And I came up with this monstrosity. Inspired by the design of the Tuba HT and old horn subwoofers, I packed a 21" sub into a folded horn, outer dimensions measuring 32" (front) by 39" (length) by 42" (height). 10" opening at the mouth. Just under 4.8 Cu Ft sealed box for the woofer. horn starts at 3" by 30.5" and ends at 10" by 30.5". Powered by a Yung plate amp, the 500Watt SD500-6, with the 6db boost nicely complementing the 25hz drop in the driver response. The driver was the, surprisingly much better than would think, the Pyle PDW-21250. Though the specs are definitely exaggerated, its definitely pretty nice at the price point here. I used 3/4" MDF to build the enclosure, and some spare 2x4's I had laying around for the supports. I used TiteBond wood glue and 16 gauge finishing nails for assembly. Weighs somewhere in the range of 200-300lbs. Sealed all joints with GE 100% Silicone. Haven't turned it up beyond notch 1 of 5 so far, and was incredibly loud and sounded much nicer than I expected. Ill look into getting some equipment to measure a rough frequency chart, check loudness, etc. Ill also add some pictures after this post. Hope you guys find this fun if nothing else!:headshot::spin:
 
First load of pics:
 

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Some more:
 

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This is how far I've gotten. I am going to finish off with either bedlinering or carpeting the outside of it.


For reference, the guy standing next to it is over 6'2" tall,
 

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What did you use to sim the horn before building it? If HornResp, what settings did you use?

I ran a quick sim as an offset driver horn, 120L rear chamber, S1=S2=900, S3=1900, L12=25, L23=200. Useful response down to 40Hz, and quite a lot of output. I'm not sure if it wins over a TH or similar, but looks like a way of getting a lot out of a cheap driver.

Chris
 
Very cool build. Way beyond the simple sealed boxes we were doing in the 90's, or in my teens when I stuck some sealed 12" woofer boxes in an empty closet at back of bedroom, facing into an aquarium I had set on the side to mimic a car trunk-effect as subs fired into aquarium, then bounced back into the room, and the high-tech slider doors I'd leave roughly 4" open to control the output spread :D

Did you add any type of of poly fill in the sealed section? Sealed speaker boxes always seemed to benefit greatly from it. Gave it a bigger presence and removed any hollow sounds.

Regardless, cool build. Now you need to scavenge some roller casters off an office chair and stick them on the bottom to move that beast!
 
Wow!

That's a lot of work there!

Nice use of mitre joints on your curves. Must have taken a bit of head scratching.

I guestimate about 130 inches of path length. So roughly eleven feet. You should get some decent amplification of the drivers output in use. Not optimized but it will sound pretty loud.

There is a free program available that would enable you to design an optimised horn for this driver if you are interested.

A few gents have either mentioned it or quoted simulation parameters from it.

If you find this to be worth while when you have listened to it going the extra mile will be worth it.

Hope that 6 foot 2 inch friend will help you lift it. There is over 2 sheets of MDF in there. 110 lbs a sheet if I remember correctly at 3/4 inch thickness.