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Mal 21 Sealed Sonotube Build

3953 Views 28 Replies 6 Participants Last post by  kryptonitewhite
This driver is from the closeout sale. I have run it for a few days with tones and music and so far it has held up.

This stage of the build is a budget build. I'm not convinced 100% that the driver is defect-free, but I am hopeful. More importantly, I am in the process of getting a new job and will be moving my family across the country. This build is just to get it into place and working. When I move I will most likely rebuild it and place it into a dedicated HT room.

  • 8.3 cubic feet
  • 24" diameter Sonotube
  • 35.5" length tube
  • 1.5" thick baffles top and bottom (Doubled up 3/4" Baltic Birch)
  • 5 wally world polyester pillows (standard size)
  • 1 polyurethane foam pad for lining walls

For now it will be placed right in the corner behind my couch. That section of my couch curves and has been an open area begging for a sub for a while now. I will have it fire upwards just to show it off. I might make a grill for it as well.

My current setup:

(I know it is light years behind what most of you have, but I will get it into better shape over the next couple years.)
  • Panasonic AE3000 on a cheapie 92" 1.6 gray fixed w/velvet 12' throw 15' viewing distance
  • PS3 as source
  • Sony STR-DA4300ES
  • LR mains = Cerwin Vega RE38's (OLD yes, but still sound good, relatively speaking. I had no sub prior, but as these are 15's, they handled the LFE ok. I will most likely keep them playing FR and hope I have no phase issues mixing with the sub. These will still play louder than I can take, so they will keep up with the sub.)
  • SR,SL,CC = These are some sony's I got at best buy. (they will be replaced eventually)

Need to buy:
  • Amp for the sub - Either Peavey IPR 3000 (cheap now) or one of the Lab clones (expensive now, but will be useful for future HT).
  • MiniDSP

My question:

Is there any type of bracing needed for a sealed sonotube? Any dowels across the diameter in a few places? Or a few pieces running up the length?



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Here is the temporary enclosure. It hit 100db at 1m on the rat shack meter @20hz and the receiver was at -31. Not too bad for a 1.9ft3 plastic tub with two pillows stuffed in it, and a driver just sitting on a couple microfiber towels to seal it. Corner loading FTW

should be finished with the real enclosure tomorrow. Just waiting for the glue to set on the rings.



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Almost done. Being patient and letting PL cure overnight.

All that's left is to add 2 cross braces and drop the driver in.



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So it is effectively done for now. It digs pretty deep. I'll get some numbers when I have some alone time with it.

If it holds up, I will add WAF to it.



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looks like you're getting some enjoyment out of your $25 subwoofer, I'm still upset that I checked this site a day late.
kick ass! Hope your rebuild after the move is another sono but floor to ceiling for more airspace and a port running full length for an 8Hz tuning :p
I don't have a time for a full update. I'll just leave this here.

Its working great so far. the deep bass is soooo effortless.

Rat shack meter showed 120 at listening position during a Pink Floyd song.

I need a miniDSP to get some EQ on it. I might need to cut it down somewhere around 35. I don't have a setup to do sweeps yet, but I'll do some manual tone tests to see how it looks.

I know it looks a bit crude since its not covered, but honestly I really want to know this thing is good before spending more on it. I will add a flush mount top plate later as well.

I also know that it is amp limited at the moment, but even with the 320 watts I'm throwing at it, it plays loud. I watched a bit of Iron Man 2 today and both my brother and I thought it may be too much lol. When he jumped out of the cargo plane and hit the thrusters it was my first "OH ****" moment with the sub.
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Nice build. I hope those drivers hold up. If they do you got an amazing amount of displacement for the money. I like dual opposed sonotube. It doesn't get much easier or stronger. I'm sure Bossobass is smiling.
Glad to hear its working out well for you
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Originally Posted by kryptonitewhite /forum/post/0

Glad to hear its working out well for you

Thanks kw,

I watched my first full movie with it on Friday night. I streamed "Rampage" from Netflix. The opening scene has some really good ULF. I'm not as good as you at calling out the frequency, but if I had to guess it was 8 or 9hz. It's amazing what it add to the "feel" of a scene.

I'm loving it so far.

I was listening to music today thinking "I remember this tool song having way more bass".

"Hey, why isnt the sub louder right now" as u walk closer. "WTF, the sub isnt moving"

I look over at the temporary amp I have setup and.......PROTECTION LIGHT. ????? checked all the wiring, rebooted everything. still nothing.

The light goes off when I pull the RCA line from the receiver. I plugged in my ihpone to test and it works fine, the light goes off and the amp will drive the sub. When I put the LFE RCA back into the amp, the protection light goes right on.

This setup has played fine for days, but now does not work with any changes made.

There was a slight hum in the sub from a ground issue (very slight, I was the only person that could hear it). Could a ground loop issue kill the amp. wait...is my receiver hosed???DOH time to break out the scope.
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Hook up the sub amp to one of your normal speakers to rule out the sub as the problem?
I reread what I put and I wasn't too clear about it LOL

I used my iphone and plugged the headphone out with one of the 3.5mm to stereo RCA cable into the amp. that setup still works fine and the sub played just as expected. no protection light at all.

the protection only turns on when the receiver is plugged into the amp, but it had played for days without an issue so...I dunno?

Ground loop issue.

Ran a wire from the signal ground post on the receiver to a screw point on the amp.

I'm not sure why is became unhappy today, but whatever.

This just gives me more time on the peavey IPR + DSP vs inukeDSP choice.
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man youre stressin me out. so it still works, all is well at this point?
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KW I know you like vids, I'll see if I can get an excursion vid up today. That might calm you down a bit LOL

How would you like a 21" matching passive radiator for the other end of your sonotube?


Originally Posted by MoFinWiley /forum/post/20854786

KW I know you like vids, I'll see if I can get an excursion vid up today. That might calm you down a bit LOL

That would be great, it's just a roller coaster of it works, it doesnt, oh wait, it does!

Originally Posted by Creative Sound /forum/post/20854986


How would you like a 21" matching passive radiator for the other end of your sonotube?


Hi Bob! How about a 21" SDX21?
You could charge $1000 each and I bet they'd sell!
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