Monster Sonosub build

[john trials]

Recent luck and generosity got me a free Ascendent Audio Avalanche 18" subwoofer driver. Not only that, but from another very generous person, I got an eight foot section of 24" diameter sonotube. I had some 3/4" plywood under my porch collecting dust for the past 10 years that will serve as the end caps. I bought an 8" diameter sonotube for the port (not quite sure of the tuning yet, so I'll start long and see what happens). I've got a whole $6.02 invested in this so far (not counting the gas to drive all over CT and MA to get the driver and sonotube...but I get about 40 mpg, so less than $20 for gas...and time is free, right!?!?). I had to make an extension for my router's circle jig, and then the endplates could be made.

So the Monster Sonosub is in the works. I just couldn't pass up the opportunity to go a little overboard. Luckily my wife lets me do stupid stuff sometimes. We're both in agreement that this is a little bit much, but it should be interesting.

Related, prebuild threads: http://techtalk.parts-express.com/sh...d.php?t=217719

http://techtalk.parts-express.com/showthread.php?t=217745

Hopefully sometime over the Memorial Day weekend, I'll get a chance to assemble the parts and test this beast. If all goes well, I will make it look nice with some fabric covering for the sonotube, and some MDF endcap covers. A few years ago, I picked up a nice piece of 3/4" BB plywood that was being thrown out. I'll cut a nice baseplate and legs out of the BB.

[joeybutts]

Re: Monster Sonosub build

I need to find some generous people like that!:D

Should be a killer sub! Can't wait to see some results!

[gorbs]

Re: Monster Sonosub build

you could turn that thing loose in the Gulf and blast the oil back out to sea that has come to shore lol. that is huge. !!

[john trials]

Re: Monster Sonosub build

you could turn that thing loose in the Gulf and blast the oil back out to sea that has come to shore lol. that is huge. !!

Before I went to pick up the sonotube, I measured the corner of the room where I plan on placing this, and I measured my car to make sure the sonotube would fit (I was going on a 3 hour round-trip to get it, so I wanted to make sure it would fit). I figured, 24" isn't too big, right?

When I finally saw the sonotube, I was AMAZED at how large it was. 24" with a tape measure isn't big. But take 24" into 2 dimensions, then make that over 7' long...WOW. It is big. I had to cut about 10" off it to get it into my car. The resonance from the tube inside the car was interesting.

[Evan O]

Re: Monster Sonosub build

Before I went to pick up the sonotube, I measured the corner of the room where I plan on placing this, and I measured my car to make sure the sonotube would fit (I was going on a 3 hour round-trip to get it, so I wanted to make sure it would fit). I figured, 24" isn't too big, right?

When I finally saw the sonotube, I was AMAZED at how large it was. 24" with a tape measure isn't big. But take 24" into 2 dimensions, then make that over 7' long...WOW. It is big. I had to cut about 10" off it to get it into my car. The resonance from the tube inside the car was interesting.

If measly 3-ways with a 12" are considered monkey coffins on this board, then what name can be given to something that larger.:eek:

I think we need a pic of you inside that tube to fully illustrate the size. ;)

[exojam]

Re: Monster Sonosub build

John,

Looking forward to see how this goes. I forgot, but when we spoke did you say how you would “cover” the tube itself? Below is how I had finished mine off when I had it. As you can see I just used some left over carpet I had so it somewhat matched the room.

James

[john trials]

Re: Monster Sonosub build

John,

Looking forward to see how this goes. I forgot, but when we spoke did you say how you would “cover” the tube itself? Below is how I had finished mine off when I had it. As you can see I just used some left over carpet I had so it somewhat matched the room.

James

James (exojam) is the generous sonotube donor. That looks like a great cat-scratching post!

I'm not sure how I'm going to cover it. I don't have anything laying around the house, so I'm actually going to have to spend money to get this to look good. I read in one sonosub thread that someone used a bed sheet, which I think is a good idea, if it's thick enough to be opaque. I'll need something that is approx 71" x 75", and most fabric doesn't come that wide.

I'm planning on trying it without any lining this weekend, but from what I've read, I'm going to need to line the inner walls (probably with a open-cell foam mattress pad or something similar. I don't want to deal with the huge amount of fiberglass that would be needed to cover the inside of this thing).

[badman]

Re: Monster Sonosub build

James (exojam) is the generous sonotube donor. That looks like a great cat-scratching post!

I'm not sure how I'm going to cover it. I don't have anything laying around the house, so I'm actually going to have to spend money to get this to look good. I read in one sonosub thread that someone used a bed sheet, which I think is a good idea, if it's thick enough to be opaque. I'll need something that is approx 71" x 75", and most fabric doesn't come that wide.

I'm planning on trying it without any lining this weekend, but from what I've read, I'm going to need to line the inner walls (probably with a open-cell foam mattress pad or something similar. I don't want to deal with the huge amount of fiberglass that would be needed to cover the inside of this thing).

Check out "Ultratouch" cotton insulation. Effectively an easy-to-handle fiberglass for your app. You'll want to use speaker grille cloth and some sort of fasteners to lock it down as it'll shake loose (as will any non-coherent material) when that sub is put to use. None of it will make a lot of difference at bass freqs. If it were me I'd probably get my tuning figured out, slightly higher Q than final, and wrap the inner 8" duct to entirely fill the gap to the outer. This will kill top-bottom modes which are the major concern for your app.

[WWWJD]

Re: Monster Sonosub build

If measly 3-ways with a 12" are considered monkey coffins on this board, then what name can be given to something that larger.:eek:

Caisson-o-sub!!

[Wolf]

Re: Monster Sonosub build

One concern- Can you downfire that 18"???? I would be thinking it has too much Mms to be optimal.
Maybe you could make an added baffle like I did:



Possibly use the cutoff 10" section to adapt a baffle.
Later,
Wolf

[john trials]

Re: Monster Sonosub build

One concern- Can you downfire that 18"???? I would be thinking it has too much Mms to be optimal.
Maybe you could make an added baffle like I did:


Possibly use the cutoff 10" section to adapt a baffle.
Later,
Wolf

I've seen a few sonotube build threads with this driver at HTGuide and AVSforum. They've run them downfiring. That doesn't mean downfiring it is right, but I'm going to do it anyway.

I'm not being too serious/technical with this build (although I did try WinISD for the first time!). I mainly want to have fun, and learn about subs (and room gain) in the process. Making it downfiring in a sonotube is about as simple as it can be. This is going to be used exclusively for movies. I just want some BOOOM!

This past winter, I made a 'high quality' sub...sealed RSS315HF...I wanted to make that downfiring for aesthetic reasons, but I eventually made it side-firing, because I wanted that sub to be as good as it could be.

This driver has been sitting unused for about 4-5 years, probably in the upward facing position. Facing it downward may balance the sag it has gotten over the years.:D

[robert]

Re: Monster Sonosub build

On bracing - shouldn't need any radial bracing, but may need some top-bottom. When I built my tube subs, I ran 3 2" dowels 120 degrees apart from top to bottom plate. With gorilla glue and 3" drywall screws, it 'pulled' the ends together through the tube.
You'd need some serious lengthy dowels, though :eek:

Cheers / Robert

[philiparcario]

Re: Monster Sonosub build

he can use two 2 by fours. with a few cross pieces of mdf the mdf would hold the inner port still. worse case is it may vibrate. he may need triple thick end caps. 2.25 inches. it should be a beast. does anyone have a link to el pipe o a huge sonotube build in speaker builder 10 years ago

[lennon_68]

Re: Monster Sonosub build

Man, this is gonna' be one heck of a "budget" sub! :D

Regarding bracing/lining there's a great thread from a while back at AVSForum where a member took an afternoon to test the effects of adding stuffing around the port, the results were quite impressive. Without anything there is a large null/peak around 92hz (the sonotube is about 1/2 wavelength of 92hz). Simply adding pillows around the port completely removed it. The sonotube was not braced but did not show any panel resonances. Based on the measurements in the link below I would skip the bracing (that's if it was me - it won't hurt to do some bracing) but definitely add stuffing around the port:

http://www.avsforum.com/avs-vb/showthread.php?t=1141956

[john trials]

Re: Monster Sonosub build

Thanks (everyone) for all of the advice. I probably will need a bit of bracing, as part of the sonotube is delaminated due to moisture. It's a little soft in one area.

That link with the pillows for stuffing was interesting. Good info. I will eventually get something to line the insides (foam mattress pad and pillows for stuffing, and a black bed sheet to cover the outside...seems like I need a trip to a bedding store).

I'm going to try it this weekend with no stuffing or bracing (because I haven't gotten that far yet...I know I will have to add both, I just want to play with it and see how much bracing and stuffing are needed). My first test probably won't sound too good. I plan on just press fitting everything together (maybe some screws to keep things in place). I'm not ready for glue yet. I just want to hear what the explosions in "The Incredibles" sound like with this sonosub for now.