Help the Ijit -- Build a "Bose Cannon" knockoff - Page 11 - diyAudio
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Old 13th February 2014, 10:42 PM   #101
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Some subwoofer trivia:

1) Danley used to make transmission lines out of sonotubes. This was quite a while ago, but was mentioned on the bass list.

2) My 'Tapped Horn for Dummies' didn't work the way it was supposed to.
Click the image to open in full size.
Click the image to open in full size.
The main problem was that the Sonotube had an eight foot long divider, and it was almost impossible to get a good seal. The lack of a good seal basically screws up the quarter wave resonance.

I tried all kinds of things. Caulk, polyurethane glue, screws. Nothing could fix it. All of this is exacerbated by the wax coating on the inside of the sonotube. (Nothing sticks to it!)

So I ended up throwing it away.

It's too bad, because it looked good on paper.

Click the image to open in full size.
Click the image to open in full size.
Click the image to open in full size.

^^^ This sonotube sub worked a lot better. Basically the horn is folded inside of the sonotube. This has some advantages over the Bose Bass Cannon:

1) The Bose Bass Cannon basically requires no taper. And it's hard to get flat response without taper.
2) The big advantage over the "Tapped Horn For Dummies" is that the sonotube is shallow enough that you can seal it properly. The former sub was 8' long, and due to the extreme length, there was just no way of sealing it, short of chopping it into pieces.
3) The latter sub allows for a taper; basically you can have any taper you want, by resizing the pieces of the pie.
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Old 14th February 2014, 01:16 AM   #102
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Default Turn ready-to-assemble furniture into a monster TH?

I recall from decades ago, an article (probably in Audio) about tape recording heads and using a comb frequency as calibration test signal. "The only thing wrong with this theory is it doesn't work." Was the punch line.

I don't want to build my TH with a Tapir. According to Wikipedia, I would need a very large diameter tube (> 3 ft) for the Tapir to fit inside. I will use more conventional materials to stuff my tube.

I'd still like to pursue the Carpentry-Free(TM) options.

Another idea, surely not original: for the woodshop-wary, how about repurposing existing mass-produced items for a speaker cabinet? If people can make small speakers of out salad bowls, how about a TH monster out of a wardrobe? I've been an Ikea fan for decades (I was the 45" oscillating model, but discontinued...ok, bad joke)..and we conveniently have one here in Tamper, FL

Here is a possible victim:
PAX Wardrobe with 1 door - Ballstad white, white, 19 5/8x23 1/2x93 1/8 " - IKEA

$130 + tax buys me (perhaps) a big box that I can wreak mayhem upon with my caulk gun and jigsaw. I realize this is kind of ("Kind of"?) designing a TH bass-ackwards, so to speak[er], but it'd be fun! I mean, hell, people here are building all kinds of things out of coroplast for Pete's sake. Ikea's low-end stuff is a little bit upgrade from that. This might just work...?
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Last edited by Soldermizer; 14th February 2014 at 01:19 AM.
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Old 14th February 2014, 02:57 AM   #103
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Did some quick calcs for that Ikea wardrobe. Volume is > 700 Liters. By long dimension, 1/4 wave is about 36 Hz so 1/2 wave would be 18 Hz. Hmmmm......
The Ikea wardrobe is very flimsy and appears to not have a back, or just cardboard. So...

The morbid (?) idea occurs: how about a plain coffin? Nope, too expensive ($500 up + shipping). Even Wal-mart sells them! Would make an excellent conversation piece for people who listen to "Goth Metal" or the Grateful Dead.

There must be some way to repurpose a sturdy wooden box. I am willing to compromise my no carpentry criteria somewhat. How about this: could a TH be built from two (say) 4x8 sides of plywood with sides of precut lumber? I want to make a monster sub, and that would be a good start.

I have not dismissed the option of using pipe (PVC or flexible) but judging from my other PVC projects (smaller) it would cost much more.

Another option for using (mostly) Sonotube would be to add a 2nd one for the "return" sub, thus having two parallel long tubes. I don't see any advantage over my earlier idea (nested tubes), in fact it would require boxes at each end.

I will puzzle this out for a while longer..see what if any suggestions come in from you guys. Despite the recent brain-storming ( = "brain fart") I still lean to the nested Sonotube as being the most workable.
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Old 14th February 2014, 04:29 AM   #104
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Do I have to hit ya upside the head with a proper woofer donut for that beast?

Ya you're in arms reach or rather a donut toss

When i built sonotube subs way way back would use naptha to clean the wax away from critical areas. Much better grip. Have sakrete tubes now, unwaxed. Used only Titebond to secure the divider, along with two 2x4x48" boards straddling the divider held by four strap clamps for 24 hours. Have a 54" carbon fiber pultruded tube with a 1" foam brush ty wrapped to the end to get all the way down the line when sealing it up while clamped up.

Soldermizer do you really require it internal, can be powered from one end if all you are looking for is deep bass and cross before first peak. Have seen ones done like this using 4/ 12" in a cube box with the tube out the top.

Patrick, have thought of a circular TL design where the port encircles the woofer like Jamo did back in the '80's. That would be slick, but problem finding proper diameter tubes to pull off.

Ok had another epiphany, gotta write it down before I fart...
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Old 14th February 2014, 09:44 PM   #105
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Default Build the enclosure and then worry about the driver...maybe...

Greebster, good points. I am actually quite happy with my basic Sonotube + driver on the end. I just want to experiment (or more likely, wait until this urge passes...). Like my Karlson "research" weeks ago, which thank goodness I gave up on, I have been reading up on the tapped horn.

I'm still torn between going the easy Sonotube route...not a taper to be found, but at the low frequencies we are working with, does flare really matter? I am skeptical (but equally unimformed!). I mean, a 12" diameter tube: we are talking about a 1/4 wave resonance of 2K Hz, a bit outside the passband.

I'm still angling for Carpentry-Free[TM] methods to make a huge TH. Latest idea is why not use a 4x8' (2x8' maybe) sheet of plywood for the internal mounting of the speaker and the waveguide?

Pro: you could mount the biggest damned driver you want to

And similar sized for top and bottom. Sides would be smaller and apparently might require cutting (darn!) to size.

I'm slowly working my way thorugh the "Collaborative Tapped Horn" thread. Still, I want to "fiddle about" as Uncle Ernie said and who needs those stinking sims??? Just trying to minimize the amount of cutting required!

I do have two guinea pigs so holes can be created, just slowly and in unpredictable locations (DSL cord is a favorite!). Cat makes a good rasping tool (he's been working on a night table leg for years, amazingly still standing) whilst the guinea pig is good for boring holes in wood. Also produces fertilizer pellets
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Last edited by Soldermizer; 14th February 2014 at 09:53 PM.
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Old 15th February 2014, 01:41 AM   #106
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Default I started a thread specifically for the Tapped Horn

Help the Ijit -- build his 1st Tapped Horn
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Old 15th February 2014, 03:27 AM   #107
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You really really have to use Gorrila Tape only once to realise you might actually be able to build an airplane with it. Cant imagine a plate taped to the end of a tube leaving home for half a decade. Try.
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Old 19th February 2014, 04:58 PM   #108
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Default Yes, but will it fit in the living room?

Here is an idea for my next straight pipe, if I can find a large enough driver
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Old 19th February 2014, 08:17 PM   #109
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Quote:
Originally Posted by Soldermizer View Post
Here is an idea for my next straight pipe, if I can find a large enough driver
No need for a single driver with that beast, load it up with a bunch of 18's and invite the neighbor kids over for a thrill
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