First Build - A Single JBL 804 16" AutoTuba

[bassmonster]

You've got me thinking now...fiberglass coated cardboard + random off-spec driver like a recycled computer sub (I just happen to have one sitting in my room waiting for a better box to drop in)= cheap, LIGHTWEIGHT, horn-loaded sub for pennies on the dollar! Bill probably wouldn't want you to advertise it as a BFM sub because its sound is probably a disgrace to a real, quality wooden AT, but it would still be a cool office toy that you can build in two days. This is a good idea.

[sine143]

use the blue or pink foam from big box stores like lowes or hd. you can get it in 1/4 or 5/8s basically. very easy to epoxy/fiberglass. as soon as you start messing with fiberglass stuff gets expensiveeee though.

[Harley]

You've got me thinking now...:

You haven't been hanging around with Welshmen by any chance?

[bassmonster]

You haven't been hanging around with Welshmen by any chance?

Oh no, the disease is spreading!

[67baja]

So how would you 'glass the last side on? That is the question I have. I'm considering building a sub (TT? AT?) out of foam and fiberglass, but not sure how to attach the last side properly. Also, glassing all the joints of the first fold of the horn would not be easy or fun, but doable. You would want to make sure the glass fibers are well stuck down without large bubbles so it doesn't buzz with the bass.

[sine143]

So how would you 'glass the last side on? That is the question I have. I'm considering building a sub (TT? AT?) out of foam and fiberglass, but not sure how to attach the last side properly. Also, glassing all the joints of the first fold of the horn would not be easy or fun, but doable. You would want to make sure the glass fibers are well stuck down without large bubbles so it doesn't buzz with the bass.

an omnitop was hard enough. i wouldnt go any farther than a t18/AT out of glass board. I think the easiest way to do it would be to cut all your panels out of foam, including angles, a bit shy, then build up fiber glass all the way around (including angles). after you have all your panels done you can form the driver chamber, make sure its sound, then attach that to side panel 1. easiest method for side panel one would be have a non recessed driver access chamber, that would be mounted to tee nuts that have been adhered to a 1/4 ply backing plate on the inside of the combosite board. Then you can go ahead and attatch the rest of the boards, and install a 1 piece brace (that would have to be painstakingly measured and covered with fiberglass, to ensure it fits inside all the panels, and can be attatched. the last side is still a pain though, but you can use really long staples to hold it in place. obviously, you would use about 3x as much epoxy in this process than necessary, which will drive the weight up (and price) but ensure it is airtight and functional.

[njolliffe]

Hello again,

Good news, haven't been banned from the forum

So the second set of T-nut's I ordered finally arrived last week and I have been cracking on with the build. The first lot I ordered on the 25th arrived today Wouldn't really call that first class.
So I haven't really come across any major problems so far, the biggest muck up was cutting brace 4/6 too small but that's no biggy.
Overall its coming together quite nicely and I'm pretty pleased with the build so far.

Unfortunately I haven't taken that many pics but here are a few...

Breaking in the driver. Hanging is a great idea

Hanging the speaker is great, keeps the noise and vibrations to a minimum during burn in.

This is the typical amount of squeeze out I'm getting, I assume this is OK/a sign of a good seal?

Also I was reading that some members were having trouble getting a good seal from the JBL to the baffle due to the hard rubber surround on the woofer.
I decided to make a gasket as shown below.
I was wondering what you guys thought of this? I recon it could work but equally it may just 'squash' out the way when I crank up the bolts.

I have also attached panels 7 and 8 but I don't have any photos yet.

Hoping to fit 9 tomorrow and then should start work on the flange access cover as I'm planning to do this before attaching the second side.
With a bit of luck should be on track to test it some time next week

[bassmonster]

Nice. The gasket looks good. Squeezeout is your friend. He is telling you "no leaks here".

[Ryan A]

The JBL gasket is fine by itself in my builds...its rubber gasket can compress about 1/4" - 1/2" when tightening the bolts.

[Tom Smit]

BOWLINE!

[67baja]

BOWLINE!

Holy crap - it IS. good eye

[Grant Bunter]

SWMBO just said "it's not a bowline, it's a rabbit out of the burrow, around the tree and down the burrow again."

Nice build so far!

[LelandCrooks]

Man I had trouble teaching that knot when I was a scoutmaster years ago.

[bassmonster]

The bowline was my nemesis, my favorite was the two half hitches. Ever tried a sheep-shank knot? Release pressure and it all falls apart.

[sine143]

Man I had trouble teaching that knot when I was a scoutmaster years ago.

honestly, the one handed method for tying the knot around yourself is the easiest.
http://www.youtube.com/watch?v=H85cMlvwwXA[/youtube]