Unique Sealed Sub Box Build
 

I wanted to add a sub to the boat and I needed a project to keep my mind occupied, so embarked on this little project. I bought a JL Audio 13w3v3-4 and a sheet of 3/4" birch plywood. I didn't want to relocate the start battery to the observers storage compartment, so in order to get enough volume behind the speaker, I had to create this uniquely shaped box. Without bracing the volume is 1.86 cu ft. With speaker and bracing the internal volume is 1.496 cu ft. Pretty close to the 1.5 cu ft that JL Audio recommends for the 13w. I used biscuits, wood glue, finish screws and epoxy to glue it together. Surprisingly, all my joints fit flush except for one.

Seriously, that is one heck of a box.

"Clyde built" as we call it - in other words, it will probably outlast your boat!
Not sure what all the various angles and baffles will do to the acoustics, but I am sure it will be better than a free air sub.

Thanks David for your QTC/box size advice in my previous post.

Here's a few shots of the interior which shows how the speaker aligns with the box. It's a very stiff box.

How are going to "water proof" it?

That is the beefiest 13w3 box I have ever see!!!

seriously nice job. A lot of attention to detail to maximize space. The internal bracings are cool too.

Lance - I'm either going to spray it with truck bed liner or urethane auto paint.

http://store.acrytech.com/Speaker-Cabinet-Coatings/


I used this on my speaker box and love it!! Goes on extremely easy!!

I cant wait to see the finished product, you box inspires me...

LanceM

I know Duratex is water resistant, but is it waterproof?

It's not water proof, but it's held up better than my previous boxes that were line x or some type of truck bed liner.

I am also inspired by box 😎

Preach!

what boat is that going in?

Nice Job, now just coat it inside and out with fiberglass

Not trying to hijack your thread, but I kind of did the same thing a few years ago for my Moomba. I liked it so much that when I sold the Moomba, I kept the Sub!

How do you plan on finishing it?


http://i699.photobucket.com/albums/v...ps394e5480.jpg

http://i699.photobucket.com/albums/v...ps25f8491b.jpg

http://i699.photobucket.com/albums/v...ps56bf040a.jpg

02 Sanger DLX

Hey Eric
That's a really cool box and I bet it looks great in the boat. Good work. I'm glad you posted photos. Which driver is that? How does it sound? Where did you install it? What are your thoughts about glassing both the interior and exterior. My understanding is that the resin is not waterproof and my box will be, "sealed", so I'm unclear on the advantages of coating the inside.

I won't be taking my box to the pro-finish level as you did. It will be tucked up under the helm behind some kind of cover and not really visible. My primary concern is waterproofing followed by appearance. My current thoughts are to spray it with some kind of truck bed liner and/or urethane automotive paint. I've been wanting practice spraying auto finishes and this would be a great project for that.

Thanks again for sharing.

Rounded corners and rough edges with a router and belt sander. Applied a coat of epoxy resin, filled the screw holes with resin/filler mixture and re-sanded with 100 grit. Ready for primer.

Also, I attached a photo of the space that it will fit into.

Ken,

Thanks for the props!

The Sub is a 12" JL W6 - Sounds Awesome
I used to have it under the drivers helm on my old '02 Moomba which is now gone (insert sad face)

I originally did mine in a high gloss paint (the red is only for a guide coat) but then decided to go with the marine vinyl cover with the inserts.

Definitely use resin inside and out, then shoot the interior with (rattle can works well) with primer and a gloss. Then finish the exterior. Paint it yourself, if you screw up, sand and shoot again.

On a different backyard outdoor sub project that I did, I used the roll on Acrytech and it worked really well, I still used primer and gloss paint to seal the interior and exterior, then just use the roll on as a textured exterior coating. But I wouldn't use it in a boat, doesn't look finished enough.

Finished!
3 coats of white single stage urethane, speakON connector and speaker installed. Will conduct listening tests tomorrow. Fingers crossed.

That looks great! Hope you're pleased with the sound (something tells me you will be . . . .)

Looks great!

LanceM

That really looks nice! Great job!

Thanks to all for the kind words!
I'm going to fire it up today and do some preliminary box tuning before installing it into the boat.

Very nice job, now just make sure you throw enough of an amp at it, tune it right and get the boat on the water!

What spray rig did you use?

very nice man!

As far as using a Neutrix connection for the wires that go to the box I havent found a Neutrix connecting that will accept large diameter wire. What I use is High Current Battery disconnects
http://www.amazon.com/Battery-Connec...Quick+Connects

Grant - Those are great connectors. I may use the water resistant version on my tower speakers project. Thanks for sharing.

I installed the Neutrik because I like the way it mounts. Also, it's the 4-pole version with both negs (-1,-2) and both pos (+1,+2) tied together. My wire is 14 awg, LTE insulated that is doubled, so it's essentially 11 awg. Including the wiring inside the box the total length to the amp will be under 3 ft. That should easily suffice.

BTW - That's a sweet Wilton vise.

Eric - I used a $15 Harbor Freight HVLP to spray 2 coats of Feather Fill primer and my buddy's Sata copy to spray the white urethane. The paint has a slight orange peel surface and it ran in two places. Since the paint is primarily for water proofing and it won't be seen I'm not going to do anything about it.

Played around with coarse box tuning this week.
I placed the box on the garage floor facing upward towards the ceiling and connected a JL Audio 500/1 amplifier fed by my iPhone function generator app.
I double checked all of the connections and flipped the ON switch in my test set up. First the click of the switch... Then a click of a relay in the amp... Then to my surprise, an enormous 47 Hz rumble started shaking everything in the garage. I lurched for the pause button saving the driver (and the garage) from any damage. I almost pee'd myself. You think I would know better by now, but for some reason I didn't confirm that the volume on the iPhone was muted prior to turning on the amp. This is very important when connecting directly to the amp!
After gathering myself, I set out to testing. I set up a 10 second sweep 20 Hz to 90 Hz on the function generator, checked for air leaks and made note of what I heard. At 20 Hz there was little to no discernible sound, but garage shook like crazy. At 24 Hz an audible tone developed and increased in amplitude until 32 Hz. 33 Hz to 63 Hz seemed pretty even, but there was a huge peak centered on 67 Hz. I didn't measure it, but I would bet it was a 4-6 db peak! It was so big, I rechecked the amp settings and the function generator to make sure that there wasn't some kind of filter/eq affecting the signal. Interestingly, all filters/eq were off. 70 Hz - 90 Hz were pretty flat.
After a short break, the box was filled with about 2 lbs of fiber fill (Stuffing from my daughter's old body pillow) and ran the same sweep as previous test. Much, much better! The response was much smoother and the tone of the bass greatly improved. It sounded more like bass than noise. There was still a peak, but interestingly it moved down to 56 Hz and reduced in amplitude to what sounds like 2-3 db.
Installed the box into the boat today. Looking forward to final in-boat tuning over the next few weeks.

A couple of observations.
With a 'Q' a lot higher than .7 you can to get a small bump in the response, which equals a higher perceived output, which is welcomed in the context of an open boat.
What is maximum flat my not sound the best. But a large peak certainly isn't what you are after.
With all the internal dividers, and especially with the ones running parallel to the front baffle plus the box appendages, the woofer may not recognize the entire box displacement. And that would raise the 'Q' and thus introduce a bit of a hump in the response. So the internal damping material is a way to lower the 'Q' and flatten the response. The correct move.
I would welcome a small peak between 50 to 60 Hz. That's low bass in respect to music content.
You need a small crown in the response of an acoustic suspension box. Tuning the enclosure too large will leave you with a rather 'dead' sounding woofer.
Ultimately your ear is the best instrument if you've got some good test material = meaning real bass.