JBL B380 Clones

[christo]

Here some picture of the JBL B380 Clones I recently finished. It was based on information contained in the 1983 “New Lows in Home-Built Subwoofers” article.

URL: http://www.lansingheritage.org/html/.../1983-subs.htm

I was using the B380 build as a test run (carpentry and finishing techniques) for building a 4344 so some of the things I did may seem overboard for a subwoofer box.

I used ¾ MDF for all the panels with a Baltic birch bracing 3 x 1.25 inches.

Speakers are 2235s newly re-coned which when you add up the cost of acquiring and re-coning sure makes for a pricy pair of speakers. And add two more for the 4344s…nothing cheap about this vintage stuff at all.

[christo]

I started out with white birch veneer which I stained black for the baffle.

[christo]

Boxes are veneered and I’m now chamfering the edge at 30 degrees. Scrap wood is clamped at each end to allow the router bit guide wheel to roll straight off the edge of the box. Once each side are has been chamfered you can’t do this on the top or bottom you have to use a straight edged to guide the router. Cause if you don’t the router guide wheel would follow the chamfered edge and a grown man will cry.

[highcut28]

Excellent thread, beautiful build.
I have assembled 077, LE85/H92, 2235H drivers and i have built Mr Pass s XOs .
My cabs were built a few yrs ago. Not very well i dont think.
I am looking to build better cabs. Not sure if I should build these H380 clones or the 4333 cabs.
i have sent you a friend request Christo to discuss some specifics. Hope thats ok.
Ta very much

[christo]

The bracing I locked together by leaving a 3” gap for the next brace to slip in to.
One of the most usefully tools I picked up for the project was the some metal 90 degree corner braces which allowed for the dry fitting prior to gluing. Not cheap but indispensable.

[christo]

Now the box is done and ready for finishing.

[christo]

I used a table based router to rabbit all the edges and down the center of all panels where the internal bracing will be installed.

I also did all the 4344 panels at the same time; it was a long day at the router table.

[christo]

I used four coats of Watco Danish Oil - “Natural” with one coat wet sanded. I then covered this with 3 coats of clear Varathane with a final coat of statin. The Varathane was water based, first time I had used the water based version - nice stuff.

The boxes are tuned to 25.6 Hz.

I’m using the Dayton SA1000 subwoofer amplifier which was mentioned in this thread post 42.
http://www.audioheritage.org/vbulletin/showthread.php?32060-JBL-2245-10-or-12cft/page3

It is inexpensive, the amplifier section is adequate, and with all the controls it makes it easy to blend in to the room and other speakers.

[gferrell]

Nice job! I wish I knew how to make that kind of woodworking.

[Lee in Montreal]

I love it. You have great skillz my friend. Tons of very nice building details.

[Audiobeer]

That is some sound cabinetry Brother! That looks beautiful. Can't wait to see you respond as to how they sound!

[christo]

The box is now together with the internal panel bracing installed. With each piece of bracing locking together and recessed the box very tight.

[christo]

What I’m doing here is drilling the dowel holes for the cross braces that runs between the baffle the back panel. Set the panels face down together, place the straight edge at the correct height, measure equal distance in from each edge and drill the holes using the Dowelmax jig. This tool makes tricky stuff a breeze I highly recommend this tool. http://www.dowelmax.com/

[christo]

And in the next picture everything lines up, good thing as the front baffle had already been veneered, strained and had the first layers lacquer applied – no room for error.

[christo]

This shows the dowel pins installed with the cross brace and a more complex use of dowels for the grill frame corners.