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/jbl/reference/technical/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]

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]

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]

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.

[christo]

Here are the stands built out of Baltic birch and using the Dowelmax jig to drill dowel holes on the 45 degree face of each piece. Getting these pieces to close up once the glue was applied a nightmare as I could not close the gap with pipe clamps I had to use a 5 pound mallet to gently hammer them together.

[christo]

Another use for the 90 degree metal corner braces, keeping the stands square while the glue dries.

[christo]

Here are the stands with the recessed holes drilled for the bolts used to attach the stands to the box. Burned my drill out using a large forstner bit doing this, That Baltic birch is ridiculously hard when going through the side of the laminated layers.

[christo]

Back panel and fiberglass installed now time to mount the baffle and cross brace.

[gasfan]

Excellent! More inspiration to get my ass in gear. I don't know what I'm waiting for. I have everything I need to completely build my 4345s. I was going to have the cabs built decided I'll probably end up regretting that so here I am. Beautiful speakers btw.

[christo]

I used a long threaded rod to pull the back panel and baffle together. Since I was the designer I made sure the Speakon connector hole and port lineup to allow me to do this.

Lesson learned here - I used way too many dowels to attach the baffle.

[christo]

And now I had to cut the dowels off with a one-sided saw.

[christo]

The walnut trim is now attached and trimmed flush with the panels ready for the veneer.

[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.

[christo]

Now the box is done and ready for finishing.

[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:// (http://www.audioheritage.org/vbulletin/showthread.php?32060-JBL-2245-10-or-12cft/page3)[/URL][URL="http://www.audioheritage.org/vbulletin/showthread.php?32060-JBL-2245-10-or-12cft/page3"]www.audioheritage.org/vbulletin/showthread.php?32060-JBL-2245-10-or-12cft/page3 (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!

[Mostlydiy]

Beautiful!

[christo]

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

Thanks Audiobeer

The sub-woofers sound great I’m very happy with them. I’ve got them doing double duty. I use them my 4344s but more so with my K2 99s. I find the 4344 doesn’t need much help on the bottom end and for critical listening I turn the subs off. With the K2s they help with the last bottom octave in medium to low listening levels (mind you medium is loud according to my wife) but if I raise the volume I shut them off as from a speaker efficiency point of view they struggle to keep up with the 1500AL-1s and I don’t want to blow the 2235s up, fixing these things now a days is expensive. One has to be careful with the Dayton SA1000 as it can deliver 950 watts per channel at 4 ohms.

[pmakres1]

Thanks Audiobeer

The sub-woofers sound great I’m very happy with them. I’ve got them doing double duty. I use them my 4344s but more so with my K2 99s. I find the 4344 doesn’t need much help on the bottom end and for critical listening I turn the subs off. With the K2s they help with the last bottom octave in medium to low listening levels (mind you medium is loud according to my wife) but if I raise the volume I shut them off as from a speaker efficiency point of view they struggle to keep up with the 1500AL-1s and I don’t want to blow the 2235s up, fixing these things now a days is expensive. One has to be careful with the Dayton SA1000 as it can deliver 950 watts per channel at 4 ohms.

I know this is an old thread but this is the first I'd seen it. Very very nice job! I have a B460 that I use with my L220's, each driven with a McIntosh MC501 amp. Crossing over with a Sumo Delilah active crossover. From time to time I've wondered if using 2 B380's with say, a McIntosh MC452 (450W/ch) would be superior to my single B460 with the MC501 500 watt amp.

[rusty jefferson]

........ From time to time I've wondered if using 2 B380's with say, a McIntosh MC452 (450W/ch) would be superior to my single B460 with the MC501 500 watt amp.

Not in my opinion. I've had 1, then 2 B380s. Then 1, and now 2 B460s (clones) and I would take the single 18" over the pair of 15"s

[svollmer]

Not in my opinion. I've had 1, then 2 B380s. Then 1, and now 2 B460s (clones) and I would take the single 18" over the pair of 15"s

I agree. I had a B380 for a short time and felt a single (DIY) B460 was superior to the one B380. It didn't seem that 2 B380's would beat the single B460; especially in the low end. But, two subs (of any brand) might offer some other benefits such as flatter in-room response.

Rusty's 2 B460's are awesome!!!

[pmakres1]

Thanks guys for the input....I could squeeze two B380's in the area where my B460 resides, but there is no way I can get two B460's in the room. It sounds like I should just "stay put".

[rusty jefferson]

......It sounds like I should just "stay put".
There shouldn't be any reason not to be getting plenty of bass out of that set-up. Is it safe to assume you've hooked up your B460 in both the "normal" and "inverted" manner to ensure by listening it's in phase with your full range speakers? It's surprising how many people just hook up red to + and black to - and never look back.

[svollmer]

Great looking room!!!

I don't know about your seating arrangement, but one time I temporarily set a B380 right behind my couch and set the volume lower than the normal sub. It really worked well, especially on the sub "back massage" bass.

[opimax]

In the picture, it appears as though the ports don't have enough room to breathe properly???

[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