JBL 2226J, 2445J, 2405 250 Hz Tractrix Horn build

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danvprod

Re: JBL 2226J, 2445J, 2405 250 Hz Tractrix Horn build
« Reply #20 on: 26 Jan 2015, 02:23 am »



This is the way that things are looking today. I made new mounts for the CDs. They are now sitting higher and not occluding the woofers anymore. I've been contemplating replacing the 2405 super tweeters with something that can cover a bit more range. Right now I run my 2445J 2" CDs from 400 Hz - 8kHz.  And the super tweeters above that.

I've been looking at the Dayton AMT mid/tweeters. I am contemplating running this in place of the 2405s:
http://www.parts-express.com/dayton-audio-amt3-4-air-motion-transformer-tweeter-4-ohm--275-093

I'd run them from 3500 Hz up and cross over the CDs below that so that they only have to cover 400 Hz - 3500 Hz, where they are basically ruler flat. The CDs are being powered by a pair of 300b monoblocks right now.

Part of the upgrade would involve moving from a MiniDSP 2x4 to a 4x10, which would let me tri-amp the whole thing. The 2405s are being passively crossed over @ 8 kHz with the CDs naturally rolling off where they do at 8 kHz. The plan might be to run the dayton tweeters with an active crossover, plus a class D amp for now, looking to upgrade to a Decware mini zen in the near future.

I'd still like to configure a mounting system where I could run W T M, with the the tweeter firing between the woofer and the tweeter. The other option is to always mount the tweeter in the woofer box, but I don't necessarily like the idea of cutting holes in my woofer box.

DaveC113

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Re: JBL 2226J, 2445J, 2405 250 Hz Tractrix Horn build
« Reply #21 on: 26 Jan 2015, 03:22 am »
Cool project, thanks for posting! I am working on something kind of similar and am thinking of mounting the horn in between 2 pieces of plywood attached to the sides of the bass cabs. It's a very popular method used in many horn/horn hybrid speakers, it's simple and good looking (imo). The plywood can be cut with artistic curves and possibly a nice contrasting color or veneer...

Was there an audible issue with the horns being too close to the woofers? It seems reducing the spacing would be good but not if the horn interferes with the woofer's output...



danvprod

Re: JBL 2226J, 2445J, 2405 250 Hz Tractrix Horn build
« Reply #22 on: 26 Jan 2015, 03:57 am »
I'm not sure I can visualize what you mean.

Do you mean something like this?
http://www.cessaro-horn-acoustics.com/index.php?id=25

I've contemplated doing something like this. I have the ability now with the aluminum mounting bracket to bolt my big horn and driver onto something. And I could make a shelf for the super tweeter/yet to be purchased ribbon tweeter.

I have it in the back of my head that I would like to rebuild my bass cabinets. Make them deeper, less wide in the front, and substantially more volume. And use a rear port instead of the front ports. Something something like the Alpha design would let me do just that. I'd like to get a 5 cu ft enclosure for the 2226Js.

Hmm you have me thinking.

DaveC113

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Re: JBL 2226J, 2445J, 2405 250 Hz Tractrix Horn build
« Reply #23 on: 26 Jan 2015, 05:45 am »
Yeah, the Cessaros are a good example. The other nice thing about that kind of design is the woofer cab is very simple.

I think 5 cu ft would be nice, I have a pair of 2226 as well as Audio Elegance and Volt woofers to try out. I'll probably build a ~5 cu ft test cab.