DIY JBL 2235h/2440/2397/2405

[srm51555]

These speakers started out as Zilch's Econo-Waveguide system from Audiokarma with a JBL 2235H in a 5.5cf cabinet. About 3 years later for some reason I looking up the JBL 375 driver and came across a post from Mr. Widget explaining how the 2440 and the 375 were essentially the same driver. Prior experience told me to ask questions before building. I PM’d Widget and explained to him what I was planning. He sent the recommendation of using the Westlake or 2397 horn and Giskards charged coupled crossover. Due to limitations of tooling when building the horn, I used 1”x2” pine for the fin construction and plywood for the horn. The side and fins were glued and screwed to the bottom half of the horn and 2 part epoxy primer was applied(2x's) on it. The top was also painted with epoxy and screwed to the bottom half of the horn. I chose flat black for a finish and it looked awesome but unfortunately fingerprinted. I decided to use a clear coat but I applied it too heavy and it left the horns gray. My listening impressions are in most cases these produce ultra-Smooth and a lifelike reproduction of music. I have found some songs seem thin in the midrange a bit, but I still need to replace the diaphragms and hope it will clear this up. The best things I found about the 2397 is the very wide dispersion of the sound, larger sweet spot, and the neutrality of the wood horn. For comparison I do have model 19’s and 846B’s(With Modified Zilch crossovers, best money spent for a 846) and if I had to decide on what ones are my favorite, I couldn’t. You do need both styles of speakers as previously posted in other L300 vs Model 19 threads. I really do enjoy the musical control and accuracy of these though. This build is an awesome combination and appreciate Mr. Widget and Giskard for the great information sources that they are. Any setup suggestions or questions?

[pos]

Nice speakers, simple and efficient.
I like your tweeter stands!

Can you share your crossover schematic?

[Lee in Montreal]

Definitely my school of thought. Separate bass cabinet and horn on top, with optional tweeter.

Good job.

Lee

[srm51555]

Thanks everyone, the horns are propped up by a foam building block, it works for now. I used the schematic from http://audioheritage.org/vbulletin/s...=1042#post1042.

[badman]

I'd cut some acoustic foam or thick wool felt and make a big lip around the mouth of the horn- right now, there are a lot of diffraction artifacts surely happening there that could be mitigated that way.

[danvprod]

I really like what you have done here with these. Thanks for the detailed write-up. I have 2226Js in my system in a 4 cu ft. enclosure and thinking of bumping up to a 5.5 cu ft. to get a bit more low bass.

Nice job also on the DIY smith's. And thanks for the link on the crossovers.

Did you make the bass cabs yourself? Do you have any pics of the build process? I'd love to see how you did the bracing, construction etc.

And +1 for the creative super tweeter mounting solution

[Lee in Montreal]

BTW Dan

Cabinet volume is, among other things, dictated by how much room you have to spare and what you intend to do with your cabinets. Bigger cabinets will go lower at the expense of cone excursion. The 2226 can take a lot of power. I suggest you download a simulator and see by yourself. I just simmed the 2226 in a 10cft cabinet tuned to 30Hz and you can go almost flat down to 30 Hz and end up out of excursion at 400w, which is most likely enough for home duty.

[srm51555]

I'd cut some acoustic foam or thick wool felt and make a big lip around the mouth of the horn- right now, there are a lot of diffraction artifacts surely happening there that could be mitigated that way.

I'd try this if I could figure out how to mount the foam discretely. It would be something Urei did back in the day.

Did you make the bass cabs yourself? Do you have any pics of the build process? I'd love to see how you did the bracing, construction etc.

I have some pictures of cabinet and horn construction somewhere. I'll try to dig them out this weekend. They were built with 3/4 plywood and braced with 2x4's inside. Liquid nails and screws hold them together. I used mohagany veneer. I got the sticky backed stuff. When I got my 846's I was surprised to see they were almost the same size. One day I will get around to properly mounting the horns. It stinks since I'm down 2 clamps when working on other projects.

[srm51555]

Below is the best picture that I took during the build process of the cabinets. . Does anyone have any thoughts on the addition of a second pair of 2235’s or an addition of 2245’s? I wonder if running the 2 woofers without a mid-bass hurt more than help, and is there a big mismatch when running the 2235 and 2245 together? I would think Bi-Amping would be necessary.

[srm51555]

Update: I installed TrueXtent Beryllium diaphragms in the 2440's today. The detail of these diaphrams are incredible even after only three hours of break in. Having never heard Beryllium in a JBL compression driver before I was a bit reluctant due to the price, but after selling some other audio equipment that was only kept as "just in case", it was well worth it. One question I do have is why is the recommended frequency by TrueXtent 1000hz when they should be capable of well below that?

[JeffW]

I recently listened to a TruExtent Be crossed over at 350Hz, not sure what the horn was doing down that low, but I think the key is it wasn't cranked up. I imagine they specify 1K since sound reinforcement is the target market, home users can probably get by with something lower.

[spkrman57]

Update: I installed TrueXtent Beryllium diaphragms in the 2440's today. The detail of these diaphrams are incredible even after only three hours of break in. Having never heard Beryllium in a JBL compression driver before I was a bit reluctant due to the price, but after selling some other audio equipment that was only kept as "just in case", it was well worth it. One question I do have is why is the recommended frequency by TrueXtent 1000hz when they should be capable of well below that?

More for protection than anything else. I like them above 800hz min myself! I can't remember the thread that discussed crossover freqs for Be but a search might pull it up.

Regards, Ron

[srm51555]

I also remember reading that thread and remember thinking the consensus was that 800Hz is still acceptable. I can’t stress enough to others that replacing old diaphragms with new (Be or Not) is necessary. I didn’t realize how tired the old ones were and what I thought was smooth was just lacking detail.

[spkrman57]

I bought my Be phrams new and love them!

They are on 500hz Edgarhorns.

Ron sends...

[Maron Horonzakz]

BADMAN,,, vertical diffraction is part of the design of the SMITH horn..... Just like the T35 EV tweeter.. its supposed to.