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/showthread.php?166-4333-S300-L300-equivalent-bandbass-circuit&p=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.

[ivica]

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?
Hi srm51555,

owing to JBL 2397 data and the measurements from the forum

http://www.audioheritage.org/vbulletin/showthread.php?3849-JBL-2397-Curves&p=263329&viewfull=1#post263329

I think that even 800Hz would be too low, as 2397 horn mouth has relative small area. I think that for lower frequency a Yuichi A290 would be better solution, but its DIY construction would be much more complicated project to be realised.

regards
ivica

[srm51555]

I bought my Be phrams new and love them!

They are on 500hz Edgarhorns.

Ron sends...

I've enjoyed reading you audio journey, thanks for it.

Ivica, I've given some serious thought on making the Yuichi horn and would like to build one when I have time.

I'm currently running the 2235's with a Mcintosh MC2155 and feel a bit more power is needed. So my next upgrade will most likely be a purchase of my friends Crown K2.

[Champster]

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?

My 2¢ is that I would echo the 1khz minimum comment. I just recently changed out the ribbed Ti in my 2446's with new TruExtent Be diaphragms. I should preface this with the comment that the following frequency changes were all made at 24db/oct. I started with 800hz and hated the sound. I was so disappointed and thought I made a huge mistake spending so much money on the Be. Since I am all DSP, I listened extensively to them with frequencies ranging from 600hz to 1500hz. At lower frequencies the sound definitely takes on a strange character (how is that for audiophile speak?). For now, I've settled at 1200hz where it just sounds live. At 1200hz, It all came together and blends wonderfully into one seamless driver with the 2123 midrange. Above 1300hz, the midrange and CD don't seem to blend as well and the sound takes on a deeper, throaty characteristic. So, I continue listening to various tracks striving to find the best choice, but think I'm pretty close at 1200hz.

[ivica]

My 2¢ is that I would echo the 1khz minimum comment. I just recently changed out the ribbed Ti in my 2446's with new TruExtent Be diaphragms. I should preface this with the comment that the following frequency changes were all made at 24db/oct. I started with 800hz and hated the sound. I was so disappointed and thought I made a huge mistake spending so much money on the Be. Since I am all DSP, I listened extensively to them with frequencies ranging from 600hz to 1500hz. At lower frequencies the sound definitely takes on a strange character (how is that for audiophile speak?). For now, I've settled at 1200hz where it just sounds live. At 1200hz, It all came together and blends wonderfully into one seamless driver with the 2123 midrange. Above 1300hz, the midrange and CD don't seem to blend as well and the sound takes on a deeper, throaty characteristic. So, I continue listening to various tracks striving to find the best choice, but think I'm pretty close at 1200hz.

Hi Champster,

Thanks for the shown experience using 2446 BE-Tx driver with Bob Smith - like horn with JBL 2123.
As shown in the:

http://www.audioheritage.org/vbulletin/showthread.php?5951-Wood-Horn-3-way&p=58582&viewfull=1#post58582

"........Here is a curve of a stock JBL 2397 "800Hz" horn. It is decidedly rolled off below 1200Hz. I expect you will get the smaller horn to "work", but I am not sure how well.

Widget...

..In those particular plots I was using a TAD 4001. I have also measured JBL 2441s and they are identical in the lower portion of the curve. The TAD's larger magnet and Beryllium diaphragm gives it a slightly flatter and more extended top end. The two plots were comparing a stock 2328 with a custom adapter.

Yes, I too was disappointed.

Realize the scale is relatively expanded, with 5 dB per major vertical division. The response between 1200Hz and 12KHz, which is where I was using the driver horn combo is +/- 2.5 dB... not to shabby really.

Widget......"

it confirms Your decision as correct.

regards
ivica

[JeffW]

it confirms Your decision as correct.



For his horn, or Widget's 2397-ish horn.

[srm51555]

This horn was built mostly to Widgets horn plans, the difference is the homemade 2" horn adaptor. The internal dimensions of this adaptor are 2" for height and 5" total length. At the time I was unable to source a 2328 adaptor due to lack of project funds. And since it sound good to me and a couple of other ears I never got one. When running my DBX 10/20 there was a need to boost +1db at 1khz, but that could be room accoustiscs. 500hz was the same, I have no way to test at the 800hz point.

[JeffW]

So 1KHz~1.2KHz is going to be about the bottom for your horn as well. And probably not much lower than that for most any horn a person would be able to fit in their house. I just don't think the 1K lower limit was specified by TruExtent because they thought it sounded best there. The design of the horn and the associated loading of said horn is going to have an influence on the lower crossover point of the driver/diaphragm. Champster is using a 2380 I think I recall. It's spec'd as a 500Hz horn, and must guys seem to agree that crossing over at least 2X the horn's lower limit is about right. So something north of 1KHz is going to be correct for that horn, based on the design of the horn - not because of what TruExtent printed on their instructions.

A couple of days before I listened to a TruExtent crossed at 350Hz, I also listened to one crossed at 800 (IIRC), both sounded excellent, both crossed below what was printed on the paper and both on horns that could load them properly below 1KHz (at home environment levels).

You probably aren't going to have a lot of horns that can support much lower than 1KHz, so that's not going to be an issue for most systems, but I still don't think that's why TruExtent printed that figure on their sheet.

[cooky1257]

800hz is fine on the 2397. the none Be 2440 sounds sublime used this way with 2x2235/2405 at either end with as I recall a 3105 x over. This 'Westlake' configuration endured the punishments of many recording studio environments for years too.

[srm51555]

I’ve been itchin for a new project and keep on coming back to the idea of making these into a 3.5way. My thought is to replace the 2235H with a 2206H and then run the 2235H up to 80-100HZ as a sub. I would use an electronic crossover for both the 2235 and 2206. The 2240 and 2405 would use the existing passive network for now until the networks could be reworked for 1200 hz crossover points. The speakers sound great as is but my experiment to gain some power with the Crown K2 didn’t work out as planned. In a bi-amp configuration with the K2 I found the low mid of the 2235 to be lacking. These usually don't get played loud enough for the MC2155 to run out of steam but wouldn’t mind the extra power of the K2 on the 2235’s (only when used in a sub configuration).

[Lee in Montreal]

2235 as a sub? You are asking for trouble. You will soon find their excursion limitations. Not to mention that a sub shall go no higher than 40Hz, or you will start noticing the source.

If you want to go to a 3.5 then perhaps you could use a 2226 for bass and 2245 or any automotive sub for the bottom octave. The 2226 is a potent bass driver if well eq'ed.

Lee

[srm51555]

"Sub" may have been the wrong word. I was thinking more like the 2nd 2234H in the 4435. A proper sized 2226/2245 setup might be a little large for my budget right now, but I have though of it. Thanks, Scott

[speakerdave]

It strikes me that you are not playing at crazy loud levels, so the 2235 would probably work ok as a sub in the box you have, since I believe JBL's B380 is the same size. If you are using this system to play movies you could track down a BX63A or set up a minidsp equivalent so that you do not hit it too hard below cabinet tuning, where the woofer would be unloaded.