JBL 2226H & 2426H cd/2370 horn combo in OB project..?

[JandG]

I have a pair of JBL SR4725's I would like to rob these drivers from & start a OB project. I would then purchase a pair of the higher quality OB bass drivers at $300.+ a pop. Would this be a feasable way to go. I have done OB before with passive/bi & tri amp modes. I found large high quality mids.midbass drivers to be much easier to integrate with the lower 40-100hz drivers. I would go active on the bottom end bass driver & maybe passive on the 2226H & 2426H/2370 horn combo, but most likely active via Steve Bench tube active XO's. Any suggestions on any of this idea ..?
I am not in large funds because of sh... economy so useing the Sr4725 drivers would be almost a requirement for me at this time. I could spring for the $600 or so it will take for the quality bass drivers. Thanks J & G

 

[david yost]

The 2226 can take a ton of power, so maybe you could find another pair of them and go active with a 3 driver 2 way OB. Perhaps a tractrix waveguide for the 2426, everything crossed about 1K....a poor man's Emerald Physics CS2.

 

[JandG]

Intresting. Which wave guide would you suggest for using the 2426H cd.? I suspect the use of the 2370 horn I have is out the window..? Configuration of W-cd-W...? I think the factory XO of JBL 4725's are 1.2k & sound good there so 1k is where I will start. Let the 2226H roll off naturally..?
Thanks J & G

 

[badman]

4725

Hi JandG:

I'm doing some work with the 4725 to enhance it's already good performance, and make it a little more 'refined' for home sound. I'm inclined to keep the current crossovers, which are fairly well designed, and allow for use as "Party speakers" when the need comes up due to the built in massive power handling. One easy tweak for these is felt-lining as much of the baffle as you feel comfortable with, and removing the woofer protection grille which can ring a bit. I put 1/4" f13 wool felt on the baffle sidemembers and around the horn frame, and this helped a bit. A more aggressive treatment would be useful, but I'm going slowly so as to keep the aesthetics looking 'stock', so if I ever decide to sell them that remains an option. McMaster Carr sells the stuff in 1' squares with adhesive, most useful.

Also, take care with placement. These are big surface area speakers, so you want them as far back as you can get them to assist with driver integration.

Also on the board is testing of a supertweeter with these, the Fostex FT17H which has a good efficiency match, and could be rolled in with a 1uF cap. I may post when I get a little further with mods. It's entirely possible that I'll go to an active crossover, but for now, I'm enjoying them quite a bit as is. Pretty decent cabs with very nice components. The 2226H is quite the nice bass driver. Also, the venting alignment is well-chosen.

An externally hosted image should be here but it was not working when we last tested it.

 

[JandG]

Yep, I been running the 4725's with stock passive XO's w/ a 45 SET I built long agao with good iron & tubes. In a 20 x20 room is does overly well. More real than any of my certified Hi-fi home stuff. Let me know what you try.. I really hate to part these out for OB project, but iching for something to build & very limiited now on cash for awhile. I don't know though if I can top what they do now, which is scare the dog out of ya dynamics even with a little 45....does it clean too..mmmm allways decisions. If you go active definately let me know.
Thanks J & G

 

[JandG]

Hey Badman,
Have you thught of pulling the cd & horn & plugging that area useing the factory mounting hole on fron baffle, then placeing the cd & horn on top on cab & mone it back & forth to find a sweet spot.? or do all this & maybe change the 2370 horns out but retain the 2426h cd. maybe a more friendly small area horn.?
Also I thought maybe to try all this & use a autoformer for addition padding on the 2426h..? Just throwing ideas out there to maybe may this a real sleeper hi-fi killer rig for cheap.
J & G

 

[badman]

Hey Badman,
Have you thught of pulling the cd & horn & plugging that area useing the factory mounting hole on fron baffle, then placeing the cd & horn on top on cab & mone it back & forth to find a sweet spot.? or do all this & maybe change the 2370 horns out but retain the 2426h cd. maybe a more friendly small area horn.?
Also I thought maybe to try all this & use a autoformer for addition padding on the 2426h..? Just throwing ideas out there to maybe may this a real sleeper hi-fi killer rig for cheap.
J & G

Hi J&G:

No, I hadn't considered that. The increased cabinet volume would lower the cabinet tuning a tad, probably an okay thing, but not necessarily desirable. You may be able to improve things this way, but then, you can always tweak placement for the same end. Given the lowish crossover, the "time alignment" shouldn't be too big of an issue to where I think this would be critical. Certainly using an autoformer for the padding would be desirable in some systems, so long as the amplifier is friendly to a high impedance, peaky load. This would require experimentation for some amps, particularly transformer coupled styles. Actually, you need to be aware, that if you're considering biamping, you will want to make sure the amp is okay with a peaky horn-load.

For the supertweeter, my plan is to place it on top of the cab with 1uF connected to the tweeter 'direct' input on the SRX (for convenience) and use a bunch of felt underneath/in front of it to prevent early reflection off the cabinet. At about 2.5k (a couple octaves below the 20k "crossover") I'll bring in a parallel coil (.5mH or so), to help keep the supertweeter from overload with the sizable output ability of these speakers.

These can be had for around $1000 the pair, which is indeed a very good price for nice cabs like these.

I'll keep you in the loop on where I go with these, please do the same, we may come up with a pretty slick speaker system. They already have some formidable strengths, in terms of dynamics especially.