JBL L200b upgrade

[Jimerson]

Good morning,
I've had some 200B's for a few years, and while I liked the sound, there was just something missing on the top. I recently aquired some 2405 tweets, and after cruising AK and the web I decided to make new crossovers. This is new territory for me, so I chose a simple Nelson Pass design from an article he did on the l300. My speaker components are similar, except for the length of the horn, I think. I did not want to modify the original crossovers, nor did I want to cut holes in the cabinets.
Anyway, the first pic shows the speaker with all the connections and crossover on the outside, as there was little hope they would work the first try. Imagine my surprise when sound came out of all the speakers.
I was going to make little cabs for the tweeters, but as I was in a hurry to hear them in the house, so I used 6 inch PVC and cut end plugs out of the softest wood in the pile, some reclaimed cedar. They actually came out pretty good for a quicky. As for the sound, it's everything I hoped for, and worth the effort.
Anyway, thanks to AK for all the info and support, and thanks for reading.
Jim

 

[Brad Muller]

Nice!:yes:

 

[hjames]

The tube cabinet is a cool concept!

You might want to make some kind of base to go under the main cabinet and raise your mid-horns closer to ear level.
Mine had the original particle board bases, so I made a box with wheels to go around that base and it makes it easier to move
and vacuum around them.

Oh - I did the google and found the Nelson Pass L300 crossover article here: http://www.firstwatt.com/pdf/art_l300.pdf

Good morning,

I was going to make little cabs for the tweeters, but as I was in a hurry to hear them in the house, so I used 6 inch PVC and cut end plugs out of the softest wood in the pile, some reclaimed cedar. They actually came out pretty good for a quicky. As for the sound, it's everything I hoped for, and worth the effort.
Anyway, thanks to AK for all the info and support, and thanks for reading.
Jim

 

[pdevil]

I really like the way that tube design came out. It looks more "high end" than other designs I have seen. Sort of reminds me of a Fostex tweeter on steriods!

 

[Jimerson]

Thank you. I might stay with that design and use better wood for the ends, I was in a hurry. Also, the only brown paint I had in the shop was what you see. I'm wondering if it's possible to veneer over PVC?
Heather, that's a good idea on the bases, and an easy fix. Also over the years that MFD gets pretty beat up down there from moving them around with a hand-truck.

 

[pdevil]

I'm pretty sure you can veneer PVC but I have never tried it. Contact cement will stick to anything. I would think you could just keep the same cabinets and veneer the PVC and the fronts & backs with the same matching veneer.

 

[mythless]

That is what I need! Looks great!

 

[pjrengineer]

Good morning,
I've had some 200B's for a few years, and while I liked the sound, there was just something missing on the top. I recently aquired some 2405 tweets, and after cruising AK and the web I decided to make new crossovers. This is new territory for me, so I chose a simple Nelson Pass design from an article he did on the l300. My speaker components are similar, except for the length of the horn, I think. I did not want to modify the original crossovers, nor did I want to cut holes in the cabinets.
Anyway, the first pic shows the speaker with all the connections and crossover on the outside, as there was little hope they would work the first try. Imagine my surprise when sound came out of all the speakers.
I was going to make little cabs for the tweeters, but as I was in a hurry to hear them in the house, so I used 6 inch PVC and cut end plugs out of the softest wood in the pile, some reclaimed cedar. They actually came out pretty good for a quicky. As for the sound, it's everything I hoped for, and worth the effort.
Anyway, thanks to AK for all the info and support, and thanks for reading.
Jim

I’m getting ready to build the Nelson pass crossover for my L-200a. Hope it works for mine as well as it works for your b version

 

[bimasta]

That PVC pipe was a fortuitous find: they look great.

I had L200's and added the 077's (same as 2405) and the difference is extraordinary — I read that the tweeter adds "shimmer" but it's far more than that: it adds dimensions.

I think the Heil AMT's are slightly better in this role – as noted by others in other threads – but there's something just "right" about the LE85/2405 combo that JBL used in so many of their classic designs.

 

[Jimerson]

Dang, eight years have passed since then! Still enjoy the JBL's, but I did make a more presentable tweet enclosures. Walnut veneer with the L pads on back. Can't remember if I posted them elsewhere on the sight.

 

[toddalin]

I think I still may have a couple of these:

 

[Tom Brennan]

One could consider going tweeterless by EQing the compression driver to extend the highs, as with the Altec 19 and JBL 4430. Depress the midrange from the compression driver and you flatten and extend the response and still have energy to spare compared to the direct radiating woofer.

 

[pjrengineer]

One crossover complete. One left to do. Going the external route. Figured they’d be pretty cool looking with the tweeter in another custom wood box in front cate-corner to the crossover. We’ll see.

 

[WaynerN]

The original XO caps are older then hell and probably out of spec, screwing up the XO frequency.

 

[pjrengineer]

The original XO caps are older then hell and probably out of spec, screwing up the XO frequency.

Not to mention the resistors believe it or not.

 

[wallacefl]

I have a concern about the physical separation you create by moving the tweeter away from the midrange ie look at how the 300 and 4333 drivers are arranged in view of the crossover.

 

[pjrengineer]

There may be some validity to your concerns. We’ll see and I’ll adjust as needed. I can’t bring my heart to cutting the baffle for an experiment.

I now have twins. Next for the speaker wire. I have this really thick monster cable or the standard 14 gauge mono price copper stuff. Can’t decide.

 

[pjrengineer]

Love seeing these red wax seals.
That le-85 is a bugger to get in and out.

now that I have one speaker rewired and crossover installed I tested it. It sounds much better now. I am not doing any measurements as I haven’t done it before but I can tell you they pass the listening test.

 

[Alobar]

I can’t bring my heart to cutting the baffle for an experiment.

I felt the same way so I ordered these 2405 brackets from the member of over on Lansing Heritage. The 077's just fit inside the grill and no big holesaw project.

 

[SaturationPt]

@Alobar where did you get the guards over the woofers? Do they make them in 18?