JBL 3-way overhaul

[95Honda]

A friend of mine will be dropping off a pair of large JBL 3-way speakers that are in need of a complete overhaul. The 18" woofers are blown, as are the crossovers. I will start posting the step by-step tear-down and re-build of these. I have already decided on some Selenuim woofers and a completely different crossover. The cabinets will also be re-enforced and re-tuned. I'll keep you guys posted......

[95Honda]

The parts will be here tomorrow. Man, I was designing some new crossovers for these things, and looking at the old ones I noticed there wasn't even a lowpass filter on the 18" sub..... Hehh heh heh, talk about some cheap ass design work... My god... These were almost a $1000 a piece new!

Anyway, I repaired the cabinets (2 lbs of 3" deck screws and 2 pints of polyurethane glue later) and I think they will come out alright. The new crossovers will have 400V poly caps and 14 awg coils... Big upgrade, the old crossovers were fried, you don't see that too often... But they had 18 awg coils and 150V caps.... Mix that with a few KW's of power, and crap tends to blow apart...

Hey Mike S, you should stop by this weekend, I think you would get a kick outta these monsters.....

[MikeS]

The parts will be here tomorrow. Man, I was designing some new crossovers for these things, and looking at the old ones I noticed there wasn't even a lowpass filter on the 18" sub..... Hehh heh heh, talk about some cheap ass design work... My god... These were almost a $1000 a piece new!

Anyway, I repaired the cabinets (2 lbs of 3" deck screws and 2 pints of polyurethane glue later) and I think they will come out alright. The new crossovers will have 400V poly caps and 14 awg coils... Big upgrade, the old crossovers were fried, you don't see that too often... But they had 18 awg coils and 150V caps.... Mix that with a few KW's of power, and crap tends to blow apart...

Hey Mike S, you should stop by this weekend, I think you would get a kick outta these monsters.....


Sure, why not? I'd like to check them out.

[95Honda]

Some pictures. You can get a good look at that beefy Selenium 18" sub. Fucker has 10mm of xmax!.... Not bad for a PA sub... Also you can see a picture of the new crossovers and L-pad/terminal plate that replaced the intedrated unit sitting next to it. I used 3 pints of poly glue inside these things. 2 down, 2 cabs to go....

[MikeS]

I stopped by Mike's last weekend, and he was just finishing a pair of those JBL pro sound cabinets.

The Selenium 18" PA sub is rather nice, it's a beast with a nice hammertone basket.

We listened to one stock JBL pro sound cab on one side, and one with the Selenium 18" with the stiffened cabinet on the other.

The JBL/Selenium speaker sounded more smooth and balanced. And stayed that way at higher power levels.
Listening to the finished pair cruised right on down in the bass, and had a better sound quality overall, IMO.

The stock JBL cabinet resonated and rattled, and would go ragged and unglued when pushed with a bit of power. It even made his garage rattle worse.
It had more midbass from the stock JBL 18" being run fullrange in the 8 foot cabinet jammed with fiberglass damping.

I didn't mind the warmer midbass sound the stock JBL cab had over the resonance, but that was about the ONLY thing it had going for it.

You could easily notice the (800?) Hz high-pass cut-off for the sub in the crossover of the refinished cabs.
Of course, Mike's crossover networks and terminal plate rework is top notch.

The stock x-over's were real cheap and cheesy. Fucken shitty would be a understatement..........


If I had a really, really large house, I could live with those big ol' JBL's.

[95Honda]

I was pretty surprised at how good they sounded. They don't sound awsome by any means, but I expected alot worse.

You definetly loose a little midbass with the moddified version, but I'm not sure if that is because I am now running a lowpass on the sub, or the fact that the Selenium subs are 8 ohm and the JBL subs were 4 ohms, and that difference in power is making the JBL woofer sound louder, and therefore making the midbass more prominent. I think after a little EQ, my friend should be able to get these things to hammer.

All in all, I'm pretty happy. The speaker sounds overall much better to me and is much more solid now. The crossovers are top-notch and the new terminals on the back don't fall apart like the old ones.

I'll get a picture of the first finished set tonight.

[MikeS]

Yeah, lowpass....... :oops:

This place I work at is a newer big ass open steel truss building, with at least a 25, 30 foot ceiling. It's up there, the trusses are pretty big.

Over a area with six assembly lines, they have a framework built around the lines. Up above 10, 12 feet above the framework is 12 little Bose 2-ways mounted on top. Six in the front, six in the back of the assembly lines.

Satellite radio from what I'm told. 80's music drones from them daily......


Now a pair of those JBL's hung facing each way in the center truss in the middle of the building with the right wattage would get them workers dancin'...

[TalNLnky]

if you're dancin you're not working tho.... i think they used bose on purpose... to drain all hope & will from the workers souls.