L55 tweetwrs

[tennesota]

I have a pair of L55's. I need to replace the tweeters. Whats the model # and where can I get em???

[boputnam]

Hey...

That L55 is the same as the "S12 System" of components JBL offered during 1974.

The tweet is the last version (I believe...) of the LE20 - it has a funky grill screen on it, and AlNiCo magnet. JBL loved to pair the LE14's with the LE20, in both it's versions.

You will find LE20's on eBay, just be patient for the exact style. I have a pair that I'm not using if you're interested. They were a "package deal" with some LE14's.

Here's a picture of the S12 where JBL likens it to the L55:

[Mr. Widget]

Yep, LE20... eBay is your most likely source.

Check this out:

http://www.lansingheritage.org/html/...s/1973-l55.htm

[boputnam]

Exactly, my friend Mr. Widget!

But those dang consumer brochures were loath to give specific component numbers - a real loss for us JBL Faithful now, hey?

Oh well - with the generous help you and (Dr...) Giskard, we'll get through this!!

[tennesota]

Thanks guys I'll chech out eBay and let everyone know !

[4313B]

Just an F.Y.I.

JBL still has a few LE20 / LE20-1 diaphragm kits left

Unfortunately they are marked "NLA when depleted" so if you like that silky smooth little transducer...

The kits are pre-assembled wherein the paper cone is already cemented to the aluminum frame. You take out the old frame and screw the new frame into the alnico assembly. In the early days they were Factory Service Only because the kits weren't available. The ladies would recone the actual unit in for repair and it was a real bear.

Just in case someone isn't aware, the difference between the LE20 and LE20-1 is the LE20 has the larger (removeable) frame and screen. They disassemble and you are left with the LE20-1 core.

[boputnam]

So THAT brings up a question:

How do you / can you recone the first vintage of LE20's - the ones with the wires soldered right onto the side connections as paired with the LE10A and P10 in Lancer 77's.

I've not tried to disassemble one. Possible, or just get replacements?

Also, any noticeable frequency response difference in the LE20 and LE20-1?

Thanks.

[4313B]

The assembly that the wires are soldered to is the part that comes in the recone kit. That whole front part unscrews and is replaced.

I'm sure the LE20-1 would measure better if only because of diffraction effects from the LE20 frame.

I can't remember who posted this awhile back. I'm sorry
Here it is again and hopefully the original poster will respond.

[Earl K]

Hi Rob G

Those response graphs were from a rare posting by Bill Woods.

Questions;
With the removable "Frame Assembly" enclosing the entire cone kit, does that suggest I could dissassemble my le20 tweets and "pop back out" the pushed in dust caps ?
How does one recenter the voicecoil in new or old kits ?
( without the use of shims )

regards <> Earl K

[4313B]

Hi Earl,

"With the removable "Frame Assembly" enclosing the entire cone kit, does that suggest I could dissassemble my le20 tweets and "pop back out" the pushed in dust caps ?"

Definitely, just unscrew the screws, pull the assembly out of the magnetic assembly and push out the dust caps.

"How does one recenter the voicecoil in new or old kits ?
( without the use of shims )"

They "self-center" on the pins. I can look up the "centering frequency" and test sweep if you want.

[Earl K]

Thanks ! That's good news.
Now I just need to get them out of the S99 enclosure without destroying that metal trim facing. ( probably some other day )
I think I have the test info for that era of driver. If you find it first , you might post it for the sake of archiving .

regards <. Earl K

[4313B]

Ah yes, the black foilcal. You can try warming it up but they are pretty hard to remove without trashing them. The part number is 21600. I have two left which I will never use.

The centering frequency is 1 kHz with 6 V input. Sweep is 1 kHz to 6 kHz.
You HAVE to use the following test jig though as 6 V straight in will kill it.

[tennesota]

Big thanks to everyone. I was able to hook up with Bo on the LE 20's. Thanks Again, keep up the good work!

[boputnam]

And sold 'em for my cost - anything to see vintage JBL cabinets stay vintage...

Give us a full report after you get them Radio Shuck tweets outa there!

This should be as good as - second only in sequence to - Tom's recent 4343 re-birth!

Whoowa...

[tennesota]

I just insalled the LE 20's. They sound smoooooooooooooth!!!!
Had to re -cut the hole from 3" to 4". The originals must have been LE 20-1's,but these have a much better look and the same guts.Thanks again to everyone and special thanks Bo for the great deal!!