View Full Version : L36 custom restore - Best LE5's & LE25's

07-22-2006, 02:42 PM
Hello everyone!

I am currently restoring an old set of JBL Decade L36's. I have the cabs w/crossovers and the 125A 10" woofers to pop in presently. Now I am looking to add the mids and tweeters. I am not remotely concerned with building them back to factory specs, just want the best sound from like drivers.

What I need to know is: Which are the best LE5 series 5" midranges and the best LE25 series tweeters to add to finish them off? I think I have heard the LE5-2 had the alnico magnets where as the rest didn't? I have also heard things about some of the 5" mids requiring a "subenclosure'???

Anyhoo - just wanted to get you guys opinion as to what versions YOU would use in order to produce the best sound and see what the consensus might be.

Much appreciation for any advice you fellows can offer up!

07-22-2006, 02:53 PM

07-22-2006, 03:05 PM
Thank you Zilch for that link with the technical information. Do you have an opinion on what models I should use?


07-22-2006, 03:17 PM
Alas, I have never studied them. :(

07-22-2006, 06:30 PM
I am not knowledgeable enough to give an opinion or I would but I wonder if the XO will restict your choices??? if a filter doesn't match the driver , even a "better" driver might sound "worse". Hopefully you will get a good response from the experts


07-22-2006, 08:06 PM
I too was worried about the compatibility with the x-overs, but I figured if I stuck w/ the same basic series of components (i.e. LE5 and LE25) then I might be alright, but again, I am no expert.

07-22-2006, 11:20 PM
Our forum authority on these matters is Giskard, who is on sabbatical right now.... :(

Mr. Widget
07-23-2006, 04:44 PM
Do you have an opinion on what models I should use?
From the Giskard Matrix you can see that the L36 and L36A used the LE5-6... and that the LE5-6, LE5-8, LE5-10, and LE5-12 all use the same recone kit. Therefore it should be safe to assume that any of those four mids should work.

So be on the look out for mids from the L50, L50A, L86, L96, L110, L110A, L112, L120, L120A, L150, L150A, L150A-B, L166, L166A, 4311B, and 4312... that is plenty to choose from!


07-23-2006, 05:05 PM
I think I want to do the really irrational thing and go after the LE5-2's from an L100 century, (more $$$) then finish them off with the original tweeters LE25-4's. Those (LE25-4's) just had a flat paper surround. I wish I hadn't sold the pair I used to own for $75 to that guy in California last year. Are the tweeters in that series all ferrite?

Don McRitchie
07-24-2006, 07:56 AM
Be warned that the LE5-2 does not have a flat response in its bandwidth. It is purposely designed with a rising amplitude response with frequency. Originally, this was designed to mimic the peaked midrange response of the Altec 604 Duplex that the 4310/L100 was intended to copy. That is why the L100 is often described as "forward" sounding or excelling in "presence". If you like that sound, go for it, but don't expect it to be neutral.

The LE5-6, originally developed for the L36, utilized a ferrite magnet as a means of keeping down costs. However, this driver was found to be more neutral than the Alnico LE5-2. That is why the much more expensive L65 Jubal used a variant of this ferrite driver. At the price point of the Jubal, JBL could have easily employed the more expensive Alnico LE5-2, but they felt that the ferrite driver was more accurate.

Personally, I wouldn't mess around with substituting drivers unless I had a specific design goal that I was trying to achieve and I had the knowledge and measurement equipment to confirm that such a goal was being met. Taking this approach would almost certainly mean designing your own cross-over since you would be using drivers that were never designed for the system application that you are developing. To me, this sounds like a lot more work than the potential benefits, unless you are just interested in the experimentation and lessons learned.

It should be noted that there are a great number of LE5 variants because JBL took the approach of developing their own drivers for specific systems. This is part of the attraction of JBL products. They were one of the few loudspeaker companies with the resources and skills to develop their own transducers. Rather than trying to find an existing driver that came closest to a given design requirement, they could, and would, design a unique driver just for the system at hand. Therefore, there is no such thing as the "best" LE5 midrange. Each was best at its given application.

07-24-2006, 09:30 AM
I think I want to do the really irrational thing and go after the LE5-2's from an L100 century, (more $$$) then finish them off with the original tweeters LE25-4's. Those (LE25-4's) just had a flat paper surround. I wish I hadn't sold the pair I used to own for $75 to that guy in California last year. Are the tweeters in that series all ferrite?

I've got an original set of L36-Decade speakers I bought back in 1976 ... I did replace the surround about 8 years ago, but otherwise, they are original. I really enjoyed the sound of them, but, of course, once I got the 4320 big box JBLs and got used to 15 inch woofers, horn mids and slot tweeters, I haven't used the L-36s much.

I think the original L36s are very nice speakers - I'd recommend putting them back in original shape - or replace them completely with one of the other fine JBL systems - rather than try to re-engineer them into something else ...

07-24-2006, 02:36 PM
Thanks guys,

After much research, I think I WILL be restoring them back to original specs with the LE5-6 mids and the LE25-4 tweeters. The parts seem less expensive and more readily available. I also found a post where a person wanted to swap out L100 mids and highs with those from a L36 anyway.

So, looks like they will be as close to original as I can make them. After all, I guess the engineers at JBL would be more qualified to decide what goes in the cabs than me...

Much appreciation for the good advice!

09-23-2006, 09:36 PM
Having owned and enjoyed my L36's for several months, I'd recommend leaving them original. I like the LE5-6 mids best amounst all the 70's midrange transducers and as explained by Don McRitchie, they are a bit more neutral than the LE5-2 Alnico mids that gave the L100 that distinct late 70's JBL sound. It all depends on your tastes in music, but I think that you'll be pleasantly surprised with the L36 in stock form. I have original LE25-4 tweeters and LE5-6 mids from an unused pair of L36's along with the cabinets, crossovers etc. I think I actually have 2 sets of both in nice condition, PM me if interested. I will sell it all very cheaply...

09-23-2006, 11:19 PM
The alnico ones are inherently magneticly sheilded.You can put them right next to your tv. If your woofer isn't I guess it doesn't make much difference. As far as its own enclosure, all of my le5's have open backs. Unless you have ones that don't have open backs, they need their own enclosure. It's simple. It can be a peach can, a piece of cardboard carpet roll with a board glued on the bottom, anything. You don' want the woofer pumping the midrange in and out. Liquid nails type construction adhesive will hold it together. I like the urethane stuff myself. Don't use silicon. It isn't very strong, and nothing else will ever stick there. If your midrange has a solid back, then disregard. As far as sound, it's personal, if it's even percievable. The efficiency is low enough on that speaker that given your stated goals you actually have your choice of manufacturers,but then you might ask yourself why that tweeter. I hear them yelling already, gotta go.