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Thread: L100 Century help

  1. #1
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    L100 Century help

    I have a set of L100 Century Cabs, no drivers yet. My question is how do I find out if the crossovers used the 123A-1 or 123A-3 woofer? The cabinet numbers are 55619 A and 55624 A, any help would be appreciated. I have read that the two different woofers use different phasing. For the heck of it, here’s a pic of front of label.
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    http://manuals.harman.com/JBL/HOM/Te...NTURY%20ts.pdf

    http://manuals.harman.com/JBL/HOM/Te...0LATE%20ts.pdf

    http://manuals.harman.com/JBL/HOM/Te...L100A%20ts.pdf

    It doesn't matter. The different woofers did not use different phasing; the different models did.

    BUT, if your crossover has coils in it, it used 123A-1, according to the tech sheets, above, and the polarity was reversed internally in the crossover.

    In the "A" versions you have, no coils, either woofer, it's the tweeter that's reversed, not the woofer, looks like....

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    Quote Originally Posted by Zilch
    http://manuals.harman.com/JBL/HOM/Te...NTURY%20ts.pdf

    http://manuals.harman.com/JBL/HOM/Te...0LATE%20ts.pdf

    http://manuals.harman.com/JBL/HOM/Te...L100A%20ts.pdf

    It doesn't matter. The different woofers did not use different phasing; the different models did.

    BUT, if your crossover has coils in it, it used 123A-1, according to the tech sheets, above, and the polarity was reversed internally in the crossover.
    In the "A" versions, no coils, either woofer, it's the tweeter that's reversed, looks like....
    Thanks for the reply, I do follow your drift, I do know the cab uses the LE25 tweeter, with 4 screw holes. Two more questions though, I have seen a couple different crossovers for the L100, mine has the 2 small epoxy filled cylinders next to the pots if that helps any.

    And also it seems I can use the LE25-4 tweeters or the LE25-2 tweeters...I don't want to start a cat fight here, but is there much sound difference from the -2 and the -4 ? ...I am kinda new to putting it all back together again, but, what I really like is good sound.

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    RIP 2011 Zilch's Avatar
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    Quote Originally Posted by John K
    I am kinda new to putting it all back together again, but, what I really like is good sound.
    I can't help you with the last part at this point.

    Put 'em together; then we'll talk....

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    HI John K,

    it looks like the linage of L-100 you have only uses (as you put it, 'the 2 small epoxy filled cylinders next to the pots')

    .....the two capacitors and the pots for an entire crossover network.

    The values of the capacitors are 8mF and 3mF (or uF as it used to be laid out)...Microfarad, nevertheless

    The epoxy filled cylinders ARE the capacitors. They usually spec out good even after all these years. I did in fact install some updated caps when I once owned L-100's and to me they were "a good bit louder" than the stock caps and the stock caps went back in.

    Yes, they did run the woofer fullrange. This in itself helps to pad some nastyness away from the midrange with those componets.

    As per the /4 and the /2 tweeters, I would think "no appreciable differences at all" would be the proper answer there.

    Hope this is somewhat useful.

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    Quote Originally Posted by JCC1
    HI John K,

    it looks like the linage of L-100 you have only uses (as you put it, 'the 2 small epoxy filled cylinders next to the pots')

    .....the two capacitors and the pots for an entire crossover network.

    The values of the capacitors are 8mF and 3mF (or uF as it used to be laid out)...Microfarad, nevertheless

    The epoxy filled cylinders ARE the capacitors. They usually spec out good even after all these years. I did in fact install some updated caps when I once owned L-100's and to me they were "a good bit louder" than the stock caps and the stock caps went back in.

    Yes, they did run the woofer fullrange. This in itself helps to pad some nastyness away from the midrange with those componets.

    As per the /4 and the /2 tweeters, I would think "no appreciable differences at all" would be the proper answer there.

    Hope this is somewhat useful.
    Ok...you have been helpfull, I going to take my time to find to find the drivers, leave the original capacitors in. I was getting a little confused with the different "flavors" of the L100's.

    I'm not completly new to restoring speakers, I refoamed and refinished my set of L100t'3, I love the sound of these, they just got that sound that you KNOW they can snap you head off. And my recent refinish and restore of a set of L55's (my wanna be jubal look).

    My hobbies have changed from building computer's to sound, and going back to the early 70's with JBL's. I live in a small town, so in order to hear what I want to hear, you gotta find it, (buy it) and listen to them, and I'm one of THOSE people that gotta have the look that goes with the sound, Thanks again.

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    Hi, John
    I've just finished restoration of pair of L100 Century purchase back in 1975 (not sure of that date, but I have my dad's invoice and original manual somewhere around here). They had mid and high transducers damaged by a teenager loud music freak (myself 20 years ago). After starting replacement of transducers (easily found at e-bay but not so easily delivered, since I am in Brazil, and customs clearance is a pain) and after a lot of research here, I've also decided to fix and upgrade the x-overs.
    You gonna find all information needed searching this site (the guys here know everything and are very helpful) but you may ask to help you find the threads, if needed.


    Below are some pics.

    The speaker ----> Name:  DSC01602.JPG
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  8. #8
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    The label (my pair is from a later production). ----> Name:  DSC01601.JPG
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    Transducers
    • HF - Based on what I found here, there is no sensible difference between LE-25 models. In fact they are so similar that I preferred to replace with LE-26, just because they were newer models, did not have foams and I found them easily.
    • LF – I am using original 123A-1 transducers (In fact, besides these woofers and the wood enclosure, no other original parts were actually left). I am not sure if I read here somewhere that 123A-3 is a better woofer (it is a newer model anyaway). I did not paint the woofer as suggested at another thread. It would look better (brand new white aquaplas) but I did not have enough courage to try it.
    • MF – A pair of LE-5-2 found at e-bay, just like the HF transducers
    Below is a very useful table copied from another thread. You will find the polarity differences between models.

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    X-Overs

    As I said above I have upgraded the crossovers. Reasons? All L-pads (the pots) were rusted, and sounded terrible, even after cleaning. And since I was already playing with the X-overs (and most of the work is dedicated to removing the "foilcal" label - try a search) I found interesting to upgrade them, including "bypass" capacitors in parallel with the existing caps. Before upgrading, my X-overs looked like the ones below, copied and pasted from a[very nice thread:

    Name:  xover l100.jpg
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  11. #11
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    For the X-over upgrade I’ve purchased Dayton Caps (0,1 uf) and 15w L-pads from Parts Express. That was my first upgrade. After including the caps the result was.... crap! The sound was falt, dull. I could not hear any improvement.

    So I've searched other threads here and found out that would be interesting to replace the old original caps. Also found that the bypass caps must be of higher quality. I am not sure about of the reasons for all that but I trusted in what I read. After all, I wanted back the sound of those speakers (and maybe go back in time to my 20’s if I could). So I went to Parts Xpress again and got Solen caps (at that time found only 8,2 and 3,3 uf, both Polyprop caps) and Audiocap PPT Theta 0,01 uf film foil caps for bypass. Of higher quality? Don't know, but they were far more expensive. Also installed a Speaker Circuit Breaker on the inputs of the speakers as a safety (I don’t actually use the speakers so loud as before, but my kids are growing up….)

    After putting all together, the results were great! The sound is now much crispier and image effect is higher (although I can not tell you if it sounds better than originally). The new X-overs looked like this:


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    Center Speaker

    These L100 speakers are used as front speakers in my system and I was looking for a Center Channel Speaker that would match with them. During this restoration and after running out of ideas, I’ve decided to build a center speaker using the same HF and MF transducers used in L100 (better than a perfect match).


    So I’ve purchased a pair of Dayton Classic 5.25” shielded speakers, built a MDF cabinet and installed the same X-over above. I’ve found the result great. Good sound for music and for movies.

    Below are pics of this speaker,





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    and another from restored L100.




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    Finally, a list with some threads used here (many thanks to who posted the information) which might be useful.



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    Hope to have helped you. Good luck !!!



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    hosken , i put le25 tweeters in my straight line L100 cabs,le52 mids and i am going to use 123a-3 woofers. do i need to follow your update method to get best sound?

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    I would upgrade it for sure, even if I had everything working fine. But you need to have in mind that it takes some work, in particular to remove the foilcals to access the fourth screw holding the crossover board in place. You will find many threads to support this upgrade procedure, below are some examples:


    This would be valid for all LE-25 models to LE-26 (as I used for replacement) using the N-100 crossover. See schematics below and search the threads for more details:


    L100a - N100 crossover.pdf

    L100a late- N100 crossover.pdf

    THe upgraded crossover will be equivalent to JBL 4312's, below:


    4312 xover.pdf



    If you decide to upgrade, please tell me later if you liked the results.

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    jspeaker has acquired the original "In-line" cabinets, arguably better than the later versions, presumbably with LX12-10 crossovers installed.

    I'm not aware that anyone has documented upgrading those here; presumably there's a reasonable way to do it. The coils and capacitors are typically potted (see below).

    http://manuals.harman.com/JBL/HOM/Te...NTURY%20ts.pdf

    I have a pair, and will take a closer look.

    Here's a "Real" upgrade, but it's not L100 anymore:

    http://manuals.harman.com/JBL/HOM/Te.../L112%20ts.pdf
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