JBL Century 100 recap
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Zonker92
All shiny and chrome
8uF and 3uF per speaker. Here is the schematic, showing the values:
Here is a great thread about recapping the virtually-identical 4311:
http://www.audiokarma.org/forums/showthread.php?t=106180&highlight=4311
And another good post on same:
http://www.audiokarma.org/forums/showpost.php?p=5596338&postcount=6
And a vastly improved crossover:
http://www.troelsgravesen.dk/JBL_L100.htm
And another:
Here is a great thread about recapping the virtually-identical 4311:
http://www.audiokarma.org/forums/showthread.php?t=106180&highlight=4311
And another good post on same:
http://www.audiokarma.org/forums/showpost.php?p=5596338&postcount=6
And a vastly improved crossover:
http://www.troelsgravesen.dk/JBL_L100.htm
And another:
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Copa1934
My ears are bleeding
I don't wish to deviate from the OP question, but who has tried these "upgrades"? Also, I have all the drivers to build clones, but have been wondering about cabinet dimensions. Should they remain the same as original?8uF and 3uF per speaker. Here is the schematic, showing the values:
Here is a great thread about recapping the virtually-identical 4311:
http://www.audiokarma.org/forums/showthread.php?t=106180&highlight=4311
And another good post on same:
http://www.audiokarma.org/forums/showpost.php?p=5596338&postcount=6
And a vastly improved crossover:
http://www.troelsgravesen.dk/JBL_L100.htm
And another:
Zonker92
All shiny and chrome
I have only read anecdotes endorsing both of the "improved" crossovers, but Troels' site linked above also has a lot of data to back up his claims. I simply recapped my 4311s with bypassed Daytons, and I guess they sound better; not sure. (My garage is a simply horrible-sounding room.)
The stock cabinet is too small for that woofer, per many knowledgeable sources (including Troels and Zilch, IIRC). Check out the larger cabinet shown in one photo on Troels' site. I think you might do better copying the cabinet from the later L100T if you want a much better cabinet than stock: Flush baffle, vertical alignment, more volume, probably more bracing (and maybe mirror-imaged?). I might do that myself someday. If I did that, I'd go with a revised XO, too.
The stock cabinet is too small for that woofer, per many knowledgeable sources (including Troels and Zilch, IIRC). Check out the larger cabinet shown in one photo on Troels' site. I think you might do better copying the cabinet from the later L100T if you want a much better cabinet than stock: Flush baffle, vertical alignment, more volume, probably more bracing (and maybe mirror-imaged?). I might do that myself someday. If I did that, I'd go with a revised XO, too.
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I'd be leary. They don't look so impressive to me. They do succeed at piling in as many components as possible. Not the way I approach those things.
Copa1934
My ears are bleeding
I definitely was thinking mirror image since I have full design control. Unless speakers are vertically aligned mirror image always made sense to me.
Hey Kramp, take stuff here with a grain of salt. Pinch of this, a pinch of that, but mostly if you replace like for like you'll be doing what JBL thought was right, which means you can't go wrong. Can you do better? Who knows, only your ears will say for sure.
Nevertheless, Enjoy!
Zonker92
All shiny and chrome
Which reminds me why I have not tried them: All those parts are quite expensive. I do like the idea of putting a Zobel and low-pass filter on the woofer, though, instead of running it full-range. I also like the idea of smoothing out the midrange. If there were a simple design to that end, I'd go for it. The way it is now, the drivers are basically "going commando" and doing whatever they want to do, with no crossover control whatsoever except for the two high-pass caps and the pads.
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rcspkramp
Super Member
I plan to enjoy these. And no mods, just better currently available caps and wire. I don't want to change the sound since I like them the way they are.
I actually sold L-100s when they were new and I'm glad to have a pair come home to me.
Great minds, eh? Exactly my thoughts too.
What I find really strange is I had no idea the 4311s were "going commando" all the years I owned them. Back in those days I had no knowledge of electronics and crossovers. I never opened them up. I'm surprised they sounded as good as they did. I think that basically speaks highly of the JBL drivers.
Still, I'm curious how the JBLs would react to some simple tweaks.
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bluejazzer
New Member
JBL L100 Recap
I kept mine simple...Clarity Caps....New L pads...Cold Beer...Enjoy!
http://www.audiokarma.org/forums/showpost.php?p=4950841&postcount=26
I kept mine simple...Clarity Caps....New L pads...Cold Beer...Enjoy!
http://www.audiokarma.org/forums/showpost.php?p=4950841&postcount=26
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There's nothing particularly unusual about this crossover configuration. Recall that the L100/4310/4311 was designed to sound like the Altec duplex in a smaller package. As such, the components were designed and built, and the needed crossover was pretty minimal - in part to improve efficiency, and what was needed for the voicing with these particular components.
In order to create a flatter response (away from the "west coast sound") using the same components and cabinet, the above designs used higher order crossovers (12db/tweeter, double 18db/midrange, 12db/woofer) and some frequency shaping, all a design decision to get the drivers to operate much more in their passband and not almost full open as in the original configuration.
If you want a flatter JBL, many have suggested moving on to the 441x series of monitors which have newer and flatter designed drivers with more complex crossovers using improved crossover theory developed in the 5-7 years between the 4311 and 4411 for example. The L100T/T3 use the 2214H woofer (completely different response from the 123a) in a much larger cabinet and with a better tweeter and crossover, especially the T3 version. The 2214 was used well in the 2 way 4425 Studio Monitor.
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Looking at Troels site and having had an JBL 88+12 which is the L-88 where you can pop in the midrange later...I did just that and liked the speaker better without the midrange! The problem seems to be that nasty peak he measured in the midrange driver..if one could design a simple LCR circuit to knock this down you might be able to get away with the simplicity of the rest of the original crossover.
How about this link?
http://www.audiokarma.org/forums/showthread.php?t=349002
It details my own restoration of a pair of L100s, complete with switchable crossovers so you can go back to the original sound if you like.
Lee.
http://www.audiokarma.org/forums/showthread.php?t=349002
It details my own restoration of a pair of L100s, complete with switchable crossovers so you can go back to the original sound if you like.
Lee.
I've installed the crossovers designed by Troels G. in my L100s.
They took a speaker that sounded fairly obnoxious and turned them into something that was considerably better in my opinion.
Did any of you bother to look at the data that Troels provided? (aside from Zonker92, who appears to have done so)
As I mentioned before, I should have just waited to find a pair of 4412s, but I don't even think I was aware of what a 4412 was at the time I bought my L100s.
As our legendary Zilch stated, "fun but fake" applies, or at least in my opinion. I'd probably have dumped mine if it weren't for those crossovers. I don't listen to mine often now as I bought some NS-1000s a few years ago. I've wondered about upgrading the crossovers in the Yamahas to Troels' new design, or going active. Not sure, and the investment is pretty steep on those crossovers, app'x $500 if I recall correctly -- although an active solution is going to cost far more than that.
And if anyone has any questions regarding Troels' designs, send him an email. He great about responding. He does his own thing, but he reminds me of our own Zilch.
John
Rocko81
Super Member
Same thing I did. Just added some new caps (even kept the old ones in there just in case I want to change them back) also some new wiring and binding posts.
I want to keep the original sound for a reason, because I like it. :yes:
Just my 2 cents worth :thmbsp: Enjoy them!
-Rocko
