New to me JBL L100's

Steven Tate

CEO Flat Forehead Soc.
I love vintage speakers, with all of their shortcomings, but I've never had the legendary L100's. I know there is a love/hate tug of war among speaker afficionados, and I'm not in either camp.....yet. These were very clean externally. They have the original wood grille frames and newer grill inserts - but not the sculptured foam ones. I hooked them up to my Marantz 2325 that usually drives Klipsch Fortes, and my first impression is....pretty good. I'm not blown away yet. No significant distortion at quite high volume levels playing classic rock. Bass is strong but pretty muddy to me. I haven't fiddled with the presence and brilliance controls yet to see what effect they have. I know a lot of people hate the crossovers in these. Some leave them alone, some rebuild them and some burn them in the fireplace and get some exotic new ones. So.....since I'm new to these historically popular speakers, just looking for opinions about them over all and particularly opinions about the crossovers -- leave them alone, recap or upgrade to exotic?
Steve

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Steve, congrats on your new L100's :)

Here is a bump for you as I am shocked no one has responded to your question. I own L100T's so I'm no help on the L100 as they are 2 different speakers, but I would say replacing capacitors would be a good start.
 
Nice. If they were mine, I'd probably go for the bone stock approach. Clean the L pads, "refoam" the tweeters, get new waffle grills and oil the veneer. They're never going to sound very neutral without spending hundreds on exotic crossovers, so enjoy them for what they are. At most, I'd recap them and maybe plug the ports.
 
Steve, congrats on your new L100's :)

Here is a bump for you as I am shocked no one has responded to your question. I own L100T's so I'm no help on the L100 as they are 2 different speakers, but I would say replacing capacitors would be a good start.
Thanks! I happen to have a pair of L80T's in transit to be delivered tomorrow. I'm anxious to see how they compare to the L100's. That's assuming they arrive in one piece.:eek: This is the first time I have ever bought speakers via a shipping sale.
 
Nice. If they were mine, I'd probably go for the bone stock approach. Clean the L pads, "refoam" the tweeters, get new waffle grills and oil the veneer. They're never going to sound very neutral without spending hundreds on exotic crossovers, so enjoy them for what they are. At most, I'd recap them and maybe plug the ports.
Tweeter foam already ordered from Simply Speakers. I'm thinking like you. I'm curious how much better they can sound with the expensive crossovers, but I'm not sure I'm $500 curious. :rflmao:
 
So.....since I'm new to these historically popular speakers, just looking for opinions about them over all and particularly opinions about the crossovers -- leave them alone, recap or upgrade to exotic?
You can build your totally redesigned crossovers for these speakers and get significantly improved sound. They were designed by a well known and well respected DIY speaker designer, Dennis Murphy. I did that a number of years ago, and the results are strikingly good.

See details here:
http://forums.audioholics.com/forums/threads/the-vintage-jbl-west-coast-sound-becomes-the….25014/

I last looked up prices at Madisound in April 2016. If you buy cheap non-polar electrolytic (NPE) caps for those two large caps (40 and 30 µF in the diagram) the price is about $118 per two crossover boards. If you buy somewhat more expensive metallized polypropylene (MPP) caps, the price goes up to $170.
 
Although then you lose the L pads, which has both pluses and minuses.
All pluses in my opinion.

Those variable L pads never could deal with the very ragged frequency response of the original L100a. Those L pads could only lower the responses of the mid range and/or tweeter. I forget what the old crossover frequencies were (they were simple 1st order high-pass filters only for the mid range and tweeter), but they clearly could not solve the abundant problems above 1 kHz.

With time, the L pads always oxidized and made more trouble than they were worth. The new crossover is as close to neutral as those drivers can get, and no L pads are needed to adjust their balance.
 
The minuses are that you can't adjust the outputs of the midrange and tweeter (obviously), you wind up with two dead controls on the front panel, and you've changed the classic JBL nature of the speaker model. Overall, though, maybe not deal-breakers.
 
Frequency response with original crossovers
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And with the redesigned crossovers
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Schematic of the new crossover
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I find it hard to believe that, all by themselves, a bunch or resistors, capacitors and inductors can remove the several sharp notches and bumps in the tweeter region. They look more like baffle reflections. I would love to see frequency response plots of the midrange and tweeter networks into a resistive load. Do they look like mirror images of the original measured response curves?
 
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I've never really liked the L100 since they were introduced and I've owned JBLs for over 55 years. I recently purchased the first pair I ever heard from a high-school and college friend who was the original owner. He ran them with a JBL SA660 back then. I'm restoring them to original condition and will keep them as the iconic artifact that they are. It will be fun to compare them with the other dozens of JBLs I have, most of which should easily outperform them. I'm looking forward to the L100 vs. LSR305 comparison. We've come a long way, baby!
 
I find it hard to believe that, all by themselves, a bunch or resistors, capacitors and inductors can remove the several sharp notches and bumps in the tweeter region. They look more like baffle reflections.
A good crossover can make quite a difference. The major problem with the original L100a was that it's crossover was too minimal. The woofer was unfiltered. The mid range driver had a single 8 µF cap, a 1st order high-pass filter without any higher frequency low-pass. And the tweeter also had a single cap, 3 µF. That mid range driver had a particularly ragged response (see below). Adding a low-pass filter to it below 5000 Hz helped. Yes, there were baffle reflections, as well as additive peaks and valleys because the mid and tweeter were both operating over such a wide range. All those required additional filtering or equalization – all done by the new crossover.
I would love to see frequency response plots of the midrange and tweeter networks into a resistive load. Do they look like mirror images of the original measured response curves?
All those plots you asked about, and more, can be seen in these links
http://forums.audioholics.com/forums/threads/the-vintage-jbl-west-coast-sound-becomes-the….25014/

http://www.audioheritage.org/vbulletin/showthread.php?13105-New-crossover-design-for-L-100A

Here are frequency response plots of each driver, unfiltered, but mounted in the L100a cabinet:
Woofer – pretty good for a 12" woofer
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Mid range – the biggest problem
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Tweeter – not bad below 10 kHz
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And here is the simulated (predicted) frequency response with 4th order (acoustic) crossovers at ~950 Hz and ~5000 Hz.
The woofer response is blue, the mid range is red, the tweeter is green, and all together is black.
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And finally, the measured frequency response with a real crossover in the speaker.
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I have a stock pair.I was quite enamored with them in the beginning.The shine eventually wore off as I saw how bright or harsh they can be compared to other speakers.So much so that they were on the fence.They found new life here being run with a tube preamp.It smoothed the harshness out quite a bit.As one can see they are not for everyone but in the right application they can be quite enjoyable.
 
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The minuses are that you can't adjust the outputs of the midrange and tweeter (obviously), you wind up with two dead controls on the front panel, and you've changed the classic JBL nature of the speaker model. Overall, though, maybe not deal-breakers.
Could be a dealbreaker if you decide to sell and yes your right...you will be changing the nature of a very classic speaker.One other thing I heard mentioned was stuff a sock in the port to tighten up the bass.
 
I loaned a friend of mine my 120Ti's (a later and much more refined version of an L100) to compare to his Fortes. The bass was the one area where the JBL clearly ruled. It was deeper, stronger and clearer by a long shot. Everywhere else though he preferred the transparency and dynamics of the Forte's horns. His wife did like the 120's better, but that wasn't enough for him to keep them.

Even if you did get the bass to be the same or better than the Forte, what you love about the Forte will never be present in the L100.

jblnut
 
I loaned a friend of mine my 120Ti's (a later and much more refined version of an L100) to compare to his Fortes. The bass was the one area where the JBL clearly ruled. It was deeper, stronger and clearer by a long shot. Everywhere else though he preferred the transparency and dynamics of the Forte's horns. His wife did like the 120's better, but that wasn't enough for him to keep them.

Even if you did get the bass to be the same or better than the Forte, what you love about the Forte will never be present in the L100.

jblnut
After a little more listening, I have to agree with you. The Fortes just have an overall cleaner sound than the L100. I like the JBL, and I will use them when I want to blast out some rock. But my daily drivers will still be the Fortes. I have some JBL L80t's that are going to be delivered today. I'm anxious to see how they measure up to the other two.
 
The L80t will get you better xover design and a much better tweeter, and it's closer to the 120ti than the L100. It's a great speaker in its own right but once you get into that Forte sound, it's hard to go back to anything without horns. Even I with my admitted JBL bias (and a house full) will admit that a properly setup Forte can be amazing with its lifelike dynamics and transparency. You just don't get that sound with a non-horn JBL.

But if you want to get into the high-end world of JBL's *with* horns...the game changes :)

jblnut
 
But if you want to get into the high-end world of JBL's *with* horns...the game changes :)

jblnut
I would love to have them, but I've seen the price on those and can't justify it. I've never heard the L300's, but I'll bet they are sweet sounding.
 
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