New crossover design for L-100A

[Zilch]

I just finished reading that whole thread that you linked. Nice to meet another person loony enough to try to measure freq responses on 30 year-old speakers and then crazy enough to try and flatten them out. Didn't know another one existed !

Using "Search," you'll find these forums have wrestled with L100 ad nauseam.

Tweaking with them is great good fun, but, in the end, for me at least, the bottom line is keep them for what they are, with all of their glorious '70s coloration, and build closed-box mirror-image 3 cuft L100t3 floorstanders using any of the L100 woofers, 104H-2/3, and 035tiA, for serious listening:

http://manuals.harman.com/JBL/HOM/Te...100t3%20ts.pdf

Also, perhaps of potential interest, another member and I are surreptitiously building two-ways with L100 woofers in this thread:

http://audioheritage.org/vbulletin/s...ad.php?t=12887

[Zilch]

I already had the woofer hole open so put them in from the inside so I wouldn't have a big wing-nut visible or interfering with the grilles.

You'll befuddle audio "experts" for years to come with those, Heather!

[Heh, heh.... ]

[Swerd]

Using "Search," you'll find these forums have wrestled with L100 ad nauseam.

Tweaking with them is great good fun, but, in the end, for me at least, the bottom line is keep them for what they are, with all of their glorious '70s coloration, and build closed-box mirror-image 3 cuft L100t3 floorstanders using any of the L100 woofers, 104H-2/3, and 035tiA for serious listening.

I did search this site before I posted this story, because I wanted to be sure that a completely new L-100 crossover wouldn't be flamed as heresy. I saw that more than a few had complained about the lack of smoothness, but I didn't read them in detail.

I first got into DIY speaker building because I had shopped for new speakers about 6 years ago and realized that I would have to spend a lot before I would be satisfied. I'm basically cheap, and I didn't want to drop roughly $2,000 for a decent sounding pair of full-range speakers. DIY has been fun, and led me to realize that commercial speakers cost about 3- to 5-fold more than the cost of individual parts available in the USA.

As for the L-100s, I had first expected that I would need to replace the tweeter, the midrange, or both. I always thought the woofer was rather good. But for $130 in caps, coils & resistors ($98 if you buy cheaper nonpolar electrolytic caps for the two large 30 µF and 40 µF caps) I got smooth sounding speakers that keep a lot of the great bass and lower midrange sound of the originals. I honestly think they are better than much of what is now available. The tightwad in me likes that .

I do hope that one of the respected regulars here will try these new crossovers (at least temporarily) and provide their comment. As a long-time L-100 owner, I have no hesitation at all in recommending them. This forum is by far the best place to find other L-100 owners who might be interested.

[Zilch]

I did search this site before I posted this story, because I wanted to be sure that a completely new L-100 crossover wouldn't be flamed as heresy. I saw that more than a few had complained about the lack of smoothness, but I didn't read them in detail.

To the best of my recollection, you're the first to post a comprehensive rework of L100 crossovers....

[Swerd]

Also, perhaps of potential interest, another member and I are surreptitiously building two-ways with L100 woofers in this thread:

http://audioheritage.org/vbulletin/s...ad.php?t=12887

I hadn't mentioned it in my original posts, but I encountered a Danish DIY speaker builder, Troels Gravesen, who has a detailed page on restoring an L26 http://www.troelsgravesen.dk/JBL-L26.htm. He has designed new crossovers for this as a 2-way and, after completely rebuilding them, as a 3-way http://www.troelsgravesen.dk/JBL-L26-3way.htm. Have you ever seen these sites?

I haven't heard either of his two designs, but his written English as well as his work in general appears to be very good. The photos of the finished woodwork of his DIY designs make me drool. Apparently, he has some L-100 drivers in his shop for a future restoration/rebuild.

I did send him my new crossover to see what he thought. He tried it on his emulator, and except for the usual fears of low impedance, he liked it.

[Zilch]

Have you ever seen these sites?

Thank you for the links. I see now I shouldn't be so hesitant to cut out front baffles and replace them with new mirror-imaged ones.

[Ian Mackenzie]

I did search this site before I posted this story, because I wanted to be sure that a completely new L-100 crossover wouldn't be flamed as heresy. I saw that more than a few had complained about the lack of smoothness, but I didn't read them in detail.

I first got into DIY speaker building because I had shopped for new speakers about 6 years ago and realized that I would have to spend a lot before I would be satisfied. I'm basically cheap, and I didn't want to drop roughly $2,000 for a decent sounding pair of full-range speakers. DIY has been fun, and led me to realize that commercial speakers cost about 3- to 5-fold more than the cost of individual parts available in the USA.

As for the L-100s, I had first expected that I would need to replace the tweeter, the midrange, or both. I always thought the woofer was rather good. But for $130 in caps, coils & resistors ($98 if you buy cheaper nonpolar electrolytic caps for the two large 30 µF and 40 µF caps) I got smooth sounding speakers that keep a lot of the great bass and lower midrange sound of the originals. I honestly think they are better than much of what is now available. The tightwad in me likes that .

I do hope that one of the respected regulars here will try these new crossovers (at least temporarily) and provide their comment. As a long-time L-100 owner, I have no hesitation at all in recommending them. This forum is by far the best place to find other L-100 owners who might be interested.

I would love to give it a try!

Ian

[Robh3606]

There was an article in Speaker Builder??? years back where they redid the network and changed the tweeter. This is from here-say as I never saw the article myself. Could be urban legend territory

Rob

[Earl K]

The woofer-mid crossover, at ~950 Hz, involves Linkwitz-Riley 4th order crossover slopes. The mid-tweeter crossover, at 5 kHz is also LR 4th order. The glaring 6-7 kHz peak is essentially eliminated, and the high frequency comb filter cancellations are also gone! According to Dennis,

- I don't understand the claim of LR ( 24 db per octave ) slopes ( or performance ) .
- The posted crossover schematic clearly shows a 2-pole lowpass crossing into a 3 pole ( per section ) bandpass , followed by a 3-pole hipass into the tweeter . Electrically; thats' a lowpass at 12 db, crossing into an 18 db bandpass , crossing into a 18 db per octave hipass . Perhaps you could ask Dennis how he achieves LR performance from this .
- Zilches' voltage run also seems to confirm these electrical slopes .
- The "sims" in post 4 also confirm the electrical slopes I just mentioned .

- Apart from my nitpicking, it's a nice effort at improving this icon .

[DavidF]

There was an article in Speaker Builder??? years back where they redid the network and changed the tweeter. This is from here-say as I never saw the article myself. Could be urban legend territory

Rob

Yes, you have it about right. Used the L100 as a test dummy for a software xover program under review. The author swapped out the JBL for a Focal 120 (fiberglass model I think). I have the issue somewhere in the closet. Can't scan it (no working scanner and would be copyrighted anyway, yes?) but I can provide info if anyone is interested.

DavidF

[Zilch]

David: When you find the article, PM me and I'll scan it for posting here.

I've done that with several articles before -- LHF is an educational non-profit, right?

[We are but students of legacy audio arts and sciences here.... ]

[L100t Owner]

I would love to give it a try!

Ian

I was surprised that there are not new crossover designs for the L100's here. The folks on the Klipsch site have several crossover designs for the Heritage line. it seems liek there was a lot of L100's made over the years and the crossovers seem too simple using the driver's natural rolloff.

[Mr. Widget]

I was surprised that there are not new crossover designs for the L100's here. The folks on the Klipsch site have several crossover designs for the Heritage line. it seems liek there was a lot of L100's made over the years and the crossovers seem too simple using the driver's natural rolloff.

That's an easy one... those Klipsch speakers really need a lot of help!


I think the main reason that the L100 hasn't received more attention along these lines is that if the goal is to improve upon it, JBL already did that for you... buy any one of the half dozen or so later 12" 3-ways that JBL has developed... they are all using better drivers and neworks and are real improvements... with the LSR32 and the LSR6332 being the ultimate reworking of this system.

There is also another reason that more people haven't reworked their L100s to make them more accurate. They have a signature sound that to many is much of their appeal. I get a kick out of firing mine up from time to time... it's a sonic time machine. A few years ago I was going to dump them, then I decided that firing them up once in a great while was a real kick and I'd keep them just for that purpose.


Widget

[Ducatista47]

Nice to meet another person loony enough to try to measure freq responses on 30 year-old speakers and then crazy enough to try and flatten them out. Didn't know another one existed !

Zilch is notable for his tenacity and resourcefulness, but he is not a solitary creature at Lansing Heritage. If attempting to improve thirty year old speakers were a paying profession, there would be some pretty wealthy folks here. Quite a few, actually.

Clark in Peoria, messing with my 1980 era 4345's.

[duaneage]

Widget nailed that one. I went with 4411s because I think they had the most advanced crossover of all the 3 way compact monitors. JBL went all out on those networks. A serious evolution of design.