New crossover design for L-100A

[Swerd]

My first speakers were a pair JBL L-100As that I bought in 1973. I always enjoyed them and still use them today. I have recently built totally new crossovers for them that correct some of the flaws of these historic 3-ways and improve their sound. No doubt, some here might consider that as a sin. I hope others will be interested in the details.

Even by today's standards, they do amazingly well for a 3-way speaker with only 2 crossover components. Their relatively high sensitivity generates an incredible attack giving music an energy and presence that few other speakers could reproduce then or today.

A few years ago, I began playing with DIY speaker building. I was originally interested in learning what features are important in making a speaker sound good. To make a long story short, it’s all in the crossover, and to a lesser extent, cabinet design. A well designed crossover can make average or even poor drivers sound decent, and a well designed crossover combined with genuinely good drivers can make for a truly excellent speaker. Other exotic or expensive tweaks that we so often hear about all make much smaller differences – if they are audible at all – in comparison to the big improvements from a good crossover.

I eventually hit upon a DIY design that is my favorite, the CAOW1, a small 2-way speaker designed by Dennis Murphy (http://murphyblaster.com/) that combines a 5¼" midwoofer (SEAS CA15RLY) with a ¾" dome tweeter (Hiquphon OW1). Although I didn’t realize it at the time, I was carefully avoiding any DIY 3-way design that might compete with my JBLs. After I built the CAOW1s, I found that I preferred listening to music over them. Except for their obvious lack of deep bass below 50 Hz, they sound much more balanced and are more satisfying for listening. Not surprisingly, their frequency response curve is flat. The JBLs, my first love, sat in silence, except for movies. They just didn’t do it for me any more. I occasionally cranked them up to get a taste of their wonderful bass attack, but they sounded wrong in the critical midrange frequencies. But before completely giving up on them, I decided to test the idea that it’s all in the crossover.

The original L-100A crossover is a good example that vintage is not always better. It contains only 1st order high-pass filters at 1.5 kHz for the midrange and 6 kHz for the tweeter. The woofer had no filter at all, and the midrange lacked any low-pass filter. It is certainly simple, but as we’ll see, it’s far too simple.

Note that some JBL drivers at that time were made with the opposite absolute polarity compared to what most manufacturers do today. On my 123A-1 woofers the red terminals were positive. I did not directly see the terminals of the other two drivers, but the midrange had black and white wires attached with the black wire positive, and the tweeter had red and black wires with red the positive. It was easy to find the polarity of a driver by using a 1.5 volt AA battery. If the plus terminals of the battery and driver were wired together, the speaker cone would pop forward.

[Swerd]

At this point, I asked Dennis Murphy, my crossover designer friend, if he was interested in this vintage make over project. His eager response generated most of the details below. I am most grateful for his expert help and enthusiastic guidance.

With his first look at the speakers he measured their frequency response curve. The curve (below) graphically shows just what “The West Coast Sound” means. Several features are prominent:


A big ugly peak appears from 6 to 7 kHz. Perhaps caused by the unfiltered breakup of the midrange driver, this peak certainly would have to be tamed.
A general rising response as frequency increases, especially above 2 kHz, that probably contributes to the L-100’s forward sound. This probably can be easily corrected.
Destructive cancellations were seen resulting in deep troughs at 3.3 kHz and above 9 kHz, producing a prominent comb filter effect. This is probably due to the unfortunate placement of the midrange driver relative to the tweeter and woofer on the front baffle.The prominent rise and fall of frequency response below 200 Hz may be the product of room reflections and their resulting standing waves and cancellations. It may not be directly due to the speaker.

[Swerd]

Further testing revealed that none of the individual drivers seemed all that bad. In fact, Dennis commented, “Those paper drivers are much better behaved at higher frequencies than many modern drivers.” A decent solution might be found without swapping in a different driver as I had originally expected. The unfiltered frequency response of the woofer is shown below, followed by the midrange, and finally by the tweeter.

[Swerd]

Dennis used his years of experience and his crossover design software to work up a new crossover. While listening to it via his crossover emulation software, he sent me this rather provoking email:

“It sounds freaking great to me. The tweeter isn’t state of the art, but it gets the job done…”

For those who don’t know Dennis Murphy, he avoids colloquial exaggerations ands is usually rather understated. When he gets excited, I sit up and take notice.

The predicted frequency response with the redesigned crossover is shown below, first with proper driver polarity and then below that with the midrange’s polarity reversed. The latter curve shows the new crossover points, and demonstrates that the drivers are in phase around the crossover frequencies when the polarities of the connections are correct.

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,

“It took more than adding a low pass filter for the midrange driver above 5 kHz because the big peak was not caused by driver break-up. It’s actually an additive diffraction artifact caused by the wide baffle and the goofy layout of the drivers. Getting rid of it wasn’t easy, and certainly wouldn’t have been possible using the design technology of the '70s.”
The profile from 10 to 20 kHz remains uneven, and is probably the best the tweeter can do – looking just like the unfiltered tweeter response curve.

[Swerd]

Dennis built a test version of the new crossover which produced the following directly measured frequency response curve. Below that is the schematic of the crossover.

I listened to it and quickly knew that I would be building them soon. If the original sound of the JBL L-100A was the "West Coast Sound", then I call this new modification the "Coast to Coast Sound".

Building the crossovers was straight forward. With the woofer removed, it was nice having an 11" diameter hole in the cabinet. All the crossover parts mounted on a 10"×7" pegboard fit in easily. I mounted the pegboard on the inside bottom of the cabinet using 1" tall plastic spacers and wood screws so that the pegboard wouldn’t crush the fiberglass cabinet lining. I also replaced the original JBL binding posts with some nice but inexpensive gold-plated brass binding posts ($1.25 each at Madisound).

How do they sound? In a word, excellent! My very first impression when I installed the first crossover, was that it made the speakers a lot less sensitive. I had expected that, but it was still quite noticeable. But despite that loss of about 5 dB, the new crossover did not suck the life out of those JBLs.

I spent about a week listening to one speaker with the new crossover, comparing it to the other speaker with the old crossover, adjusting for the change in volume. Both my wife and I agreed that the new crossover was a clear winner. I tried a wide variety of music that I knew well, including some music where I actually liked the effect that the bright JBL upper-midrange had. The new crossovers eliminate the glare and brightness that I thought I had gotten used to after all these years. The listener fatigue is gone, but the JBL excitement was still there. I remembered that years ago, I used to play with the bass and treble controls, and fiddle with the variable L-pads on the speakers, adjusting midrange and tweeter levels, trying without success to control that ear-fatigue-inducing brightness. The new crossover does it much better. It really amazes me how much better speakers sound when the frequency response curve is flat. You haven't really heard one of these old book-shelf JBL speakers until you have heard it with a proper crossover.

All the parts for two new crossovers cost me about $130. If any one is interested in a parts list, email or PM me with your email address and I'll send it to you.

[Zilch]

Does this look like the voltage drive with nominal 8-ohm loads?

[4313B]

Neato! :applaud:

http://murphyblaster.com/content.php?f=cabinets.html

Interesting... kind of goes with what JBL has done but against what others have argued.

[GordonW]

Got an impedance plot for the system? My only concern, is the 3.9uf cap going directly to ground, on the tweeter. Looks like it might have a pretty significant impedance dip at high frequencies. That kind of capacitive load might make some amps have problems...


Regards,
Gordon.

[Zilch]

The prominent rise and fall of frequency response below 200 Hz may be the product of room reflections and their resulting standing waves and cancellations. It may not be directly due to the speaker.

It is real, and intentional. The boomy bass was a major selling feature.

Plug the ports and see if you don't like the bass better:

http://audioheritage.org/vbulletin/showthread.php?p=122946#post122946

You may have to attenuate the mids and highs a bit for balance, and apply boundary reinforcement (let 'em be against the wall) to bring up the newly extended bass response....

[duaneage]

I've always said the L100 needed a crossover because it only came with two capacitors. THe cap across the tweeter is definately a potential problem, you could have ultra high frequency oscillations that may damage the amplifier. A small coil, around .2 - .4 mh would also attenuate the network further and be safer. Alternatively you could use a 4 ohm resistor between the ground of the tweeter and the leg of the cap (like a Zobel)so that it sees 4 ohms of resistance as the tweeter impedance rises. That would protect the amp.

I would use a small gauge air core choke for the .68 mH coil to give a final resistance close to what the resistor and the coil are together, it simplifies the network. Resistors can be inductive as well.

The 123A is a sealed box driver in a smallish vented box. As Zilch alludes to, plug the port and test again. You'll get a lower rolloff with less midbass boom and better transient response.

[Swerd]

Got an impedance plot for the system? My only concern, is the 3.9uf cap going directly to ground, on the tweeter. Looks like it might have a pretty significant impedance dip at high frequencies. That kind of capacitive load might make some amps have problems...
We were concerned about that, but no problems have appeared in use with 3 different amps: a small 30 wpc Marantz stereo receiver, a medium Denon 75 wpc HT receiver, and a large B&K 200 wpc external 2-channel amp. A predicted impedance plot (from LspCAD) is seen below. The blue trace is the woofer (Net 1), red is the midrange (Net 2), and green is the tweeter (Net 3). The lowest point is around 3 kHz. Note that nothing below 100 Hz shows on this plot.

Zilch
At first I didn't want to believe that woofer peak was real, but you are right. Now that the upper frequencies are tamed, the bass peak is much more prominent. I have stuffed the port with a large wad of polyfill and am thinking of other ways to block it better. I will also add more polyfill stuffing. The best solution would be to build an entirely new cabinet. I'm not ready for that quite yet.

Giskard
I'm glad to see you've read some of Dennis Murphy's web pages. He is quite interesting. He is an economist (Ph.D.), an accomplished musician (violin and piano), who is self taught in speaker design. His experience and ears make him the best crossover designer I've witnessed. In addition to the designs on his own web page (I've now heard several) he also has designed the crossovers for several commercial products: Jim Salk's speakers http://www.salksound.com/ and Dave Ellis's 1801b http://www.ellisaudio.com/1801.htm. Dennis believes obervation and direct measurements can trump theory, as he shows in the short article that you found interesting.

[Zilch]

I have stuffed the port with a large wad of polyfill and am thinking of other ways to block it better.Zilch's proprietary port blocking device, a plumbers' test plug, is available at your local hardware store for ~$3.98.

It has to be a true seal. Stuffing the port with socks, etc. won't get it.... :p

[hjames]

Zilch's proprietary port blocking device, a plumbers' test plug, is available at your local hardware store for ~$3.98.

It has to be a true seal. Stuffing the port with socks, etc. won't get it.... :p

Zilchplugz (TM) are GREAT! I got them at Lowe's/Home Despot and used a pair of them to seal the tweeter hole, and where the bass port used to be in the formerly-2ways I turned into midbass boxes.
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.

[Swerd]

Zilch's proprietary port blocking device, a plumbers' test plug, is available at your local hardware store for ~$3.98.

It has to be a true seal. Stuffing the port with socks, etc. won't get it.... :pThanks for the tip. I had been looking for something like a small Nerf football made of closed cell foam that I could cram in the port. The ZilchPlug™ seems like just the thing. I'm going to Lowe's tonight. I love the adjustable wingnut. Have you considered a remote control version? Then you could have speakers with adjustable Q ;).

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 :cheers:!

[Zilch]

Have you considered a remote control version?!


:rotfl:

[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 :cheers:!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/Technical%20Sheet/L100t3%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/showthread.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.... :thmbsup:]

[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 :D.

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.... :thmbsup:

[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/showthread.php?t=12887I 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. :thmbsup:

[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 :D.

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.... :yes: ]

[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! :duck:


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 :cheers:!

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.

[Zilch]

Zilch is notable for his tenacity and resourcefulness, but he is not a solitary creature at Lansing Heritage.Heh.

We have many, MANY loonies on LHF.

[And plenty room for more.... :thmbsup:]

[Tom Loizeaux]

Does anyone think it might be good to take some of this "new crossover..." idea and use it in a modified, low-impact way on 4312As?
By "modified" I mean:
1) Reducing the port area by adding straws(as was discussed a while back) instead of sealing the ports, and
2) adding a coil & cap on the 12" woofer to get a 12dB/octave rolloff.

Would these "low impact" mods improve the 4312 without having to change the woofer or re-do the whole network?

Just wondering.

Tom

[duaneage]

1) Reducing the port area by adding straws(as was discussed a while back) instead of sealing the ports, and
2) adding a coil & cap on the 12" woofer to get a 12dB/octave rolloff.

Would these "low impact" mods improve the 4312 without having to change the woofer or re-do the whole network?

Just wondering.

Tom
1. No. Straw ports are too restrictive. You'd be better off with a vario-vent.

2. Yes but it would impact the midrange driver, necessitating a redesign there too. You would have voltage and current phase problems that would show up either as peaks or valleys. best to do it right. It would be wise to start with another network that has 12 db slopes on the two drivers as a starting point and work from there.

If I was to do anything simple it would be a 2.5 Mh choke on the woofer with a Zobel to tame the impedance rise and allow the coil to work better. A 6 db slop is phase friendly enough and would offer modest improvements at minimal fuss.

[Swerd]

- 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 .:)It's a good question - not nitpicking. From my point of view, there's a difference between the electrical performance of a filter and the acoustic performance of a driver combined with the filter. In this case, the filters, which are clearly not 4th order electrical, when combined with the drivers result in acoustic roll-off slopes that more closely resemble LR 4th order than anything else. You can see this in the second graph in part 4 of my long write up, where the polarity of the midrange is reversed. I should have been more clear about that when I first wrote this.

[4313B]

In this case, the filters, which are clearly not 4th order electrical, when combined with the drivers result in acoustic roll-off slopes that more closely resemble LR 4th order than anything else.Yes. For instance, some systems end up having 2-pole electrical filters summed with sealed enclosures (which are 2-pole mechanical filters) to achieve a 4th order acoustic roll-off. Note that compression drivers are "sealed enclosures".

The glaring 6-7 kHz peak is essentially eliminated, and the high frequency comb filter cancellations are also gone! According to Dennis,


“It took more than adding a low pass filter for the midrange driver above 5 kHz because the big peak was not caused by driver break-up. It’s actually an additive diffraction artifact caused by the wide baffle and the goofy layout of the drivers. Getting rid of it wasn’t easy, and certainly wouldn’t have been possible using the design technology of the '70s.”
Very nice! Driver layout can't be stressed enough. Of course in this particular instance the whole design was "by design" and people really liked them (or disliked them). I liked them during their era. They were fun. It's pretty fun to mess around with new filters since they have such a profound effect on the various systems.

[Swerd]

Driver layout can't be stressed enough.Agreed

This whole excercise has been a vivid lesson for me why almost all speakers today keep the drivers arranged in a vertical line. This photo http://www.audioheritage.org/html/profiles/jbl/l100.htm ) shows different layouts of various JBL studio monitors made in the '70s. The redesigned crossover I’ve described above is designed specifically for the L-100A (2nd from left). It fixes the additive and subtractive peaks caused by its particular "goofy" driver layout. For other layouts, the crossover may work OK, but because I haven't had a chance to test it with those layouts, all bets are off.

[4313B]

For other layouts, the crossover may work OK, but because I haven't had a chance to test it with those layouts, all bets are off.Very true.

There have been more than a few who have taken various driver complements and changed baffle dimensions and driver layouts who then wondered why the results didn't sound nearly as good as expected due to them not reworking the filters as well.

There are really good points that have been stressed again in this thread and I won't belabor them.

Thanks for starting the thread. It is a great example of the kinds of threads I'd hoped to eventually see occur here. Excellent presentation and no real flak from the peanut gallery. I like it. :)

[GordonW]

Very true.

There have been more than a few who have taken various driver complements and changed baffle dimensions and driver layouts who then wondered why the results didn't sound nearly as good as expected due to them not reworking the filters as well.


No doubt! Even small differences in baffles can make a difference! My modified L100s in the larger cabinets (using a straight-line config on the mid and tweeter, with the drivers offset less extremely compared to a stock L100) had MUCH BETTER behaviour in the 3-5KHz region than a stock L100, even using a stock L100 crossover! All because of the driver LOCATION in the baffle, as the width was the SAME as the original L100!




Thanks for starting the thread. It is a great example of the kinds of threads I'd hoped to eventually see occur here. Excellent presentation and no real flak from the peanut gallery. I like it. :)

As they say on "the street": Game recognizes game! :coolness:

Regards,
Gordon.

[L100t Owner]

Agreed

This whole excercise has been a vivid lesson for me why almost all speakers today keep the drivers arranged in a vertical line. This photo http://www.audioheritage.org/html/profiles/jbl/l100.htm ) shows different layouts of various JBL studio monitors made in the '70s. The redesigned crossover I’ve described above is designed specifically for the L-100A (2nd from left). It fixes the additive and subtractive peaks caused by its particular "goofy" driver layout. For other layouts, the crossover may work OK, but because I haven't had a chance to test it with those layouts, all bets are off.

I have the L100A's and was planning on a crossover rebuild. You say that there is a 5 db drop in efficiency? That's quite a bit, where do you end up, about 86 db at 1 watt/ 1 meter?

[Tom Loizeaux]

Agreed

[FONT=Verdana] ...particular "goofy" driver layout...

I believe these "goofy" driver layouts were an attempt to get all the drivers as close to each other as possible. Remember, these monitors were designed to work in both a vertical and horizontal orientation. A line of drivers would work in only one orientation.

Tom

[Swerd]

I have the L100A's and was planning on a crossover rebuild. You say that there is a 5 db drop in efficiency? That's quite a bit, where do you end up, about 86 db at 1 watt/ 1 meter?I estimated a 5 dB drop from eyeballing the old and new frequency response curves. Both of them are posted in my earlier posts. Look at them and decide for yourself. A problem with such a comparison is that the old frequency response curve was far from smooth and how do you decide which SPL level represents the nominal sensitivity. Is it the peaks or the low points which are about 5 dB lower? The new crossover is much flatter and seems to hover around 80 dB (as measured), with a few higher frequency dips below that.

Please remember that no effort was made to measure the correct overall SPL levels. You would need a known calibration standard to do that accurately. They do, however, show the relative differences in SPL between the old and new crossovers.

I drive these speakers with a moderately powered Denon AVR-1800 home theater receiver. It is rated at 75 wpc RMS when two channels are used. It works fine with the new crossovers. I do increase the volume somewhat over levels that I used to use, but it is not a problem in my family room (about 16 × 22'). Although a larger amp might be great with these speakers, they do not require one.

I was concerned with the possibility of loosing sensitivity when I did this redesign. In my hands, this has not been a problem, and I don't want this to discourage any one from trying this design. I hope this helps.

[Swerd]

Look at the frequency response curve of the original crossover (post #2). There are two triangular markers labled 1 and 2, located at 500 Hz and 1,000 Hz respectively. Below the graph itself are two boxes that show the relative SPL of each of those markers. At 500 Hz it is 81.4 dB and at 1,000 Hz it is 81.7 dB.

Scroll down to post #7 and see those two markers at the same frequencies for the new crossover. 500 Hz is now 79.7 dB and 1,000 Hz is 78.7 dB. Subtracting, you get a loss of 1.7 dB at 500 Hz and 3.0 dB at 1,000 Hz.

500 Hz is an octave below the crossover point, where the new crossover rolls-off little of the woofer's response, and 1,000 Hz is where both the woofer and midrange contribute nearly equally, in the middle of the woofer-midrange crossover point. At those two points, the new crossover lowers sensitivity by 3 dB or less. That is better than my previous estimate of a 5 dB loss.

[duaneage]

No doubt! Even small differences in baffles can make a difference! My modified L100s in the larger cabinets (using a straight-line config on the mid and tweeter, with the drivers offset less extremely compared to a stock L100) had MUCH BETTER behaviour in the 3-5KHz region than a stock L100, even using a stock L100 crossover! All because of the driver LOCATION in the baffle, as the width was the SAME as the original L100!
Originally Posted by Giskard http://audioheritage.org/vbulletin/images/buttons/viewpost.gif (http://audioheritage.org/vbulletin/showthread.php?p=134679#post134679)

Thanks for starting the thread. It is a great example of the kinds of threads I'd hoped to eventually see occur here. Excellent presentation and no real flak from the peanut gallery. I like it.


As they say on "the street": Game recognizes game! :coolness:

Regards,
Gordon.

I duplicated exactly the L20 driver offsets and distances for my tower redesign because the acoustic centers are critical for comparing one box design to another. This left the box as the only variable.

I also agree that we should continue to recognize efforts for what they are and learn from them without bigger pictures of " why do that" or " that's not the way it was done". I plan to show how to cheaply and easily tune the L100T crossover to L100T3 specs without buying a fortune in parts. The exercise should show a way to get there without much trouble

[Zilch]

Article courtesy DavidF.

[Zilchscan Enterprises, Inc.]

[Zilch]

.

[Zilch]

O.K., L100 enthusiasts, start building crossovers, now!


:bouncy: :bouncy: :bouncy:


The Zobel I came up with empirically is 6 Ohms and 30 uF, yielding a 5-Ohm impedance with the woofer.


White shows 5.5 Ohms and 31 uF.... :thmbsup:


Who'll tackle this with LEAP?

Are White's models of the drivers good by today's standards?

[boputnam]

...it’s all in the crossover, and to a lesser extent, cabinet design. A well designed crossover can make average or even poor drivers sound decent, and a well designed crossover combined with genuinely good drivers can make for a truly excellent speaker. So true, and a valuable discovery (worth sharing!). Individual measurements of each driver's response mounted IN the actual baffle and cabinet provide invaluable information as to their contribution to the whole. Designing for that response is the only way.

Collecting meaningful measurements is key. Can you provide details on the set-up Dennis Murphy uses? I cannot find description on his website. Poor data collection results in a flawed understanding of driver/baffle/cabinet response. Clearly, your results were good, having been based upon representative/reproducable measurements. It would be nice to know how he approaches this.


There are really good points that have been stressed again in this thread and I won't belabor them. ... Excellent presentation Agreed. From individual driver response and polarity (:applaud: ), to baffle layout, crossover point and slopes, and listening impressions (besides just nice plots) - and all that on L100's!!

[DavidF]

O.K., L100 enthusiasts, start building crossovers, now!


:bouncy: :bouncy: :bouncy:


The Zobel I came up with empirically is 6 Ohms and 30 uF, yielding a 5-Ohm impedance with the woofer.


White shows 5.5 Ohms and 31 uF.... :thmbsup:


Who'll tackle this with LEAP?



Are White's models of the drivers good by today's standards?




A pop quiz for true JBL D.Y.I types on the xover schematic on the magazine page 48. What is the translation to cone motion for the polarity scheme as shown?

DavidF








“+” x-over leg to woofer black terminal giving outward motion-positive pulse.
“+” x-over leg to mid black terminal giving outward motion-positive pulse.
“+” x-over leg to tweeter negative terminal giving inward motion-positive pulse.
This was confirmed in a later issue. White mentioned he preferred this arrangement after listening and testing the polarity of the system drivers with a switch and a run of speaker wire that could invert phase in the listening position.

[Hoerninger]

Article courtesy DavidF.

Great grip back! (1989)

Found at Prosoundweb.com:

... CASD ... DOS-based package from Scientific Design Software that has since been discontinued ... Anywhere available? (could let it run)
____________
Peter

[Hoerninger]

Are White's models of the drivers good by today's standards?

Although I'm not sure about today's standards, seriously spoken, I regard White's model as sufficient in most cases.

He models
- speaker resonance and
- the voice coil specs
as far as i have understood the article. (Simulation of cone brakeups would be very specific and are hardly to implement in a general model.)

In a "younger" articel in Speaker Builder 3/91 by Roy Mallory, I have a German translation published in ELRAD, they are only modeling the resonance frequency by SPICE.

Marshall Leach has investigated the influence of voice coil losses using SPICE, which is very specific and not so much known:
http://users.ece.gatech.edu/~mleach/papers/vcinduc.pdf (http://users.ece.gatech.edu/%7Emleach/papers/vcinduc.pdf)

Hope this was helpful.
____________
Peter

PS: OT in this thread, but I'm wondering how the influence of a horn /waveguide can be modeled in SPICE.

[boputnam]

What is the translation to cone motion for the polarity scheme as shown?I don't see anyone having replied, so...

If that is a 123A-1 (likely since it's the L100A...), as diagramed, the woof will move in on (+) voltage. The 123A-1 is a positive transducer, a "lone woof" back in the day, but here is (+) signal connected to BLK terminal.

What'd I win...?

[Swerd]

Can you provide details on the set-up Dennis Murphy uses?When I read your post yesterday, I emailed Dennis to get some details. No answer yet.

I do know he uses LspCAD professional (http://www.ijdata.com/products.html) for design and emulation and Praxis (http://www.libinst.com/) for measurements. LspCAD pro requires a full duplex sound card. I don't know which sound card or microphone he uses.

When I hear from Dennis I'll pass on whatever additional info he adds.

[boputnam]

When I hear from Dennis I'll pass on whatever additional info he adds.Great, thanks.

Also ask about the physical set-up - driver and mic placement/positioning, in-doors or out, proximity, etc.

Everyone has their little tweaks that work for them...

[Swerd]

Also ask about the physical set-up - driver and mic placement/positioning, in-doors or out, proximity, etc.This is what I can remember.

All the measurements were done in-doors. So the responses below 200 Hz reflected the standing wave patterns in Dennis's workroom. He had recently moved to different house and was not real familiar with these bass patterns. This was one reason why I was initially inclined to ignore the bass peak from the ported small-volume L-100 cabinet. We thought it might be due to room response.

The cabinet was always standing vertically on an 18" tall stand with the tweeter on top.

The overall distance from the mic to the front baffle was more than 1 meter, perhaps as much as 2 meters, but not more than that. A lot of trial and error was done to determine mic placement relative to the drivers while making measurements. With a large 3-way speaker, just where you place the mic relative to each of the drivers makes a difference, and I don't remember what that placement was. Dennis tried a large number of locations before he was satisfied that he was getting representative sweeps.

A listening distance of about 10' or 3 meters was assumed while designing the crossover.

[boputnam]

A listening distance of about 10' or 3 meters was assumed while designing the crossover.That is a very interesting thought - it may engender some discussion here. By that I mean, in a parallel topic, many EQ their system at close-in positions - others prefer the listening position. Results certainly differ, but what matters is the result in the listening position.

I know that using my roadgear I "tune" the response of the mains at fairly close range (out-doors) - this includes parametric EQ presets for each output (i.e., speaker element) of my tri-amp system, and then time align, same-same. When I get to the venue, I leave those output presets unchanged, and use input parametrics to tune to the venue.

Since you are optimizing the speakers for your setting, in your case it makes sense to go the "listening position" route. I suppose mass marketing for variable / unknown listening positions demands speaker makers use closer-in measurements of the elements themselves / together, minimizing room / acoustic affects.

Thanks for the reply. Interesting thread - and it's about L100's!! ;)

[johnhb]

One of my new JBL converts is starting with 4311s. Years ago I hot rodded a set with a 12 db crossover and replaced the LE25 with an 035T. I cannot find my schematic so I forwarded him your crossover design. I did find in my pile of JBL literature the tech sheet for S70 Alpha III. It had a 12db crossover typical of other L series and had almost the same components as the L-100. I was thinking this crossover might be another starting point.

[Swerd]

All the parts for two new crossovers cost me about $130. If any one is interested in a parts list, email or PM me with your email address and I'll send it to you.Several people have asked for this parts list along with a crossover layout diagram. I posted these on another thread located here:

http://audioheritage.org/vbulletin/showthread.php?p=156952#post156952

[johnhb]

I'm sure it has been discussed many times but is there a copy of the JBL technical bulletin on polarity posted? It should be referenced whenever the 4311 or L-100s and crossovers are discussed because of the oddity of the 123A polarity. If the bulletin isn't posted I can scan it and post it.

[Zilch]

http://www.jblpro.com/tech-library/JBL_TechNoteN1V12C_v5.pdf

[Russellc]

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:)
You are correct, I may still have that issue. I believe it was audio Amatuer back then. I'm in the middle of getting ready to move, so it will likely turn up.
Whoops, forgot how old this post was...I see it was scanned long ago!

Russellc

[markdam]

my L100s are crapping out after 2 years of daily use.Il ove them and as the slowly went i didn notice it.... till today midrange is intermittently going in and out and the tweeter seems to have become a min midrange! anywy my question is..in the new Xover design why have we eliminated the adjustable pots? they are very useful in taming the room...... I will be building a set of Xovers or buying a kit from Jantzen still doing resaech on the two.... anyone else do a rebuild? please chime in with reports!!!!!

[Rusnzha]

I made charge coupled crossovers for my L100s. There was a real improvement. I also swapped out the LE5-2s for 104H mids -- real nice and since your mids might be crapping out, this would improve things also.

[markdam]

I made charge coupled crossovers for my L100s. There was a real improvement. I also swapped out the LE5-2s for 104H mids -- real nice and since your mids might be crapping out, this would improve things also.

thank you sir! ! believe i will retain the basic stock XOVER but tweak a little by adding the .01 by pass caps and replace L pads.

anyone else recap their L100's?

[Swerd]

my L100s are crapping out after 2 years of daily use.Il ove them and as the slowly went i didn notice it.... till today midrange is intermittently going in and out and the tweeter seems to have become a min midrange! anywy my question is..in the new Xover design why have we eliminated the adjustable pots? they are very useful in taming the room...... I will be building a set of Xovers or buying a kit from Jantzen still doing resaech on the two.... anyone else do a rebuild? please chime in with reports!!!!!The reason why I (and others) eliminated those adjustable L-pads is that they get oxidized and pitted with time, causing those intermittent losses you experienced. New ones will eventually suffer the same fate.

The new L100A crossover eliminates the treble brightness and glaring peaks in the upper midrange that led so many people to fiddle constantly with those L-pads, seeking to tame them.

Sorry about the late reply to your question. I'm afraid I may be too late for you, but perhaps others may read this with the same question in mind.

[pos]

Just fell upon this while surfing on partsexpress.com:
http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=260-896

[markdam]

Can we use the jantzen crossovers AND Lpads?
I still like the Lpad option for room tuning as all rooms are different. plus new lpads are available.

[Swerd]

Can we use the jantzen crossovers AND Lpads?
I still like the Lpad option for room tuning as all rooms are different. plus new lpads are available.Other than the fact that L-pads fail with time, there is no reason why you can't add them in. I personally don't think they are needed.

Thanks for that link from Parts Express. Wow $298! The parts for my crossover should cost a lot less than that. Two years ago, I priced it at about $130/pair. Get parts list here (http://audioheritage.org/vbulletin/showpost.php?p=156952&postcount=67).

I can't say which crossover may work better, I've only heard mine.

Neither of those crossovers can correct the bloated bass of the L-100s. In fact I noticed it more after installing the new crossovers. I do recommend closing up the port vents with Zilch Plugs.

[jules_gerfault]

hi folks,

I apologize in advance for my poor english....

I own since 6 years a pair of JBL 4311wx-a. the speakers are le25, le5-2, and a 2213, special one, reconed with a 21005p, designed for 123a. but the result sounds good to me, as I haven't heard any other speaker, such as original 123a or 2213.

After many tries to find the best place in my living room, I found it. but it was very uncomfortable fore anything else than listening to music. I became resonable, and came back in a compromise situation: sound quite good, and easier living.

To fight this bommy bass, I started filling (half filling only) the ports with wrapped corrugated cardboard to reduce the diameter,and so lower the tuning frequency. The result is quite nice, but doesn't extend the bass response. But I haven't measured, so it's an "impression" only. For sure, bass is tighter, more precise.I really would like to try the zilch plugs, but it's impossible to find in France, and not very simple to import them from US or Canada. but, one day... I'm patient !!!

I'm also interested in build th improved crossover, but i'm afraid it didn't fit with the 2213 for the bass. Do you have any opinions about it ?

thanks and good night (it's 11 pm for me !!)

[p_korner]

Interesting that this good old thread is dug out again…

To remedy the boomy bass, I prefer lowering the bass reflex tuning rather than closing the port. This can be done by lengthening the duct inside the box, and be easily be done experimentally on the outside by inserting a rolled piece of paper and trying out different additional lengths…
When lowering the bass reflex tuning, not only does the frequency response get more even and extended, but also the transient response is improved. When doing this, both impedance peaks due to the bass reflex tuning are lowered in frequency, but the lowest one is shifted much more. Consequently, the frequency range where the bass reflex tuning controls woofer cone movement is extended.

A note on the 4310/4311/4312/L100/L100A woofers.
It is often stated that they should be a more or less alike since sharing the same spec, but I found that to be not entirely true. I own, or have owned, the 2212, 2213, 2213H and 123A-1. Here are some impressions of my units:
The 2212 and the 123A-1 share the same frame, but the magnets have different weights. I have found the 123A-1 to feel generally “weaker”, have lower perceived sensitivity, less dynamics, and not be as transient capable as the 2212.
The 2213 also feels a bit “weaker” than the 2212, but not like the 123A-1.
The 2213H has a somewhat different impedance curve compared to the others, and doesn’t function well with x-over networks optimized for the 2212 in the 500-1000 Hz range. My units only?

I prefer the subjective low level clarity of the Alnico magnet types.

All these woofers benefit from venting the spiders, which can be done by carefully cutting a couple of square-centimeter holes in the spider. This generally “releases” the bass, and also makes their Q even higher. If used in bass reflex enclosures, you typically need to lower the tuning after having vented the spiders. E.g. I use vented 2212s in 120 liter reflex boxes with an Fb of 17 Hz with very good and “extended” results. My modified L100s use vented 2213s with the reflex ducts lengthened by as much as 4”.

[mgadei]

Hello from Canada

Hi, few months ago I bought a pair of 4311wxa almost mint, drivers in perfect shape, originals but due to their age, I recapped them and I also changed the Lpads. The drives were also installed with the corect polarity.
After a while I noticed that glare in the high spectrum and I started to look for an updated crossover. I found this thread, and because till now I did not had the oportunity to thank you "officially" Swerd, I thank you now, for this great thread. I ordered the parts, still not received all of them (from PE- very slow shipping with ups) i started to make my printed boards. Since I am not doing this often anymore, I use the old technique, drilling, painting traces and etching. so... maybe it does not have a professional look, but they will be ok. I will try to post a few pictures of the boards.
I think it's a well designed crossover, although, I have a little reserve with the 3.9uF over the tweeter. I kept a place on my printed boards for an aditional resistor with this cap. I will test when they will be ready. Being in size as big as a letter page, each board is big enough to confortably get all the components.On the edges they are many holes for fixation, with spacers, and right in the middle they are the main source connections. The binding posts will be changed with more reliable ones, and the contacts to the board will be made with nuts and washers, on the ended screws of the binding posts. The coils will be placed on an adhesive silycone bed, and fixed with plastic ties. The big core coil I will fix it with silicone and laiton/plastic screws. All capacitors will be glued with silycone too to avoid vibrations. Hope this will help, at lest with some ideas if not a complete solution, for the interested guys willing to give a second life to these speakers.Thanks to all of you for this great update.

[Swerd]

… I found this thread, and because till now I did not have the oportunity to thank you "officially" Swerd, I thank you now, for this great thread.De rien :). Thank you for your efforts at making the printed circuit board. I hope someone here finds them useful.

I think is a well designed crossover, although, I have a little reserve with the 3.9uF over the tweeter. I kept a place on my printed boards for an aditional resistor with this cap. I will test when they will be ready.I discussed your question with Dennis Murphy by email. He said he will have to look into his old files and get back to me with an answer.

In brief, mgadei wonders about the 3.9 µF capacitor (C3061) in the tweeter circuit:http://www.audioheritage.org/vbulletin/attachment.php?attachmentid=20551&stc=1&d=1163708993
In post #8 of this thread, GordonW asked a similar question:
Got an impedance plot for the system? My only concern, is the 3.9uf cap going directly to ground, on the tweeter. Looks like it might have a pretty significant impedance dip at high frequencies. That kind of capacitive load might make some amps have problems...


My answer (post #11):
We were concerned about that, but no problems have appeared in use with 3 different amps: a small 30 wpc Marantz stereo receiver, a medium Denon 75 wpc HT receiver, and a large B&K 200 wpc external 2-channel amp. A predicted impedance plot (from LspCAD) is seen below. The blue trace is the woofer (Net 1), red is the midrange (Net 2), and green is the tweeter (Net 3). The lowest point is around 3 kHz. Note that nothing below 100 Hz shows on this plot.


http://www.audioheritage.org/vbulletin/attachment.php?attachmentid=20593&stc=1&d=1163775093

I would also add that the tweeter is active at 5 kHz and higher. At those frequencies, the impedance is no lower than 10 ohms. The lowest impedance (about 4 ohms) for the entire frequency range shown appears around 3 kHz, where the mid range operates. So, I don't see any low impedance for the tweeter that could be attributed to the location of that 3.9 µF cap. And with the amplifiers I've used, I have not encountered any problems.

This does not directly address the question, but I hope it shows how it doesn't appear to be a problem.

[mgadei]

... one board assembled...
I forgot to take some pictures of the board installed, I will post some when the second speaker will be done. I tested the board, with an aditional resistor 3.9ohm serial with 3.9uF and I also tested with Lpads. Finally it sounds amazing WITHOUT Lpads and WITHOUT any aditional components, exactly as Swerd post it. Good ballance, far more neutral than the original crossover.

[Tony Sullivan]

mgadei (http://www.audioheritage.org/vbulletin/member.php?23029-mgadei)
How are you wiring the woofer?
I see your schematic but what convention?
With your new network installed is it wired to move the cone in or out with a positive voltage applied to the red speaker wire input terminal for the whole cabinet?
Very beautiful work I am happy to see you do this
Will you please post an up to date parts list for this project when you have time?
Thank you

[mgadei]

mgadei (http://www.audioheritage.org/vbulletin/member.php?23029-mgadei)
How are you wiring the woofer?
I see your schematic but what convention?
With your new network installed is it wired to move the cone in or out with a positive voltage applied to the red speaker wire input terminal for the whole cabinet?
Very beautiful work I am happy to see you do this
Will you please post an up to date parts list for this project when you have time?
Thank you

Hi.The cones should move outside, all of them. so + of the batt will be + of the speaker. The "real" + of the woofer goes to the + w (woofer) of the crossover. The red post on the drives might be the negative (old JBL convention). On mines it was like this. so I took a black marker and ...made the red one... black. For the other one I used a red paint dot. Just to be shure that in future ( If I ever need to reopen these speakers) I will not conect them with the original, wrong polarity. Check all the drives individually and mark the positive post correctly. This problem was so much discussed that it might create confussion.Hope to be clear. Don't test the polarity with the battery conected on cabinet posts, the mids and tweeters will not move, as you have capacitors in their circuits . Disconect them, test and mark them corectly.
For an updated part list.... there is no update practically.
I ordered just the 2.5mH core inductor( Erse) from PE, because it was not available at Solen Canada. All the rest I ordered from Canada because of the currency and shipping/import taxes.All resistors are 16watts non inductive, the air coils 16awg or 15, and caps rated 250volts. (Dayton or Solen). On the board you have plenty of space even for larger caps, and anyway you can modify it very easy. Just keep the copper traces as large as possible. If you need further info just ask.

[Tony Sullivan]

Hi.The cones should move outside, all of them. so + of the batt will be + of the speaker. The "real" + of the woofer goes to the + w (woofer) of the crossover. The red post on the drives might be the negative (old JBL convention). On mines it was like this. so I took a black marker and ...made the red one... black. For the other one I used a red paint dot. Just to be shure that in future ( If I ever need to reopen these speakers) I will not conect them with the original, wrong polarity. Check all the drives individually and mark the positive post correctly. This problem was so much discussed that it might create confussion.Hope to be clear. Don't test the polarity with the battery conected on cabinet posts, the mids and tweeters will not move, as you have capacitors in their circuits . Disconect them, test and mark them corectly.
For an updated part list.... there is no update practically.
I ordered just the 2.5mH core inductor( Erse) from PE, because it was not available at Solen Canada. All the rest I ordered from Canada because of the currency and shipping/import taxes.All resistors are 16watts non inductive, the air coils 16awg or 15, and caps rated 250volts. (Dayton or Solen). On the board you have plenty of space even for larger caps, and anyway you can modify it very easy. Just keep the copper traces as large as possible. If you need further info just ask.
Thank you
Was just hoping for an up to date parts list of all your specific values, brands and types choices-without trying to discern them from the several drawings and photos
I think I will build this as you did except I will hard wire it
Thank you again
Tony

[Swerd]

How are you wiring the woofer?
I see your schematic but what convention?To be sure, test each individual driver with a 1.5 volt AA battery. A driver's terminal is positive if attaching the positive end of the battery makes the cone move forward.

Was just hoping for an up to date parts list of all your specific values, brands and types choices-without trying to discern them from the several drawings and photosTony,

I will send you, by private message (PM), my email address. If you email me, I will send you a pdf of the full write up for the new crossover design, along with a photo and diagram of the board I built, and a parts list with prices as of April 2016.

Richard

[mgadei]

http://forums.audioholics.com/forums/threads/the-vintage-jbl-west-coast-sound-becomes-the%E2%80%A6.25014/page-2#post-277052


the lists originally posted by Swerd are there too. Post 32, see attached files. Hope the link will work...

[dcoates]

To be sure, test each individual driver with a 1.5 volt AA battery. A driver's terminal is positive if attaching the positive end of the battery makes the cone move forward.
Tony,

I will send you, by private message (PM), my email address. If you email me, I will send you a pdf of the full write up for the new crossover design, along with a photo and diagram of the board I built, and a parts list with prices as of April 2016.

Richard

Hello All, New member - or at least poster - here. I have slowly been acquiring L-100's to replace my aging Paradigm speakers in my shop system. I now have 5 pair consisting of:

#1 sn 14293 & 14404 (original vertically aligned drivers) - 123A-1, LE5-2, LE20
#2 sn 84289A & 88301A 123A-1, LE5-2, LE25
#3 sn 147270A & 162389A 2213, LE5-2, LE25
#4 sn 2102018A & 210222A 123A-3, LE5-2, LE25 (replacing with LE25-2)
#5 sn 306140A & 306168A 123A-3, LE5-2, LE25

I have been through all the cabinets (not the first) to replace binding posts and get them all in phase. By "in phase" I mean woofers firing out with amp+ connected to red+ binding post. Changes were as follows:

#1 Cabinet fired neg. (woofer moves in with amp+ to red binding post). I reversed connections at all 3 speakers.
#2 Cabinet fired pos. No changes made
#3 Cabinet fired neg. (woofer should have been 123A-1 - a pos. woofer) I reversed woofer connections only.
#4 Same as #3
#5 Cabinet fired neg. (correct for late model orange - non Century - foilcal) I reversed connections at all 3 speakers.

I believe by doing all this I have been listening to the speakers as JBL designed them to sound.

This said, I've had these up and running for a few weeks and have grown a bit weary of the upper mid/high response. Even with all "presence" pots turned all the way down.
I am building Murphy Xovers for at least 4 pair (#2 through #5). I will also be installing "Zilch plugs" as an attempt to tighten up the low/mid response. I employ (4) 4645B sub cabinets in my system so I'm not looking for much low end from the L-100's - just more punch. My questions are these:

1) I will be connecting new Xover speaker +out to the ACTUAL + terminal of each driver (not necessarily red). All drivers fire out. CORRECT???
2) Has anyone used the Murphy design with the original L-100 (vertical alignment and L20 tweeter)? Should I be building 5 sets of Xovers?

[Swerd]

This said, I've had these up and running for a few weeks and have grown a bit weary of the upper mid/high response. Even with all "presence" pots turned all the way down.I'm not surprised at that.

I am building Murphy Xovers for at least 4 pair (#2 through #5). I will also be installing "Zilch plugs" as an attempt to tighten up the low/mid response. I employ (4) 4645B sub cabinets in my system so I'm not looking for much low end from the L-100's - just more punch. My questions are these:

1) I will be connecting new Xover speaker +out to the ACTUAL + terminal of each driver (not necessarily red). All drivers fire out. CORRECT???Yes. In the Murphy crossover, all 3 drivers should be wired with the same polarity. The crossover requires that.

In the L-100A speakers I had, the woofer and tweeter were originally wired with the same polarity (in phase with each other), but the mid range was intentionally wired with opposite polarity. With the original crossover, that wiring allowed all 3 drivers to work in phase with each other. Over time, JBL apparently manufactured some of its drivers with different polarity. That's why I made the point about testing the drivers you have, as you did.

2) Has anyone used the Murphy design with the original L-100 (vertical alignment and L20 tweeter)? Should I be building 5 sets of Xovers?I've heard the Murphy crossover only in the L-100A but not in the original L-100. So I don't have a direct answer for you. You'll be building at least 4 pairs of crossovers. You could easily temporarily wire one of them into one of your L-100s and compare it's sound to that of the Murphy crossover in the L-100A.

Please tell us about your results.

If you want a pdf copy of the design, send me your email address by PM.