New crossover design for L-100A

[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/showd...number=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.

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:
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.

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
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
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