View Full Version : Need L-36 Crossover schematic

04-20-2005, 07:27 AM
I have done a number of searches with different terms but no luck. Can someone provide me with the schmatic for the crossover network of an L-36 3-way system?

I just bought a pair off of ebay to scavenge parts, especially the L-Pads and little knobs to convert a pair of L-88P 2-ways to 3-ways.

Out of curiosity, what type of capacitors (with the brown paper covers) are used in these networks, non-polarized electrolytics?

John Lovda

04-20-2005, 07:31 AM

04-20-2005, 08:31 AM
Thank you for your prompt reply.

I notice the L-36 network rolls off the high end of the woofer at 12 db/oct rather than letting the high end acoustical output die on its own. Have you ever tried this network in an L-100?

Second, the L-36 networks I bought have the common looking L-Pads with a gold-tone plating and a circular ring or punched out vent holes on the back. Are these the type considered "normal" or "high powered"? The schematic you provided lists them as 5 watts.

I am going to have to construct a new masonite "base" with T-nuts for my 3-way crossovers. I'm going to try to use the existing front panel screw holes to attach them including the four screws that hold the add-on midrange crossover box. The crossover inside the L-88P cabinet is crazy. There is even a black box behind the two amplifier terminals in the rear. I'll remove them tonight but I wonder what is inside them?

I haven't given up on the homemade aluminum logo plate for the L-Pad knobs. I've just had higher priorities. It's interesting. About a month ago, someone got $700 (!) for a pair of these L-88P's converted to 3-ways and he called them L-100's. He removed the front label and the cast model and serial number plate on the rear so there was no reference to the actual model.


04-20-2005, 08:42 AM
Have you ever tried this network in an L-100?Nope. Too many projects, too little time.

04-20-2005, 09:17 AM
Could you please answer the question above about the L-Pad power rating? Are the L-Pads in the image considered "high-power" or just 5 watts as noted on the schematic?


04-20-2005, 09:55 AM
"Could you please answer the question above about the L-Pad power rating? Are the L-Pads in the image considered "high-power" or just 5 watts as noted on the schematic?'

Those are as stated on the techsheet. You could always upgrade them if you want. Just go to Parts Express if you feel the need. Just watch the fit on the new ones.


04-20-2005, 10:29 AM
To second Rob...Those are the same as the ones in the schematic and look identical to the L36 crosssovers in my pair.
I would imagine that they would work quite well in an L-100. There are many similarities to the sound of the L36 to the L100. The 10" works quite well in the L36 Cabinet.

04-20-2005, 09:17 PM
My only concern, is that due to the different high-end response of the 125A vs. the 123A, there MIGHT be a "hole" in the frequency response, using the L36 crossover in an L100, between the woofer and midrange.

In an L100, there is NO woofer crossover whatsoever, and the midrange has a LARGER cap (8uf instead of 6uf). With the additional lowpass on the woofer, it may reduce output too much on the top end of that driver, and at the same time, the smaller midrange cap may prevent the midrange from going down to where it would in the L100. Hence, nothing really providing output, in that region between...

If this is the case, you could always re-build the L36 crossover (remove the entire woofer lowpass- wire the woofer directly in parallel to the input), and change the midrange cap from 6uf to 8uf (I'd probably just parallel a 2uf cap with the one that's there, instead of ripping it out) to duplicate the L100 crossover...


04-21-2005, 09:48 AM
Thanks for the info. I am probably going to just scrap the L-36 crossovers and build new ones using only the L-Pads and knobs from the L-36 units. The first problem is that on L-88P's the hole spacing between the Mid and High freq L-Pads is greater than an L-100. JBL had the kludgy metal box that came with the LE5 containing an L-Pad and capacitor and required extra clearance. I will also have to cut the masonite crossover mounting board the correct shape and place the T-nuts in locations that match holes already coming through the front baffle.

One additional question... what type of capacitors did JBL use in L-100's, L-36's, etc? These are the ones with a brown cardboard tube cover and filled with epoxy. Would these be considered junk or worth saving by crossover afficianatos? I also have to figure out how to remove them from the base board since they are held down with hot-melt glue.


07-27-2007, 06:42 AM
two years ago you have been involved in modification of L36 crossovers
and you where asking if the cardboard capacitors could be upgraded.
did you got any indication or did you experimented any upgrade?