Swerd, have you compared the Murphy and the Jantzen/Gravesen crossover designs? If so, does one have an advantage over the other?
I have never heard L100 speakers with the Jantzen/Gravesen crossover. Troels Gravesen has a good reputation among DIY builders, so I believe his design should also sound good. I only know the Dennis Murphy design, which I am certain sounds good. Dennis Murphy also has an excellent reputation both as a DIY speaker designer, and as designer for the internet-direct sold commercial brands Salk Speakers and Philharmonic Audio. Dennis's crossover makes the L100's frequency response curve as flat a possible and tames much of the mid-range driver's misbehavior. The bass peak around 70-80 Hz comes from the too small cabinet, and only a new much larger sealed cabinet could fix that.
Is it possible to work the L-pads into the design or would it better to fashion a simple switch for toggling between the old and new crossover?
I think the L-pads are a problem best avoided by eliminating them. They always oxidize and pit over time, causing major noise or drop outs if you move them. If you replace the L-pads with new ones, they eventually suffer from the same problem.
Dennis Murphy's new crossover has built-in resistor padding to create a balanced neutral sound. I, and others as well, found that pleasing and eliminated any desire to raise or lower volume of the mid-range or tweeter.
One of the people who built the new Murphy crossover fashioned some elaborately wired switches to allow toggling back and forth from the original JBL crossover (including the L-pads) to the new design. He posted under the name
leesonic starting at post #73
http://forums.audioholics.com/forum...bl-west-coast-sound-becomes-the….25014/page-4. Unfortunately, the extensive photos of his work are now gone, probably they were on photobucket. He occasionally posts here.
@leesonic, If you're reading, please post your switchable crossover schematic and photos again.
You should probably read through that Audioholics thread for all of leesonic's posts. I'm not certain, but I recall that he later decided he liked the new crossovers much better and rarely switched back to the original JBL crossovers.