When I built the crossovers in my modified L200/300s, the system was using LE175s on the short horns and 075s as the tweeters. I modified the L200 Studio Master and we came up with "Zilch tested and approved" the "Keeper Crossovers."
These used the a variation of the N7000/N8000 circuit for the high frequencies substituting a 0.5mH choke in place of the 0.7mH choke in the N7000 and 0.2 mH choke in the N8000. Let's call it a second order ~7,300 Hz.
The problem was that the 075 was so "hot" that I could never turn the L-pad up past ~1/4-1/3 of the way without the sound becoming too bright. At Zilch recommendation, I added the two resistors as a voltage divider (don't recall the values), and this knocked the 075s down to where the L-pad became useful throughout its range.
The 075s were later replaced by 2405s. Of course these are much quieter than the 075s and with the crossover components now hot glued in place on the circuit boards, it would be difficult to remove the voltage divider. I would typically run with the 2405 "wide open" just to get a decent match.
But with lots of listening and A/Bing with other speakers, I knew that I was missing the high highs and even though the voltage dividers should attenuate all frequencies similarly. Particually what was missing was the "tink" of the ride cybols, etc. Yes, I know that you hear it with the 2405, but until you can instaneously compare them with other offerings, you just don't know what you are missing.
I wanted a circuit that I could apply externally to the speakers (I can access the driver wires from the back at the crossovers) without opening them up, at least to develop it.
This is what I came up with. It adds a very high pass, 1st order filter to the existing 2nd order filter to flatten out the higher range. Because the 1st order is connected directly to the speaker, it doesn't pass through the L-pad windings and thus attenuates at a much slower rate. The 2nd order attenuates because the L-pad selects less voltage to go to the speaker
AND the speaker goes to ground. The 1st order only attenuates because the speaker goes to ground.
All caps are Solen Fast Caps with AuraCap Theta 0.10 By-pass caps riding piggyback. All resistors are Mills.