Info about Spendor SP1/2E crossover?

[Jose1964]

Hi everybody. This is my first post here and I hope you can help me. I own a pair of Spendor SP1/2E loudspeaker, now 10 years old, and I'm planning to upgrade them (if possible, because they sound great... only perhaps a litle polite) with an outboard filter made with better internal wiring and crossover parts.

What I know is the model of drive units (a polypropylene midwoofer made by Spendor for their SP1/2 and SP2/2, a tweeter Scanspeak D3806/8200 and a supertweeter Scanspeak D2008/8512) and the crossover points (3kHz midwoofer to tweeter and 13kHz tweeter to supertweeter), but not the circuit, slopes, inductor values, etc. It seems a very complex filter, with 14 components and a circuit I can't understand, specially the high-pass section (it's biwirable).

I'd be grateful with any suggestion or, ideally, a drawing of the original schematic.