AndyGrandy

I realize that this is an old thread but I'm looking to do the same thing and was wondering if NCBlueTJ had accomplished what he was aspiring to do here? Basically rebuilding the passive xover for the mid/high, while actively crossing between them and the bass bin. Anyone have a schematic for such a passive xover?

Problem solved... I decided to revert to a full range, passive setup, mute the top end, and listen to just the bass. Everything was as it should be; no muddiness etc. So, the bass bin not being the problem, nor the passive network - must be the active crossover... and then it struck me; the Marchand XM-44 is a four way xover: low, low/mid, high/mid and high. I had the 400 low pass modules in the "low" spot when they should have been in the "low/mid" one. I changed them, and voila! Thanks to everyone for the suggestions, I do appreciate that. I think I'll stick with the "hybrid" xover network (active on SS for the bass; passive SET on the top) but I'm wondering about the xover point for the active. The 15C is rated at 63 to 2800 Hz, however we all know that the response is all about the horn. In the LS, the passive (for the K-33) was set at 400 Hz (1977), however that is a bit low for the EV SM120A horn, which is stated to have a "useable" response down to 500 Hz, although in the literature it is given as 800 Hz... (the later Sentry was said to have crossed it at 400...). I'm thinking I need to cross at least at 500 but perhaps higher if the LS bass bin would allow that. Ideally I would go as high as 800 Hz but that's probably unrealistic. Anyone know how high the LS bass bin will go?

Thanks for the responses. I'll try to answer your questions... full range music sounds pretty good - except that I know that underneath that sound something is wrong, and when I mute the top end - there it is. I don't believe it goes away when the top is back, and it's affecting my enjoyment. Polarity has been checked and double checked. All OK. The original woofers had been sold before I bought the LS; don't think I didn't ask! The caps are Sonicaps from Bob Crites. Tonight I thought I'd try a pair of SET amps (left and right) on the woofs just to see if it made a difference from the SS amps I've tried. BTW, all these amps have their own attenuators. No difference. I'm afraid I don't own any of the test equipment you mention Mark 1101, but what can go wrong with the bass cabinets? I haven't opened them up, nor did I do any of the resto work on them. Besides, it appears that others who've responded have similar experiences... One thing I can (and will do), is revert to the full passive system, and try the bass (alone) that way. What opinions are there on crossover frequencies between bass and mid? Keep in mind I have Eminence 15C and EV SM120A horns (using the original K55V drivers). Also, would there be any improvement with new diaphragms in the K55s? The tweeters are time aligned physically with the mids... And to think I bought LS and a 1.3 watt SET amp to keep things simple...

1977 LaScalas. Sidewalls have been strengthened with 3/4" MDF. New Eminence Kappa 15C drivers. New Cardas internal wiring. I'm bi-amping using a Marchand XM-44 in a hybrid configuration, so Actively crossing at 400Hz, 24db slope Linkwitz Riley type. So everything above 400hz is going through the re-capped AA passive to the original K55 attached to an EV SM120A horn and Beyma CP 25 tweeters. That's the set-up. When I mute the top end, i.e. everything above 400 Hz, the sound coming from the bass bins is, well, very muddy, boomy and basically horrible sounding. Like the drivers are in a closed, padded box... I've tried two other active crossovers (Behringer and ART both two way stereo), as well as two different ss amps (Sony and Audio Source). Not that it matters but I'm driving the mid/hi combo with a Decware Zen amp, and I'm using two PSB subs on the low end. Sonic Frontiers Line 3 preamp and Cambridge CD transport and DAC. I've done a lot of reading on the Klipsch site but have not encountered any one discussing this "problem". Is it normal? No, can't be! Is their a fix? Something I've missed, something I can explore? Help! Please... AndyGrandy