Well...this explains it.

Here's the OB response w/o crossover and w/o the Fostex. In-room and at the listening position:



Here's the response of each w/ just the first-order filters in place:



Things worth noting:

• Low pass is ineffective at reaching the ideal curve because of the rising impedance of woofer (inductive load). See here http://www.parts-express.com/pedocs/specs/290-407-eminence-alpha-15a-specifications-44604.pdf. Fortunately, I accounted for this and cooked up an impedance flattening circuit, which should shunt away the extra HF above 200Hz, similar to a second order filter. Will be added once I actually solder the xover 
• The high pass also sucks at achieving its curve because it's still stuck in the horn. The summed response is elevated in the upper bass because of this. This shouldn't be a problem once it's out of the horn, so I'm not worried about it. The FE126 has a 10dB/octave roll off starting at 200Hz that will be working with me instead of against me
• Woofer still contributing at 1k and 2k is probably what was making vocals sound nasty
• Great bass extension. Better than I imagined. This system is able to excite the lowest mode at 38Hz, unlike the BK12 or OSMT

Now the big question is WTF is going on at 500Hz. I seem to be getting nulls at every odd multiple of that. And the weirdness still showed up in the high-pass response even when the woofer was unplugged. My best guess is that the presence of this big ass baffle in the room has to do with it. Any ideas? Possibly relevant information:

Distance from baffle to front wall: 112" -> 2.84m -> Half wave resonance at 60Hz

Distance from baffle to back wall: 70" -> 1.77m -> Half wave resonance at 100Hz

Baffle width: 24" -> .6m -> Half wave resonance at 286Hz

Baffle height: 48" -> 1.21m -> Half wave resonance at 142Hz

Perhaps a more structurally sound baffle will eliminate those nulls. Or perhaps this is par for the course with dipoles/OBs.

100u.



Again, I still have no idea what's going on at 500Hz and its odd harmonics. Some sort of weird comb filtering or whatever. Also, it seems the break-up nodes from the woofer still aren't being suppressed as well as they should be. More on this in a bit.



Fortunately, EQ is very good at curing these. Takes away the plasticky, artificial timbre from guitars which is painfully obvious on A/B. The coloration is much less noticeable with vocals actually, but the EQ still helps there too. Pushed down the 6k spike which smooths things out in the treble. Should mention that the PN seems much more indicative of what I'm hearing, so bugger the sweeps. Still think I'm noticing some weirdness with male vocals. I'm going to listen more for the next few days and compare to the my HD600 rig. I'll have them side-by-side for direct comparison.

Lessons learned:

• Trying to work first order slopes in this design was a major mistake. I originally planned with 2nd order but I figured I could be a cheap ass and get away first order (less component cost). In the end, being a cheap bastard is going to cost me more because this configuration is not up to snuff and I'm going to need to change things
• Breakup nodes from woofer still shine through. Low pass slope is not steep enough and this driver is poorly behaved
• Bass handling: the Fostex is much better behaved throughout, but lacks the ability (or rather, sounds bad) when trying to produce bass at the same time. It's just the limited excursion that's killing it. I am unable to boost subbass to compensate for dipole roll-off because it would drive the 4.5" driver crazy. Only fix for this is separate channels (bi-amping)
• Dynamat is very useful for building loudspeakers
• I seem to have placed the FE126En in just the right spot. Knowing it's got a bit of rising response on top, I put it higher on the baffle so that I would be just enough off-axis vertically. Results are good to my ears.

Don't think I was seeing it that bad before with the BK12. I'm going to haul them into my backyard and try.

Without having completely finished this thread, I already want to give big ass sucking thumbs up for this. Very nice.