Update. I suspected the woofer was not playing clear. I experimented with stuffing, but it didn't help. I asked for help on diyaudio, and a local DIY speaker expert called to talk about speaker boxes, Q, acoustics etc. I met him once before but I'm glad to meet him again now that I am doing speakers more seriously than before.
My measurements indicated that my speakers are fine. The problem is room acoustics blurring the sound. So today I used my new OmniMic to better position the speakers, fine tune the baffle step compensation to match the room gain on each side individually, then applied 4 different paraEQs to each speaker to get flat, and R/L level compensations. The digital adjustments available in JRiver are very useful.
The speakers are a foot closer together now, and a foot closer to me. While the sound is still not perfect, it is much better. The room effect has been reduced enough (in the sweet spot) that I can now hear that the room is the problem. Before the room mud was everywhere so there were no clean references, so I assumed the speakers were the problem.
I have some EQ notches of up to -15dB and some boosts of 8dB. I'll probably reduce the boosts as I can hear them causing wicked blooms at those ringing freqs. Speakers can't be moved to positions that would stop those rings at the listening position.
Resulting FR looks good on paper, Flat 20-10k +/-5dB, rolling another 5dB top oct. It sounds flattish, much clearer overall than before. Imaging is better. The bass clarity is 50% better so far on first non critical listening. But the blooming fatness and room ringing can still be heard now and then.
Now that levels are equalized I'll try increasing the woofer to mid crossover frequency. The mids can play very low, but they loose dynamics. The woofers can play clean to >1k so I'm safe up to 500Hz, and I can notch the woofer breakup if I need to. My old Ushers crossed 2nd order at 640Hz, with no notch I liked the midrange of those. I have better midrange driver now, and far better center to center spacing. So there's great potential for more tuning.
The OmniMic has a cool feature called "Bass Delay" which shows the room nodes ringing. Now we can see our enemy. We could always see the enemy in the 4 walls and ceiling, but now we see the dirty deed as it happens.
With the bass improved the midrange blooming and peaking is more noticeable now too. Ahh Waiter!?! More acoustic treatments please!
I have some new tweeter DC protection caps coming, 100uF good sounding electrolytics to get rid of the cheap chinese cap harsh on the tweeters, until my new amps are built then I can dispose of the protection cap. The amp I'm using now has a turn on thump so I need the cap for now. The new tweeter amps have opamp servo to remove DC completely from the output.
All the parts to build the Modulus86s have arrived from Mouser, even a new roll of Cardas solder. The Sympaticos came with all the parts already. I keep saying I will start building them tomorrow, but it didn't happen yet! Wintertime I am 1 lazy MF.
Tomorrow will be a fun day of listening to "that new system sound."