Well, I can answer some of my own questions now. The right pot controls the FST, from no sound counter-clockwise to full sound clockwise. The left pot controls the 4 ribbons, same thing, that's it. The cone speakers are unaffected by the pots. I ran the ribbons with no bass and found good settings for the pots. The FST sure sounds funny all by itself, but with the four ribbons the sound is surprisingly good without the cones. Settled on 1 o'clock FST, 12 o'clock Ribbons.
Turned on the bass amp and adjusted the volumes, bass and ribbon amps, to taste. Started removing mortite. Kept thinking about that picture of the scorpion lurking in there. Got tired of little fingernails full so, against Brian's directions, I started taking out chunks. First the bass got softer, then louder again, then softer. Ended up with two balls of mortite 1/2" in diameter. Put back ~1/8" piece on the left speaker and got lucky, I could hear a big difference. Turned off the ribbon amp and played just the cone drivers. I was real tired of listening to Sultans of Swing over and over so I put on SRV, Cold Spot. Sounded good. Put back a 1/8" chunk on the right speaker and got fantastic resonance, from head to toe, right through my body, on the bass guitar. But what really surprised me was the imaging. Dead center, outside the room behind the speakers, tight focus at about 5' high. Very nice. Not too difficult, took about two hours, and really tightened up the bass and the imaging. Now I've got two 3/8" balls of mortite that I have removed from each speaker.
Re-adjusted the pots. Ended up backing off the FST to 12 o'clock and backing off the ribbons to 11 o'clock. The bass and midrange now sound fantastic, I have no complaints or concerns. The top end is still funky. I attribute that to my old HK amp and poor speaker wires. If I can get the high frequency sound real clear without smearing this is going to be a great setup.
So far what has really impressed me is the presentation of overtones, phasing and resonance, especially on stringed instruments like guitars. To be able to hear and feel the resonance/interference of a bass guitar chord fluctuating is a real treat. Even better is listening to the intertwining of acoustic guitars playing harmonies together. The harmonic overtones are what make music special for me, and they just aren't reproduced well by average stereo systems.
