[EDIT: 03.04.12]
Now, the other side of the coin. If I were to to it all over again, what I would do differently:
Sonicap platinums. The tweeters deserve (would "need" be too strong a word?) it, and for as much detail as I was getting, I could just feel the drivers had more to give. Either add some bypasses into the crossover, or maybe even go to a higher-end cap in a few places, for my preferences maybe to something that was characterized by a smooth/softer sound - think jazzy kind of vibe (completely personal preference). Being as efficient as it is, I really also got to thinking that the coax would be one of those speakers to see a more noticeable benefit from going up the ladder in inductors to some air-core foils or something of the kind than some lesser efficiency designs where the results would maybe end up more subtle?
Cabinets. Version 2.0 of the cabinets would be stacked lamination again, but I would probably stack the other way so I could play with the internal cavity shape to manage the backwave a little more (dead cabinet is good, dead cabinet that doesn't rely as heavily on just absorbing the backwave even better). Leaving the crossovers outboard worked well enough, and I inadvertently ended up doing the "binding post wire clamp" kind of thing some folks have recently been discussing, so all good there; I would just put the crossovers into some (nice) boxes. I would also pull the plate amps from the lower cabinet and run them completely outboard as well. I was just now thinking it might be kind of neat to have small "equipment racks" near the speakers to stack sub amp, main monoblock amp, and crossover on to. I wouldn't want to put them all in the same box, but I think it might look kind of cool. Lastly, no-res and poly fill, no matter what the box shape, is probably a must. They sounded okay with the drivers loaded into the bare (admittedly overbuilt and pretty darn dead) cabinets, but just cleaned up more and more with improving the internals of the cabinets. Again, a lesson learned - or more clearly displayed - with a high-efficiency designs seems to be that where little changes can bring rewards normally, little changes make even bigger changes on the final end the higher speaker efficiency goes.
My room. Unlike the open baffle Super-V, these speakers can load (and overload) a room fast. It was refreshing for me in that I really found with these speakers my room's limits in both the highest frequency ranges (more easily done in the past) as well as the lowest frequencies (my room is darn good at handling bass, but I'm pleased to say that these found the point at which structurally my humble home said, "No more." I wanted to go all-in on these speakers, and I did as best I could, and they really were just "too big" for the space, being completely honest with myself. Pulled into the room and set up "Cardas-ish", it was awesome, but it really just underscored that to get everything these could deliver out of them, they just needed more (and better) space than I have to provide. I couldn't go crazy with professional treatments, and whatever I could do roughly (I'll use the term "field prototyping" lovingly in this regard) following the basics many folks here on Audiocircle recommend as to treatments helped each step of the way. For my living situation, the best permanent purpose-built solutions just weren't in the cards, and my best efforts just kept saying to me, "That's great! Now, just do more!" For the record, it was not that they didn't sound great anyway, but it was like having a governor on a sports car - you know the performance is there, and even worse yet is you know there is just no way you can get to it. Such is life, as it were, but it was fun for me to learn about it first-hand.
My amp and upstream gear. I have been running these with my Virtue Sensation M901. Works nice, sounds nice, perfect feature set for this kind of speaker design regarding the integrated preamp - need to accommodate passive crossovers in the speakers, high-pass functionality to the mains out, stereo plate amps needing volume controllable full range line level output. These speakers are very efficient, yes, but they can also soak up the power if you have it on tap. As beefy as this little tripath is, If I had it to do over, I would get myself some more power just to stretch the amazing dynamic range these speakers can provide. . . and or go tubes. For the record, I've looked into tubes occasionally, and at least for now, tubes just aren't my thing, but I can now see why there are a lot of folks using pro-audio driver speaker designs really liking the combo of using them with tube gear, considering what I have read to be the advantages in general of what tube gear brings to the sound. I'll admit, whether I like it or not, tube gear could do darn well with this setup. I'm not going to comment on battery power or power conditioning, but I would just presume the basic rules apply, blown up proportionately as the speaker efficiency goes up - get as clean a power as you can, it can do nothing but help. As to upstream gear, the only note I feel confident in making is that my Virtue amp has Sonicaps bypassed with Sonicap Platinums at the output, and if I were not going to try tubes, I might again try a softer/rounder flavor of capacitor here. . . but I would probably either do one or the other that way - speaker crossovers or amp/pre/source - but not both. I think "too much of a good thing" would probably lose you out on the crazy good detail and microdynamics going on here.
The Drivers. This last one is me just thinking out loud a bit. There was enough power on tap from the 600W plate amp to keep up with my main amp in driving the servos to match the coaxes. The transition between drivers was good, and I was able to play with the controls to change the flavor of the speakers to taste. If I were to do it all over again, and I was in the mood to tinker, I might try another route with the low drivers to pair with the coax, just to get the overall "flavor" of the drivers, and their sensitivities, more in sync. I know this would lose a lot of good (great!) things the servo drivers do, but I'm thinking that maybe another (or pair) of pro-audio high efficiency woofers run off something like Danny's SA-1 plate amp could solidify this design as a "hard rock" kind of concept, to give it a sense of overall identity. I know this sounds like a bit of a ramble, but I hope it kind of makes sense. Going this way would probably lose some low-end extension and maybe provide some more hard-driving punch (crunch?) to the sound that might end up making a speaker that not everybody is going to like, but as a DIY kind of thing for someone with very specific ideas/goals in mind, I think might take it down a road that could end up somewhere pretty cool. The only other real question rattling around my head regarding the drivers is what would happen if one were to pull the titanium diaphragms from the tweeters and get them cryo'ed? Again, thinking "micro changes, macro scale" with the high-efficiency design, might be an experiment worth chasing.
Wiring. For what it is worth, I didn't mess around with the wire on the servo drivers at all, but I did try out some thin silver/copper wire on the coax, as well as straight copper. I liked the straight copper better myself, probably because of the sonicaps in the crossover/amp in combo with it, but I just thought I would mention it.
I've probably missed something somewhere, but that should cover it enough for anyone following along. One last thanks to everybody who had a hand in getting this project done - it was a fun and educational ride!
