The lash up now has 132 hours on it and has settled nicely.
The original ported box Quads with their original crossover sounded pretty good, I would not have used them if they didn't.
Mounted on top of my Yamaha's and borrowing their 12" driver for bass duties, they sounded very detailed and revealing, which I like, my last few speakers have been studio monitors and I like this sound. The only criticism I had was maybe a little grain in the upper mids/treble.
The lash up, with a smaller volume sealed box and blue printed crossover with improved parts, borrowed the Yammies bass as before. The result was as I had expected, a very slight improvement, removing the grain from the top end. In addition, it also has a slightly fuller, richer mid range, not as lean as a monitor now and the bass seems tighter/faster than before. I'm guessing the 4" mid/bass is better damped in the smaller sealed box and its contribution to upper bass and the edges of bass notes is crisper and definitely audible.
I'm liking the sound - A LOT - most accurate, distortion free, across the whole frequency range, that I've had.
Initially when I had about 30 hours on the lash up, I was a bit concerned, the sound was not as good as the originals. It lacked body in the mids and was tame in the bass, but this all changed at around 65hrs and the roles were quickly reversed.
So I've proven the mid/treble drivers suitability and passive/active crossover elements, when paired with the Nakamichi Amp and 12" bass from the Yamaha's. The next step is to acquire the Scanspeak bass drivers and compare their performance. The Yammies are a short throw 12" with a paper cone, the Scanspeak are a long throw with aluminium cone, so a bit of a different animal. I'm expecting deep fast bass from their rigid cone, F3 of 38Hz or better, compared with the Yammies F3 of 53Hz. It's the tone and how they blend with the mid range that concerns me, they look great on paper, very flat from 100 to 1000Hz, but I need to hear them in this set up.
A couple of things are going to get in the way now, the next NEBO meet is a cert and possibly a try-out at the Wigwam show. I need to have them in some useable state, so they may stay in the current lash up form till these events have passed. I can purchase the Scanspeak drivers and maybe try them in a makeshift cabinet as an interim stage. I'm not lashing out on decent ply and veneer till the new bass is proven.