Hmmm...not to be a contrarian, but in my subjective opinion the Alembics that are being built today are more desirable than the Alembics built in the 70's or 80's.
Let me hasten to add that I completely agree with Keavin's wonderful post above as it pertains to the changes in wood that occur over time as the drying process continues. There's no doubt that there will be a subtle affect in tone as a result. Whether or not the change in tone will result is a sound that is better or worse is, of course, entirely subjective. Even if we want to assume for the sake of this discussion that old and drier wood sounds better, that has to be balanced against a couple of factors. First, and although this is a purely subjective opinion of mine, I really do believe that the quality of the instruments produced by Alembic today is the highest it has ever been. Of course, alembic quality has always been amazing and second to none, but it's even better now. I particularly notice the difference in the fret work, which is nothing short of spectacular these days. Again, it was always top quality - all I am saying is that I think it's better now.
A second factor that makes older Alembics sound different than newer ones relates to the finishes used. In the 70's Alembic used a lot of oil finishes, and in the 80's the clearcoat that they used was much thicker than what is used today. The finish differences will absolutely affect the instrument's tone, but whether or not the modern finishes sound better or worse is, again, purely subjective. My ears very much prefer the sound of the more modern finishes used by Alembic. They are much thinner than the old oil or poly finishes, and to my ears they produce a brighter and more open sound.
Like I said, those are subjective observations. What's fact is that the post-2000 Series electronics are quieter than the original design. I own basses built before and after the design change, and the difference is pretty noticeable.
Bottom line: I would rather own a newer Alembic than an older one. But hey, that's just me...
(Message edited by s_wood on May 20, 2009)