Re: i need a speaker for my '66 Princeton...
I have two vintage Princeton Reverb amps. Bruce replaced the baffle in my blackface with one cut for a 12" speaker and my silverface has the original baffle cut for a 10" speaker. They're both wonderful amps. In my silverface I have a Weber C10NQ. It's Ted's version of the old Jensen C10N, only Ted uses a bigger magnet and I asked for a "Q" cone rather than a "N" cone. The "Q" cone is lighter and sounds faster and has more highs while retaining a solid deep low end as well. I prefer it and think it sounds more like the original cone in a '66 Jensen C10N.
When it comes to 12" speakers I'm a Celestion guy all the way. In my blackface Princeton Reverb with the custom 12" baffle, I have a Celestion G1265 - same speaker Robben Ford uses. When I gig on electric guitar this is the amp I bring to the gig these days. The G1265 has a more textured tone than my other favorite ceramic Celestion, the G12H30.
However, I also have a one 12 Matchless cabinet and in it I have a mid 60's Celestion G12 alnico, It's silver, not blue, but it's the same speaker.
When I plug my Princeton Reverb into that speaker and bypass the speaker in the amp I get a glorious sound that's even better!
But the Matchless speaker cab is a little bigger all around than the smaller Princeton Reverb cab so that's probably helping too.
None the less, someday I'll pull the G1265 and try a Celestion G12 alnico in my Princeton Reverb. Until then, the G1265 sounds just fine and is my favorite 12" that I've used installed in my Princeton Reverb cab.
Lew