[nodiak]

Probably!
I recently received four of the 25 TV-EW woofers and two 1.5" tweeters, all circa 1971. All in really good condition. The woofers have alnico magnets. Also they have paper voice coil formers, prone to over heating and even burning when driven hard. I think these are still untoasted (I didn't smell charred paper  ), but to help keep them from overworking I think I'll make MTM's.
Will just use the crossover idea of the originals: nothing on the woofers, and a 5 uFcap on the tweeter. Probably no resistor on the tweeter because of parallel woofers-hopefully the tweeter will keep up with 2 woofers. 2 ft3 cabinets as original used 1 ft3 for single woofer. Will make them aperiodic as designed.
Should be fun/interesting. A low key project, might end up in the shop with a 70's Pioneer receiver.
I hope to get cabs built in January and will post result!
Don

[dB Cooper]

Dynaco A-25's were made in Denmark and used SEAS drivers, not EV. Last I heard, replacement drivers were still available!

Good luck with your build project. Aperiodic design is an interesting approach that I can't understand not being used more, except maybe because of the critical tuning. Dynaco did it in the A-25 by miking the woofer, feeding a low frequency square wave into the system, watching the output on an oscilloscope, and 'tuning' the slot for best response by adjusting the amount of fiberglass stuffed in the port. Each system had to be individually calibrated this way to produce the desired result, which produced the tight bass (and easy-to-drive load) that the entire line was famous for. Don't know how they tuned the sealed systems like the a-50.

[nodiak]

Yes SEAS drivers, I botched the model number last night, was late - fixed it in my post, sorry about that. The current replacement drivers (ex. Madisound's SEAS 25F-EW H085) are different in build and frequency response (more pronounced midrange). World Designs has a new speaker (WD25) derived from the A-25 that uses another new SEAS driver model - A26RE4-H1411. Looks great but is ~ $500 shipped to usa.
http://www.world-designs.co.uk/acatalog/wd25ahfw1a.html
25 TV-EW is the correct model number for the SEAS woofers I have. In some A-25 models they used different SEAS woofer (25F-EW) with non alnico mag, and another woofer version with coated cone. Even Scanspeak woofer and tweeter in early models.
I'll use scanvents and tune by ear in my (boomy) room.
Some people replace the 1.5" tweeters with current SEAS tweeters as an upgrade, might eventually try that.
May eventually try them on ob with one woofer cut off for bsc.
Lots of Dynaco info here:
http://www.classicspeakerpages.net/dc/dcboard.php?az=show_topics&forum=20&page=1 
Don

[dB Cooper]

My brother in law still has my original A-25s I bought in 1971, and they still sound quite respectable.

Thanks to the digital age, you could possibly even use a software oscilloscope to do the cabinet tuning. (Is that what Scanvents is?) It will be an interesting project; have fun.

[nodiak]

Scanvents : http://www.partsexpress.com/pe/pshowdetl.cfm?&PartNumber=296-546&DID=7
Sometimes worth the $10 each, for cleaner build and easier tuning.
I never had decent speakers in the 70's, or any good audio gear for that matter (had a Martin guitar and no $ left over!). I heard these were one of the good deals of the time, coming close to some of the AR's and Advent's territory. Will be fun to hear what I was missing!
Don