fertin 20EX- regulated power supply.

What co makes quality voltage regulator

Actually many -- in lay terms, what you're looking for is simply a transformer (5-15V usually, Fertin gives you the power rating) to drive the field coils. Any that has normal power supply (not switching) -- i.e. is heavy rather than feather light -- will do. Don't worry about it.

I suggest you focus on the baffle design and the sound tuning instead:) The field coil gives you unparalleled flexibility in tuning the drive unit's parametres to match the sound you like...
Nice drive units!

Thanks, what do you mean by sound tuning? I took different baffle plans form the net and I was going to find a carpenter to build one of them. Sound tuning- would it be to try different size of baffle and see if you like the sound. You have to build a few and different pairs, it would be expensive. As for the power regulator, can you buy it at an electronic store. Many thanks.

The power reg you can usually find in a store selling electronic components, etc. If in doubt as to the right unit for the application, ask the people there (it shoudl set you back $~20 or around there).

Yes, by tuning, I mean: a) decide on the baffle's smallest dimension (i.e. the width) which determines the low frequency at which you start rolling off (6db/octave). For experiments you can play around with a cardboard baffle to reduce costs -- until you find the best compromise for yr application. Phy and Supravox have OB designs on their sites that you've probably consulted already. Also check out Thorsten Loesh's OB spkrs -- don't have the url handy, but you can locate it easily via google.
B) You may want to add a separate woofer (or tweet or both) in which case you'd want to hi-pass the Fertin at some frequency -- which means the choice & design of a xover...

BTW, I assume you have consulted Mr Linkwitz's site.
OB are lovely spkrs! Cheers!

Tanks, I didn't know these sites : Thorsten and Linkwitz.I surely have some reading to do. Not many Audiogoners seems to know about Fertin drivers. I wonder want they will sound like. I bought them without being able to hear them.Couldn't go to France. Well tanks again.