Luigi,
Living in the States, I don't have any direct experience with a 220-240VAC version of the Felicia, but will attempt to point you in the right direction.
A schematic of the Felicia, appropriate for both 120 and 240vac can be found here -
http://www.audiocircle.com/index.php?topic=18441Although the schematic shows 120vac in and split phase , balanced 120vac out, if you feed the circuit 240vac in, you'll get balanced, split phase 240vac (or thereabouts) out. The transformers used are all dual winding primary 120/240vac which will work for either voltage. In the States we are actually building 240vac Felicias and running them at our lower voltage.
The Felica builder thread -
http://www.audiocircle.com/index.php?topic=18443does contain discussion of 240vac versions, but at its current 35 pages, its rather difficult to find the germane posts. It would be easiest to search in the lab circle for posts by 'RonR', 'Builder Brad' and 'Studley', and my flanking exchanges with them, using the search function on the upper right of the screen, as these gents, located in the UK have/are building versions with EU sourced transformers and caps. Please note that the optimal values of the caps accross the transformer's secondaries have yet to be determined. For the Signal A41 transformers used in the States, its 16-20uf, but using the Clairtronics 100va those values are too high. The appropriate caps for the Clairtronics transformers are probably somewhere between 4-12uf.
While the use of balanced (technical) power can mininimize ground loop problems, as implemented its not a universal solution. Ground loops are typically caused by differing 'ground' potentials on your various components. The voltages are often induced on the components chassis due to reactive leakage from inductive (transformers) and capacitors. While a major feature of balanced power is the cancellation of those reactive leakage currents, you've still the potential problem that the hum is cuased by differing ground potentials between your source components (which could all be fed from Felicas on the same circuit) and your amplifier which probably would not be fed from a Felicia due to power constraints.
An excellent discussion of ground loop induced hum and possible solutions can be found here -
http://www.audiocircle.com/index.php?topic=8780&highlight=ground+loop&sid=ee44932b5d6ec35394a30f1e1cefe478Would some of those who've built Felicia's for 240vac chime in? Please?
Regards,
Paul
