True symmetrically balanced isolation transformer ...
I would like to report some details abt. my most useful upgrade on the main line so far by means of symmetrically balanced isolation transformers.
I decided to develop this upgrade after testing several Schaffner' filters with the intent to reduce the AC noise and electromagnetic interferences. These were so-and-so effective, but I felt the dynamic was also affected in some way.
So, after testing the 1st prototype, I have then build four units in total :
transformer #1 for the sources of both Hi-Fi and HT setups
transformer #2 for the Hi-Fi setup's amplifier
transformer #3 for the HT setup's amplifier
transformer #4 for the HT's projector
All are based on transformers with 2x screen magnetic shielding, so that the highest reduction on AC noise, which is the cause of ground loops, can be secured.
Each unit is configured for 230VAC (France) true balanced mode operation, so a 1:1 isolation transformer with a precisely placed center tap on the transformer’s secondary.
The incoming 230VAC (115V on the L terminal and 0V on the N and G ground) is split into halves on the transformer’s output.
The "new" AC line has then 115V on the L terminal and 115V on the N terminal, all that when referenced to the new center-tapped G ground, which remains at 0VAC.
The opposite polarity between L and N is due to completely cancel all common mode noise from the incoming AC line.
I paid from 120 EUR to 250 EUR including shipment (2015) for each transformer from a French manufacturer, plus : the aluminum enclosures, the IEC sockets, wirings, circuit breakers on the outgoing, silent blocks, minor stuffs here and there, say from 300 EUR to 450 EUR depending the size each finished unit ... including the fancy voltage indicators ...
I have tested the integration of filters (Schaffner #2070) but I prefer with no filter.
Manufacturers like Balanced Power Technologies, Bryston, Keces, ect., sell these units for thousands of $ ...
The same principle can be applied to any incoming VAC, i.e. in the case of 120VAC one gets +60VAC and -60VAC on the outgoing section.
Easy, funny, but most of all, a "straight-to-the-problem" solution with an incredible value for money !
PS The most difficult task is the sourcing for the transformers, as these "symmetrically balanced isolation" ones are not very common within the manufacturer standard catalogs.