- Oct 24, 2016
- London< UK
That's the one I built, as having three large toroidal transformers in three power amps, I wanted to avoid potential problems with DC on the mains.Don't want to take too much away from Colin, but a rundown of the mechanism is here: http://sound.whsites.net/articles/xfmr-dc.htm. I actually put one of these together for a systems some years ago, with some cheap electro's; never did an exhaustive test of how beneficial it was, but it didn't appear to hurt the sound.
Even though large capacitance may be better at higher currents (low ESR speaks for itself), the dimensioning in the T+A case is a different one. The amp consumes about 40W in the idle state (some class AB operating point), probably some 200mArms (primary; real part). For this "low" current the cap voltage stays below the 1.3V "clipping voltage" of the diodes, thus avoiding any DC-generated hum. When the amp is cranked up, the voltage at the caps is limited by the flow voltage of the diodes. In this case only a limited DC rejection takes place, but nobody will notice it...The capacitors must to be low ESR with high ripple current. I recomand C=10.000uF/25v
Put it in a nice wooden box and I know where you can sell it for $4,995
Add a couple of Carbon Fiber Outlets and I think $7,995 is not out of the question.
Hard to say without knowing their values but I'd guess a snubber circuit for RFI suppression. The diodes can (will) generate noise spikes as they turn on and off. The resistor may also serve as a bleeder to discharge the caps when the circuit is disconnected.