The first thing any power amp does is rectify the AC to DC and put it in big capacitors. Maybe sets of capacitors to get rid of all the AC ripple.
Minor nit.... Actually, it's the -second- thing a power amp does. The first is to use a transformer to change the AC voltage level (up for tubes, down for solid state). It is the noise and variable voltage and instability of the AC that can affect the conversion of AC to DC Actually, the noise and variable voltage does next to nothing to the conversion of AC to DC... The conversion involves a low pass filter, which is fixed, and the noise does not affect it at all. What the noise on the input does effect, is the noise on the output. It will still be there, just reduced in level, by the filter. If you provide measurably quieter AC on the input, there will be a correspondingly quieter DC at the output. Depending on the supply design, and the frequency of the noise, it could be reduced by 10's or hundreds of db. The real question is, however, is it necessary? Which brings us to circuit design. A circuits design will affect it's Power Supply Rejection Ratio, or PSRR. This is a measure of how much noise on the power supply will appear on it's output. PSRR's can vary from as little as a few db, to as much as 140db. So if you've got a power supply that rejects noise by 100db, and a circuit design that rejects noise to another 120db, do you honestly think a line cord that might reject 1 db of noise is going to make any difference at all? Of course the reverse is also true. If the supply rejects 6db of noise, and the circuits PSRR is only 3db, then a line filter with 20db of rejection might make an noticeable improvement. IMHO, however, anybody who designs such a piece of junk should be dragged out back and forced to listen to Celine Dion for a few weeks.... If you honestly feel that your low PSRR circuit sounds better, you -must- build the power supply accordingly. As always, YMMV! Cheers, Dave -- DCtoDaylight Audiophile wish list: Zero Distortion, Infinite Signal to Noise Ratio, and a Bandwidth from DC to Daylight ------------------------------------------------------------------------ DCtoDaylight's Profile: http://forums.slimdevices.com/member.php?userid=7284 View this thread: http://forums.slimdevices.com/showthread.php?t=52348 _______________________________________________ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/mailman/listinfo/audiophiles
