Frequency range s of digital noise s

Ptss - Designers usually don't target specific frequencies and the good ones avoid using too many filters. Filters usually impact SQ. Sometimes designers must add ferrite beads or similar to pass FCC class B emissions.

Good design practices are the best way to avoid emissions and susceptibility. These include good ground-plane design, trace topology and impedance control, proper transmission-line termination and internal cabling impedance/termination. Using the correct connectors does not hurt either.

Filters can be useful and will not impact SQ if used on the ground-wires of cables that are differential or the ground-wires of power cords. Filters on power supplies usually impact SQ, even AC lines.

AC lines can radiate emissions if there is a generator present, such as SMPS that puts HF noise back into the power line. Some wallwarts are notorious for this. By themselves the frequencies on the AC service are too low to have much EMI. Magnetic fields are more prevalent with AC lines.

Thanks Steve, I should have known that; since only a few companies have stressed power supply quality. FWIW, Alpha, Esoteric and Wadia come to mind. Also it may be why I have consistently found that isolation and conditioning have benefited every digital player I have tried in my Spectral system.

I am not a fan of conditioners, with one exception, the Plasmatron from VHaudio.com. This really improves SQ for digital. I use one and many of my colleagues use one. The Plasmatron is an AC voltage regulator, not a filter.

Filters on AC generally reduce dynamics, so I steer clear.

Isolation is the best solution, both for digital and analog. I use both, so I have no ground-loops.

Steve N.
Empirical Audio

Steve. I was just reading about the improvements of the Wadia 781 over the 581. Significant p/s improvements. Have you no idea what frequencies of noise are emitted from digital processors?