Posted by Al Sekela on November 25, 2002 at 09:15:46:
In Reply to: Re: Power Cords posted by Lew on November 25, 2002 at 07:39:55:
I have no experience with electrostatic speakers, let alone the power cords to the bias supplies, but one thing power cords do that people seldom consider is act as antennas.
RF fields may be present from local broadcast towers, cell phone antennas, or the power supplies of other components in your system. Power supplies with capacitor-input filters, in particular, have the nasty propensity to generate RF pulses every time a rectifier diode goes from forward to reverse bias. This is why Hexfred rectifier diodes are a popular tweak: they minimize the charge stored within them during forward conduction, so the transition to reverse bias results in a pulse with much less energy. This is also why the European Union is putting rules in place to effectively outlaw capacitor-input filter supplies on consumer equipment.
The RF can be in the air as well as in the ac power mains wiring. A fancy power cord may act to minimize pickup from both sources. I would expect the high-voltage supply for energizing electrostatic speaker membranes to have lots of stray capacitance, so RF could get through it easily.
In-line ac filters, comprising inductors and capacitors, are cheap and easily available. It would be an easy experiment to see if one of these at the input to the bias supply gave sonic benefits comparable to a boutique power cord.