On Wed, Mar 01, 2006 at 04:52:33PM -0600, Paul Winkler wrote: > On Thu, Mar 02, 2006 at 06:47:19AM +0900, res0u2uc@xxxxxxxxxxx wrote: > > On the subject of the direction of signals in cables, I > > think I can offer to put the issue to rest by reminding > > all parties that audio signals from a microphone or to a > > loudspeaker are carried by the AC (alternating current) > > component of electron movement. Thus the direction of the > > electric current reverses many thousands of times each > > second, more or less depending on the pitch. > > thanks, I was going to say much the same thing. > > The only exception I can think of is when there's a > DC offset to the signal of sufficient voltage to force the > signal always be positive (or always negative). > But that would mean something's broken :) Not necessarily broken. Class A amplifiers do their work with sufficient DC offset that the signal never changes direction. Even so, the music is carried by an AC *component* which is present, and may be separated out by using a transformer. It is also a conceptual jump to appreciate how a DC signal can include an AC component. I balance my relative familiarity in this area with my abundant ignorance on the subject of music and recording! > > -- > > Paul Winkler > http://www.slinkp.com -- Joel Roth
