----snip----> ---snip--- Hi There is usually some compensation circuits that are intended to correct for the phase shift of frequencies caused by the tape recorder. Without feeding it through a tape recorder, you are not adding this additional phase error. Most of these early machines did simple zero crossing type detectors. This means that the phase of the harmonics of the signal going to the tape are important, since they effect the timing of the zero cross. For the most part, harmonic phase is not that important to our ears since we are most sensitive to spectral content and less so to phase. To a zero cross detector, it is more important. This phase shift is caused by the fact that the tape head only redords by the trailing edge of the head gap while the playback is from the entire width of the head gap. This causes both a high frequency rolloff and a phase shift. From an audio perspective, they use pre-emphasis and de-emphasis circuits to compensate for the gain. The problem is that some phase error is always left. It is the high frequency content that creates the sharp edge at the front of a square wave. Move the high frequency part around and it doesn't look too square anymore. Dwight _________________________________________________________________ The MSN Entertainment Guide to Golden Globes is here. Get all the scoop. http://tv.msn.com/tv/globes2007/