Replacing tracks in live mix results in bleed-through of some of the prior recording. How do I prevent this?

Question

I was doing some recording of our band yesterday using Logic Express 9 (13 tracks from a mixer going out the Firewire port into the Mac). For some songs, we wanted to replace the entire song, so I activated the replace button and started re-recording from the beginning. Visually it seemed to replace the tracks, and for many parts of the songs, it did just that. For some, however, there were still remnants of the prior recoding in the background. It was not consistent from song to song, sometimes you could hear some of the prior vocals in the background, in other cases the drums. These remnants were not throughout the entire song, however. You could hear it in some places but not in others. I do not see evidence of multiple takes when I look through all the tracks. It's as if it did not completely erase some of the prior audio, or blended it with the new recording.
Is there something else I need to do to get a complete replacement?
Thanks for any insights you may have.

Answer 1

Hi,
if you have recorded the whole band through microphones, the earlier versions are ambient sound pickup from the mics of the other tracks. This can even occur if a singer wears a very loud headphone which you can hear through the vocal microphone. Just make sure during your recording session that all instruments that should be recorded very precise - without ambient sound - are recorded separately in a dry recording booth.
Fox