Alesis ADAT - Affordable Digital Multitrack (part 12)
Drop out gap
So your guitarist needs a hundred takes to get his solo correct. It shouldnt be problem as long as you can drop him in at the right points to fix dodgy notes. The problem is that dropping in is easy enough, and analogue recorders have carefully timed erase current ramping so that the changeover will be almost perfect. Dropping out is another matter however. It is possible to drop in almost at any point, as long as your timing is good, but dropping out always produces a glitch in the recording so you have to drop out on a gap in the music. If there isnt a gap then youre in trouble. On the ADAT, dropping in and dropping out are both gap free. If you try it on a 1kHz sine wave (which is the ultimate test), youll hear a short crossfade on entry and exit. On music you are very unlikely to hear it at all.
In any analogue equipment there will always be crosstalk, which is defined as a signal leaking from a path where it is wanted to a path where it is unwanted. This is a terrible nuisance, especially in multitrack recording when, lets say, a loud snare drum beat leaks onto the vocal track. The crosstalk will be an inconvenience until you decide that the song doesnt need that snare drum after all - even when you erase it it will still be clearly audible on the vocal track, and it becomes a major problem. Digital multitracks cannot be totally free of crosstalk because there are still analogue signals within the equipment, but there is no crossover from one track to another, which is a major benefit (except that you will now become dissatisfied with the crosstalk performance of your mixer!).
This is a different manifestation of the crosstalk phenomenon. During overdubbing on a multitrack recorder you are asking one element of the head to play back while another is recording. The recording element will be carrying a large current while the playback element will be producing only a very tiny one. You will notice the effects of record crosstalk when you record on the track adjacent to the high high. As you record and monitor the signals from the multitrack you will notice that the hihat has suddenly become much louder and much brighter. If you solo the track you are recording on you will be able to hear it quite clearly as the result of record crosstalk. It wont be there when you play back (apart from normal amount of track to track crosstalk you would expect), but its a pain when you are recording. You may also notice that other tracks seem to jump up and down in level corresponding to the rhythm of the track while you are recording. This is a result of the record crosstalk sending false signals to the noise reduction system. Once again it wont happen on playback - but on a digital multitrack it doesnt happen at all.