n-Track Frequently Asked Questions

FAQ Index | Audio recording & mixing

• How can I transfer a song from a 4 track analog tape multitrack recorder?
  
  I have found an acceptable, though complicated and not perfect, solution to the '4-synchronous-channels-into-one-soundcard'-problem. In the following discussion, I assume access to a 4-track cassette mixer like a Tascam Portastudio or, like my own trusty machine, a Fostex 280. It should be capable of punch-in and out (preferably automatic) and simultaneous recording on all four tracks. I also assume access to n-Track and some other sound editing program capable of time-streching like, for example, Cool Edit. The imperfection lies in the way tape machines operate. 1) It is impossible to have a tape play back at exactly the same speed (i.e. sample-accurate) twice. 2) It is also impossible to avoid variations in the tape speed (wow and flutter) as it plays. This is how I overcome the first of these problems, as the second one is of a more subtle character and also harder to solve. Here goes... 1) Put some marker on all four tracks of the tape a few seconds before the music itself begins. this can be made by connecting a jack-cable to one input and touching the cable for a split-second while recording. Here is where the automatic punch-in/out comes in handy, punching out of recording mode before the music is reached, so the precious track itself isn't accidentially wiped. Record this signal at a sensible level on all four tracks simultaneously. 2) Repeat the procedure after the take ends, taking care not to wipe the fadeout or the next take on the tape. Now, we have two markers on each of four tracks on the tape, with identical distances between them. 3) Record the take, including the new markers, two tracks at a time, with n-track or another program, and then import the tracks afterwards. Don't split the stereo tracks up yet. 4) Zoom all the way in to the beginning of the song, and offset one of the stereo tracks so that the markers align. Then zoom in to the end of the track and note the difference in samples between the markers on the first and second set of tracks. Use the 'select' feature of n-Track to find the exact numbers at the bottom right. 5) Divide this difference with the sample rate (e.g. 44,100 samples per second for CD quality). This gives the lag time between tracks in seconds. Make a note of this number (use a calculator). 6) Using another program, such as Cool Edit, edit one of the stereo tracks. If the marker on the track is after the reference marker, the track is too long and should be shrunk to fit (i.e. subtracted from the total time) by an amount equal to the number of seconds in step 5). If the marker on the tape is before the reference marker, then the track is too short and should be stretched to fit (i.e. added to the total time) by the same amount. Don't preserve the pitch while stretching, or the result will be out of tune. This will take awhile, so this might be a good idea to 'goof off' for a coffee break. 8) Import the result into n-Track, zoom in on the beginning of the song, and adjust the markers to align with each other. Zoom to the end of the song, and check the difference in time between the markers here. This should be considerably smaller than before. The perfection of the synchronisation between tracks is of the same magnitude as the accuracy of the time stretching.The advantage of this method lies primarily in the fact that only one sound card is needed, and the inevitable error is suitably small for most types of music. The backdraw is, that variations in tape travel cannot be compensated in this way, and the process is a bit complicated. Posted by Nils (mailto:nok@post8.tele.dk)
  
  

FAQ Index | Audio recording & mixing