How timeshift 1 trk of a 2trk recording with offset heads

Special Interest Groups Audio Processing
1

I came accross a lot of 2 track recordings made in 1956 (Concertape Twin Track Monaural) where each track was recorded with offset heads. If played back on a standard deck, the two tracks are offset by about 1 second. After recording both tracks and separating them to two mono tracks, how do I set one track to delay and save so when played back, they are in sync?

I would also like to save this configuration info so I can apply it to all the other tapes recorded in this format.

I guess this was in the early days of stereo where tape decks didn’t have stereo heads and there were two mono heads side by side recording the music, thus the time offset.

BTW, these were stored in a round plastic can and when opened had a strong vinegar smell. After being aired out for a few days, the smell disappeared. Is this a significan factor?

2

Split the stereo track, then use the Time Shift tool to drag one of the tracks left/right so that it lines up with the other track. Note that if both tracks are selected (highlighted) when you drag, both tracks will move together, so ensure that the tracks are not selected when you drag.

If you use “Split Stereo Track” rather than “Split Stereo to Mono”, then there is no need to join the tracks back into a stereo track, because the upper track will still be set to the left channel and the lower track to the right channel. (See: http://manual.audacityteam.org/o/man/splitting_and_joining_stereo_tracks.html)

3

Wow! Thank you very much! It worked perfect!

I had to use trial and error to align the L and R to perfectly match the starting point of a cut when I shifted (delayed) the L track by 1.535 seconds. Is there a way I can just enter this shift amount for all the other tapes I have to correct? I can continue to use the trial and error method, but it would make it a whole lot easier just to be able to enter this number to shift for the L track for all the tapes I have.

4

Assuming that they all need a time-shift of 1.535 seconds:

  • Split the stereo track
  • Click on the track that needs to be moved to the right (later).
  • Press the “Home” key (or click the rewind button)
  • Generate menu > Silence.
  • Enter 1.535 seconds as the amount of silence to generate.
5

Once again, it worked perfect! Exactly what I needed.

The time offset is the same on all the tapes because back in the 50’s there was no two track heads, so they used two single track heads side by side (one raised in height for recording the other track) to record, creating the 0.1535 sec. time difference between tracks which is how long it took the tape to move between head #1 and head #2 at 7 1/2 ips. When playing back the tapes on these types of decks, the heads were again offset correctly, so the listener didn’t hear any time difference.

Thanks again.