Digital Re-Synchronization of Analog Recordings
April 29th, 2010 . by Alexander FisherAfter I finished working on my digitally reconstructed analog recording, Sorry It Came To This, I wanted to write down some of the steps I took to get to the finished project, or at least my thinking on a few of the variables. Unfortunately I was a little brain dead from all of the ‘cypherin’, so I put it off. After I processed my next analog restoration, Mean and Cruel, in a similar manner, I finally decided to write a few thoughts about the whole process, before I forget it all, again.
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The process of reconstructing these tracks is heavily software based and not that much to do with any one of my technical abilities. It isn’t like the old days when you needed better hand-eye coordination for cutting the tape and splicing it back together. Though the process is not completely dissimilar in it’s application.
I think many people could acquire the skills to reprocess analog recordings, with the automatic processing built into my Digital Audio Workstation (DAW), Cakewalk Sonar v8.5, under most circumstances. When I reprocessed Sorry It Came to This, I did use some of the automatic synchronizing capabilities of the software. When I began working on the song, using a MIDI drum controller, I recorded several drum tracks based on the rhythm of each progressive mix down during the original analog process.
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After determining the original tempo of the recording, I linked the internal drum synchronization to these original tracks via MIDI processing. I was able to reestablish a common beat between all of the tracks using automated audio stretching through quantization, beat grooves, and also I manually stretched or compressed portions of the audio signal when the software could not properly recognize whether it was a component of the beat or not. Doing this allowed me to replace the original MIDI created analog drum track with a MIDI drum set included with Sonar. Drum samples have improved greatly since these original recordings were made and are nearly identical to a real drum kit. The improvement in beat timing was evident as well.
The amount of synchronization that I had to do on these tracks is directly related to the recording method that I used in the beginning. I would record the initial four tracks on my Yamaha MT-100-II multi-track cassette recorder. It was designed to record on chromium dioxide cassettes (CrO2) and I always recorded at the higher speed of 3 3/4 inches per second that it also featured. The reasoning behind using the higher speed is that it enhances the audio quality and reduces the tape noise in the recordings. In addition the Yamaha recorded with dbx noise reduction.
The aural quality allowed using the dbx process was similar in many respects to the quality achieved in a digital compact disc (CD) recording. An advantage would have been the constant stream of audio as opposed to the digital sampling inherent in the CD recording process. Some have commented to me over the years that dbx, because of its use of compression in its methodology, called linear decibel companding, had an effect on the aural envelope, that you could hear. Compression/decompression technologies can be audible if it is used improperly, but I believe that like the opponents of the compact disc originally who thought they could hear sounds going on and off 44,100 times per second, they were a bit delusional as well. It’s probably the same people that complained about the inferiority of the minidisc that are now completely satisfied with the sound of the much,much inferior MP3 player.