Saturday, November 8, 2008

How to clean up (remaster) an audio track using Audacity

Although there are good remastered sets from all the main artists of the 1920's and 30's there can be times when you have a single track on a cheaper reissue CD that you would like a better copy of.
These CD's are usually made by recording directly from 78 records so there are a few processes involved.
All of these can be done using free programs available to download on the internet.

Rip track as a .wav file (if from a CD use Free Rip as its the simplest ripping program I have found). You could also record an original record to your PC using an analogue to digital converter or one of those USB turntables.

Now use Audacity to perform these tasks

  1. Use speed plugin (in the effects menu) to manually adjust speed to get pitch to A=440 because some 78 records were recorded at slightly different speeds.
  2. Use stereo plugin to create spatial Left/Right effect (I use the MDA_stereo VST plugin from http://mda.smartelectronix.com/ you need to install the VST enabler from Audacity but this is also free)
  3. Use the equalisation plugin to adjust for recordings made from 78 records (this is a preset) or experiment at removing the centre range slightly
  4. Use the noise filter plugin to remove any remaining noise (tricky, and you don't want to lose anything from the original recording)
  5. Use the amplify plugin to increase volume across track if required
  6. Output as .wav file to keep losses down and so you can burn the track to a CD

On this Bessie Smith track you can hear the original CD track up to 1:07, then it switches to the cleaned up version (although the pitch correction has been applied to both halfs).



My purpose in doing this:
  • Get pitch corrected
  • Make the vocal stand out more
  • Remove some of the noise
  • Make it play better on a larger hifi system.

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