Monday, March 26, 2012
COMPLETING THE MASTERING: DITHERING AND REMOVE DC OFFSET (with Free Vst Plugins)
This is the final part of our Mastering Tutorial, which takes place after all the dynamics are finely tuned, the last eq coloring has been given, and the overall volume has been raised to the desired level.
You could say you've finished... Wrong! There is still one last thing we need to do before giving our song to the voracious music business.
First off, if you think there is not enough headroom on your master, it may be caused by many things, and one of these things is the DC Offset. DC offset occurs when hardware, such as a sound card, adds DC current to a recorded audio signal. This current results in a recorded waveform that is not centered around the baseline, which is "-infinity", and for some reason takes away headroom.
Most of today DAWs have a "Remove DC Offset" function, that may be used to solve this problem.
Once we checked if we needed to solve this Dc problem, it's time to Dither.
This phase is when you bring your mix down to 16bit / 44khz, which is the audio cd standard, if you have recorded and mixed an audio with higher settings (e.g. 24bit / 48khz).
The first thing to check is to not have any clipping through the whole chain, so check the signal, and it's a good rule to bypass and turn on again every plugin present on the chain in order to check how they affect the signal and if there is any plugin deactivated or that you need to remove.
Now check the meters at the end of the chain; is the signal clipping? Is your Limiter set too hard? Make sure that there is still a bit of headroom left to not lose completely all the dynamics of your mix.
Now you can apply Dithering, and remember to use it only if you have worked with tracks with a bitrate superior to 16bit / 44khz, to reduce the quality to cd standards, preserving the best headroom and clarity achievable.
Why do we need this process? Because when we reduce the bit depth of a track (for example from 24 bit to 16 bit) we could have some truncation distortion (or quantization error), which can be very unpleasant, therefore dithering adds some low level noise to avoid this problem, randomizing the quantization errors.
Now, once you have exported the track, load it again on your DAW or on another single track editor, like Steinberg Wavelab or Soundforge, and check the last details, such as the beginning and ending markers, check for peaks, and if needed, apply fade ins/fade outs on the track.
Most DAWs already features a Dithering Plugin, but if you need one, try LOSER and VOXENGO R8BRAIN, which are free, and absolutely worth a trying.
Now your song is ready to rock!!
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