Preparing for Mastering: Part 2 Bit Depth.
A little while ago I did a post about Bit Rate which was extremely helpful for some of you. So today I decided to do a little piece on Bit Depth.
Everyone has heard the 8 bit sound on Mario Kart, but differences between 16 Bit and 24 Bit really can confuse new producers. Essentially the Bit Depth gives us Dynamic Range, this is important for recording large changes in SPL and headroom in a recording.
In short the lower the bit Depth the less dynamic range or headroom a recording has, each bit is worth 6dB. Therefore a 24Bit (144dB) recording has significantly more dynamic range than a 16Bit (96dB) recording. To explain what I mean, most professional audio units have ~120dB of headroom. This means the noise floor of the unit is 120db below the clipping level.
Therefore using 16bit audio is not taking advantage of the quality of your system as you are rejecting roughly ~24dB of dynamic range from your recording. Where as recording at 24 Bit actually gives you more dynamic range than your unit can handle, and you do not lose any headroom.
Most DAWs will on default record at 32 Bit which is plenty and then reduce this upon export. Audio within the DAW will preview at 32 Bit unless you have a plugin that is limiting this such as a bit crusher.
Problems with this occur when reducing the Bit Depth. When the audio is at the bottom of the dynamic range we end up with quantisation errors, essentially the processor is unsure of whether or not to play back sound or to mute the signal. You can try this in Ableton by using a redux and setting the bit depth on a track to 1 or 2 Bit and listening to the artefacts that occur during the decay of the audio you will also notice a significant quality reduction, there are many ways to do this in other DAWs.
To remedy this Dither is used, dither ads specific shapes of noise to the audio which boost the signal and stop this quantisation from occurring. If you add a white noise layer to the destructed signal in your DAW you are able to reduce these quantisation errors and hear the audio in much clearer quality, yet with the distinct addition of noise.
Of course the best method is to keep the bit depth consistent between recording and rendering and allowing the mastering engineer to deal with this during their session.
If you need any further help or wish to book in a mixing or mastering session you can contact us today!