Dither Plug-Ins : Dither : Dither Controls

Dither Controls
The Dither plug-in has a Bit Resolution button and a Noise Shaping button.
Bit Resolution Button
Use this pop-up menu to choose one of three possible resolutions for the Dither processing. Set this control to the maximum bit resolution of your destination.
16-bit
Recommended for output to digital devices with a maximum resolution of 16 bits, such as DAT and CD recorders.
18-bit
Recommended for output to digital devices with a maximum resolution of 18 bits.
20-bit
Recommended for output to digital devices that support a full 20-bit recording data path, such the Sony PCM-9000 optical mastering recorder, or the Alesis ADAT XT 20. Use this setting for output to analog devices if you are using a 20-bit audio interface, such as the 882|20 I/O audio interface. The 20-bit setting can also be used for output to digital effects devices that support 20-bit input and output, since it provides for a lower noise floor and greater dynamic range when mixing 20-bit signals directly into Pro Tools.
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The Dither plug-in only provides eight channels of uncorrelated dithering noise. If Dither is used on more than eight tracks, the dithering noise begins to repeat and dither performance is impaired. For example, if two Quad Dithers are used, both Quad instances of Dither will have all of their dither noise uncorrelated. However, any additional instances of the Dither plug-in will begin to repeat the dithering noise.
Noise Shaping Button
The Noise Shaping button engages or disengages Noise shaping. Noise shaping is on when the button is highlighted in blue.
Noise shaping can further improve audio performance and reduce perceived noise inherent in dithered audio. Noise shaping uses filtering to shift noise away from frequencies in the middle of the audio spectrum (around 4 kHz), where the human ear is most sensitive.