Specifications

Chapter 5: DigiRack Real-Time TDM and RTAS Plug-Ins 37
Dither and Output Bit Resolution
Dither has two user-selectable settings for opti-
mizing its operation:
Bit Resolution
Use this pop-up menu to choose one of three
possible resolutions for the Dither processing.
As a general rule, set this control to the maxi-
mum bit resolution of your destination.
16-bit Recommended for output to digital de-
vices such as DAT recorders and CD recorders,
since they have a maximum resolution of 16-
bits.
18-bit Recommended for output to analog de-
vices if you are using an 18-bit audio interface,
such as the 888 I/O or 882 I/O audio interface;
this is the maximum resolution available from
the 18-bit digital-to-analog convertors of these
devices.
20-bit Recommended for output to digital de-
vices that support a full 20-bit recording data
path, such the Sony PCM-9000 optical master-
ing recorder, or the Alesis ADAT XT 20. Use this
setting for output to analog devices if you are us-
ing 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 de-
vices that support 20-bit input and output, since
it provides for a lower noise floor and greater dy-
namic range when mixing 20-bit signals directly
into the TDM environment.
If you want, you can choose not to use the
Dither plug-in and instead utilize the full 24-bit
resolution of Pro Tools’ digital output, depend-
ing on your destination device. If you are using
a 24-bit audio interface (such as the 192 I/O,
96 I/O, or 888|24 I/O) and are outputting audio
to an analog destination, we recommend that
you do not use dither.
Noise Shaping
This button engages or disengages Noise Shap-
ing. Noise shaping is on when the button is
highlighted in blue. See “Noise Shaping” on
page 36 for more information.
The DigiRack Dither plug-in only provides
eight channels of uncorrelated dithering
noise. If DigiRack Dither is used on more
than eight tracks, the dithering noise begins
to repeat and dither performance is im-
paired. For example, if two Quad DigiRack
Dithers are used, both Quad instances of
Dither will have all of their dither noise un-
correlated. However, any additional in-
stances of the Dither plug-in will begin to
repeat the dithering noise.
Refer to the Pro Tools
Reference Guide for
details on using the Dither plug-in during
mixdown.