Installation guide

TDM Installation Guide54
The Calibration Process
Analog To calibrate the input level of an analog
device to a mixing console’s output level, you
would typically send a 1 kHz tone at 0 VU from
the console to the analog deck and align the re-
cording deck’s meters to read 0 VU.
Digital With a digital recording device such as
the 888/24 I/O, in order to allow for headroom,
you must align a 0 VU tone from the console to
a value less than zero on the 888/24 I/O, by ex-
actly the amount of headroom that you want.
For example, to have 12 dB of headroom above
0 VU with the 888/24 I/O, you must align the
incoming 0 VU 1kHz tone to a level of –12 dB.
For 18 dB of headroom, you would align it to
–18 dB. (Since it is assumed that you are using
the 888/24 I/O with a +4 dBu console, a 0 VU
signal level coming out of the console is actually
equivalent to a nominal +4 dBu level signal.)
Calibrating The 888/24 I/O
To calibrate the 888/24 I/O you will put
Pro Tools in a special operating mode called Cal-
ibration mode, then use the Signal Generator
plug-in to generate a test tone for alignment.
The Pro Tools Installer includes several pre-con-
figured calibration session templates that cover
most common calibration setups. You can use
these in addition to the calibration procedure
given below.
To calibrate the 888/24 I/0:
1 Launch Pro Tools by opening the Digidesign
folder, then the Pro Tools folder, and double-
clicking Pro Tools.
2 In Pro Tools, create a new session by choosing
File > New Session.
3 Choose Setups > Preferences and click Opera-
tions.
4 Enter the desired Calibration Reference Level
value in dB. A level of –18 dB is typical. (It isn’t
necessary to type a minus sign here.)
5 Click Done.
6 Create a new mono audio track by choosing
File > New Track.
7 Insert the Signal Generator TDM plug-in on
the track.
8 Set Signal Generator’s output level. This
should be the same value you entered as the Cal-
ibration Reference Level.
9 Set Signal Generator’s frequency to 1000 Hz.
10 Set Signal Generator’s signal waveform to
Sine.
11 Route the track’s output to Bus 1.
12 Create a mono Auxiliary Input track for each
888/24 I/O output you want to calibrate. Set the
output assignment for each of these Auxiliary
Inputs to its respective 888/24 I/O output.
13 Set the input of each Auxiliary Input track to
Bus 1.
Turn down your monitoring system before
beginning calibration! The Signal Genera-
tor plug-in emits a continuous signal when
inserted on a track.
TDM_Install.book Page 54 Saturday, January 13, 2001 9:35 PM